Methanol, % by weight

0.09

0.08

0.07]

°
°
DR

0.03)

Acetic Acid Activated Carbon Column
Feed Rate = 1 gpm (3.78 liters/minute)

\
Wary

0.02
oe. oO. ©. 6 Feed
x——x———-x. x Effluent
0.01
obrencX L 1 1 1 1 i 1 n L i 1 1 1
te) 1 2 3 4 5 6 T 8 9 10 n 12 13 any
Hours Column Used
Figure 18. Methanol concentration — acetic acid activated carbon

column feed and effluent
51


Methancl
from

Colum of
Separation

Water

Methanol,

Vaporizer

Ast Activated Carbon Colum
Receiver

Condenser

Feed
Tank

Gage
ad

LEGEND

Pressure Recorded

‘Temperature
Dt vaive

Q Rotameter |{ Manometer

Scale: none

Pump

?

TT

Fractionation Colum

SL

Steam

Q
(

b—-

Figure 49.

Activated carbon regeneration and furfural recovery


CH3COOH Loading = 2.78 1b/28.4 1b carbon
0.098 1b/1b carbon

0.098 g/g carbon

Furfural Loading — First Column

CyH30CHO = 12.6 gph (10.1 hours) (8.33 1b/gal) (0.00048)
0.508 lb 0.23 kg

CyH30CHO Loading = 0.508/7.08 = 0.0718 1b/1b carbon

0.0718 g/g carbon

Therefore, it was. necessary to remove methanol by steam stripping and/or
fractionation. Using various combinations of steam stripping and

fractionation column operations, the following products were recovered: ©

85% + by weight SO2 vapor
90% + by weight methanol
90% + by weight furfural

These results provided two possibilities for furfural removal and
potential recovery, fractionation and/or adsorption by activated carbon.

Using these data, a pilot plant was built at Scott's Everett Mill using
new, existing and scrap equipment to study recovery of volatile chemi-
cals from the Everett mill hot water accumulator overflow (blow gas
condensates). Essentially, it consisted of 4 inch (10.2 om D) diam-
eter glass piping with steel plates and reflux splitters, and two 10
inch (25.4 cm) diameter stainless steel adsorbers (also used as re-
actors during regeneration) complete with column packings, heat ex-
changers, and pumps. This equipment presented the opportunity to in-
expensively experiment with various combinations of steam stripping,
fractionating and/or adsorbing operations. Scott Paper Company used
this pilot plant equipment in their Everett, Washington mill to study
chemical recovery from clean evaporator and blow gas condensates. The
equipment had been installed and operated as shown on Fig. 1. All the
above mentioned chemicals, as well as 90%+ by weight ethyl acetate,
were recovered. Patents covering the processes, as well as their

17


the D electrode. The current was again turned on for an additional 10
minutes, and then shut off and a second foot (30.5 com) of air-dried
carbon added to the column. Power connections were rearranged so that
the cathode from both rectifiers was in the D position, with the anode
for Rectifier No. 1 being in the C position and for Rectifier No. 2 in
the E position. The current was activated for about 10 minutes at about
50 volts and 23 amps, after which surface temperatures were again taken.
The temperatures again were highest around the area of the D electrode

as indicated in Table 20. The carbon was then removed from the column.

The column was refilled with Filtrasorb 400 virgin carbon. It was
placed in the column in an "as received" condition without previous
wetting of the carbon or flooding of the column. Power connections
were made so that the A, C, and E positions were anodes and the B
position was the cathode for Rectifier No. 1 and the D position was the
cathode for Rectifier No, 2. By placing an anode in the A position, it
became possible to observe this electrode by removing several inches of
carbon. The heating data obtained under these conditions is given in
Table 21. Power was on both units for a period of about 35 minutes;
voltages of both 50 and 25 were applied with the resistances ranging
from 0.18 to 0.25 ohms per foot (0.59-0.82 ohm/m) of carbon in the top
2 feet (61.0 cm) of the column and 0.31 to 0.38 ohms per foot (1.02-
1.25 ohm/m) in the bottom 2 feet (61.0 cm). The temperature at No. 1
thermocouple increased from 33 to 193°C (91 to 379°F) during this
period, while at No. 4 thermocouple there was no increase. The surface
temperatures were again taken and reflected the same heating pattern at
the top of the column with very little heating at the bottom. No real
hot spots, however, developed. After operating Rectifier No. 2 for 10
minutes, the power connections were changed so that only the bottom
foot (30.5 cm) of carbon was being heated. This did result in an in-
crease in temperature at the No. 4 position from 60°C to 210°C (10°F
to 410°F). Surface temperatures were fairly even except for a possible
hot spot on the left side of the colwmn at the D electrode.

146


Baierls' system, so that basically most of the S02
>
fural had been removed.

methanol, and fur-

DATA AND DISCUSSION

To simplify the explanation of the data and operation of the column, the
procedures will be given in chronological order. Figure 52 is a diagram
which labels all of the outlets through the side of the column. All
changes made in the electrode hookup and in the location of the thermo-
couples as the work progressed will be identified by the letters and
figures in this sketch. The letters A, B, C, D, and E were the normal
outlets for the connectors to the electrodes, while the 1, 2, 3, 4

positions were the original locations of the thermocouples.

The data to be presented will represent only the significant operation-
al changes. Table 19 contains the operating conditions and the temp-
eratures obtained during the operation from January 4 through January 9,
1973. During this time the mit was operated as originally proposed by
Lowell Technological Institute and as indicated in Fig. 51; that is,
the common cathodes were A, C, and E, while the B anode was connected
to Rectifier No. 1 and the D anode to Rectifier No. 2. Prior to acti-
vating Rectifier No. 1, the carbon was wet with tap water and drained.
Initially, the voltage was set at 75, which produced 55 amps, for a
resistance of 0.68 ohms per foot (2.23 ohm/m) of carbon. Within 15
minutes the resistance had increased to 0.89 ohms per foot (2.92 ohm/m)
of carbon. After an additional 10 minutes the resistance had increased
to 2.02 ohms per foot (6.63 ohm/m), and finally after a total of 35
minutes of operation the resistance was at 28.55 ohms. However, the
temperature had risen to 95°C (203°F) after 15 minutes, which is prob-
ably at the boiling point of water, since it was later found that the
thermocouples were reading low. The second rectifier, which was to heat
the bottom 2 foot (61.0 cm) of carbon, was activated 15 minutes after

Rectifier No. 1 and approximately poiling temperatures were reached in

10 minutes.

a4


RESEARCH REPORTING SERIES

Research reports of the Office of Research and
Monitoring, Environmental Protection Agency, have
been grouped into five series. These five broad
categories were established to facilitate further
development and application of environmental
technology. Elimination of traditional grouping
was consciously planned to foster technology
transfer and a maximum interface in related
fields. The five series are:

1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research

4. Environmental Monitoring

5. Socioeconomic Environmental Studies

This report has been assigned to the ENVIRONMENTAL

PROTECTION TECHNOLOGY series. This series
describes research performed to develop and
demonstrate instrumentation, equipment and

methodology to repair or prevent environmental
degradation from point and non-point sources of
pollution. This work provides the new or improved
technology required for the control and treatment
of pollution sources to meet environmental quality
standards.


TIt

HF, 1b 56.0
far 36.3 (TF, 1b -
LEGEND i) r 1
-b (Hg0 483,
TF, 1p total. Flow, (MecooH 3.51) ret
EtOH ethanol (Poly Matis. toey
H0 water 0.0600) 124
MeCOOH acetic seid [cF, 1b 184
Matls. materials 2.57] ! ‘
io) to be retained {MeCOoH Lied
() originally
retained

Qnd Activated Carbon Column

Receiver

EtOH 56.0

Scale: none HEO0 5 Bt Hg0 3.66; MeCOOH
Basis: 56.0; MeCOOH 0.978; Poly Matis.
Recovery of ethyl acetate: 12 hr 0.978; Poly 0.0136
Recovery of ethanol: 4 hr Matis. 0.0200

Activated carbon regeneration and ethyl acetate recovery.

Figure 46.
1. Draining of colum

moma eer wm em ew ew ee eee

5

Fractionation Column and Condenser

wer rm eee ee ee eee el

u

rer
fReboilen
ae |


Sulfur Dioxide,
Organic Loosely Combined, g/liter

0.8

Steam Stripping, Furfural Activated Carbon and

Feed Rate = 1 gpm (3.78 liters /minute)
Stripping Steam = 6% by Weight of Feed

Steam Stripping Column
Feed

Steam Stripping Column
Bottoms

Furfural Activated Car-
bon Column Effluent

Acetic Acid Activated
Carbon Column Effluent

Nov. 6, 1972

L i i 1

R—

° 1 2 3

Hours Column Used

Acetic Acid Activated Carbon Columns
OTe
0.6
O.5F
_
——
—
Ob
z
0.3
x
0.2b xa
oO.
Oct. 23, 1972
0 L 1 l a]
0 2 2 3 4 5
Figure 26.

=
wa
aL

steam stripping and activated carbon column flow
using regenerated carbon

60

=)
7

Organic loosely combined sulfur dioxide concentrations —


The carbon was rewet several times more and following each wetting good
amperage was obtained for a short period, after which there would be a
sudden increase in resistance. Following the third rewetting, however,
at 2:15 p.m. the resistance of No. 1 rectifier was at 4.75 ohms and on
No. 2 rectifier at 2.88 ohms and the resistance remained high during
the trials of January 5, 1973 and January 8, 1973. On January 9, since
the resistance continued to be high, it was decided to remove the carbon

for inspection of the unit.

This inspection showed that the electrodes which had been in the posi-
tive position were completely covered with a scale or coked carbon
material, and that the teflon coating on the interior of the column was
blistered extensively. This even extended to the bottom plate. Analysis
of the corrosion, which was scraped from the anode electrodes, revealed
that on a dried basis, it contained 80.4% ash, 7.8% iron, 9.3% chro-
mium and 1.8% calcium. Thus, it became apparent that the electrodes
were literally being disintegrated by electrolysis. It was realized
that electrolytic action would result in disintegration when in contact
with liquid media, but it was not certain that this would happen in a
vapor atmosphere.

The electrodes were cleaned by sand blasting and reinstalled in the
column. Initially, one foot (30.5 cm) of carbon was packed into the
column and two electrodes connected to Rectifier No. 2; the anode being
in the E position and the cathode in the D position. The carbon used
was the same that had been removed previously from the column and which
had been air dried. Table 20 contains the data obtained. Initially,
the resistance was 1.5 ohms per foot (4.92 ohm/m) of carbon but this
increased to 13.5 in 15 minutes. During this time a stream of air was
fed through the column. Surface temperatures were then determined
using a surface pyrometer. The temperatures were very consistent
around the periphery of the column. Current was applied for an addi-
tional hour, with continued low amperage, after which surface temper-

atures were again taken. Temperatures were highest in the vicinity of

hy


evaporator condensates. The condensate feed was less than ideal for
their purpose. Since they have several evaporator systems, a composite
of their condensates was processed after these flows had been used for
evaporator wash. The feed is dilute and contains lignosulfonates and

other spent liquor solids. The chemical concentrations expressed as %
by weight varied as follows:

High Low Mean
Methanol 0.170 0.025 - 0.065
Acetic Acid 0.364 0.170 0.268
Furfural 0.040 0.010 0.016
Sulfur Dioxide-TI 0.233 0.017 0.064
Sulfur Dioxide-OLC :0.076 0.015 0.034
Biochemical Oxygen Demand 6540 2270 4063 milligrams

per liter

The methanol, furfural, and acetic acid balances, Tables 5, 6, 7, and

8, were made using the instantaneous values, graphically integrating

to determine recoverable quantities. The main function of these
balances was to determine operating and analytical proficiency. The
evaporator studies had already indicated that splitting the evaporators
and/or their condensates was the path to pursue for Consolidated Papers,
Inc.'s Appleton Mill. No other mill showed any enthusiasm for this
approach.

Since the establishment of a market for the crude products was essential
to the economic evaluation of the process, the following information was
presented. Assuming 300,000 gallons (1,134,000 liters) per day evap-
orator condensate capacity for the Consolidated Mill and using the mean
concentrations list in the "Previous Work" section and 350 days oper-
ation per year, Consolidated Papers, Inc. produced the following:

Methanol 569,000 1b/year 258,500 kg/year
Acetic acid 2,345,000 lb/year 1,063,000 kg/year
Furfural 140,000 1b/year 63,600 kg/year

71


Formic Acid

The: formic acid was determined from the residual remaining after the
titration for the volatile organic acids. It was determined by removal
of the ether by evaporation followed by acidification and reduction of
mercuric chloride to mercurous chloride. The mercurous chloride is
separated by filtration and determined by the addition of an excess of
standard iodine followed by a back-titration with standard thiosulfate.

Acetic Acid

The acetic acid was determined by difference between total volatile

organic acid and the formic acid.

Gas Chromatography . ,

Methanol, furfural, and acetic acid were determined by gas chromatog-
raphy using an Aerograph 1520 instrument. Separation was on a PORA
PAC Q column. Butanol was used as an internal standard with a flame

detector.
Calcium-and Sodium

Both calcium and Sodium were determined on a Beckman Flame Spectro-

photometer reading at the appropriate wavelengths.
ASSAYS

Data covering the assays on the various samples received from the
cooperators are given in Tables 1, 2, and 3. Origin of the samples is
given only.under a mill code letter. However, in order to compare with
data being obtained in the operation of the process at the Consolidated
mill, the composite data from that mill are identified as Sample No. 21,
or Mill G. The data under Sample No. 21 are either averages of eight
samples or assays performed on a composite of those eight samples.
These samples were taken at periods during normal operation, which

included channel switching of the Rosenblad evaporator.


A. Around the activated carbon column:
a. In:
Methanol 640 1b (290.56 ky
640 1b (290.56 kg
b. Removed from column:
Furfural . 4.00 1b (1.816 kg)
Polymerized materials 4.00 1b (1.816 kg)
Water 92.0 1b (41.768 kg)
100 Tb (45.400 kg
c. Retained:
Methanol vapor = 0.639 1b (0.290 kg)
calculated as follows:
volume of column = 60 gal. (227.1 1)
number of moles MeOH vapor in the colum = n
compressibility factor = 1
Sones be = 0.01995 no. moles
.". methanol vapor = 0.639 1b (0.290 kg)
d. Out:
Furfural 4.00 1b (1.816 kg)
Methanol 639 1b (290.106 kg)
Polymerized materials 4.00 Ib (1.816 kg)
Water 92.0 1b (41.768 kg)
739 Lb (335.506 kg)

B. Around the fractionation column:

1.

640 + 100 = 0.639 + 739

In:

Furfural

Methanol

Polymerized materials
Water

120

4.00 lb (1.816 kg)
639 1b (290.106 kg)

4.00 lb (1.816 kg)

2.0 1b (41.768 ke)
139 1b (335.506 kg)


Methanol 15.3 1b (6.9 kg)
Sulfur dioxide 17.0 1b (7.7-kg)
Acetic acid 5.60 lb (2.5 ke)
Unaccounted HAc 11.4 1b (5.2 kg)
Hp [2920 (1) + 3.10 (0.428) + 15.3 (0.566) + 17.0 (0.5) +
5.60 (0.487) + 11.4 (0.5)] (166-149) = 50,100 Btu (12625
kg-cal). :
4, Heat out with methanol, Hs = 0
5. Heat out with furfural stream:
Hy, = [3.10 (0.428) + 0.200 (1)] (213-149) = 96.0 Btu
(24.2 kg-cal).
6. Heat out with the bottom stream:
Hs = [5920 (1) + 3.30 (0.5) + 5.60 (0.487) + 11.4 (0.5)]
(210-149) = 36,200 Btu (9122.4 kg-cal).
7. Heat out with sulfur dioxide stream, He = 0.
8. Neglect the heat of solution and heat of dilution.
9. Heat loss of the column, H7.
3,100,000 + 50,100 = 96 + 36,200 + Hy.
Heat loss = 3,110,000 Btu (783720 kg-cal).
Cooler before the first carbon column. The stripping column
bottom is 50,000 1b (22700 kg) containing:

Purfural 4.00. 1b (1.82 kg)
Methanol 16.0 1b (7.26 kg)
Sulfur dioxide 8.00 1b (3.63 kg)
Acetic acid 117 1b (53.12 kg)
Water - 49900 1b (22654.6 kg).

To cool this stream from 212°F (100°C) to 140°F (60°C), the
heat required = [4.00 (0.418) + 16.0 (0.566) + 8.00 (0.5) +

117 (0.487) + 49900 (1)] (212-140) = 3,600,000 Btu (907200 ke-
cal).

Condenser after fractionation column.

The S02 gas stream comes in at 149°F (65°C) and leaves at 97°F
(36.1°C).

126


Activated Carbon Columns-Regeneration

The activated carbon was regenerated as shown in Fig. 3 and 4. That
adsorbing primarily acetic acid was regenerated vaporizing ethanol,
while that adsorbing furfural was regenerated vaporizing methanol. The
Furfural Balance, Table 7 was discussed. The Acetic Acid Balance,
Table 8, shows 6.65 lb (3.02 kg) of acetic acid adsorbed in 3 trial
runs. This is the equivalent of 9.75 lb (4.42 kg) of ethyl acetate.
Since no analytical program was prepared to analyze the wide range of
ethyl acetate samples recovered in each run, they were batch distilled,
and the overhead samples analyzed for ethyl and methyl acetate concen-
tration. The results were used to calculate the total ethyl acetate
recovered. The equivalent of 9.13 1b (4.14 kg) of ethyl acetate, or
93.7% of that retained on the carbon was recovered. Ethyl acetate
purity of 89% by weight was accomplished. The remaining 11% was water

and ethanol, indicating pure ethyl acetate was possible.

It took approximately 16 and 24 hours operating time to regenerate the
carbon adsorbing acetic acid and furfural, respectively. While this
presented no problem for that retaining the furfural, it must be reduc-
.ed for that retaining acetic acid. The limiting factor for regenerat-
ing the activated carbon retaining acetic acid is the heat exchanger
vaporizing the ethanol. This unit was too small. An optimum vapor
rate through the carbon has not been established. The 16-hour period
was used to assure maximum conversion of acetic acid to ethyl acetate,
maximum ethyl acetate recovery, and maximum ethanol recovery. Since no
gas chromatograph was available for pilot plant use, no effort was made

to optimize regeneration time.

While efforts were expended to maximize S02, methanol, furfural, and
acetic acid recovery, as much polymerized material was recovered when
regenerating the activated carbon holding furfural as furfural. Poly-
merized material was also recovered from regenerating the activated
carbon containing acetic acid. No efforts were made to determine the

quantity. Whereas most of that coming from the furfural carbon was not

66


(98.3 to 99.4°C). The stripping column is 4 inch (10.2 cm) diameter
and contains a 4 ft (121.9 cm) height of packing. The packing used was
Goodloe 316 $.S. mesh. The evaporator condensate was fed into the top
of the column and steam was fed into the bottom, The steam,rate was
controlled by pumping water into the reboiler and super-heating it in-
directly with steam. In that way all the water was converted to steam,
The vapor left the top and flowed down through the condenser. The con-
densed vapor was collected in the 4 inch (10.2 cm) diameter glass re-
ceiver. By controlling the temperature of the vapor leaving the  re-
ceiver at 205 (96.1) to 190°F (87.8°C), the S02 concentration in the
exhaust vapor was controlled. The steam stripped evaporator ‘condensate
was pumped from the bottom of the column to the first activated carbon
column. The feed rate capability was 1.5 gpm maximum (5.7 liters per
minute). Plans were made to evaluate the steam stripping column system
while varying the feed rates from 0.5 to 1.5 gpm (1.9 to 5.7 liters per
minute) and using 2 to 12% by weight of feed stripping steam.

Fractionation

The fractionation system consisted of a fractionation column, a re-
boiler and a condenser. The fractionation column had four packed
sections of 4 inch (10.2 cm) diameter x 4 ft (121.9 om) high glass
piping between the feed and bottom of the column [16 ft (487.7 cm) of
packing total], one packed section of 4 inch (10.2 cm) diameter x 4
inch (121.9 cm) high glass piping between the feed and the first reflux
splitter [4 ft (121.9 om) of packing] and one packed section of 4 inch
(10.2 cm) diameter x 2 ft (61.0 cm) high glass piping between the first
splitter and top splitter (2 ft (61.0 cm) of packing]. Ail packing were
Goodloe §.S. mesh. The condenser was directly above the top reflux
splitter. The reboiler was operated the same as that on the steam

stripping column to ensure complete vaporization.

Initially, condensed overheads from the steam stripping columns were
fed into this system. Sulfur dioxide as a vapor was vented through the

top of the condenser, a methanol crude was withdrawn from the top

2h


Acetic Acid, % by weight

O——— @———8 “Steam Stripping Column Feed
x XX Steam Stripping Column Bottoms
o———o-———-© Furfural Activated Carbon Column Effluent

o——-0———0 Acetic Acid Activated Carbon Column

0.6 Effluent
April 10, 1973. April 23, 1973
x
0.5
°
x
e
0.4
' x
0.3
0.2
Ethanol in All Semples
0.1
ol__¢-e-4-¢-¢-eL__ Ls 1
o i 2 3 & 5 o 2 2 3 4 5

Hours Column Used

Figure 38. Steam stripping, furfural activated carbon
and acetic acid activated carbon columns

95


109-

° Ft °
9q-
— °
8q I
®
74.
x Scott Paper Company
Everett Mill Blow Gas Condensate
e 6-Inch (15.24 cm) Goodloe Packing
6. +  12-Inch (30.48 cm) Goodloe Packing
a x 18-Inch (45.72 cm) Goodloe Packing
3 @ 24-Inch (60.96 cm) Goodloe Packing
© 30-Inch (76.20 cm) Goodloe Packing
+
3 sd
x
é
a
a
Baud.
30-
2q-
1q-
n n {ot a ! 1 m n 4
to) 1 2 3 4 5 6 1 8 9 lo Mm 122

Stripping Steam, % weight of feed

Figure 8. Sulfur dioxide removal vs. stripping steam
used — Scott Paper Company — variable packing

31


more minutes of operation, the temperature at the No. 3 thermocouple
suddenly increased to 260+°C (500+°F): and the power turned off for ten
minutes. At 12:55 p.m. the electrical resistance was 0.30 ohm per foot
(0.98 ohm/m) but increased to 1.62 ohms within 15 minutes. After 1:20
p.m. the unit was shut down and the carbon removed so that the three
unused electrodes could be taken out of the system.

The A and E electrodes were cleaned with steelwool prior to reinstalling
in the column. The cleaning may not have been necessary as there was no
evidence of the previous extensive corrosion which resulted when using
the direct current: The column was then filled with water and the car-
bon slowly added and allowed to settle without any physical packing,
excess water being drained from the bottom. The data for this operation
will be found in Table 25. The unit was operated for 1 hour and 10
minutes with the top flange removed, and during this time the tempera-
ture at the No. 1 thermocouple increased from 32 to 100°C (90 to 212°F),
at the No. 2 thermocouple from 32 to 84°C (90 to 183°F), at the No. 3
thermocouple from 34 to 50°C (93 to 122°F) and at the No. 4 thermocouple
from 29 to 94°C (94 to 201°F). The resistance was around 1.25 ohms per
foot (4.10 ohms/m) of carbon. From 1:10 p.m. until 3:05 p.m. operation
was with the top flange in place, and the electrical resistance varied
between 1.70 and 4.30 ohms per foot (5.58-14.11 ohms/m) of carbon. It
was suspected thet the increase in electrical resistance was caused by
loose packing of the carbon, so the side of the column was tapped with
a mallet and immediately the amperage decreased to zero. Upon removal
of the top flange it was found that the carbon had settled below the
top electrode. Carbon was added and operation was started without the
top flange and with an electrical resistance of 0.62 ohm per foot (2.03
ohms/m) of carbon. All temperatures were at 100°C (212°F) and the
vapors were being removed from the top of the column directly to the

atmosphere.

The following day on February 8, column operation was continued and
the entire day was spent in repeatedly tapping the column and adding

carbon as necessary as the carbon packed following continued drying.

156


had been adsorbed on the previous column. For the next five hours
acetic acid was being absorbed, and in the final 5 hours it was being

pushed out of the carbon at a faster rate than it was being adsorbed.

The next three graphs, Fig. 16 to 18, show the methanol concentrations
and are similar to the first four on acetic acid. About 50% of the
methanol in the feed was expected to be removed by steam stripping.
Figure 16 shows this was not always achieved. Since this was the first
run with the activated carbon columns, too much effort was placed on
their operation, and the steam stripping was not as efficient as it
should have been. Figure 17 shows that methanol goes through activated
carbon quickly with little adsorption. It also absorbs and readsorbs
depending on feed concentrations. Figure 18 is similar to Fig. 17,

put deals with the second carbon column.

Figures 19 to 22 are composite graphs covering the BOD and sulfur
dioxide analyses of the samples, as well as their pH. Figure 19 shows
the BOD reduction over the 14-hour operating period. The 700 mg/liter
range indicates the BOD of the residual methanol. The 3000 mg/liter
range is indicated for the acetic acid and residual methanol, the 3500
to 4800 range includes acetic acid, residual methanol, residual fur-
fural, and some polymerized material, and the 4000 to 5700 range con-
tains all the acetic acid, methanol, furfural, and other materials.
Any commercial acetic acid activated carbon adsorption unit that will
be, or has been recommended, would be designed on the basis of 2 1/2 to
3 hours data.

Figures 23 through 28 represent data obtained during repeats of the 14-
hour run, except the activated carbon column in which the acetic acid
was adsorbed had its carbon regenerated using ethanol. Since furfural
had not broken through the activated carbon in the first column, its
use was continued. Figure 23 shows the acetic acid breaking ‘through
the column at about 3 hours operating time, not appreciably different

from that of the virgin carbon indicating very good regeneration

56


—=f-----4
Sel-Rex
Unit 1
—f------
- +
SS 37-74
Sel-Rex

Unit 2

a

[}——Tc No.4

th

Water Out

a

|_ Sondenser

[JWater In

Input During Adsorption
Outlet During Regeneration

an

Drain

.

>

Open During Adsorption
Closed During Regeneration

Figure 51.

ho

Discharge During
. Adsorption

Activated carbon thermal regeneration column


condensed and collected in a receiver. From the receiver the conden-
sate was fed into a fractionation colum. Ethyl acetate was collected
overhead, and ethanol was recycled from a point about one third of the
height from the bottom of the column back through the carbon column.
Water recycled back through the activated carbon system and was removed
from the bottom of the column. The reboiler was used to control the top
reflux and the vaporization ‘of ethyl acetate.

EXPERIMENTAL OPERATION AND EVALUATION OF PILOT PLANT

Steam Stripping

At the September, 1972 meeting of the project sponsors, plans to evalu-
ate the steam stripping column system varying feed rates from 0.5 to
1.5 gpm (1.9 to 5.7 liters per minute) and using 2 to 12% by weight of
feed stripping steam were reported. The height of the column packing
was to be varied under similar operating conditions. This work was
completed with the equipment set up as shown in Fig. 2. The trouble

points when operating this system were:

1. Controlling the temperature of the evaporator condensate feed
entering the column at its bubble point.

2, Maintaining a constant pressure drop across the column packing.

3. Controlling the condenser so as to maintain a constant temp-
erature for the condensed steam stripping column overhead
vapors.

4, Maintaining a constant back pressure from the SO) venting

system.

All of these were related to the concentration of the volatile chemi-

cals in the evaporator condensate feed.

To compare Consolidated Papers, Inc.'s Appleton Div. Mill evaporator
condensate steam stripping data with that of Scott Paper Company's
Everett Mill blow gas condensate steam stripping data, refer to Fig. 5

to 12. For a fair comparison keep these points in mind. At Everett

27


Sulfur Dioxide,

Total Inorganic, g/liter

2.0

1.8

1.6

Ld

1.0

0.6

o.4

Steam Stripping, Furfural Activated Carbon and
Acetic Acid Activated Carbon Columns
Feed Rate = 1 gpm (3.78 liters/minute)
Stripping Steam = 6% by Weight of Feed
Steam Stripping Column
Feed ° ° °
Steam Stripping Column
Bottoms XX
Furfural Activated Car-
————9
bon Column Effluent
Acetic Acid Activated
Carbon Column Effluent ©——®—-®
L
_—e*.
L
—*—,
= a
e
NZ
e
Oct. 23, 1972 Nov. 6, 1972
oo,
a —=y—— a es
o 1 2 30 & 5 o 1 2 3 4

Figure 25.

Hours Column Used

Total inorganic sulfur dioxide concentrations — steam
stripping and activated carbon column flow
using regenerated carbon

59


The next steam stripping and carbon adsorption run was made April 23,
1973. The evaporator condensate was fed at the rate of 1 gpm (3.79
l/min.) into the steam stripping column. Once again samples of the
acetic acid activated carbon column effluent were taken at the end of
the first hour and every half hour thereafter for 4 hours total. No
acetic acid was detected in the samples after 3 hours, a trace amount
in the 3-1/2-hour sample and only 30% by weight of that in the feed in
the 4-hour sample. See Fig. 38. These results indicate that the new
regeneration method does an efficient job regenerating the carbon.
There was still no evidence that the acetic acid was being effectively
removed as ethyl acetate. Since all effluent samples showed ethanol,
it was obvious the regeneration purge of ethanol was stopped premature-
ly. The previous run had shown an excellent purge of ethanol, so this

is no problem.

Another regeneration attempt to verify the production of ethyl acetate
was made on April 24, 1973. This time the odor of ethyl acetate was
strongly detected. A check for leakage was to no avail. Finally, the
pipe from the steam trap taking care of condensed steam from the acti-
vated carbon vaporizer and jacket was disconnected from the drain. The
ethanol and ethyl acetate coming from the pipe was of high concen-
tration, indicating a leak in the reboiler or the jacket. The two
systems were separated and the leak was pin-pointed as being in the
jacket. Analyses of the water discharging from the carbon column and
finally leaving the bottom of the fractionation column showed 0.03% by
weight acetic acid, indicating little loss as acetic acid. ‘The run was
continued April 25, 1973 to verify the removal of acetic acid as ethyl
acetate. Approximately 2 quarts (1.9 liters) of 50%+ by weight ethyl
acetate were collected. Once the analyses showed sufficient ethyl
acetate was made, the regeneration was stopped, as the regeneration
method was shown effective and there was no need to risk further column
damage. The activated carbon was removed from the column. Inspection
showed that the inner shell of the column was pushed in opposite the

steam inlet to the jacket. A hole was under the convexed section about

96


(178°F), by 11:05 a.m. all temperatures were at the boiling point of
water and the resistance remained fairly low at 0.55 ohm. At this point
in time, however, what appeared to be a hydrogen sulfide odor was notice-
able, but its source could not be traced. At about 11:45 a.m. the
resistance had increased to 0.94 and a small jet of steam was suddenly

released from the side of the column.

The carbon was removed for inspection of the column and it became evi-
dent that localized heating had volatilized a small portion of the tef-
lon coating, which then resulted in a short circuit or arcing directly
to the shell of the column, with a subsequent breakthrough. Evidently
because of the previous disruption of the packed column, which had re-
sulted in uneven packing, the water had channeled through the column,
and one side was not wetted. Thus, this portion of the dry carbon im-
mediately became very hot, with the beforementioned results.

The column was repaired, charged with 4 feet (1.2192 m) of new Filtra-
sorb 400 carbon by adding the carbon to a flooded column and then drain-
ing. Power connections were made between the B and E position so that
the top foot (30.5 cm) of carbon would not be heated directly by the
electric current. The thermocouples were placed so that No. 1 was in
the No. 1 position 2 inches (5.08 om) into the column, No. 2 in the C!
position 6 inches (15.24 cm) into the column, No. 3 in the No. 3 posi-
tion 2 inches (5.08 em) into the column, and No. 4 in the D' position

2 inches (5.08 em) into the column. A vibrator was also installed on
the outside of the shell of the column to facilitate packing. The data
obtained when operating under these conditions are shown in Table 26.
Operation during February 16 and 19 then resulted in gradual drying and
packing of the carbon. By 3:10 p.m. on the 19th the carbon was com-
pletely dry, except for about one inch (2.54 om) around the periphery of

the column.

On February 20 the column was again wet, with power connections to the

B and E positions and the thermocouples placed the same as for February
16. By 2:15 p.m. 23.5 liters (6.21 gal.) of water had been distilled

159


A.

Unaccounted acetic acid 0.114 1b (0.05 kg)

Water

b. Steam

29.7 Lb (13.48 kg

30.0 lb (13.62 kg)

Total in = 59.7 1b (27.10 kg)

Out

a. S802 stream
S02
Methanol

b. Methanol streem
Methanol
Sulfur dioxide

ec. Furfural stream
Furfural
Water

d. Bottom
Acetic acid
Sulfur dioxide
Unaccounted HAc
Water

0.135 1b (0.061 kg)

0.003 2b (0.001 k
0.138 lb (0.063 kg

0.150 1b (0.068)
0.002 1b (0.001
0.152 lb (0.069

0.0310 1b (0.014)

0.0020 1b (0,001
0.0330 lb (0.015

0.0560 1b (0.025)
0.0330 1b (0.015)
0.124 1b (0.052)

12 lb (26.8
59. 1b (26.968)

Total out = 0.138 + 0.152 + 0.0330 + 59.4
= 59.7 lb (27.104 kg)
5. First activated carbon column:

In:

Acetic acid
Methanol
Furfural
Sulfur dioxide

Water

1.17 1b (0.532 kg)
0.160 1b (0.073 kg)
0.0400 1b (0.018 kg)
0.0800 1b (0.036 kg)

499 1b (226.546 kg)
500 Te (227.000 kg)

118


Figures 9 and 10 show the percentage of methanol removal from the Con-
solidated Mill evaporator condensate. The points were very widely scat-
tered, and the lines were discretely drawn. On Fig. 9 the two zero
points were neglected as being bad data. The line was drawn keeping as
many points on or near it as possible and an equal number on either
side. Note that neither line on Fig. 9 and 10 goes through zero. This
indicated the bubble point of our feed was probably exceeded ard it
partially vaporized in the preheater. Figures 11 and 12 show the per-
centage SOj. removal of both TI and OLC. The SO2-TI removal was similar
to that: shown for Scott in Fig. 8. The analyses were done in The
Institute of Paper Chemistry laboratory hours or days after the samples
were taken. An important fact shown in Fig. 11 and 12 was that no more
than 75% of the SQ2-OLC was removed. Similar work on Scott's blow gas
condensate showed 90+% SO2-OLC consistently being removed. The dif-
ference was attributed to the SO2-OLC in Consolidated Mill's evaporator
condensate as the result of residual spent sulfite liquor removed from
the evaporator by the condensate in the washing cycle. This S02-OLC

was much more firmly combined.

This concluded the steam stripping experimental portion of this pro-
ject. These data can assist any pulp and paper company interested in
steam stripping sulfite mill evaporator condensate with their design,
construction, and operation of a steam stripping system. The pilot
plant also was in a position, with Consolidated Papers, Inc.'s approval,
to test individual mill's evaporator condensates under predetermined

operating conditions.
Fractionation

During the steam stripping runs the condensed overheads from the steam
stripping column were fed into the fractionation column. Methanol and
furfural crudes were recovered. Balances based on gas chromatographic
analyses of the steam stripping column's feeds and condensed overheads
are given in Tables 5 and 6. From the methanol balance, Table 5

methanol analyses showed 4.196 1b (1.90 kg) to be in the condensed

37


Table 10,

ANALYSES OF EVAPORATOR EFFECTS OF COOPERATOR MILL

Solids Volatile acids Calculated volatile
content. on solids acids in condensate
we. as acetic acid, wt. % as acetic acid, wt. %
Feed 13.2 10.6 1.54
From 5th 17.66 9.2 1.83
4th 21.88 1.2 0.945
3rd 31.24 5.9 2.19
ena 55651 2.6 _
Table 11. CARBON ADSORPTION WORK AT SCOTT PAPER COMPANY
OCONTO FALLS EVAPORATOR CONDENSATE
As received ‘Steam stripped
Methanol 0.119% by weight 0.049% by weight
Acetic acid 0.600% by weight 0.530% by weight
Furfural 0.122% by weight 0.048% by weight
Steam stripping column — 4~inches deep x 16 feet high
using 10% by weight of feed stripping steam.
Table 12. CARBON ADSORPTION WORK AT CONSOLIDATED PAPERS, INC.
APPLETON DIV. EVAPORATOR CONDENSATE
As received April 23, 1973 — 11:30 AM
As received Steam stripped
Methanol 0.065% by weight 0.06% by weight 0.01% by weight
Acetic acid 0.268% by weight 0.21% by weight 0.22% by weight
Furfural 0.016% by weight 0.01% by weight 0.00% by weight

Steam stripping colum — feet deep x 4 feet high using 6% by weight feed
stripping steam.

19


ACKNOWLEDGMENTS

Sponsors of this project, in addition to Environmental Protection Agency

and The Institute of Paper Chemistry, the prime contractor, were:

Authorized

Organization Representative
Wisconsin Department of Natural Resources Everett D. Cann
American Can Company Richard F. Benning
Consolidated Papers, Inc. S. H. Dorcheus
Finch, Priyn & Company, Inc. John Shema
Flambeau Paper Company Walter A, Sherman
Great Northern Paper Company Vv. F. Mattson
ITT Rayonier Inc. J. J. Leithem
Masonite Corporation H. A. Spalt
Publishers Paper Company Zenon Rozycki
Scott Paper Company Lyle J. Gordon
Wausa.. Paper Mills Company Richard L. Post

The Project Director was A. J. Wiley, with direct supervision and
engineering of the pilot plant operation under K. W. Baierl, assisted
by John E. Baumann, pilot plant operator. The low-temperature carbon
regeneration investigation was under the supervision of B. F. Lueck.
Those responsible for and assisting in the laboratory phases were
George A. Dubey, Arthur A. Webb, Gerald W. Hovind, Mrs. Linda Benkers,
and Miss Gay Thurner. Engineering balance calculations were made by
Nai L. Chang. With the exception of Mr. Chang, all are members of the
IPC Effluent Processes Group, which is a section of the Division of

Industrial and Environmental Systems headed by Robert A. Holm.

The support of the personnel of the Appleton Division of Consolidated
Papers, Inc., especially W. R. Durdell, Plant Manager, and Dennis G.
Wilch, who acted as liaison between the mill and IPC where the pilot

plant was located, is acknowledged with sincere thanks.


ABSTRACT

A pilot plant study of a process to recover the volatile constituents
of the condensate derived from the evaporation of a sulfite spent wood
pulping liquor has been made. The data from this one-year evaluation
confirm prior work demonstrating that recovery of sulfur dioxide, fur-
fural, methanol, and acetic acid (in the form of ethyl acetate) will
yield reusable and salable materials, and provide either 60 or 90% BODs
reduction on the condensate depending on whether the condensate is

contaminated by using it as wash liquor.

The work reported covers four major sections:

1. Assay of condensate samples from supporting mills,

2. Operation and data of a pilot system comprising steam
stripping, activated carbon adsorption, and fractional
distillation,

3. Mass, heat, and BODs balances made according to the
actual operating condition of the pilot plant at the
Appleton Division mill of Consolidated Papers, Inc. to
January 1973,

4. Low temperature (200°C-390°F) regeneration of carbon.

Assays of the condensate samples indicated a large variation in con-
densates from different mills which would necessitate tailoring of the

complete process to the individual mill.

Operation of the pilot system, an extension of work previously done

at the Scott Paper Company, has shown that the above-mentioned materials
ean be recovered as relatively pure products. Mass and heat balances,
recoverable product values, and credits for BODs removal combine to
show the process to be a favorable avenue for the elimination of the

pollution potential of the sulfite condensate waste.

iii


[coms =>
ACPorr- 3-74 PaA'
iq
BOh-------4 bB'
2q
cthece---= te!
3d
DOe-se- pp"
4g
EOpese an PE!
{ ma!

Figure 52. Location of electrode and thermocouple terminals

Lhe


Sulfur Dioxide Removal, %

8o-

eq.

Consolidated Papers, Inc.
Appleton Division Mill Evaporator Condensate
48-Inch (121.9 cm) Goodloe Packing

i J i] L L 1 L l L

1 it n
10 411 12

1 2 3 4 5 6 7 8 9
Stripping Steam, % weight of feed

Figure 11. Sulfur dioxide removal vs. stripping steam used

Consolidated Papers, Inc. ~ 48-inch (121.9 em) packing
34


resistance of 0.32 ohm per foot (1.05 ohm/m) of carbon. Packing on the

second foot (30.5 om) of carbon in a like manner and connecting the
electrodes in the C and D position produced the same resistance. After

packing the third foot (30.5 om) of carbon, the resistance was 0.68 ohm,

and since this was double the resistance in the first two feet (61.0 om)
packing was continued until the resistance was at 0.28 ohm. The top

foot (0.3048 m) of carbon after packing had a resistance of 0.28 ohm
(0.92 chm/m).

It had also been necessary to make other repairs and changes to the
column. Shortly after operation of the column was initiated, inspection
had shown that a considerable portion of the teflon coating had blis-
tered. These blisters were not immediately broken and the column was
used in that condition; however, when they did break, repairs were
made with high-temperature. electrical insulation tape. The ceramic
electrode and thermocouple insert insulators also gradually cracked

and failed and they were replaced with a machined insulator constructed
from nylon. While nylon has a rather low melting point, these insu-
lators were easily fabricated and acted as a safety valve if localized

hot spots developed.

A 4k0-volt transformer with a step output between 110 and 220 volts was .
obtained for an alternating current power source. A carbon disk rheo-
stat was also placed in the line in order to obtain voltages below 110
when desired. Having only a single power source, however, did provide
disadvantages in that operation flexibility was considerably handi-
capped. It was thus necessary to pass the current through 4 feet
(1.219 m) of carbon with a single unit rather than through 2 feet

(61.0 em) each with two units, as done when using direct current.

The data for the first operation using alternating current are given

in Table 2h.

Power connections were made between A and E and the other three elec-

trodes were allowed to “ejoat"' in the system. Power was on the column

153


Table 7. FURFURAL BALANCE ACTIVATED CARBON ADSORPTION
10-9-72 to 11-15-72

Furfural adsorbed

Furfural = 1.0 gpm (60 min./hr) (8.33 1b/gal.) (70.5 hr) (0.0001)
= 3.52 1b (1.596 kg)

Furfural recovered — methanol regeneration

Sample No. 359 = 330 g
Analyses = 88.8% furfural
91.0% furfural
Average = 89.9% furfural
Furfural = 330 g (0.899) = 296 g
Sample No. 360 = 435 + 555 + 530 = 1520 g
Analyses = 88.5%
= 91.0%
= 90.5%
= 93.8%
= 93.6%
= 93.4%
= 93.4%
= 92.6%
= 93.1%
= 92.5%
Average = 922.4/10 = 92.2%
Furfural = 1520 (0.922) = 1400 g
Furfural
recovered = (296 + 1400)/454 = 3.74 1b (1.697 kg)
% Furfural
recovery = (3.74/3.52) 100 = 106%

65


‘chemicals at a central location. Over 8 1/2% by weight ethyl
acetate in ethanol was used in the pilot studies at Scott with
no adverse effects in carbon regeneration.

7. Design and do economic evaluation on the process as it is now
operated. Use the best available data.

8. Identify and evaluate the acids and other chemicals removed with
the furfural.

9. Rerun equipment as it is now installed to establish carbon life.

Additional Experimental Operation and Evaluation of Pilot System

Methodology

During the January 17, 1973 meeting of the members of this Group Pro-
ject it was agreed that Mr. Lueck continue with his low temperature,
thermal, activated carbon regeneration work, while Mr. Baierl pursue
Process Options 5 and 9 of the nine options.presented. Unfortunately,
it was not possible to run these experiments simultaneously. Initial
emphasis was placed on Mr. Lueck's work. The pilot plant was modified
to provide processed evaporator condensate to his unit as shown on

Fig. 30. Recirculation pumps were added at the bottom of the steam
stripping and fractionation columns, and water lines were eliminated.
Simultaneously, the steam stripping column condensed overheads were fed
into the fractionation column in an effort to optimize its size and
operation, and studies were made on Consolidated Papers Aqua Chem No. 1

and Rosenblad evaporation units.
Evaporator Studies

The data in Table 9 were compiled during the evaporator studies, while

the Aqua Chem No. 1 units were operated in series with and ahead of the
Rosenblad units.

It was readily discernible from these data that it woula be advantag-
eous for Consolidated Papers, Inc. to separate these condensates, The
condensate flow was from Effect 3 to Effect 2 to Effect 1 to Effect \

Th


EPA-660/2-73-030
DECEMBER 1973

Environmental Protection Technology Series



oot

Con-
8 den-
a 2 ser
2
| |Fraction-
©} Jation
Steam
strip- Column
» 4 |
5 8| ping
28 ‘| Column
$3 3
a 3
8a *
Cy &
3 >|
F °
2 §
5
a
3
8
2
83
ae
Evaporator go
Condensate Pump °3
Low Solids v8
Effects $2
3
a
3
: 2
Pump
Ed
fe §
is
ito
iS
2 sd —
Evaporator { Pump Reusable
Condensate _ ater
High Solids
Effects

Pump

Figure 40. Projected plant — Consolidated Papers, Inc.
Appleton mill


2. Heat of vaporization = 2920 (970.3) + 4.00 (107.5) (1.8) +
16.5 (262.8) (1,8) + 41.0 (94.9) (1.8) + 5.60 (96.8) (1.8)
+ 11.4 (300) (1.8) = 2,860,000 Btu (720,720 kg-cal).

3. The bottom stream leaves at 210°F (98.9°C). Heat given up
by the bottom stream = [(49900 + x) (1) + 4.00 (0.418) +
16.0 (0.566) + 8.00 (0.5) + 117 (0.487)] (212-210) = 99,900
+ 2x.

If 73 psig (51.3 kg/cm?) live stream is used: 2,860,000 -
(99,900 + 2x) = [ (318-212) (0.482) + 970.3 + (212-210)] x
1025x = 2,959,900

xX = 2690 1b (1221.3 kg)
Total heat required = 2,750,000 Btu (693,000 kg-cal). This
compares with 3,390,000 Btu (854,280 kg-cal).

Stripping column condenser

c, of the components at gaseous state

Water vapor 0.482 Btu/lb/°F (0.482 kg-cal/kg/°C)

Methanol 0.458 Btu/1b/°F (0.458 kg-cal/kg/°C)

Sulfur dioxide 0.134 Btu/lb/°F (0.134 kg-cal/kg/°C)

Acetic acid 1.50 Btu/lb/°F (1.50 kg-cal/kg/°C)

Furfurel 0.6 Btu/1b/°F (0.6 kg-cal/kg/°C)
(estimated).

c of components at liquid state

Water 1 Btu/lb/°F (1 kg-cal/kg/°C)

Sulfur dioxide 0.5 (estimated)

Methanol 0.566

Acetic acid 0.487

Furfural 0.418

Unaccounted HAc 0.5 (estimated)

Heats of vaporization of components

Water 970.3 Btu/lb (539.0 kg-cal/kg)

Acetic acid 96.8 cal/g (ca) (174.2 Btu/lb)

Methanol _ 262.8 cal/g (ca) (473.0 Btu/lb)

Furfural 107.5 cal/g (ca) (193.5 Btu/1b)

Sulfur dioxide 94.9 cal/g (ca) (170.8 Btu/1b)

123


Table 23. LOWELL UNIT — DIRECT CURRENT

Water Evaporation
Filtrasorb 400 Carbon
Carbon Bed 1 ft x 4 ft (30.5 cm x 1.219 m)

Rectifier No. 1 Rectifier No. 2 Temperature, °C (°F
Date Time Volts Amps Volts Amps 1 eS 7 4 ) q

Power connection — anodes ~ A, C, & E
cathodes — B — Rectifier No. 1

—D-— Rectifier No. 2
Wet carbon with tap water

1-25-73 9:02 22 Th 32-50 22( 72) 43(209) 50(122) 53(122)
9:20 19 6) 13 25 38(100) 50(133) 69(156) 68(154)
9:50 19 70 12 25 85(185) 91(196) 86(187) 81(178)
10:00 33 15 28 ke 91(196) 91(196) 91(196) 88(190)

Reversed vapor flow from top to bottom
10:10 3h 12 28 18 91(196) 91(196) 911196) 91(196)

10-Lb/in? (0.7 kg/cm?) air pressure on column ~ momentary increase in amperage
Wet carbon with tap water

10:k7 32 ve) .) 0 62(144) 70(158) 67(253) 64{247)
12:10 34 12 yy 15 76(169) 90(194) 92(196) 91(196)

3-Lb/in? (0.21 kg/cm?) air pressure on colum — no increase in amperage
Removed carbon and cleaned electrodes

Refilled column with 4 ft- (1.219 m) of Filtrasorb 400 carbon

Wet carbon
1-30-73 8:1 31 50 aT 50 36( 97) 38(100) 37( 99) 36( 97)
aa: 8:35 15 6 68 6 57(135) 57(135) 59(138) 78(172)

Shell of column hottest at No. C electrode
Isolated C electrode — no improvement in top foot
Ran steam through carbon to dispel eir

: \ 36 35 93(199) 93(199) 93(199) 94(201)
3:30 43 pa 36 32 93(199) 92(198) 92(198) 92(198)

. Drop off in amperage
Tamped top foot (0.305 m) of carbon

-- 2T 16 36 20 -- — - --

Removed carbon from column

be
Fs


EPA Review Notice

This report has been reviewed by the Environmental
Protection Agency and approved for publication.
Approval does not signify that the contents neces-
sarily. reflect the views and policies of the
Environmental Protection Agency, nor does mention
of trade names or commercial products constitute
endorsement or recommendation for use.


c Crude Ethyl Acetate

Vent

Con-
den-
ser

Ethanol
Storage
Tank

Fractionation
Column

——

Activated
Carbon
Column
Acetic

Acid

Vaporizer

Figure 41.

Receivers

ie—

[fo Spray Drier.)

Papers, Inc. Appleton mill

101

and/or Pulp Washers

Suggested commercial application Consolidated


2

Make Up
Ethanol

Ethanol
Feed

end

Activated Carbon Column
Acetic Acid

o
1
i)
2
2
&
3 EB
@
& l~_——
2
S
3
——_>J
ty
ri
ES
“a
oO
8
o
a —
FCACRSC-]f
ACCACRE
Transfer
Pump

Conden-|
S$€)

FCACRO

Ethanol — Ethyl Acetate
Fractionation Column

(Methanol — Furfural
Fractionation Column
Modified)

Water to Drain

FCACRB

Figure 4, Activated carbon column acetic acid regeneration


& by Weight

Sample Time MeOH HAc Furfural
Feed 1:40 p.m. 0.045 0.216 0.013
Bottoms 1:40 p.m. 0.005 0.189 ()

This pointed out the disadvantages of overdesign; it can be worse than

underdesign. These results verified similar work at Scott Paper Com-
pany's Everett Mill.

From February 12 through February 22, 1973 the evaporator condensate
was pumped through the steam stripping column system at the rate of

0.5 gpm (1.9 1/min.). Approximately 10% by weight of feed stripping
steam was used, and the condensed overhead was processed in the frac-
etionation column system. The stripping column bottom liquid was
either processed through the activated carbon column and/or drained.
The main objectives were to determine the capacity of the fractionation
column system, to establish carbon loading times and to provide loaded
activated carbon units for further regeneration work. Using al tol
ratio of feed to steam in the fractionation column, furfural was re-
moved as a 90%+ by weight crude from the bottom splitter, while no
methanol or furfural was detected in the fractionation column bottom
liquor. This indicated that only 9 ft (274 cm) of Goodloe Packing was
necessary to remove all the furfural in the steam stripping column con-
densed overhead vapors. The 9 ft (274 cm) of packing was probably
conservative, since the fractionation column feed was introduced in the
column above the furfural take-off point. It was interesting to note
that the furfural coming off the middle splitter, above the feed, had
about 1.0% by weight methanol in it, whereas that coming off the bot-
tom splitter, under the feed, showed little or no methanol in it. Ap-
proximately 1565 g, or 3.5 pounds of 90%+ by weight methenol was held
in the top of the fractionation column.

Activated Carbon Adsorption and Regeneration

Since the activated carbon column-acetic acid was loaded and the
activated carbon column-furfural was partially loaded, it was decided

81


9L

Table 9. EVAPORATOR STUDIES DATA

1. Operation on Channel A

% by Weight % Solids SO2, g/l VOA, mg/1 BODs,
Sample MeOH HAc Furf, pH Neut. 24 Br Tr OLC Total HAc Formic mg/1
Aqua Chem Feed 0.069 0.340 0.028 2.85 10.34 9.90 0.804 3.996 4212 4177 27

Aqua Chem Prod.
Rosenblad Feed 0.035 0.343 0.023 3.70 12.87 12.60 0.252 3.975 3792 3583 160

Rosenblad #3 0.018 0.330 0.023 3.89 15.16 14.71 0.183 4.179 3901 3717 141
Rosenblad #4 0.01 0.386 0.020 4.05 20.58 20.39 0.207 5.421 4602 4100 385
Rosenblad #1 4.03 31.82 32.19 0.411 6.054 6340 5691 498
Rosenblad #2 4.05 54.73 55.57 0.604 9.171 6736 5295 1105

0.210 2 :
Aqua Chem Cond. 0.113 0.240 0.03 2.89 0.29 0.07 0.040 0.048 1969 1948 16 3357
Aqua Chem
Scrubber Cond. 0.205 0.219 0.06 2.52 0.27 0.03 0.084 0.147 2006 =. 2006 ti) 4241
Rosenblad
#3 Cond. 0 0.431 0 2.61 0.57 0.12 0.037 0.253 4054 4054 0 3798
Rosenblad
#2 Cond. Trace 0.373 t) 2.55 0.50 0.09 0.131 0.227 3590 3577 10 2892
Rosenblad °
#1 Cond. 0 0.255 1) 2.88 0.30 0.06 0.024 0.103 2201 2193 6 1618
Rosenblad

#4 Cond. 0.02 0.252 0.120 2.21 0.48 0.14 0.796 0.267 2871 + =©2860 8 2409


the various mills to evaluate the process under study by comparison of
their condensate to that of the Appleton Division of Consolidated
Papers, Inc., where the pilot work was undertaken.

Data and discussion are presented in the following order:

1. Assay of condensate samples from supporting mills.

2. Design and construction of Pilot System at the Appleton
mill of Consolidated Papers, Inc.

3. Mass, heat, and BODs balances.

4, Low temperature (200°C-390°F) regeneration of carbon.


Acetic Acid, % by weight

0. be

0.37

O37

Steam Stripping Column
Feed Rate = 1 gpm (3.78 liter/minute)
Stripping Steam = 6% by Weight of Feed

Feed 9,

Bottoms X——x——— x——_-»

l | n n i ! l l I F j , ;

y 2 3 & 5 6° 7B 9 49
Hours Column Used ae 3a

Figure 13. Acetic acid concentrations — steam stri
rippt
feed and bottoms Ppeng column

46


per minute, which was equivalent to 23.85 liters per minute per square
meter (0.586 gallon per minute Per square foot), 102k additional grams

(2.26 pounds) of volatile organic acids were added to the carbon. This

was from a feed similar to that used in Run 1. The succeeding regener-

ation data are given in Table 28. Power connections and thermocouple

configurations were the same as at the start of Run 1. At the end of
4 hours of operation the power connections were changed to the A and B
position in order to heat the top foot (30.5 cm) ‘of carbon. Shortly

after, however, electrical arcing was in evidence at the top electrode.

Upon removing some of the carbon it was evident that arcing had occurred
on the left side of the top electrode. The insulation on the wall of
the column was repaired, the electrode was replaced and carbon was added
to a depth of one inch (2.54 cm) above the electrode. ‘The column was
also insulated with 2 inches (5.08 cm) of glass wool to eliminate the
condensation around the periphery of the column. It was also necessary
at this time to wet the carbon with tap water to make necessary in-
sulator adjustments. On March 8 the power connections were made over
the entire 4 foot (1.2192 m) of carbon between the A and E positions,
with the thermocouple configuration as follows: No. 1 at No. 1 posi-
tion 4 inches (10.16 cm) into the carbon, No. 2 in the No. 2 position

2 inches (5.08 cm) into the carbon, No. 3 in the C' position 6 inches
(15.24 cm) into the carbon, and No. 4 in the D' position 5 inches (12.7
cm) into the carbon. After about 20 minutes of operation there was
again evidence of arcing, and so the connections were changed to the B
and E position. Heating was continued for about two hours, and the
power connections were again changed to cover the entire 4 foot (1.2192
m) of carbon, to the A and E positions. After about 20 minutes of
operation, a strong unidentified odor was detected and power was shut
off. On March 9, the following day, the power was again activated
without making any changes in the configuration of the power hookup,
but after about 10 minutes a strong odor was again in evidence. The
insulation was removed and it was found that a spot had burned on the
left side, about 11/2 feet (45.7 cm) down from the top of the carbon

163


column. The vapors would then enter the bottom disengaging section from
the side similar to the reboiler on the fractionation column. When this
heat exchanger was removed and inspected, better than 60% of its tubes
(mostly those around its outer circumference) were completely plugged
with the black polymerized material. This verified that there was no
escape path for the nonvolatile material and indicated the heat exchanger
was too large for the job it was doing. The smaller heat exchanger that
was used for vaporizing the methanol when regenerating the activated
carbon column-furfural was used to replace this one. Piping modifica-
tions and changes to the activated carbon column-acetic acid regenera-
tion system were made in an effort to recirculate liquid through the
smaller heat exchanger now installed on the side of the colum's bottom
disengaging section. Existing equipment, with the exception of new
brass pressure gages to replace the older corroded ones, was used. A
check of the new system operation, shown schematically in Fig. 34 to 37,
indicated that theoretically it functioned well. However, so much
black material, plastic in appearance, was removed it plugged the rotom-
eter, pumps, and packing in the fractionation. column. Operational
problems, such as controlling the steam pressures and feed rates, were
encountered. Steam pressure regulators had to be changed, and since

all but one pump that was available lost their flows when discharge
pressures exceeded 15 psig (1.05 kg/cm? gage), maintaining constant
flows was almost impossible. With erratic operation, it was extremely
difficult to know what the concentrations of ethyl acetate, ethanol,

and water were in the various streams. Attempts were made to get a gas
chromatograph capable of determining these in extreme concentrations.

None was available.

During the latter part of March and the early part of April a concen-
trated effort was made to perfect the new regeneration system. Ethanol-
water runs were made to establish steam pressure controls and constant
pumping rates. In previous regeneration experiments no reflux was used
in the activated carbon column. The new system is demonstrated in Fig.

34 through 37. In this system steam rates had been reduced to the

88


29T

Table 27. LOWELL UNIT — ALTERNATING CURRENT

Run 1 — Desorption or Regeneration
Piltrasorb 400 Carbon
Carbon Bed 2 ft x 4 ft (30.5 cm x 1.219 m)

Sample volatile organic acids
Temperature, °C (°F) Elec. resistance Sample size, Concentration, Removed,
Date Time Volts Amps T 2 3 oms/ft oim/meter No. liters g/t 8
2-21-73 Acetic acid adsorbed on carbon — 1576 grams or 3.48 lbs

2-22-73 Power connection B to E
‘Thermocouple configuration: ;
1—¥No. 1 position, 2 inches (5.1 cm) into carbon
2-—C' position, 6 inches (15.2 cm) into carbon
3—¥o. 3 position, 2 inches (5.1 cm) into carbon
4 —D* position, 2 inches (5.1 cm) into carbon

8:20 100 100 = 40(104) 36( 97) 40(104) hook) 0.33 1.08 - _ - -
8:50 102 107 © 100(212) 96(205) 99(210) 98(208) 0.30 1.98 - _ = —
9:00 103 87 © 100(212) g9(210)  100(212) + 100(212) 0.39 1.28 2 2.00 4.22 Bt
9:20 © 109 TL loo(ai2) 109228) 98(208) 99(210) 0.51 1.67 2 2.00 4.25 8.50
9:30 110 4h = -98(208) += 140(28h) +=. 100(212) 99(210) 0.83 2.72 3 2.00 4.86 9.72
9:50 106 28 100(212) +: 167(333) 98(208) 99(210) 1.23 Kol 4 2.00 4,26 8.52
10:0 122 21 100(212) 218424) 99(210)  100(212) 19h 6.36 5 2.00 42 B.2k
21:20 «135 21 1or(2ik) 20k8(399) + 100(212)~—-103(217) 2.14 7.02 6 2.00 4.02 8.0h
12:10 (137 22 100(212) 160°(320) 98(208) 125(239) 2 6.92 7 2.00 3.90 7.80
12:30 «137 25  99(210) 106° (223) g7(207)  —-118(2ks) 1.83 6.00 8 0.80. 3.75 3.00
12:ho | 135 27 = 99(210) + 108° (226) 98(208)  —124(255) 1.67 548 9 0.50 3.54 1.77
1:00 121 2T — 98208) 119° (2h6) 97(20T) — 146(295) 1.49 4.89 20 0.50 3.82 1.90
1:10 © 122 28 = 99210) 1h08 (284) 98(208) 164 (327) 1S 4.76 n 0.50 4.00 2.00
1:30 122 29 99210} 182° (360) 98(208) 128° (262) 1.40 4.59 12 0.50 3-92 1.96
asko | 122 29 © 99(210)  193°(379) g99{210) 131, (268) 1.ho 4.59 13 0.50 3.88 1.94
1:50 122 27 —99(210) © 2068(403) .00(212) 1352 (275) 1.51 4.95 Bt 0.50 3.92 1.96
2:10 120 27 = 91(20T)-2135(415) g99(210) 1508 (302) 1.48 4.86 15 30 3.87 1.94
2:20 13h 32 gt(2o7) aake(ha7) = Lon{ank) _ 158°{316) 1.39 4.56 16 0 3.60 1.80
2:30 0 13h 35 93(203) 2182(h2k) —xo(219) 21765 (349) 1.28 4.20 ya 1 3.87 1.9%
2:50 135 37 © «93g(199) 22500437) —:130(266) 2003 (392) 1.21 3.97 28 0 4.58 2.29
3: 134 42 954(203) 2265 (439) 169(336) 2185 (42h) 1.06 3.18 19 0 3.46 1.73
3:10° 134 46 93°(299) — 2h2°(h68) —115°(239) ako" (he) 0.97 3.18 = _ _ a
3:13 Power off — spot temperature check on shell — 226.7°C (4k0°F)
3:20 — —92%(198) — 253°(487)159°(318) 255° (491) - = 20 0.52 3.56 1.85
Bottom drain - - aa 1.32 2.88 3.80
- - 21.62 - 89.14

Total -

‘rhermocouple inserted 3 inches (7.6 cm) into colum.
mmermocouple inserted 2 inches (5.1 cm). into colum.
Syhermocouple inserted 1 inch (2.5 cm) into eolum. |

mnermocouple inserted 5 inches (12.7 em) into colum.


Table 8. ACETIC ACID BALANCE ACTIVATED CARBON ADSORPTION
10-9-72 10-23-72 11-6-72

Acetic acid absorbed
10-9-72

By graphic integration — large squares
5 + 8-5/8 + 7-3/k + 3-1/2 + 4-1/2 + 3-1/2

32-7/8 - 11-7/8
al :

One square = 0.02% by weight per hour
Acetic acid absorbed = 21 (0.0002) (1 gpm) (60 min./nr) (8.33 1b/gal.)
2.1 lb (0.954 kg)

Drainage = 60 gallon
Acetic acid in drainage =‘60 (8.33) (0.00199)

= 500 (0.00199) = 0.995 1b (0.452 kg)
Total acetic acid absorbed = 2.1 - 1.0 = 1.1 1b (0,50 kg)

10-23-72

By graphic integration — large squares

16.8 + 14.5 + 9.0 + 2.5 = 42.8 squares
Acetic acid absorbed = 42.8 (0.0002) (1) (60) (8.33)
= 4,28 1b (1.942 kg)
Drainage = 60 gallon
Acetic acid in drainage = 60 (8.33) (0.0021)
= 500 (0.0021)
= 1.05 1b (0.476 kg)
Total acetic acid absorbed = 4.28 - 1.05 = 3.23 1b (1.465 kg)

11-6-72

By graphic integration — large squares
12.0 + 12.9 + 9.3 - 1.0 = 33.2
Acetic acid absorbed = 33.2 (0.0002) (1) (60) (8.33)
3.32 lb (1.507 kg)
Drainage = 1.0 1b (0.457 kg)
Total acetic acid absorbed = 3.32 - 1.0 = 2.32 1b

Total acetic acid absorbed in 3 runs
Acetic acid = 1.10 + 3.23 + 2.32 = 6.65 1b (3.02 kg)

Total acetic acid absorbed as ethyl acetate
Ethyl acetate = 6.65 (88/60) = 9.75 1b (4.h2 kg)


Methanol Removal, %

1007-

90° Scott Paper Company

Everett Mill Blow Gas Condensate
4B-Inch (121.9 cm) Goodloe Packing
Bok
°
TOF
oe
60L
50--
°
hot
°
° °
z0b
°
°
20
°
10
°
Cy) i 1 L n n i Ll t ' 1 : \
° 1 2 3 4 5 6 1 8
9 lo am 12
Stripping Steam, % weight of feed

Figure 5. Methanol removal vs.

stripping steam used — S
Company — 48-inch (121.9 cm) Packing e cott Paper

28


Table 5 (cont'd). METHANOL BALANCE STEAM STRIPPING RUNS
9-11-72 to 9-20-72

9-20-72

In Feed

4 (0.608) (8.33) (60) (0.000725) = 0.881 1b (0.40 kg)
In Overhead

4 (0.050) (8.33) (60) (0.00412) = 0.412 1b (0.187 kg)
% Recovery = (0.412/0.881) 100 = 46.8%

9-20-72

In Feed .

4 (0.502) (8.33) (60) (0.0007) = 0.704 1b (0.32 kg)
In Overhead

4 (0.051) (8.33) (60) (0.00369) = 0.376 1b (0.171 kg)
&% Recovery = (0.374/0.704}'100 = 53.5%

Total methanol in overhead

0.430 1b
0.290 1b
0.290 1b
0.320 1b
0.360 1b
0.328 1b
0.405 1b
0.318 1b
0.212 1b
0.207 1b
0.248 1b
0.412 1d
0.376 1b

4.196 1b (1.90 kg)

Collected — 4.3 1b (1.95 kg)

ho


60T

ist Activated Carbon Colum

4
8
8
BE
8
£
0.639)
(TF, hr
0.639)
TF, 1b 640
MeOH 640
Scale: none
Basis:
Recovery of furfural: 16 hours
Recovery of methanol: 8 hours
‘LEGEND
TP, 1b total flow
Furt. furfural
MeOH methanol
Poly Matls. polymerized materials
FeO water
{] to be retained
() originally retained
Figure hh.

TF, 1b 739

MeOH 639; H20
92.0; Furf. 4.00;
Poly Matis. 4.00

1.

4
8
$
a
3
8
8 |

Receiver

Furfural recovery

Fractionation Column and Condenser

TF, 1b 4.00 FPurfural,
Furf. 4.00

Reboiler|

gR, 1b 96.0

HAO 92.0;

Poly Matls. 4.00

Activated carbon regeneration and furfural recovery.

‘Sewer


unit operations. Hundreds of separate analyses were made on these
samples. The data accumulated have been plotted in Fig. 13 to 22.
Figure 13 shows the acetic acid concentrations in the feed to and in
the bottom liquid from the steam stripping column. Interestingly, the
acetic acid concentration was consistently lower than that in the feed,
most of the time much lower than can be accounted for by the 6% strip-
ping steam dilution. Since a darkening of color in the processed con-
densate was apparent, the acetic acid lost may be responsible in part
for some-of the polymerized material collected. No analytical effort
has been made to verify or disprove this. Figure 14 shows the acetic
acid concentrations of the feed to and effluent from the first. activat—
ed carbon column. There was no acetic acid in the effluent for over 3
hours. From previous Scott work the breakthrough point had been cal-
culated to occur after 2-3/4 hours. The increased time may have been
due to lower concentrations of acetic acid in the feed. Note that
after 5 hours there was more acetic acid in the effluent than in the
feed. Then, after 8 hours the carbon was adsorbing it again. During
this period the feed concentration was rising. After 13 hours there
was more in the effluent once again. Figure 15 demonstrates some
analytical problems. Up until this time one injection of the sample
was made into the gas chromatograph. Since the acetic acid concen-
trations of the samples were relatively close, no problems had arisen.
Now injections of samples with acetic acid concentrations varying from
1% or better were mixed with those containing no acetic acid. Since

it was illogical that the acetic acid would break through both activat-
ed carbon columns at the same time, two of the effluent samples fortu-
nately saved were checked. They showed no acetic acid, ith the improv-
ed injection procedure, so it was concluded the acetic acid shown
previously was coming from the injection needle and/or gas chromato-
graph column. Poropak Q columns require some column conditioning with
acetic acid. Similar experiences were encountered at Scott. All later
quantitative work on the gas chromatograph utilized 3 sample injections.
With this modification of analytical procedure it could be shown that

little or no acetic acid was adsorbed in the first 4 hours because it

45


This is the exit temperature of the ethanol vapor. Since the
heater is attached to the activated carbon column, this is
also the inlet ethanol vapor temperature to the column.

= 204 cal/g
0.406 cal/g/°C (0.406 Btu/1b/°F) (vapor)
0-456 cal/g°c (0.456 Btu/1b/°F) (liquid)

Cc
o
Pp

u

For acetic acid

d = 96.8 cal/g (174.2 Btu/1b)
Cy 1.50 cal/g/°c (1.50 Btu/1b/°F) (vapor)
c= 0.468. cal/g/°C (0.468 Btu/1b/°F) (liquia)

For ethyl acetate

dX = 102 cal/g (183.6 Btu/1d)
C, = 0-371 cal/g/°C (0.371 Btu/1b./°F) (vapor)
c, = 0.459 cal/g/°C (0.459 Bti/1b/°F) (liquid)

1. Heater before the activated carbon column.
Ethanol flow = 1416 at (100) = 47,200 1b (21428.8 kg)

Assume at 70°F (21.1°C)
Heat required = 47,200 [0.456 (173-70) + 204 (1.8)] =
19,500,000 Btu (4914000 kg-cal).

2. No information for the steam consumption in the steam
jacket is available. It is believed that unless some
unusual source of high heat loss exists, the steam
requirement for this item should not be high.

3. Heat of reaction
CH3COOH(g) + CzHsOH(g) + CHsCOOC2Hs(g) + H20(g)
Assuming constant pressure and volume, the heat of re-

action is estimated as follows:

aH, of CH3COOH(g) = ~219.82 K cal/g-mole
AH, of C2Hs0H(g) = -336.82 K cal/g-mole
aH, of CH3COOCaHs(g) = -547.46 K cal/g-mole.

130


Table 6. FURFURAL BALANCE STEAM STRIPPING RUNS
9-11-72 to 9-20-72

9-11-72

In Feed
4 hr (1.52 gpm) (60 min.) (8.33 1b/gal.) (0.0001) = 0.30 1b (0,136 kg)
In Overhead
4 (0.008) (60) (8.33) (0.0022)

= 0.019 1b (0.0086 kg)
% Recovery = (0.019/0.30) 100 = 6.3%

9-12-72

In Feed

4 (1.368) (60) (8.33) (0.00025) = 0.684 1b (0.310 kg)
In Overhead . ’

4 (0.038) (60) (8.33) (0.00155) = 0.117 1b (0.053 kg)
% Recovery = (0.117/0.684) 100 = 17.1%

9-12-72

In Feed
4 (1.215) (60) (8.33) (0.00020) = 0.486 1b (0.221 kg)
In Overhead

4 (0.049) (60) (8.33) (0.001385) = 0.133 1b (0.0604 kg)
% Recovery = (0.133/0.486) 100 = 27.4%

9-14-72

In Feed

4 (0.76) (60) (8.33) (0.000175) = 0.267 1b (0.121 kg)
In Overhead

4 (0.045) (60) (8.33) (0.001) = 0.090 1b (0.0408 kg)
% Recovery = (0.090/0.267) 100 = 33.7%

9-14-72

In Feed :
4 (0.608) (60) (8.33) (0.0002) = 0.243 1b (0.110 kg)
In Overhead

4 (0.043) (60) (8.33) (0.00105) = 0.089 1b (0.0404 kg)
% Recovery = (0.089/0.243) 100 = 36.8%

41


effects. Therefore, it is apparent that the bulk of the methanol and
furfural were removed in the 10% solids effect. Note that, although
condensate flow is less than weak spent liquor feed flow, the condensate
had 79% of the methanol concentration, 77% of the acetic acid concen-
tration, and 47% of the furfural concentration that was in the feed.
This indicated an appreciable loss of those chemicals in the evapora-
tion system. If equal evaporation is assumed in each evaporator effect,
it is apparent that almost 4 times the methanol and furfural concen-
tration, or a 0.28% methanol and 0.084% furfural, would occur in the
condensate from the 10% solids effect if the other condensates were
separated. Examination of Fig. 9 shows that the other 75% of the
evaporator condensate contains substantially less ‘methanol than our
best steam stripped evaporator condensate. Essentially the same thing
is true for the furfural (see Fig. 29).

Project Status in February, 1973

The merits of these unit operations have been established. A high
percentage of SOs vapor that can be reused in the mill has been pro-
duced. Crude methanol, furfural, and ethyl acetates have been re-
covered. Four important areas of study must be further developed

before this process is ready conclusively for commercialization:

1. <A market for the crude products produced must be
established.

2. The life of the carbon must be determined when feeding
evaporator condensate that has been used as a backwash
in the evaporators.

3. Regeneration procedures for the activated carbon used in
adsorbing acetic acid must be optimized.

4, An overall economic evaluation of the process is required.

To date the evaporator condensate used was readily available from the
Consolidated Pepers, Inc.'s mill without suggesting any changes in
their operating procedures for producing and/or utilizing their

70


evaporator effects. There is a dual purpose for showing them. First
the number of hours the activated carbon adsorbed acetic acid was al-
most identical for these condensates. The carbon load at Scott was 10%,
and 3 to 4% at Consolidated. That is about 20 times the concentration.
That means the carbon loading for this condensate showing 1.54 to 2.19%
by weight would be 30 to 40%. The second fact that this could be 40%
versus 30% shows the increase in concentration is significant for the
developed process. Furfural has a multiple of over 100. The loading
at Consolidated was 1 to 2% from 0.01 to 0.02% concentration. At Scott
it was 20 to 30% for a 0.2 to 0.3% concentration.

Fractionation

As the steam stripping system and activated carbon column-furfural were
providing feed to the Lowell Unit, the fractionation column system was
run to establish optimum equipment size. On February 1, 1973 evaporator
condensate was pumped through the steam stripping column preheater to
the fractionation column at a point about 14 feet above the bottom of
the column. The rate was 0.76 gpm (2.88 1/min.).

From the following data it was apparent that the fractionation column
rapidly lost its efficiency:

& by Weight
Sample Time MeOH HAc Furfural
Feed 11:35 a.m. 0.030 0.2h0 0.012
Bottoms 11:35 a.m. 0.010 0.260 fe)
Feed 3:30 p.m. 0.055 0.215 0.010
Bottoms 3:30 p.m. 0.030 0.210 0.007

Column flooding occurred about 4 feet below the feed. The following
data showed a similar run in the 4-foot steam stripping column, with

equivalent steam to that used in the fraction column:

80


Sulfur Dioxide Removal, %

90

70

30)

20)

10)

Consolidated Papers, Inc.
Appleton Division Mill Evaporator Condensate
12-Inch (30.48 em) Goodloe Packing

L ! i J 1 4 J i i 1 1 j

C) 1 2 3 4 5 6 7 8 9 10 l le

Stripping Steam, % weight of feed

Figure 12. Sulfur dioxide removal vs. stripping steam
used — Consolidated Papers, Inc. — 12-inch
(30.48 cm) packing

35


2. Out:
a. Furfural stream

Purfural 4.00 lb {ate kg)
+00 1b (1.816 kg)

b. Bottom
Polymerized materials 4,00 1b (1.816 kg)
Water 92.0 1b (41.768 a}
. 96.0 1b (43.584 kg
¢. Methanol

Methanol 639 ibd {299.106 8
639 1b (290.106 kg
739 (335.506 kg) = 4.00 + 96.0 + 639
VII. Fig. 45 — Activated carbon regeneration and furfural recovery:

2. Methanol recovery.

The balances are based on an 8-hour cycle of methanol recovery and
the flow quantities shown on this flow sheet are the total flows of 8
hours.

VIII. Fig. 46 — Activated carbon regeneration and ethyl acetate re-
covery:

1. Draining of column.
IX. Fig. 47 — Activated carbon regeneration and ethyl acetate recov-

ery:
2. Recovery of ethyl acetate and recovery of ethanol.

The balances shown are based on an ethyl acetate recovery cycle of 12

hours and ethanol recovery cycle of 4 hours. The flow quantities
shown are totals of 12 hours, except that of the water flow, which is

the total of 4 hours.

HEAT BALANCES FOR PILOT PLANT

The balances shown in this section are primarily based on the recorded
data shown in the interim report to sponsors of this project and the
mass flow quantities in Fig. 42, Since the basic flow quantities in
Fig. 42 are 100 times that of Fig. 43, the balances for the separation

121


Table 15, TYPICAL ACTIVATED CARBON ACETIC ACID. COLUMN REGENERATION DATA

Fractionation Column Reboiler, lst Pressure Gage
Fractionation Column Reboiler, 2nd Pressure Gage
Fractionation Column Bottom Pressure Gage

Fractionation Column Manometer (Feed to Bottom)
Fractionation Column Top Pressure Gage

Fractionation Column Middle Pressure Gage

Acetic Acid Activated Carbon Column Top Pressure Gage
Acetic Acid Activated Carbon Column Jacket Steam Pressure
Acetic Acid Activated Carbon Column Bottom Pressure Gage

Acetic Acid Activated Carbon Column Vaporizer lst Steam
Pressure Gage

Acetic Acid Activated Carbon Column Vaporizer 2nd Steam
Pressure Gage

Acetic Acid Activated Carbon Column Rotameter to Acetic
Carbon Column

Acetic Acid Activated Carbon Column Fractionator (Alcohol)
Temperatures

Fractionation Column Liquid Bottoms
Fractionation Column Steam

Fractionation Column Bottom Splitter
Fractionation Column Feed

Fractionation Column at Feed Plate
Fractionation Column at Middle Splitter
Fractionation Column at Top Splitter
Fractionation Column Vapor after Condenser
Acetic Acid Activated Carbon Column Top
Acetic Acid Activated Carbon Column Bottom

105

6T psig
66 psig
0 psig
1" #20
23" #20
3" #20
0 psig
4 psig
T psig

135 psig

115 psig

(4.72 kg/om?)
(4.64 kg/em?)
(0.00 kg/cm*)
(2.54 cm H20)
(6.35 cm #20)
(7.62 cm H20)
(0.00 kg/cm)
(0.28 kg/cm?)
(0.49 kg/em?)

(9.49 kg/cm?)

(8.08 kg/cm?)

0.30 gpm (1.14 l/min.)
0.30 gym {1.14 1/min,)

212°F
213°F
113°F
174°F
172°F
162°F
157°F
100°F
115°F
173°F

{100.0°c)
(100.6%c)
(78.3°c)
(78.9°c)
(17.8°C)
(12.2°c)
(69.4°C)
(37.8°c)
(79.4°c)
(78.3°C)


=

@ ‘Thermometer

@ Pressure Gage q Rotemeter Sulfur Dioxiss

Sulfur Dioxide

>

eH Methanol

tf
Ven’

‘LEGEND
@ recorded ( m pe vaave
i] Manometer
wat
oe
~ j eo
8
g 2
H 5 f
2
a &
be }—» 3
3 7 &
Hy 8 z
z 3
\ E 3 &
" ®

Condenser

Receiver

J

@

Th ATI
Calyamn

Se

Ast Activated Carbon Colum
2nd Activated Carbon Column

Ey o
; i
8 &
&
y
: or ?
3
- “oy Sever
x Pump Pump
Water | ‘ |
Seale: none sever

Figure 48. Separation process


B. Out:
Acetic acid 1.17 lb (0.531 kg)
Methanol 0.160 1b (0.073 kg)
Sulfur dioxide 0.0300 1b (0.014 kg)
Water 499 lb_ (226.546 ke)
500 1b (227.000 kg)
C. Retained:
Furfural 0.0400 1b (0.018 kg)
Sulfur dioxide 0.0500 1b (0.023 kg)
0.0900 1b (0.041 kg)
In = Out + Retained
6. Second activated carbon column:
A. In:
Acetic acid 1.17 2b (0-531 kg)
Methanol 0.160 1b (0.073 kg)
Sulfur dioxide 0.0300 1b (0.014 kg)
Water 499 lb (226.546 kg)
500 1b (227.000 kg)
B. Out: :
Methanol 0.160 1b (0.073 kg)
Sulfur dioxide 0.0100 1b (0.004 kg)
Water 499 1b (226.546 kg)
499 1b (226.546 kg)
Cc. Retained:
Acetic acid 1.17 lb (0.531 kg)

Sulfur dioxide

In = Out + Retained
VI.

1. Furfural recovery.

0.0200 1b oe 3
1.19 1b (0.540 kg

Fig. 44 — Activated carbon regeneration and furfural recovery:

This flow sheet shows the mass flows during the cycle of furfural

recovery.

covery and an 8-hour cycle of methanol recovery.

The balances are based on a 16-hour cycle of furfural re-

The flow quantities

shown on this sheet are the total flows of 16 hours. The balances of

importance are:

119


Table 19. LOWELL UNIT — DIRECT CURRENT

Water Evaporation
Filtrasorbd 300 Carbon
Carbon Bed 1 ft x 4 ft (30.5 cm x 1.219 m)

Rectifier No. 1 Rectifier No. 2 Temperature, °C_(°F
Date Time Volts Amps Volts Amps 1 2 ue Ce}

Power connection — cathodes — A, C, & EB
anodes ~ B ~ Rectifier No. 1
—D-— Rectifier No. 2

Wet column
1-4-73 10:07 75 55 0 0  20( 68) 30( 86) -- ~
10:22 9 55 0 0  —95(203) gk(201) =~ -
10:32 13 (28 200 85 ~ - 22( 72) 29( 84)
10:43 ns 2 oT OMB 95(203) 95(203) 95(203) 95(203)
Re-wet carbon
11:00 us 55 0 0 15 59) 20( 68) 16( 61) 45(113)
11:20 115 50 64 TT 92(198) 90(19%) 28( 82) 58(136)
11:40 115 3 98 5 95(203) 95(203) 95(203) 92(198)
Re-wet carhon
12:00 nh 33 C) ) 18( 64) 26( 79) 33( 91) 60(140)
1:10 us 8 0 0) 18( 64) 25( TT) 33( 91) 60(240)
Re-wet carbon
2:15 95 5 1510 gu(201) 94(20) 84(183) 84(183)
-5~ : 0 8 50 T THl165) TH(165) 74(165)  74(165)
aalie 3:50 30 7 50 15 87(189) 93(199) 93(199) 93(199)
10:20 5 5 5 2 87(189) 94(201) 94(201) 94(201)
=" : 6 1% 39 27( 81) 27( 81) 27( 81) 30( 86)
Mes nia ae 9 100 = 30 29( 84) 91(196) 89(192) 50(122)
11:30 100 16 100 «17 gk(201) 94(201) 94(201) 50(122)
11:50 125 9 116 9 93(199) 93(199) 93(199) 7T4(165)
12:25 50 T 50 ll 94 (201) 94(201) 94(201) 76(169)
1:25 50 6 50 8 93(199) 93(199) 93(199) 75(167)
2:05 50 1 50 1 93(199) 91(196) 94(201) 75(267)
3:10 100 «16 0 t) 7(189) 85(185) 91(196) 72(162)
3:30 100 5 to) 0 ga(190) 83(181) 92(198) 71(160)

Attempted to dry carbon with stream of air overnight

1d carbon for
-! 210 112 6 + Low emperage (high resistance), remove
eos 9 inspection of the unit

1h3


Table 21. LOWELL UNIT — DIRECT CURRENT

Water Evaporation
Filtrasorb 400 Carbon
Carbon Bed 1 ft x 4 ft (30.5 cm x 1.219 m)

Date

1-22-73

Date

1-22-73

Rectifier No.1 Rectifier No. 2
Time Volts Amps Volts Amps 1

Temperature, °C (°F)
2 3

Power connection — anodes — A, C, & E

cathode — B — Rectifier No. 1
~—'D — Rectifier No. 2

2:ho 50 93 50 65 33( 91) 70(158) 84(183) 47(117)
2:43 50-122 50 12 95(203) 87(189) 88(190) 47(117)
2:hh 25 50 25 33 88(190) 87(189) 86(187) 47(117)
3:05 25 53 25 37 — 123(253) 107(225) 96(205) 40104)
3:14 25 69 25 Ko -193(379) 142(288) 116(241) 47(227)
Surface temperature, °C (°F)
Location Right side Front Left side Back
At A 66.8(152) 63.9(147) 63.5(146) 61.8(143)
Between A&B 66,8(152) 58.9(138) 58.5(137) — 67.9{15})
At B 66.1(151) — 58.5(137) 61.7(143) — 67.5(153)
Between B&C 65.0(149) 6.4 (12) 63.5(146) — 62.7(143)
At C 66.8(152)  54.6(130) 65.0(149) 62.1 (144)
Between C&D 61.1142) 55.0(131) 58.5(137) 53.5(128)
At D 56.1(133) —47.8(118) 53.5(128)  4b.5(112)
Between D&E 47.2(117) = 4..8 (107) 41.8(107) —-39.5(103)
- At E B4.4( 94) 31.1 88) 33.3( 92)  31.1( 88)
Rectifier No. 1 Rectifier No. 2 Temperature, °C_(°F) r
Time Volts Amps Volts Amps 1 2 3
: 25 37  213(415) 150(302) 126(259) 33( 91)
3:31 38 25 38ers) 18(298) 157(315) 57(135)
Power connection — D~E only
-- -- 60(140)
: fe) 25 21 --
3:30 3 ry 50 ka —-213(415) ak7(297) 165(329) 92(198)
i,:20 0) C) 15 46 -197(387) 154(309) 117(243) 1021216)
+33 o 0 1 61 - ~ 210
Surface temperature, °C (°F)
Location Right side Front Left. side Back
-8(197)
90.0(194) 92.3(198) 88.4(191) 91
Between ¢ 4D 90-0019) 89.6093) 1-897) 88.4192)
MOD 93.5(200)  89.6(193) . 103.3(218) BB otnee)
Between D&E 88.9(192)  88.4(191) ——-89.6(193) Be ete)
At E 85.0(185) 78.4 (173) 75.6(168) 5.

LAT


EPA~660/2-73-030
December 1973

TREATMENT OF SULFITE EVAPORATOR CONDENSATES FOR
RECOVERY OF VOLATILE COMPONENTS

by

Kenneth W. Baierl
Nei L. Chang
Bernard F. Lueck
Averill J. Wiley
Robert A. Holm

Grant No. 8801207
Program Element 152037

Project Officer

Ralph H. Scott
Chief, Paper and Forest Industries
U.S. Environmental Protection Agency
National Environmental Research Center
Corvallis, Oregon 97330

Prepared for

Office of Research and Development
U.S. Environmental Protection Agency
Washington, D.C. 20460


The general process for which pilot data were available was not
specifically designed for processing the evaporator condensate at
the Appleton Division Mill of Consolidated Papers, Inc.3

The individual pieces of equipment were mostly not optimized;

The chemical constituents and physical conditions of the evaporator
condensates from different effects of the evaporating systems at
different mills would be different; and

The flow quantities would vary from case to case.

It is felt that to avoid misleading the reader, the design of full-scale
equipment, calculation of energy balance, cost estimation and the com-
plete economic analysis should be done for the individual mills. Based
upon the mass and heat balances done, the following points have caught
our attention:

1. The use of direct steam instead of a reboiler for the strip-
ping column would save some heat and capital expense.

2. More saving if direct steam is used for the fractionation
column. ;

3. The elimination of the condenser after the first activated
carbon column in the furfural recovery process would be
logical from both capital and operating cost standpoints.

4. The elimination of the condenser after the second activated
carbon column would be reasonable. A vapor feed to the

fractionation column could work out well.

137


a Y__ vent

Conden4
ser
Crude Ethyl Acetate
~<
Fractionation
Column
end

Activated
Carbon
Column
Acetic
Acid
capes
Ethanol
Storage
Tank 3
oe
ry
8 ®
= "
Pump

Pump

To Drain

Figure 39. Suggested regeneration

98


Methanol, % by weight

0.10-—

Steam Stripping, Furfural Activated Carbon and
Acetic Acid Activated Carbon Columns
Feea Rate = 1 gpm (3.78 liters/minute)

0.09F- Stripping Steam = 6% by Weight of Feed
Steam Stripping Column ° o——e
Feed
Steam Stripping Column x x x!
0.08] Bottoms ~

Furfural Activated Car-

a bon Column Effluent
/ Acetic Acia Activated -
, CarbonColuim Effluent o—o—®
.

0.07F- ».

0.05-- x
0.04

0.03-

0.0]

Oct. 23, 1972

Nov. 6, 1972

it i i it J L it it l
o 2 @ 3 4 5 oe 3 t 1 ! !

Hours Column Used

Figure 24, Methanol concentrations — steam stripping and activated
e@

carbon column flows using regenerated carbon
58


overheads. ‘The methanol recovered was 4.3 1b (1.95 kg). Although
analyses showed it to be in the 85 to 90% by weight range, the bubble
point and specific gravity indicated a 95+% by weight methanol crude.
From the furfural balance, Table 6 furfural analyses showed 1.055 1b
(0.48 kg) to be in the condensed overheads. Furfural recovered was
0.925 1b (0.42 kg). Analyses showed it to be in the 84 to 92% by
weight range. This work was done before we developed our gas chromato-
graphic programs for analyzing high purity methanol, ethanol, ethyl
acetate, methyl acetate, and furfural products. No sample of the
fractionation column bottoms contained even trace quantities of
methanol or furfural. There was zero pressure drop from the feed port
to the bottom of the fractionation column indicating this column was
grossly oversized. No attempt was made to preheat the condensate to
its bubble point. The reboiler and condenser were more than adequate.
The work at Scott Paper Company utilized steam stripping and fraction-
ation on the evaporator condensate before it was pumped through the
activated carbon columns, and the fractionation column was the piece
of equipment thet limited the pilot plant capacity to processing less
than 1/2 gpm (1.9 liters per minute) of the condensate. No attempt was
made to optimize the size of the fractionation column, since the pro-
ject priority was shifted to getting activated carbon adsorption and
regeneration data.

Activated Carbon Adsorption

After the steam stripping work was completed, steam stripped evaporator
condensate was processed through the activated carbon columns at the
rate of 1 gpm (3.8 liters per minute). Six percent by weight of feed
stripping steam was used. The overhead vapors were condensed and pro-
cessed through the fractionation column. The steam stripped evaporator
condensate was processed as shown in Fig. 2 (p. 20).

The first run was made October 9, 1972. Efforts were concentrated on

the steam stripping and activated carbon adsorption columns. Almost

100 samples were taken over a 16-hour period to effectively study these

4h


bed. The i
carbon was removed and it was found that arcing had occurred

in three places.

At thi . .
this point in time it was decided that, although this method of

heati .
eating the carbon column might still be successfully concluded, the
level of work required ana possible additional expenditures were too

high to proceed under this particular project, and this phase of the
work was terminated.

The idea was presented that perhaps the addition of a granular metal
dispersed among the carbon particles would tend to prevent channeling
of the electric current. In order to rapidly prove or disprove this
theory, a small 2-inch diameter (5.08 cm) carbon column was set up in

the laboratory. After several runs using granular aluminum, there was
no evidence of improvement.

CONCLUSIONS

Attempted heating of the carbon column by the direct application of an
electric current through the carbon has resulted in the following

observations.

1. If direct current is used, then the anode must be at least
platinum coated to prevent disintegration.

2. The packing of carbon is very important; it may even be
necessary to selectively size the carbon particles.

3. A method needs to be devised to prevent localized heating
and/or arcing. Proper packing would be partly helpful in
preventing this.

4. Work with alternating current was hindered on this project
py having only one transformer available.

5. The column should be constructed of a more heat-resistant
electrical insulating material.

6. A change in design would be a requirement for successful

operation. This would probably require some type of pressure

165


extent that more steam leaked by the original steam pressure regulator
than was required now to vaporize the ethanol. A smaller pressure
regulator was installed. The ethanol held in the system was reduced to
10 gal. (37.9 1) from the 4o (151.5) previously used, and the ethanol
rate was 0.05 gpm (0.18 l/min.) instead of 0.30 gpm (1.14 1/min.). ‘This
necessitated the installation of smaller rotameters. A successful
ethanol-water run was made establishing operating parameters during the
week of April 2-6, 1973. These operating parameters (see Table 13) were

the basis for the newly developed, possibly patentable activated carbon
regeneration system.

On April 10, 1973 a steam stripping and activated carbon adsorption run
was made. Samples of the acetic acid carbon column effluent were taken
after one hour of operation and then every half-hour until a total of
3-1/2 hours adsorption time had elapsed. The feed rate was 1 gpm (3.79
l/min.). The results shown on Fig. 38 were interesting in that no ace-
tic acid was detected in any sample. Previously acetic acid was found
in the samples after 2-1/2 hours of adsorption operation and had com-
pletely broken through after 3 hours. This indicated the new regener-
ation system was very effective, and the piping changes may have provid-
ed better liquid distribution over the carbon, thereby getting better

adsorption.

Unfortunately, during the regeneration run the new by-pass valve to the
vent was left open. All the alcohol vaporized, other than that pumped
into the column as a liquid, by-passed the carbon column and discharged
through the vent. Ethyl acetate was made as the alcohol in the system
was vaporized; however, it also worked its way into the recirculation
system and was vented. Since it was impossible to tell whether or not
the carbon had been regenerated, this regeneration run was repeated.
Interestingly very little ethyl acetate was made during the repeat run,
indicating either the alcohol in the carbon column was sufficient to
regenerate the carbon in the previous regeneration test, or the new

regeneration system was ineffective as far as producing ethyl acetate.

93


gt

SOz Vapor

>
Methanol
>
Furfural _»
5)
Stean Fractionation st ona
Strip- onuan
ping
Column
cI g
3
3
Steam 8,
Stripping g ea
Column Fee} ag aa
Drum sé é4
gé a2
3 3°
2 E| 5
Ba 3
28 2
7
Stripping a
Column
Evaporator Feed Pump
Condensate
Feed Fractionation a bal
Column Feed a}.
Pump 3
Ty 8
Water Reusable Water
Activated Carbon
Feed Pump
Figure 1. Scott Paper Company pilot plant installation Everett mill



Table 4, POLLUTION POTENTIAL AND MATERIALS DATA

Acetic Formic Total
Semple COD, = BODs, acid, MeOH, acid, Furfural, © 502s
number mg/1 mg/l mg/2 -mg/1 mg/1 mg/1 mg/1
Hardwood
1 101k 6090 5875 heo 95 630 610
2 11016 6252 5733 530 io Tuo ~ — 6hio
3 10822 67TH Shik 420 1 ThO 670
4 "8769 5870 5308 370 us 530 920
a 12062 7890 6523 915 he 1485 298
a 10592 TH26 6964 hos 32 575 608
9 11268 5586 4650 30 4a 283 366
10 7859 5088 4960 338 14 365 254
lu 16422 Th56 S472 423 4h 362 T1O
12 9780 6438 5813 4o7 62 4h? 293
a3? 5830 4476 2618 347 110 323 123
wf 5830 4350 2976 210 36 235 305
15 9272 7234 7266 130 1 255 22h
aue 5162 3870 2591 40 25 300 263
astef 6330 4764 3551 LIT 25 133 627
Softwood
16 6152 4506 4o22 520 2 325 1023
is 9487 7113 4eTT 1035 4 wto shy
ish 773, 6258 sag was 2 535 189
a1 7620 3718 2514 620 47 120 1058
29° 3191 2334 1896 243 43 190 3h
30 2981 1548 1246 233 60 160 150
2 3885 2358 2350 aur 60 107 487

2938 Hardwood, 7% softwood.
00% Softwood, 14% hardwood.
‘From prestripped SSL.
e 5% Aspen, 5% spruce.
Used for wash.

fgecond effect.
14


3 feet (91.4 cm) from the top of the column. Further checking revealed
that the installed pop-off valve was for 70 psig (4.9 kg/cm? gage) in-
stead of 7 psig (0.49 kg/cm? gage) as was expected. It is probable
that during the runs when trouble controlling the steam préssures occur-
red, the combination of high jacket pressure and a vacuum inside the
column occurred simultaneously buckling the inner shell. Since the pop-
off valve never released, the high pressure was not revealed. This was

the second time the inner column had collapsed, so no attempt was made
to repair it.

The new regeneration system appears more complicated than it is. A
simplified form is shown in Fig. 39. Essentially, the system involves
using the activated carbon column as a distillation column during the
carbon regeneration cycle. A smaller fractionation column is added to
the top of the carbon column for product purity improvement. This may,
or may not, be required. Alcohol (ethanol is used) is pumped into the
carbon column below the fractionation column and above the activated
carbon. Water containing acetic acid, polymerized material, and portions
of spent sulfite liquor comes out the bottom of the carbon column, and
is collected in the receivers. From there it is recirculated by means
of a pump through a vaporizer and disengaging section at the bottom of
the carbon column. The vapor from the partially vaporized recirculating:
liquor passes up the carbon column. By controlling the heat to the
vaporizer the carbon column is gradually converted into a reactor and
distillation column. As the vapors move up the column, water condenses
and is displaced, while the alcohol veporizes and reacts with the acetic
acid to form esters (ethyl acetate). As the alcohol and acetate are
rectified at the top of the carbon column and in the fractionation
column by means of refluxing the condensed overhead vapors, the water
containing furfural, polymerized material, and residual spent sulfite
liquor are collected in the receivers. Once all the acetic acid has
been converted to ethyl acetate, the alcohol is recovered by vaporizing

the recirculating liquor and concentrating the collected matérials in it.

97


Table 24.

Water Evaporation

Filtrasord

LOWELL UNIT — ALTERNATING CURRENT

00 Carbon

Carbon Bed 1 ft x k ft (30.5 cm x 1.219 m)

2-5-T3

25-73

2-5-T3

2-6-T3

‘Time

Time

4300

W423
4333

10;51
1yho
11450
12320
22:40

12:58
1;10
1:20

Volts Amps Tr i ohus/ft ohn/meter’
Power connection — A to E
Wet carbon
109 «6 $6. «S33 91) +30 86) 32( 90) 32 90) 0.b2 1,38
209° 6h = 79(1T74) — 67(253) 80(176) 82(180) 0.42 1.38
109 «52, 85(185) 84183) 83(181) 86(187) 0.52 1.72
Surface temperature, °C (°F)
Location Right side Front Left side Back
AGA 57.2(135) 46.7(116) —-55.6(132)-55.6(132)
Between A&B  51.1(124) 50.0(122) —53.3(128) — 62.2(144)
At B 47.8(228) 47.8(118) — 52.8(127) —57.8(136)
Between B&C 53.3(128) 50.0(122) — 54.4(130) 58. 9(138)
At 86.7(188) 83.9(183) — 88.9(192) —85.0(185)
Between C&D 86.1(187) 83.3(162) —84.4(202) 83. 9(183)
At D 69.4(157) 63.3(146) — 78.3(173) —-75.0(167)
Between D&E  7h.4 (166) 67.2(153) — 83.9(183)  80.6(177)
ACE 53.3(128) 98.9(238) —56.2(133) 58. 9(138)
Temperature, °C (°F) Elec. resistance
Volts Amps r 2 3 7 otms/ft ohm/meter
109 «47 = 82{180) _78(172) 81(178) 82(180) 0.58 1.90
124 48 = 88(190)  88(190) 87(189) 84(183) 0.64 2.10
152 73 -107(225)  88(190) 96(205) 88(190) 0.52 1.7
Surface temperature, °C (°F)
Location Right side Front Left side Back
At A 81.1(278) 81.1(178) —83.3(182) 83.9(183)
Between A&B 79.4(275) 83.9(183) 87.8190) 88.9(192)
At B 88.9(192) 86.7(188) — 85.6(186) ~ 88.9(192)
Between B&C 90.0(19h) -90.0(194) —-89.4(193) 88.9192)
At Cc 91.1(196) 91.1(196) 90.6195) 86.1(187)
Between C&D 90.0(194) 89.4(193) 91.1196) 89.9(19h)
At D 91.1196) 91.1096) — 91.1(196) 81.1(178)
Between D&E 92.2(198) 90.6(195) 89-81193) 89.4(193)
AE 66.7052) 1T.8(172) (248) 66.7(152)
Temperature, °C_(°F) Elec. resistance
Volts Amps T 2 3 7 ‘otms/ft otm/meter
Power connection — A to ¢ & E to ¢
109 180 © 99210) 87(189) 95(203) 92(198) 0.15 Og
Readinga E to C only
209, 40 127(26) ~96(205) 99210) 99(210) 1.36 Kb
Power connection B to E
173° «G1 lo7(225) —97(207) 100(212) 100(212) 0.94 5
173° «1 oh(@19) ro1(2ih) 169(336) 108(226) 0.94 308
Wet Column — Pover connection A to E
130 40) 16CM)  16C 1) 17 63) 18( 64) O72.
156 42850485] 88G90) BUGS) Tra) 019338
256 12 84283) 84283) 83(281) 82(180) 3.54 13.61
158 21 88(190) 87 (189) 8789) 78(172) 1.88 6.17
157 == ~—88(190) 870489) —260+(500+) —77(171) -—
Power off for ten minutes
156 129 = 86(187) 88(190), 163(325) 751167) 0.30
156 “2h 850485) 85185) gost) TrTL) See S32
15632 86(187) | 85(185) 191376) 78(a72) 1.22 4.00

Temperature, °C (°F)
2 3

Elec. resistance

Removed carbon from colum

15h


Table 25. LOWELL UNIT — ALTERNATING CURRENT

Water Evaporation
Filtrasord 400 Carbon
Carbon Bed 1 ft x 4 ft (0.30K8 x 1.291 m)

Date ‘Time Volts Amps pegs {er 5 ese
7% oha/neter

Power connection A to E (clean glectrodes), other electrodes removed
Wet carbon — top flange off

21-13 :h5 11025 32( 90) 32( 90) 3k 9: 29( Bh

Bas he Ble} Bhs} BGS) Blea) rat
12:55 0 22 100(212) 84 (183) 50(122)  9h(201) 4.20

Top flange in place

1:50 138 = 20 1oL(2ik) 98(208 ) 58(136) 101(214) 1.80 90
2:12 1360 ak g9(210) — 100(212) g9(210) 200(212) 1.44 ie
2:25 138 8 99(210) 99(210) 98(208) 97207) 4.30 ak.na
3:05 138 1k zoo(2i2) 100(212) + 100(212) 100(212) 2.46 8.07

Tapped side of column ~ amperage decreased to 0 — carbon settled below trode —
added carbon — left top flange off ap chectrode

3:ko 12h 50 1o0(212)  1oo(2i2)-100(212) 100(212) 0.62 = 2.03

Power off
2-8-73 8:24 123 29 46(115) 48(118) 4g(120) = W7(11T) 2.06 3.48
8:30 12h 17 56(133) s¥29) 5h(129) 52(126) 1.82 5.97

‘Tapped column with mallet repeatedly

8:40 125 eT 64(147) 60(140) 60(140) 56(133) 1.15 3-17
8:50 12h bk 85(181) e(62) 68(154) — 6a(akh) O.7L 2.33
9:20 126 32 aai(232) 101 (214) g9(2i0) 100(212) 0.98 3.22

Added carbon repeatedly es needed

1260-32 115(239) —-L02(216) 98(208) 100(212) 0.98 3.22
yeh 32 ~—«-113(235) +s doatené) 9399) ro0(z12) 0.97 3.18
1260 «(89 ie7(261) + 108(226) 100212) 100(212) 1.09 3.58
1260 (28 ye2(32h) -113(235) —-109(228) 102(216) 1.12 3.67

Power off during noon hour

riko 12k (36 200(392) -126(21) ~—«122(23) 1031217) 0.86 = 2.82
Intermittent power

3:27 12h 3T 251(4B4)  188(370) -128(244) — 107(225) 0.84 2.76

Power on continuously

ging 12h he aseB(270) 2330450) 163(325)  109(228) o.7h 2.43
30 12h «78 ~=—«(102) (216) 203,(397) 120) (28) 260(500) 0.40 = 1-31
4iks 123 27 ~—-u02(2a6) 107 (225) 165°(329) 2038(397) 9-24 0.79
Set thermocouples 2% inches (6.4 cm) into column
Wet carbon — when adding water side “cork blew out (unused electrode site)
Tost dry carbon thraugh opening ~ added carbon ~ top flenge on
= 2, 1! 3 28( 82) 26; 62) 28( 62) 3h 93) 9.39 1.28
2913 9:3 UF BB folios) 35k 95) 38 Os) ta(o8) 1.26 aaa
10:5 0 iL 55 100(212) 100(212) 1(178) 1oo(212) 0.50 1.64
yi:05 «(12858 ioe(216) ror(erk) ron (2a4> ror(2ih) 9.55 1.80

Hydrogen sulfide odor
1a;45 ho 37 yoo(p12) 100(212) + L00(212) 1oa(z12 0.94 3.08

gmail hole blown through side of column — shut down

—_——————
Sermocouple inserted 3 inches (7.6 cm) into column.
Papermocouple inserted 1% inches (3.8 em) into column.

15T


from the carbon and 5 liters (1.32 gal.) had been collected at the bot-

tom of the column. It was then decided that the column was ready for
adsorption of acetic acid,

The first run in which acetic acid was adsorbed on the carbon was made
on February 21. Condensate that had been steam stripped and passed
through the furfural carbon adsorption column was used as feed. Thus,
this condensate had most of the S02, methanol, and furfural removed.

The column was fed at 1.66 liters (0.4% gal.) per minute, which is equiv-
alent to 22.75 liters per minute per square meter (0.559 gallon per min-
ute per square foot). 1576 Grams (3.48 pounds) of acetic acid were ad-
sorbed on the carbon. The following day, February 22, an attempt at
regenerating the column was made. The regenerating data are found in
Table 27. Power connections were in the B and E position, which re-
sulted in one foot (0.3048 m) of carbon not being heated by the electric
current. The thermocouples were placed in the following position: No.

1 in the No. 1 position 2 inches (5.08 cm) into the carbon, No. 2 in the
C' position 6 inches (15.24 cm) into the carbon, No. 3 in the No. 3
position 2 inches (5.08 cm) into the carbon, and No. 4 in the D' position
2 inches (5.08 cm) into the carbon. Heating was continued for 7 hours
during which time 21.62 liters (5.71 gal.) of water were evaporated,
which contained 89.14 grams (0.20 lb) of acetic acid. The temperature
at the No. 2 thermocouple, which was in the center of the carbon, rose
to 218°C (42°F) after 2 hours and 20 minutes of operation. This thermo-
couple was then gradually moved toward the periphery of the column, in
order to more closely watch the temperature pattern. Since the top foot
(30.5 em) of carbon was not heated directly, its temperature never rose
above the boiling point. ‘The higher temperatures at the No. 2 and 4
thermocouples indicated that the left side of the column was heating

much faster than the right side.

The second absorption run was made prior to obtaining all of the
analytical data from the regeneration of Run 1, and it was not known at

that time that such a very small amount of acetic acid had been removed

from the column. However, with a feed rate of 1.74 liters (0.46 gal.)

° 161


sulfite liquor, methanol was pumped from the feed drum through a heat
exchanger where it was vaporized and slightly superheated. The super-
heated vapor entered the top of the carbon column and forced the con-
densed methanol, water, furfural, polymerized material and that adsorb-
ed portion of spent sulfite liquor out the bottom. The first portion
of liquid removed, approximately 10 gallons (37.8 liters) was drained.
Analyses had shown it to contain less furfural and roughly the same
amount of methanol and acetic acid as in the feed to the column. Event-
ually, higher concentrations of methanol, furfural, and residual
material came through as a liquid. Finally, the methanol vapor came
out the bottom, and was condensed and collected in the receiver. Once
the condensed methanol vapor contained only trace quantities of furfur-
al, water was fed into the vaporizer to produce steam. The steam
forced the methanol vapor out of the carbon. The methanol was conden-
sed, collected in the receiver, and pumped into the fractionation col-
umn for eventual recovery. When only steam remained in the column, the
steau stripped evaporator condensate, cooled, was pumped into the carbon
column displacing and condensing the steam. The carbon column was thus
back on its normal adsorption cycle. The methanol and furfural were
recovered in the fractionation column in the same manner as described
for recovering them from the steam stripping column condensed overhead
vapors. The polymerized material and residual spent sulfite liquor
were held in the bottom of the fractionation column. When the concen-
tration (over 20% by weight) affected the pumps recirculation rate or

when there was an excessive amount of water, it was discharged to the

drain.

Activated carbon serves as a catalyst for the esterification of acetic
acid with ethanol in the vapor phase and the resultant ethyl acetate is
a readily marketable product. These facts provided the bases for choos-
ing ethanol as the regenerating agent for the second activated carbon
column. Figure 4 shows the manner in which the vaporized ethanol was
passed upward through it. This column was jacketed for steam to pre-

vent condensation in the carbon. The overhead vapors were then

26


SECTION VIII
INVENTION RECORD AND PUBLICATION

Invention record — A granular activated carbon regeneration
system using alcohol as the regeneration agent and the acti-
vated carbon column as a distillation unit was conceived and

reduced to practice by K. W. Baierl in the course of this
research.

Publication — Treatment of Sulfite Evaporator Condensates for
Recovery of Volatile Components, Kenneth W. Baierl, Bernard F.
Lueck, and Averill J. Wiley, Tappi 56, no. 7:58-61(July, 1973).

167


LOT

TF, 1b 43.8 Sulfur Dioxide H,0 3-90; Furf. 0.900; MeOH 1.50; SO, 37.5

LEGEND >
HO water
Furr. furfural TF, 1b 15.2 Methanol MeOH 15.0; SO, 0.200
MeOH methanol —t >
sulfur dioxide
wekook acetic acid TF, 1b 7.30 Furfural #0 0.200; Furf. 7.10
EtOH ethanol ~
Etoac ethyl acetate “bo 2
Poly Matls. polymerized material: ae ae TF, 1b 124 Ethyl Acetate ~
TF, 1d total flow, 1b 4 5 al: { EtOAc 124
Evap. Cond. TF, 1b 50,000 Eke ele
HAO 49,800; Furf. 8.00;
Me 33 7
MeCooH 134 ,
Water TF, 1b 6000
HO
Za
Water TF, 1b 4oo z Eg #8
gow E---7 i iF
Water TF, 1b 16,100 B BS g2
#0 16,100 mo pa >
Ethanol TF, lb 64.7
- ----------4 ----—y
3
ng lp a
gFEz cfs wa oad?
2 eg
Rese Se SAL alas
AP ae aRe 4 4 4d ANE eS
“Bo a lo 3 lo “BBS do
SeoSd BES Bet ERS BLre
TF, 1b 68,900 Sewer (or recycle)

He0 68,900; 50, 5.30; MeCoom 38.2;
MeOH 16.0; unaccounted HAc 11.4;
Poly Matis. 6.00

Figure 42. Overall mass balances of the pilot plant


Assume that the liquid comes in at 210°F (98.9°C) and
goes out at 247°F (119.4°C) (same as the other re-
poilers in "separation process"), and that 9.60 1b
(4.36 kg) of the liquid are reboiled. In 9.60 1b
(4.36 kg) of the bottom liquid there are 9.20 1b (4.17
kg) of water and 0.400 1b (0.18 kg) of polymerized

materials.

Make the following assumptions for the polymerized

materials:

Cc (liquid) 0.6

ms (vapor ) 0.3

d 300 cal/g (540 Btu/1b)
b.p. 212°F (100°C)

Heat required to heat liquid from 210°F (98.9°C) to
212°F (100°C) = 9.20 (1)

(2) + 0.400 (0.6) (2) = 18.9 Btu (4.76 kg-cal)

Heat of vaporization = 9.20 (970.3) + 0.400 (300)
(1.8) = 9140 Btu (2303 kg-cal) ,

Heat required to heat the vapor from 212°F (100°C) to
2h7°F (119.4°C) = 35

{9.20 (0.482) + 0.400 (0.3)] = 159 Btu (40 kg-cal)
Total heat required = 9320 Btu (2348.6 kg-cal)

Use of 149°F (65°C) as reference temperature.

Heat in = [9.20 (0.482) + 0.400 (0.3)] (213-212) +
9.20 (970.3) + 0.400 (300) (1.8) + [9.20 (1) + 0.400
(0.6)] (212-149) = 9740 Btu (2454.5 kg-cal)

Heat out = [101(1) + 4.40 (0.6)] (213-149) = 6630

Btu (1670.8 kg-cal)

Heat loss = 3110 Btu (783.7 kg-cal)

It can be seen that the heat loss is based on several

assumptions. The actual loss can be either higher or

lower.

128


SELECTED WATER 1, Revort No] 2.
RESOURCES ABSTRACTS

INPUT TRANSACTION FORM Ww
5. “Keport Date
TREATMENT OF SULFITE EVAPORATOR CONDENSATES FOR &.
RECOVERY OF VOLATILE COMPONENTS 4. 1g Organ cation

Baierl, Kenneth W., Chang, Nai L., Lueck, Bernard F.
Wil Averill J, and Holm, Rohert

The Institute of Paper Chemistry, Appleton,
Wisconsin, Division of Industrial and $801207

Envir U5. Tyne 6 Rego eaund
vironmental Systems Period Covered

42. Swonsorir Organi: :tion

Environmental Protection Agency report number,
EPA-660/2-73-030, December 1973.

Pilot studies were conducted on two routes for recovery of volatile components
in condensates from evaporation of spent liquors from acid sulfite pulping.
The condensates were steam stripped prior to adsorption on activated carbon.
The first route utilized fractional distillation and solvent extraction from
the carbon, while the second route used low-temperature thermal regeneration.
Relatively pure SO2, methanol, furfural, and ethyl acetate were recovered.
Estimated process economy, based upon recovery of saleable volatiles, favor-
able mass and heat balances, and credits for BOD removal, indicates the first
route may provide a favorable method for the removal of pollutants from con-
densates. Low temperature regeneration studies failed due to mechanical
design problems, but this second route continues to be considered as techni-
cally feasible. In an important auxiliary study, a substantial number of
condensate samples from cooperating mills were analyzed. Differences in
quality, quantity, and dilution of the condensates from different sources
were apparent. Individual design of processing facilities for each mill is
indicated, and especially so in those mills where backwashing of the evapo-
rators contaminate the condensate with nonvolatile materials.

17a, Descriptors pyanorators, Condensation, Activated Carbon, Adsorption,
Solvent Extraction, Separation Techniques, Distillation, Alcohols,
Acids, Organic Acids, Sulfite Pulp Wastes, Pulp and Paper Industry,
Biochemical Oxygen Demand, Chemical Oxygen Demand, Water Pollution,
Industrial Wastes, Heat Balance, Mass Transfer.

17b, Identifiers

Steam Stripping, Fractional Distillation, Spent Sulfite Liquor,
Acetic Acid, Methanol, Furfural, Ethyl Acetate, Volatile Acids,
Neutral Volatiles, Nonvolatile Organics, Lignin, Lignosulfonic Acids.

lve. COWRR Field & Group 05D

18, Avaita securtty Class. 31 No.of | Send To:
f Report) Pages
WATER RESOURCES SCIENTIFIC INFORMATION CENTER
29, See sity Chess. 2 Pre US DEPARTMENT OF THE INTERIOR
Prue) WASHINGTON. D.C. 20240



Methanol, % by weight

0.10—

Furfural Activated Carbon Column
0.09-- Feed Rate = 1 gpm (3.78 liters/minute)
0.08
0.07e
x
0.06 x NK,
\ / °
0.05 Ba, oe ¥
“Al
.7 TY x x x
/ \/ \
x
0.04 @ fee ° \A, \
/\ o” x
° 2
ry VI e a
of x y,
0.03 y \
°
x
}
x
0.02.
°
oe —— 0 © Feea
x X——*-——-x Effluent
0.01b
Odea ewe ———L 1 ! 1 L 4 i ! ! t I j
0

11 le 13 14
Hours Column Used

Figure 17. Methanol concentration — furfural activated carbon
column feed and effluent

50


Table 14, TYPICAL PILOT-PLANT OPERATING DATA

Evaporator Condensate Transfer Pump Rotameter Reading
Evaporator Condensate Transfer Pump Pressure Gage
Steam Stripper Feed Tank Level

Steam Stripper Feed Pressure Gage

Steam Stripper Feed Rotameter — 67%

Steam Stripper Steam Rotameter — 10 setting

Steam Stripper Manometer

Main Line Steam Pressure Gage

Preheater, lst Pressure Gage

Preheater, 2nd Pressure Gage

Preheater, Dial Thermometer

Reboiler, lst Pressure Gage

Reboiler, 2nd Pressure Gage

Steam Stripping Column Top Pressure Gage

Steam Stripping Column Bottom Pressure Gage

Water to Steam Stripping Column Condenser Rotameter
‘Steam Stripping Column Condensed Overhead Rotameter, 9.5
Fractionation Column Reboiler Rotameter — 8.5 setting
Fractionation Column Steam, lst Pressure Gage
Fractionation Column Steam, 2nd Pressure Gage
Fractionation Column Bottom Pressure Gage
Fractionation Colum Manometer (Feed to Bottom)
Fractionation Column Top Pressure Gage

Furfural Activated Carbon Column Feed Pressure Gage
Furfurel Activated Carbon Column Feed Rotameter
Furfural Activated Carbon Column Bottom Pressure Gage
Furfural Activated Carbon Column Top Pressure Gage
Acetic Acid Activated Carbon Column Top Pressure Gage
Acetic Acid Activated Carbon Column Bottom Pressure Gage

Temperatures

Steam Stripping Column Feed before Preheater
Steam Stripping Column Feed after Preheater
Steam Stripping Column Liquid Bottoms

Steam Stripping Column Top Vapor

Steam Stripping Column Vapor after Condenser
Steam Stripping Column Steam

Fractionation Column Liquid Bottoms
Fractionation Column Steam

Fractionation Column Feed

Fractionation Column at Feed Plate
Fractionation Column lst Splitter
Fractionation Column 2nd Splitter
Fractionation Column Vapor after Condenser
Activated Carbon Colum Bottom (Furfural)
Activeted Carbon Colum Center (Furfurel)
Activated Carbon Column Top

Activated Carhon Column Bottom (Acetic Acid)
Activated Carbon Column Top (Acetic Acid)

104

Peer

20
15 psig (1.05 kg/cm?)
Full
41 psig (2.88 kg/cm”)
1 gpm (3.79 1/min.)
0.060 gpm (0.23 1/min.)
0" #20 (0 cm H20)
130 psig (9.14 kg/cm?)
130 psig (9.14 kg/cm?)
73 psig (5.13 kg/cm?)
21°F (99.4°c)
83 psig (5.83 kg/cm?)
52 psig (3.65 kg/cm”)
No good
7-4" H20 (18.8 cm H20)
7.5 Setting
0.057 gpm (0.22 1/min.)
0.049 gpm (0.18 1/min.)
135 psig (9.49 kg/cm?)
125 psig (8.79 kg/cm?)
0" 20 (0 cm H20)
0.3" B20 (0.76 cm H20)
2.5" H20 (6.35 cm H20)
18 psig (1.26 kg/cm?)
1.06 gpm (4.01 l/min, )
5 psig (0.35 kg/cm?)
\ psig (0.28 kg/cm?)
4 psig (0.28 kg/cm?)
6.7 psig (0.47 kg/cm”)
134°F (56.7°C)
212°F (100,0°C)
212°F (100.0°C)
213°F (100.6°c)
203°F (95.0°c)
2h7°Rr (119.49)
210°F (98.9°c)
213°F (100.6°C)
166°F (Th.4ec)
213°F (100.6°c)
213°F (100.6°c)
149°F (65.0°c)
OTor (36.1°c)
1h0°F (60.0°c)
hor (60.0°c)
135°F (57.2°c)
129°F (53.9°c)
133°F (56,1°C)


Table 8 (cont'd). ACETIC ACID BALANCE ACTIVATED CARBON ADSORPTION
. 10-9-72 10-23-72 11-6-72

Total ethyl acetate recovered

Semple No. 349 = 430g (0.55) = 236¢
No. 350 = 430g (0.81) = 348 ¢

No. 351 = 430g (0.85) = 365¢
Sample broken = 860g (0.85) = 730¢
No. 352 = 2170g (0.78) = 1692 ¢

No. 353 = 910g (0.55) = 501g

No. 354 = 570g (0.17) = 978

No. 355 = 385g (0.01) = ye
3973 €

Total ethyl acetate recovered = (3973/454) = 8.75 1b (3.97 kg)
Ethyl acetate in ethanol = 30 gal. (8.33) (0.0005) = 0.12 1b (0.0545 kg)

Methyl acetate . = 430 g (0.20) = 86 g
= 430 g (0.03) = 13 t
= 0.22 lb = 99 ¢~

(0.10 kg)

Methyl acetate as ethyl acetate = 0.22 (88/74) = 0,26 1b (0.116 kg)
Ethyl acetate accounted for = 8.75 + 0.12 + 0.26
= 9.13 lb (4.24 kg)

% Accountability = (9.13/9.75) 100 = 93.7%

68


02

S502 Vapor

Fg _
FCO — FCFRO Methanol >
CSC — FCFRSC Furfurel
9T°F
fa 367°C
iCon—
ACCFE
98.5-100.5°C jdense: Ee} ie
200-213°F 8 Fo °R. 04
3 135°F
g 5°) 5T.4e
‘E| | Fractiona- 133°F [56.2°C
8} | tion Column| 1st 2nd
3
209°F
65.5-76.6°C|
180 150-170°F|
4 205° -—4213°F E|
9 a
w 5 81.2 00. SIC 8
2 i eo
dg & 96.0! 140°F ad
6 A 83
o be act
: By §
7 i g og
H 23 a3
2 00.54 8 £2
ia ma kiss s 5 5
8 z
A *
sscr Ba
83
130-155°F <0
5h. 5-68. 3°C
Feed Pump Feed Pump
Stripping Distillation
Evaporator
Condensate 10°F |60°c az9er_| 53.9°¢
onde! 213°F
ma] 3] fro0.5fc aay)
a
3
3 ba] Reusable Water
Water fl 210°F ACCACE
) SSCB 98.8°C
FCB
Feed Pump
To The Drain

Figure 2.

Activated Carbon

IPC pilot plant — Consolidated Papers, Inc. Appleton Mill


pottom of the fractionation column and ethyl acetate would be allowed
to build up in the alcohol. Three successive adsorption runs, March 8,
13, and 26, showed the acetic acid coming through progressively earlier;
10 hours, 8 hours, and 7 hours, respectively, see Fig. 32 and 33. How-
ever, complete acetic acid loading was still extended beyond ten hours.
The real problem became apparent when traces of ethanol appeared in the
effluent from the activated carbon column containing acetic acid after
it was 7 hours on the adsorption cycle. Black material appeared in the
initial condensate effluent. It became apparent that residual spent
liquor in the activated carbon column containing acetic acid was not
being removed, and that the ethanol was not being quickly removed from
the carbon in the activated carbon column containing furfural. Also
the ratio of ethanol to water was not high enough. Too much acetic acid
was being removed as acetic acid and too much ethanol [almost 40 (151.5
1) gal.] was held in the system. Piping modifications and regeneration
system changes for recovery of acetic acid as ethyl acetate and the re-

moval of water and residual spent liquor simultaneously were mandatory.

Four things were learned from these runs:

1. Ethyl acetate, ethanol, furfural, and water were not going to be
recovered in one fractionation column.

2. Acetic acid and furfural were effectively removed from both
carbon columns.

3. Channeling occurred when going downstream in the Act. Carb. Col.
— Fur. and the water and steam with the ethanol made the ethanol
recovery expensive.

4. Most importantly the carbon life was deteriorating, due to
processing dirty condensates, especially in the Act. Carb. —

Acetic acid column.

New Activated Carbon Regeneration System

It was decided to move the heat exchanger from directly under the

activated carbon column-acetic acid to a position on the side of the

86


SECTION I
CONCLUSIONS

Analyses of sulfite mill evaporator condensates submitted by sponsoring
mills revealed that most of their condensates contained larger quan-'
tities of recoverable chemicals than were present in the relatively
weak condensates available for processing at the Appleton Division
mill of Consolidated Papers, Inc.

Data were compiled to assist interested sulfite pulp manufacturers
toward making feasibility studies for utilizing steam stripping,
fractionation, and activated carbon adsorption systems as tools toward
solving their condensate pollution problems. With minimum additional
pilot plant work tailored to individual mill requirements, these units
can be reasonably scaled to commercial sizes with more accurate
development of process economics. The newly developed activated car-
bon regeneration system appears economically feasible, but more
optimization work could be worthwhile.

Low-temperature regeneration of activated carbon utilizing direct
application of electric current through the carbon bed is not ready
for commercial evaluation. The problems were identified, and can be

used to evaluate further research potential.


volatile, that coming from the acetic acid carbon was. However, it
polymerized or reacted during the processing in the fractionation
column and lost its volatility. The nonvolatile material from both
columns are to be recycled back to the concentrated evaporator liquor
for burning or spray drying purposes. In the pilot plant this material
was discharged to the drain with the water at the bottom of the frac-
tionator at 15% by weight solids concentration. No attempt was made to

increase this solids concentration.
Evaporator Studies

Throughout the period that the multipoint temperature recorder was

being repaired and the pilot plant was sitting idle, arrangements were
made to discuss in detail Consolidated's evaporation system with their
supervisors and engineers. After these discussions it was agreed that
it would be beneficial to analyze the evaporator condensates from each
effect of their Rosenblad evaporator system. With Consolidated Papers
Inc.'s permission the results of these analyses are included as part of

this report. They are expressed as % by weight as follows:

Methanol Acetic Acid Furfural

Weak spent liquor feed 0.090 0.420 0.045
Condensate from 50% solids

effect 0.005 0.463 0.005
35% Solids effect 0.010 0.421 0.010
20% Solids effect 0.006 0.210 0.005
10% Solids effect 0.071 0.314 0.021

The condensate accumulated from one effect to another, but not
necessarily directly from the 50% solids effect through the 35% and 20%
effects to the 10% effect. No detail about the path of the condensate
will be given, since time will not permit an adequate description of

it. Consolidated has switching procedures that are too complicated to
describe without drawings. The important factor was that the condensate

from the 10% solids effect includes the condensate from all other

69


Sh

Screening

Evaporator
Condensate
Feed

802 Vapor

Appleton mill

FCO — FCFRO Methanol >
ex FOSC — FCFRSC__ Furfural
Tr
on-
den-
98.5-100.5°C ser real ACCKE
209-213°F 4 mo
a NS £ 135°F
3 5T.4ee
3 133°F |56.2°C
8 1st nd
Steam ft
Stripping 209 °F |
@ Coli 65.5-
= 16.6°C
180~ 150-170°R, g
205°F' L2°F g F|
a 4
81.2. 00. 59PC 3 3.
Bteam Strip. 96°C, < l mes
ping Column auorr] 8 Fl ga
eed Drun 6orc] BG Ba
oy 83
Tose 3 g2
0.
2 8 8
a a
2 2
sscF
130-155°F E
54.5068.3°C di
Feed Pump 3 Feed Pump
Stripping 2g Distillation 255
on 129°F | 53.9°C
13°F
. 00.59 e bl
3
a
3
Bg} 8
‘ACCACE
- 210°F
SSCB 98.8°C Y__ To Lowell Unit yp
Feed Pump 7
C FCB
Activated Carbon — _
Fractionation Column
Figure 30. Modified IPC pilot plant — Consolidated Papers, Inc.


20

el
22

23
ah
25
26

27
28
29

30

32
33

34
35
36
37
38

Figures (Continued)

Organic Loosely Combined Sulfur Dioxide Concen-
trations — Steam Stripping and Activated Carbon
Column Flows

Total Inorganic Sulfur Dioxide Concentrations —
Steam Stripping and Activated Carbon Column Flows

pH — Steam Stripping and Activated Carbon Column ,
Flows

Acetic Acid Concentrations — Steam Stripping and
Activated Carbon Column Flows Using Regenerated
Carbon

Methanol Concentrations — Steam Stripping and
Activated Carbon Column Flows Using Regenerated
Carbon

Total Inorganic Sulfur Dioxide Concentrations — Steam
Stripping and Activated Carbon Column Flow Using
Regenerated Carbon

Organic Loosely Combined Sulfur Dioxide Concentrations —
Steam Stripping and Activated Carbon Column Flow Using
Regenerated Carbon

Biochemical Oxygen Demand — Steam Stripping and
Activated Carbon Column Flow Using Regenerated Carbon

pH — Steam Stripping and Activated Carbon Column
Flow Using Regenerated Carbon

Furfural Concentrations — Steam Stripping and

. Furfural Activated Carbon Column Flows

Modified IPC Pilot Plant — Consolidated Papers, Inc.
Appleton Mi11

Both Activated Carbon Columns Regenerated with Ethanol

Steam Stripping, Furfural Activated Carbon and Acetic
Acid Activated Carbon Columns

Steam Stripping, Furfural Activated Carbon and Acetic
Acid Activated Carbon Columns

Process Flow

Regeneration — Step 1
Regeneration — Step 2
Regeneration — Step 3

Steam Stripping, Furfural Activated Carbon and Acetic
Acid Activated Carbon Columns

vii

53
54

55
51
58
59

60
61
62
64

15
83

85

87
89
90
91
92

95


SECTION VI

MASS, HEAT, AND BODs BALANCES

METHODOLOGY

Mass, heat and BODs balances are made according to the actual operating

, condition of the pilot plant at the Appleton Division Mill of Consoli-
dated Papers, Inc. and are based on data taken prior to January 17, 1973.
See Tables 14, 15, and 16. Since the individual items of the equipment
are not optimized and this general process may not be particularly ex-
act for the evaporator condensate processed, it is believed that totel
energy balances of this pilot plant would be of little value and could
be misleading. Only heat balances are made. From this basic infor-
mation, an estimate of the value of the products was obtained.

A pollutional balance sheet is also included. This sheet shows the
BODs values of the flow streams shown in the overall mass balances of
the pilot plent (Fig. 42). ‘he references for those theoretical con-
versions are also listed.

The balances presented are for the particular arrangement which was
studied during these experiments. The particulars of product value,
equipment arrangement, and operating costs for other evaporator systems
will, of course, be somewhat different depending upon the individual
pulp mill's opportunities and major objectives in the installation of

this process.
MASS BALANCES

The mass flows are shown in six separate mass-flow sheets: Figure 43
covers the separation process; Fig. 44 and 45, the recovery of furfural.
and methanol; and Fig. 46 and 47, the recovery of ethyl acetate and
ethanol. The three operations are then combined as Fig. 42 which shows

the overall mass balances of the complete process.

103


Process Options

The following process options were presented at a meeting of the co-

operators on January 17, 1973 and remain as valid options for appli-
cation of the system.

1. Separate the evaporator condensates from the various effects, so
that only that portion high in methanol, furfural, and sulfur
dioxide is steam stripped, and those high in acetic acid are
adsorbed on the activated carbon.

2. Steam ‘strip the weak spent liquor to remove SO., methanol, and
furfural before the evaporators. Recycle the portion of condensate
weak in acetic acid concentration, and send that which is more
concentrated to the activated carbon adsorbers.

3. Adsorb the furfural directly from the weak spent liquor with
activated carbon before evaporation. Separate the evaporator
condensates, so that only that portion with concentrations high
in methanol and sulfur dioxide is steam stripped, and those with
concentrations high in acetic acid are adsorbed on the activated
carbon. °

4, Steam strip that portion of the evaporator condensate with con-
centrations high in methanol, furfural, and sulfur dioxide.
Neutralize the overhead with Ca(OH), to destroy the furfural
and sulfur dioxide. Recover the methanol in the fractionation
column. Adsorb those portions of evaporator condensate high in
acetic acid concentration on activated carbon. Regenerate the
carbon with methanol. Treat the regeneration effluent with
Ca(OH)2 to destroy the furfural and methyl acetate. Recycle and
recover the methanol in the fractionator. Spray dry the Ca(OH).
reaction products.

5. Adsorb furfural and acetic acid in one activated carbon column,
regenerate the carbon with ethanol, recover the ethyl acetate,
furfural, and ethanol.

6. Recycle the ethyl acetate-ethanol regenerating agent until the

ethyl acetate concentration is at its economical peak. Recover

73


When only steam remains in the carbon column, it is ready for its next
adsorption cycle.

Figures 40 and 41 show the application of what was learned in this
project used as the bases to project the utilization of the developed

unit operations for clarifying evaporator condensate at Consolidated
Papers, Inc.'s Appleton Mill.

Present Project Status

During Project 3100 enough data were compiled to assist interested
sulfite pulp manufacturers toward making feasibility studies for uti-
lizing steam stripping, fractionation, and activated carbon adsorption
systems as tools toward solving their pollution problems. The major

project achievements were:

1. The development of a steam stripping system capable of removing 90%+
by weight of the sulfur dioxide in evaporator condensates. Only
the evaporator condensate data for interested mills need be estab-
lished to effectively design this system.

2. The fractionation system developed and patented by Scott Paper
Company was optimized. This system is capable of producing high
purity sulfur dioxide for reuse back in the mill, methanol for
reuse and eventual sale, and furfural for sale.

3. The verification of selective activated carbon adsorption data
compiled at Scott Paper Company and used as the bases for their
selective adsorption patent. Carbon loadings were established.

4. An activated carbon regeneration system capable of producing a high
purity ethyl acetate crude (89% by weight ethyl acetate) from ad-
sorbed acetic acid was demonstrated.

5. The use of alcohol and water for regenerating the activated carbon
when using relatively clean evaporator condensate was shown to be
effective. The carbon life showed signs of deteriorating when dirty

evaporator condensate was processed, and the carbon was regenerated

99


previously contained only methanol and acetic acid. By now it was ap=
parent that ethyl acetate, ethanol, furfural, and water removal in one
fractionation column was going to be too complicated, so the recovery
of furfural was abandoned. It was allowed to go out the bottom of the
fractionation column with the water and residual spent liquor solids.
The ethanol feed and the steam to the activated carbon column system was
shut off. The fractionation column was held at total reflux overnight.

The next day there were two partially regenerated activated carbon
columns, about 40 gallons (151.5 1) of ethanol in the complete regen-
eration system and flow rate limits to the fractionation column of about
0.15 gpm (0.57 1/min.). The regeneration was continued, and the flow
rates to the carbon columns were varied from 0.1 (0.38) to 0.3 (1.14
l/min.) gpm. The ethyl acetate was allowed to accumulate in the frac-
tionation column. Although not practical, this system worked well and
the carbon columns were regenerated, see Fig. 32. Unfortunately, about
mid-morning the water pressure in the main header dropped substantially,
and no cooling water reached the condenser at the top of the fraction-
ation column. Over a 15-minute period all the ethyl acetate and
ethanol remaining in the top of the column vaporized and discharged
through the vent. Even so, the recovery of ethyl acetate was the high-
est of any run. Although the level in the ethanol storage tank showed
almost full recovery of ethanol, results of analyses (two days later)
showed water and ethyl acetate in the alcohol and ethanol in the
activated carbon column effluent.

Since Process Option 9 was the second choice, it was decided to run the
adsorption and regeneration cycles on the two columns in series, Evap-
orator condensate feed rate was held at 0.5 gpm (1.9 l/min.) and 10% by
weight of feed stripping steam was used to assure maximum removal of
methanol and furfural. For regeneration, a line was built from the
ethanol feed pump to the top of the activated carbon column-furfural,
and from the top splitter on the fractionation column to the ethanol
feed drum. Water and residual spent liquor was to be removed from the

8h


5-Day Biochemical Oxygen Demand, mg/liter

8000 p—

7000

6000 F-

5000]

4000

3000

2000;-

1000/~

Steam Stripping, Furfural Activated Carbon and
Acetic Acid Activated Carbon Column

Feea Rate = 1 gpm (3.78 liters/minute)
Stripping Steam = 6% by Weight of Feed

Steam Stripping Column
Feed

Steam Stripping Column 7
Bottoms

Furfural Activated —O—O
Carbon Column Effluent

Acetic Acid Activated
Carbon Column Effluent

1 i 1 it i ! L }

2 3 4 5 6 1 8 9 1 mM 212 13 ww
Hours Column Used

Figure 19. Biochemical oxygen demand — steam stripping and
activated carbon column flows

52


Acetic Acid, % by weight

0.4

Acetic Acid Activated Carbon Column
Feed Rate = 1 gpm (3.78 liters/minute)
°
0.3
2 / “\ WV
“~
0.2 /V, / Wy /
°
Oe
x x ©—0—0—0—0—o- Feed
/ Xk Effluent
x
o
Z wl
Nye
ne owe Soe Ce" | ! n l t l t ' j
° 1 2 3 4 5 6 T 8 9. 1 2 43 4h
Hours Column Used
Figure 15.

Acetic acid concentrations — acetic acia activated
carbon column feed and effluent

48


Table 3. METHANOL, ACETIC ACID, AND FURFURAL ASSAYS BY GAS CHROMATOGRAPHY

Sample
Mi11 number

A a
A 2
A 3
Au
BOS
B 6
B 7
a 8
B48
B ig
B 32
B 33
c 9
c 20
con
cow
D 13
D a
D 2h
D285
zg
EB 16
zg ous
Fr 20
Fr 22
Fo 83
eo a
HO (OG
watt
R28
a Ea
I 30
J a

AND CALCTUM AND SODIUM ASSAYS

Sample tdentification
Dense hardwood 9/7/72
Dense hardwood 9/8/72
Dense hardvood 9/9/72

Aspen-dense hardwood
9/30/72

66% Hardwood, 34% softwood

Sane as No. 5 but used
for wash

938 Popler, 1% spruce

Seme as No, 7 but used
for wash

Mf Hardwood, 86% softwood

e as No. 18 tut used
for wash

SSL, 3¥% hardwood, 66%
softwood

3N% Hardwood, 66% softwood
200% Aspen 9/19/72
100% Aspen 9/20/72
100% Aspen 9/22/72
100% Aspen 9/26/72

95% Aspen, 5% spruce
‘combined condensate

95% Aspen, 5% spruce
second effect

95% Aspen, 5% spruc
combined condensate
1/2W/73

95% Aspen, 5% spruce
second effect 1/24/73

100% Hardwood
100% Softwood.

Total discharge including
surface condensate

Exploded wood pulp
Hardboard mill 12/20/72
Hardboard mitt 1/4/73

Softwood

Softwood, high solide
effect

Softwood, low solids
effect

Softwood, 26 and 27
blend

total con-

softwood 2/2/73
softwood 2/5/73

Srrom prestripped neutralized SSL.
Yrotal condensate from prestripped unneutralizea SSL.

Vie

‘MeOH,

nef
‘420
530
h20

370
1877

5

405
1035

aT
130
520

480
eT
185

Tone
420
220

23
233
at

10

chromat ogr!

Reetic
acid,
ng/L

6260
5630

5000

4790
6057

6200
7390

6100

6045:

5533
6000
5312
Sure
6088
6673,

3637

hat

2730

3770
1650
5075

1007
2450
1300
2760

<300

<300

1943,
1533

2100

Furfural,

mg/2.
630
THO.
Tho

530
2273

a5
1485

515
To

535

1000
1800
283
365

wT

323

235

133
255
325

Sut

7
285
295
220

one

190
160
107

ce,
ang/1

90.9
92.5
nyg.5

108.5

298.5,
123.0
498.5
291.0

Trace

‘Trace

89.0
3.8
LS
1.8

219.5

‘Trace

‘Trace

‘Trace
‘Trace
Trace

Na,
al
2.0
22

2.2

22
ok

0.6

0.5

OT
0.5

ab
0.7
3.0

Le

0.6

Ob

1.3
0.5
0.8


Table 5 (cont'd). METHANOL BALANCE STEAM STRIPPING RUNS
9-11-72 to 9-20-72

9-15-72

In Feed

4 (0.502) (8.33) (60) (0.000575) = 0.578 1b (0.263 kg)
In Overhead

4 (0.0409) (8.33) (60) (0.00335) = 0.328 1b (0.149 kg)
% Recovery = (0.328/0.578) 100 = 56.8%

9-18-72

In Feed

4 (1.52) (8.33) (60) (0.00094) = 2.74 1b (1.245 kg)
In Overhead

4 (0.047) (8.33) (60) (0.0043) = 0.405 1b (0.184 kg)
% Recovery = (0.405/2.74) 100 = 14.8%

9-18-72

In Feed

& (1.368) (8.33) (60) (0.00056) = 1.53 1b (0.695 kg)
In Overhead

4 (0.045) (8.33) (60) (0.00354) = 0.318 1b (0.144 kg)
% Recovery = (0.318/1.53) 100 = 20.8%

9-19-72

In Feed

2 (1.140) (8.33) (60) (0.00062) = 0.695 1b (0.316 kg)
In Overhead

2 (0.050) (8.33) (60) (0.00424) = 0.212 1b (0.096 kg)
% Recovery = (0.212/0.695) 100 = 30.5%

9-19-72

In Feed

2 (1.215) (8.33) (60) (0.00056) = 0.680 1b (0.309 kg)
In Overhead

2 (0.057) (8.33) (60) (0.00364) = 0.207 1b (0.094 kg)
% Recovery = (0.207/0.680) 100 = 30.5%

9~19-72

In Feed

4 (0.76) (8.33) (60) (0.00035) = 0.532 1b (0.2h2 kg)
In Overhead

4 (0.046) (8.33) (60) (0.00270) = 0.248 1b (0.113 kg)
% Recovery = (0.248/0.532) 100 = 46.7%

39


Table 6 (cont'd). FURFURAL BALANCE STEAM STRIPPING RUNS
9-11-72 to 9-20-72

9-20-72

In Feed

4 (0.608) (60) (8.33) (0.0001) = 0.122 1b (0.0554 kg)
In Overhead

4 (0.050) (60) (8.33) (0.000825) = 0.0825 1b (0.0374 kg)
% Recovery = (0.0825/0.122) 100 = 67.6%

9-20-72

In Feed

4 (0.502) (60) (8.33) (0.00015) = 0.151 1b (0.0685 kg)
In Overhead

k (0.051) (60) (8.33) (0.000825) = 0.084 1b (0.0381 kg)
% Recovery = (0.084/0.151) 100 = 55.6%

Total furfural in overhead

0.019 1b
0.117 1b
0.133 1b
0.090 1b
0.089 1b
0.091 1b
0.126 1b Collected — 0.925 1b (0.419 kg)
0.080 1b
0.046 1b
- 0.040 1b
0.058 1b
0.082 1b
0.084 1b

1.055 1b (0.479 kg)

43


Sulfur dioxide (TI) 560,000 1b/year 254,500 kg/year
Sulfur dioxide (OLC) 298,000 1lb/year 135,300 kg/year

Conversion of the acetic acid to ethyl acetate would give 3,440,000
lb/year (1,560,000 kg/year).

The product value is:

Ethyl Acetate

Market value — 3,440,000 ($0.12) = $412,000
Mill value - 3,440,000 ($0.09) = $310,000
Furfural
Market value — 140,000 ($0.175) = $ 24,500
Mill velue - 140,000 ($0.138) = $ 19,300
Methyl Alcohol
Market value — (569,000/7.5) ($0.12) = $ 9,100
Mill value — (569,000/7.5) ($0.104) = $ 7,900
Sulfur Dioxide
Market value — (858,000/2) ($0,001) = $ 4,290
Mill value — (858,000/2) ($0.001) = $ 4,290
Total Market Value = $412,000 + $24,500 + $9,100 + $4,290 = $449,890
Total Mill Value = $310,000 + $19,300 + $7,900 + $4,290 = $341,490
Cost of Ethanol = $166,000
Money left to pay
for operating costs,
capital expenditure,
maintenance, etc. = $175,490

No credit was taken for reusable water and/or elimination of pollution
problems. It was believed that the capital costs will compare favorably

with the secondary treating process for this waste flow.

A more complete analysis of this same information based on actual
complete material and heat balances on the pilot system are presented

in a later section.

72


removal of 200 (90.8 kg) pounds of BODs gave the following summary of
values to be derived from the process shown in Table 17. It should be
mentioned that no credit has been given to the value of the reusable

water or recovered sulfite liquor.

The major operating expense is steam, and with an estimated power con-
sumption and labor requirement for an automated system, the combined
expense and estimated gross net income per year are shown in the same
table.

These figures provide guidance as to which portions of the process are
most productive of byproducts and which might be simplified, modified,
or eliminated with little detriment to the overall economic performance
of the installation. Such modifications and more accurate data on costs
of operation would have to be provided by detailed full-scale design
work specific to the desires of the local mill management.

POLLUTIONAL BALANCES

To show the effect of recovering the various chemicals from the conden-
sates, upon the pollution load, the BODs values of these materials have
been calculated and assembled as a balance sheet. This is given in
Teble 18. The relative BODs values of these materials have been taken
from tables previously published in Sewage and Industrial Wastes. Of
the 202 pounds (91.7 kg) of BODs admitted into the system (by analyses),
161 pounds (73.1 kg) have been accounted for by using equivalent BODs
values of these materials.

CONCLUSIONS

Based on the analysis of the recovered materials and the Operating data,
the conclusion can be drawn that the process is economically feasible.

Sizing of the equipment and more accurate economic feasibility analysis
were intended but not made because of these facts:

134


Heat given up = [13.5 (0.134) + 0.300 (0.458) ] (149-97) =
101 Btu (25.4 kg-cal).

Heat given up by the methanol stream during condensing from
vapor to liquid = 15.0 (263) (1.8) + 0.2 (94.9) (1.8) = 7140
Btu (1799.3 kg-cal).

Total heat removed by cooling water = 72hO Btu (1824.5 kg-~cal).
II. Recovery of furfural and methanol

A. Furfural recovery

1.

3.

Vaporizer

Assume methanol. available at 70°F (21.1°C) from feed tank.
sp. gr. = 0.792

c, = 0.6 (liquia)

c, = 0.458 (vapor)

A = 262.8 cal/g

dep. = 64.7°C = 148.5°F

a. Heat required to heat the MeOH from 70°F (21.1°C) to
148.5°F (64.7°C). Hy = 640 (148.5-70) (0.6) = 30,100
Btu (7585.2 kg-cal).

b. Heat required to heat the vapor from 148.5°F (67.7°C)
to 151°F (66.1°C). Hs = 640 (0.458) (1.8) (2.5) =
1320 Btu (332.6 kg-cal).

Condenser after the activated carbon column.

The liquid coming out of the activated carbon column con-

tains 639 lb (290.1 kg) of methanol, 92.0 lb (41.8 kg) of

water, 4.00 1b (1.8 kg) of furfural, and 4.00 1b (1.8 kg)
of polymerized materials. The temperature is at 148°F

(64.4°C). After the condenser, it is cooled to an average

temperature of 100°F (37.8°C). Heat given up = (148-100)

[639 (0.566) + 92.0 (1) + 4.00 (0.428) + 4.0 (0.5)] =

22,000 Btu (5544 kg-cal).

Fractionation column

a. Reboiler

127


SECTION IV
ASSAY OF CONDENSATE SAMPLES FROM SUPPORTING MILLS
METHODOLOGY

Samples from ten mills of eight companies sponsoring this project, in-
cluding samples from the Appleton Division of Consolidated Papers, Inc.
taken during operation of the pilot-scale chemical recovery system,
were received. The samples have been analyzed for 12 parameters. Most
of the condensate samples showed greater potential for acetic acid and
furfural recovery than is available in the condensate at the Consoli-
dated mill. The content of a condensate varies with the pulping
process and is substantially affected, first, by the type of wood
cooked, second, by the nature of the cook and, third, by the pH of the

liquor being concentrated.
METHODS OF ANALYSIS

The procedures used in these analyses are as follows:

pH

pH was determined on a Beckman pH meter.
Sulfur Dioxide

Two types of sulfur dioxide were determined; TI (total inorganic)

and OLC (organic loosely combined). ‘The total inorganic sulfur di-
oxide which is sometimes designated as free sulfur dioxide was deter-
mined by direct titration with standard iodine at 0°C (32°F). The
organic loosely combined sulfur dioxide is that sulfur dioxide which
is combined but which is readily releasted by treatment with alkali
followed by acidification. It is determined by making the sample
strongly alkaline with sodium hydroxide followed by acidification
after one hour and titration with standard iodine at 0°C (32°C). This
is the standard TAPPI procedure.


III.

B.

Fractionation column condenser.

No flow quantity of the vent is available. Heat given up

by the methanol = 639 (263) (1.8) = 302,000 Btu (76,104
kg-cal).

Methanol recovery

Assume same operating conditions on the fractionation column.
Enthalpy balance around the fractionation column:

1.

Reboiler

Assume 30.8 1b (13.98 kg) of reboiling. Heat required to
heat the liquid (which is essentially water) from 210°F
(98.9°C) to 212°F (100°C) = 30.8 (1) (2) = 61.6 Btu (15.5
kg-cal)

Heat of evaporation = 30.8 (970.3) = 29900 Btu (7534.8 kg-
cal)

Heat required to heat vapor from 212°F (100°C) to 2h7°F
(119.4°c) = 35 (30.8) (0.482) = 520 Btu (131 kg-cal)
Total heat required = 30,500 Btu (7686 kg-cal)

Condenser after fractionation column.

No vent flow quantity is available. Heat given up by
methanol = 0.639 (263) (1.8) = 302 Btu (76.1 kg~cal)

Heat loss ~— fractionation column.

Use 149°F (65°C) as reference temperature.

Heat in = 30.8 [(0.482) (1) + 970.3 + (1) (63)] = 31,800
Btu.

Heat out = (308-30.8) (1) (64) = 21,700 Btu (5468.4 kg-
cal).

Heat loss = 10,100 Btu (2545.2 kg-cal).

The heat loss shown here can be either higher or lower for

similar reasons as indicated before.

Recovery of ethyl acetate and ethanol

A.

Ethyl acetate recovery

For ethanol:

= 0.785

bop. # 78.5°C = 173.3°F

129


Acetic Acid, % by weight

0.4

0.3

Acetic Acid Activated Carbon Column
Feed Rate = 1 gpm (3.78 liters/minute)

Figure 1h.

/ / y, J

0—0—0—0—0—o- Feed
/ . RK KR eH Effluent

i rN L 1 1 it i 1 it i

4 5 6 7 8 9 10 32 212 13 1
Hours Column Used

Acetic acid concentrations — furfural activated
carbon column feed and effluent

, 47


The low temperature regeneration of carbon was an extension of work

previously performed at The Institute of Paper Chemistry. This approach

continues to be of interest and is considered to be technically feasible.
However, all attempts to use the principles and equipment for electrical
induction heating, as developed at the Lowell Technological Institute,

failed due to mechanical design problems encountered in the pilot trials
and which could not be developed and corrected within the time and fund.

ing available for this project.

This report was submitted in fulfillment of Grant No. S-801 207 under
the partial sponsorship of the Environmental Protection Agency, by The
Institute of Paper Chemistry with the Wisconson Department of Natural
Resources and a group of pulp and paper mills cooperating. Work was

completed as of May 1973.

iv


loaded electrodes to prevent loss of contact between elec-

trodes and carbon.

166


for one-half hour at a voltage of 109 and amperage between 52 and 66,
which indicated an electrical resistance of 0.42 to 0.52 ohm per foot
(1.38-1.71 ohm/m) of carbon. Surface temperatures taken at the end of
one-half hour operation are given in Table 2h, and they indicate that
the column did not heat in a uniform manner. Temperatures around the C
location were considerably higher than either the top or bottom, al-
though the internal thermocouples did not register this variation.

The unit was operated for an additional hour during which time the
temperatures rose only very slowly, except in the No. 1 position, which
registered 107°C (225°F). During this time, electrical resistance was
between 0.52 and 0.64 ohm per foot (1.71-2.10 ohm/m) of carbon. Sur-
face temperatures were then read and, although there were not any hot
spots, the center of the column was considerably higher than either end,
with the bottom being the coolest.

An attempt was made to split the current by making connections between
A and C and E and C. With this configuration, the temperature at the
No. 1 thermocouple rose very rapidly to 127°C (261°F). Because of this,
the power connections were changed to B to E to attempt to heat only the
bottom 3 feet (91.4 em) of carbon. With the transformer output set at
173 volts, there was a current flow of 61 amps, which was equivalent to
0.94 ohm resistance per foot (3.08 ohm/m). During the 10 minutes of
operation, the temperature rose at the No. 3 thermocouple location from

100°C to 169°C (212°F to 336°F).

On the morning of February 6, the column was again flooded with tap
water and drained. A stream of air was admitted to the bottom of the
column, but no attempt was made at the exact measurement of the air.
Air was used periodically through various trials, put at no time did i+
appear to have much effect, either favorably or adversely. The trans-
former was again connected over the entire 4 feet (1.2192 m) of carbon
at A and E electrodes. During the first hour of operation, electrical
resistance changed from 0.71 to 3.54 ohms with a gradual increase in
the temperatures to around the 80°C (176°F) level. At the end of 50

155


49

Furfural, % by weight

0.05

Steam Stripping and Furfural
Activated Carbon Columns

Steam Stripping Column ° e bd
Feed

Steam Stripping Column x———x——<—*
Bottoms

O.ok-- Furfural Activated Carbon 999
. Column Effluent
0.03,-
o— AN
. ee — es e .
al \
0.02|_ / x °
Pr !
. ° + a IN - a
x
e—e aN ——
—~_ WA * IN x
0.01 -X—x > #8 xX \iK *
x Lat °o
Pf
0 Lt L ! Lp ZL 1 l ! L ! ! bd J
fe) 4 8 12 16 20 2h 28 32 36 ho 4h 48 52 56 60 64 68 T2
Hours Column Used
Figure 29. Furfural concentrations — steam stripping and furfural activated

carbon column flows


adaptability to kraft condensates, were applied for by the Scott Paper
Company in 1971.

METHODOLOGY

In July, 1972 the pilot plant at Everett was dismantled and shipped to
Appleton. Since preliminary analyses of Consolidated's evaporator con-
densates showed their methanol, acetic acid, and furfural compositions
considerably lower than those encountered at Scott, the initial pilot
plant units were arranged as shown on Fig. 2. The activated carbon
regeneration systems were built as shown on Fig. 3 and 4. No more than
50 minutes storage capacity was provided for storing the evaporator
condensate fed to the pilot plant area. No special arrangements were
made with Consolidated Papers, Inc.'s operating personnel. The evapor-
ator condensate was sent to the pilot plant in the same manner that it
was drained. The main differences between this work and that done

previously were:

1. The evaporator condensate was processed within minutes after
it was produced in the evaporators. Previous work was done on
condensates that had set long period of time (weeks) before
they were processed.

2. At times, portions were received of this condensate which had
been used to wash scale, fibers and spent sulfite liquor from
the evaporator surfaces. Previously only clean condensate

was used.

One purpose of this pilot plant project was to prove the processes
developed could handle evaporator condensate after it had been used to.
wash the evaporator surfaces. It. was also desired to provide a choice
of commercially feasible alternatives for processing of evaporator con-
densates, with recovery of saleable values wherever possible to help
pay the costs of disposal processing of this waste flow from acid
sulfite mills equipped with evaporators. It was anticipated that more

than one possible route to recovery of these volatile components would

19


10,

Steam Stripping, Furfural Activated Carbon and
Acetic Acid Activated Carbon Columns

Feed Rate = 1 gpm (3.78 liters/minute)
Stripping Steam = 6% by Weight of Feed

Steam Stripping Column
Feed

Steam Stripping Column
Bottoms

Ke Km K

Furfurel Activated Car-
bon Column Effluent

Acetic Acid Activated
Carbon Column Effluent

“~, a

Oct. 23, 1972 Nov. 6, 1972

1 it 1 1 | t i it it it n

1 2 3 4 5 0 1 2 3 4 5 6 1
Hours Column Used

Figure 28. pH — steam stripping and activated carbon column floy

using regenerated carbon

62


SECTION VII
LOW TEMPERATURE REGENERATION OF CARBON
METHODOLOGY

This phase of the project has to do with an attempt to scale up prior
laboratory development studies for low temperature [(200°C) (392°F)]
regeneration of carbon adsorption columns. Previous projects performed
at The Institute of Paper Chemistry in which removal of BODs and coD
contributing materials from the condensates derived from the evapora-
tion of spent sulfite liquors were studied utilized 2-inch (5.08 cm)
glass and stainless steel columns. Successful regeneration of this
carbon over 32 cycles by applying heat to the column by means of an
electric tape and superheated steam lead to its inclusion in this
project. It was obvious that another system for heating of the larger
column would have to be found, and without the introduction of addition-

al water which would result in diluting the concentrated materials.

Early in 1971 it had been learned that Messrs. Bela M. Fabuss and
Wilson C. Dubois of Lowell Technological Institute had applied for a
patent entitled "Apparatus and Process for Desorption of Filter Beds by
Electric Current." Basically, the process consists of utilizing the
carbon bed itself as an electrical resistance heater, permitting a
rapid temperature rise without any indirect heat transfer. Contacts
with Professor Fabuss eventually lead to an agreement with Lowell
Technological Institute to construct an activated carbon column incorp-

orating this means of heat regeneration. Operation of this unit is the
subject of this phase of the project.

The unit as constructed by Lowell consisted of a one-foot (30.5 cm)
diemeter stainless steel column with a total height of 5 feet (1.52 m)"
and containing 4 feet (1.22 m) of activated carbon. Stainless steel
grid electrodes 1/2 inch (1.27 cm) thick were spaced at 1-foot (30.48
cm) intervals. A stainless steel screen was fastened to the underside
of the bottom electrode to support the carbon. The column was electri-
cally insulated on the interior by a teflon coating and the electrodes

138


10

Steam Stripping, Furfural Activated Carbon and
Acetic Acid Activated Carbon Columns

Feed Rate = 1 gpm (3.78 liters/minute)

ok Stripping Steam = 6% by Weight of Feed

Steam Stripping Column  4—_,¢
Feed

Steam Stripping Column
Bottoms

—— KH

Furfural Activated Car- O——-O———0
L¢ R a@ bon Column Effluent

Acetic Acid Activated o—o—-©

Carbon Column Effluent

3 X————_ yy ——
————.___, . ° e ° °

ok

le

0 | ! ! ! ! i i n ! ! ! ! i l

0 1 2 3 & 5 6 7 6 9 10 a 22 13 1h
Hours Column Used

Figure 22. pH — steam stripping and activated carbon column flows
55


the same mill. This is the result of the cooking characteristics of
each individual situation. From the viewpoint of the condensate chem-
ical recovery process, those condensates containing relatively high SO2

content will have to be steam stripped.

Most condensate samples upon aging will turn darker in color. So the
color levels given in Table 1 are not necessarily indicative of what

the fresh condensate would be. However, it is evident that some of this
color is derived from lignin carry-over during evaporation or in some
cases lignin entrainment when the condensate is used to wash the evap-

orator.

The BODs (Table 2) is largely derived from the acetic acid, although in
some cases the furfural and methanol are heavy contributors. As would
be expected, the BODs on condensates derived from hardwood liquors is °
considerably higher than those derived from softwoods. It is much
easier to assess the source of the COD than for BODs. As an example,
if one calculates the COD derived from the acetic acid, the formic acid,
furfural, methanol, and SO, of Sample 21, a calculated COD of 4100 mg/1
is obtained. Comparing this with a determined COD of 7620 mg/1 shows
that a good deal of the COD must be derived from liquor carry-over or
from liquor entrained during washup of the evaporators. The high color
content of 250 color units verifies this hypothesis. If one takes
several other samples at random and determines the calculated COD on
the same basis and compares it with the determined COD, the following
results are obtained: Sample 1, calculated COD 8050 mg/1, determined
COD 10,140 mg/l COD. Again the difference indicates relatively high
lignin content and again this is verified by the high color content of
200 color units. Sample 18 had a calculated CoD of 8,631 mg/l ana a
determined COD of 9,487 mg/l. Obviously, this sample contained much
less liquor carry-over and this is verified by the lower color content
of 70 color units. Sample 29 had a calculated COD of 2,811 mg/1 and a
determined COD of 3,191 mg/1, with a low color of 15 color units.
Sample 31 had a calculated COD of 3,162 mg/1 and a determined COD of

12


100—-

Methanol Removal, %

Scott Paper Company
Everett Mill Blow Gas Condensate
gok- e 6-Inch (15.24 om) Goodloe Packing
12=Inch (30.48 cm) Goodloe Packing
X  18-Inch. (45.72 cm) Goodloe Packing
2h-Inch (60.96 cm) Goodloe Packing
Bok © 30-Inch (76.20 cm) Goodloe Packing
TOR
60}-
50
Lol
30.
20,
+
10-
0 n n ! n 1 1 1 ! L L 1 4
C) 1 2 3° 4 5 6 1 8 9 lo al 12
Stripping Steam, % weight of feed
Figure 6. Methanol removal vs. stripping steam used — Scott

. Paper Company — variable packing
29


Table 22. LOWELL UNIT ~ DIRECT CURRENT

Water Evaporation
Filtrasorb 400 Carton
Carbon Bed 1 ft x hk tt (30.5 om x 1,219 m)

Rectifier No.1 Rectifier No. 2 Tenper Sc (91
Date Time “Volts Aupe Volts Amps T poe 5 en

Power connection — anodes — A, C, & E

cathodes — B — Rectifier No. 1
—D-—Rectifier No. 2
1623-73 B2h3, 25 50 25 25 —-33( 91) 33( 91) 36( 97) 35( 95
Hed 25 60 25° 27 = 70(158) 57(135) —50(122) 3h(v29)
353, ° Q 25 2. T5(26T) G6o(aho) —58(136) 66(151)
Wet carbon with warm tap water
10:15 6 50 o QO Tt 63) 32( 88) (106) 4A(1aa
21:05 poy 83 0 9 = 56(133) 66(151) —41(106) ian}
us a 82 16 50 66(151) 76{169) 7(417) 50(122)
11:35 n TL 22 76 — 83(181) 89(192) 70(158) 70(158)
12:35 a 66 22 56 —79(174) 92(198) 91196) 91(196)
1:5 18101 at 5T ~—-92(198) 92(198) —91(196) 90(19h)
1335 18 107 he TT —91(196) 91(196) 92(296) 90(29h)
2:05 18 102 53 93 92(198) 92(198) -94(201) 93(199)
2:35 18 (76 58 130 90(294) 86(187) _245(473) 2ho(284)
22h 28 66 o © — go{igh) 88(190) 250+(482) 212(424)
3:05 2h 68 r) © —_ga(198) 92(198) 250+(482) 235(455)
3:25 50 oe ° © —123(253) 103(217) 250+(hb2) 2b3(469)
3355 50137 o  122(23h) 164(327) 250+(482) 233(452)
26 (6.87 gal) Liters vaporized from column ,
1-2b-73 8358 32 50 AT 50 37( 99) W7(112)“We(12)52(126)

Wet carbon with tap water

9:50 1305 ° © — 2i( 70) Wa(109) 48(228) 51(224)
10:10 17 100 ° © = -h5(113) 68(154) 50122) S1(12k)
10:36 1T 92 37 100 -72(260) g2{198}  92(198) 60(1ko)

Sudden drop in amperage on Wo. 2 rectifier
Power connection — anode ~ D
cathode ~ B — Rectifier No. 2

a:o7 ° o 5253 ~- - _ _

Power connection — anode
cathode - EB ~ Rectifier No. 2

~ ° ° ~- 95 _~—-Immediate arop in amperage

Power connection ~ anode — D
cathode — B — Rectifier No. 2

pease) ° ° 33
33

lo _ - _ _
aah ° 0 6 —89(292) 9ol294) 91(196) 9r(196)

Power connection ~ anode — B
cathode — D — Rectifier Ho. 2

=~ ° ° 52012 - - ~_ -

Power connection ~ anode — B
cathode — D — Rectifier No. 1

1 hh 62 33 ° ° - - ~ ~

Wet carbon with tap vater
Power connection ~ same a8 on 1-23-73 above

: 5 ° 0 © hr(a12) W7(12) 80(276) 86(287)
255 TT 0 0 -—«9u(196)' 92296) 75(267) 80(276)
5 1 p 32 50 91196) 91(196) 76(269) 80(176)

5 aq b 32 32 91196) 91(196) 91(196) 91(196)
S 18 5 ° © 91296) 91(196) go(1gh) 89(192)

in amperage on Rectifier No. 2

‘Lb pressure applied to colum ~ momentary incr

4:ho 18 itd °

10 Lv/in? (0.7 kg/cm?) pressure applied to column ~ momentary increase in amperage on
Rectifier Wo. 2

1h


Methanol, % by weight

0.0g~

0.0g.

0.0f

0,04

0.03-

Steam Stripping Column
Feed Rate = 1 gpm (3.78 liters/minute)
Stripping Steam = 6% by Weight of Feed

x
0.05.
0.0R.
x.

ee

OO
a \
/ |

0.04
°. ° ° © Feed
0.0. » X——xX—— x Bottoms
oo i 1 Lb =) Ll i i i] i i 1 L J
te) 1 2 4 5 6 1 8 9 10 a2 212 13
Hours Column Used
Figure 16. Methanol concentration — steam stripping colum

feed and bottoms
hg


effort was made to alter the gas chromatography procedure to alleviate
this problem, since the ether extraction procedure had also been used.

CONCLUSIONS

The analysis of the condensate samples submitted by sponsors of this
project have indicated the potential amount of SQ2, acetic acid,
methanol, and furfural that would be availeble for recovery. For most
of the participating mills, the output of these components would exceed
the recoverable chemicals available in the condensate from the Consoli-
dated mill where the system was under pilot-scale study.

15


Table 18. POLLUTIONAL BALANCE SHEET

Acetic Acid” 80,° Furfural® BODs~1b(kg)
Totkg! MeO GT Toke! ‘BODsLaCke) Titi. ‘BODs=Lb(kg Tete. ‘BODs-lbUke) Out

rt 32.5 27.95 134.0 100.50 49.0 12.25 8.0 6.16 146.86.
mate seven Gig) G28) Geoles) (5-63) (22125) (5.56) (3563) (2.80) (66.67)

Separation
80g stream 1.50 1.29 oO ° 9.38 0.9 0.69 212.36
(0.68) (0.58) (0) (0) ar. fe) (. 26) (0.42) (0.31) (5.26)
MeOH stream 15.0 12.9 oO oO o iJ 12.95,
(6.61) (5.86) (0) (0) (o 9) ©: 2) (0) (0) (5.88)
Furfural stream 0.0 9.0 0 0 0 0 3-1 2.39 2.39
(0.0) (0.0) (0) (0) (0) {0) (2.42) 2.08) (2.08)
Regeneration
Purfural column oO o oO oO oO oO ko 3.08 3.08
(0) (0) (0), (0), ~— (0) (0) (1.82) (2.40) (2:40)
Acetic acid column ° oO 123.7 63.25. o ° ° ° 03 +25,
(0) (0) (56.15) (28.72) (0) (0) (0) (0) (28.
93-03,
(h2.2b)
Re-ussble water stream 16.0 13.76 9 ° 2.0 0.5 oO oO 1h.26
(1.26) (6.25) ° (0) (0) (0.92) (0.23) (0) (0) 6.4
(6.47)

Waste material to be burned

From separation oO oO 5.60 4.20 9 ° oO oO
(0) (0) @.s5h) G91) (0) (0) (0) (0)
Unaccounted acetic oO o 11.50, 8.55 ° ° oO oO
acid (0) (0) G22) (3.88) (0) (0) (0) (0)
From furfural regen- ° ° ° oO ry ° 0
eration (0) (0) (0) (9) (0) (0) (0) (0)
From acetic acid oO oO 32.6 2h. bs: o o ° °
regeneration (0) (0) (24.60) (12.10) (0) (0) (0) (0)
Total, 16,86 1b.k9
(66.67) (65.60)
Total BODs into system (by analyses) based on mean data of Report Two, page 7, 202.3 1b (91.84 kg)
Total BODs into system based on calculated data, 146.86 1d (66.67 kg)
BODs in re-usable water, 14.26 Xb (6.47 ke)
BODs removal — based on 202.3 1b (91.84 kg) into system, 93.0%
BODs removal — based on 146.86 1b (66.67 kg) into system, 90.3%

Difference in calculated and anslyzed BODs into aysten largely due to carbolydrates which vould be burned with waste
material.

50,86 1b BODs/1b MeOH — Sewage Ind. Wastes 27(9):10%4 (Sept., 1955):
%.75 1b BODs/Ib acetic acta — Sewage Ind. Wastes 30(5): 677 (May, 1958).
°0.25 1b BODs/1b 802 — not a true BODs but included as BODs.

40.77 1b BoDs/1b furfural — Sevage Ind. Wastes 27(9):10K6 (Sept. , 1955).
“as ethyl acetate.

Fcarcurated from equivalent acetic acid,

136


to regenerate them in series with ethanol in accordance with Process
Option 5. The regeneration proceeded as shown in Fig. 31. Ethanol,
at the rate of 1 gpm, (3.8 1/min.) was pumped into the top of the
activated carbon column containing essentially acetic acid for 12
minutes. By plug flow essentially 10 gallons (37.8 1) of water con-
taining less methanol and acetic acid than in the evaporator conden-
sate feed was sent to the drain. In a commercial installation this
liquid would be pumped to the activated carbon column in parallel with
this one for acetic acid adsorption. The steam valve feeding steam to
the column jacket was cracked open and that feeding steam to the vapor-
izer was opened to control the steam pressure to the vaporizer at about
20 psig (1.40 kg/cm? gage). Pressure in both columns built up to about
14 psig (0.98 kg/cm* gage). Liquid was forced out the activated carbon
column containing the furfural through the condenser to the receiver.
From there it was pumped at the rate of 0.3 gpm (1.14 1/min.) to the
fractionation column, which was partially filled with ethanol. Ini-
tially, everything looked great. The liquid to the receiver rapidly
discolored. The temperature at the top of the fractionation column
was.quickly dropping its 173°F (78.3°C) temperature. What appeared to
be furfural was collecting in the tap-off section on the bottom split-
ter of the fractionation column. No furfural was detected in the liquid
from the bottom of the fractionation column. By 11:00 a.m. the temp-
erature at the top of the fractionation column had reached 158°F
(70.0°C), indicating a good grade ethyl acetate. Since alcohol was
building up in the system, a recirculation stream from the middle split-
ter back to the ethanol feed drum was started. When what appeared to
be furfural was removed from the bottom splitter and tested, it was

not furfural but highly colored water which had displaced the alcohol.
Then the problems arose. To maintain 0.3 gpm (1.14 1/min.) recircu-
lation rate of alcohol, it was necessary to recirculate from the botton
splitter. To avoid carrying water and furfural back to the ethanol
feed drum, another receiver was hooked up in parallel with it. This
corrected one problem but created another. Furfural and polymerized

material was being carried into the activated carbon column that had

82


‘Table 26. LOWELL UNIT — ALTERNATING CURRENT
Run 2 — Desorption or Regeneration
Filtrasorb 400 Caz"
Carbon bed 1 ft xb rt (s0e5 es 9 1,212.0)

Date

Sample fotets ce osgante actte
Bengerature, °C (°F) Biappistigionse temple aise, concentration, 5
Time Volts Amps T ‘Ome/fe obm/neter Wo. = liters a(t &

2-27-13 Volatile organte acids adsorbed on carton ~ 102h grams or 2.26 Ibs

2-28-73

31-73

39-13

Pover connection —B to E
‘Thermocouple configuration:

1 position, 2 inches (5.1 cm) inte carbon
2—C position, 6 inches (15.2 om) into carbon
9 —¥o. 3 position, 2 inches (5.1 cm) into carbon
4D? position, 2 inches (5.1 om) into carbon

6:22 101 gt 3902) a7 99) 35( 95) 360 97) 35 Las - - - -
8:50 103 72 r0o(2i2) —-96(205) 35 95) 100(212) OB LST - - - -
8:55 Power off — repaired top gasket leak
9:27 Power on
9:40 10h 63 96205) 97 (207) 98(208) 0.55, 2.80 L 2.00 9.05 0.10

10100133 52 gt(2oT) 98208) roo(ai2) 0.85 2.79 2 2.00 0.05 0.10

roweo 13h 3h gttzo7) onan) rov(ans) sk 30 3 200 9.18 ont

aro 1h 27 gttzor)§a3teas) i2s(a5T) «2836.00 &  2t00 0.58 1.08,

3017525 n00(2i2) —_195¢ 38a) 162(32b) 2.33 T.6k 5 2.00 0.65 Liao

aitho 17522 oo(ai2) 1188(2Nh) wosfhes) 2658.69 6 2100 13h ne

3220 17523, ou(aah) 1z2R{2s1) abr(h78) 2.54 8.33 T 2,00 2.39 4.78
1100 1N8 ho 980208) ama*(3ho) «= assR(3un), 2.23.0 6 BhT 3.56 a9

Changed pover connection from A to B
1:30 10h 6 99(210) =. - =. 2.39 456 9 2,00 5.22 5.22
1150-108 «= 20 n00(212) 183"{361) o- —-261%(333) M0172 20 1.70 9.76 16.60
Arcing at top electrode — power off for some tine
3:50 9838 ggMeto) 1n6%(2tn) == e"{253) 2.58 BANS a, 2.80 3.27 947

Botton drain wz 1,30 hos 5.26

Avoing had ocourred on the left side of the top electrode. he the wall. Repleced electrode and added carbon to a coe of

1 inch stove electrode,
adjustments

Wet carbon with

Inmulated column with 2 inchs (5.1 cn) of glass vool, sp ater to make inmulato:

Fover connection — A to
‘Thermocouple configuration:
1 —Ho. 2 position, b inches (10.2 on) into carton colin
2- position, 2 inches (5.1 om) into carbon column
Fat yoritiony @'tnchee
=D! position, 5 inches

15.2 em) into carbon colum
2.7, en) Ante carbon eolwmn

ing oh hast 99) 37 99) ae 3199) 31(99) 0.63 2.07 - - - -
Fover off — evidence of arcti <Btor

iho ley ry ertass) stash) cm sO) ke 7 ~ =

zap amit) antek) Lo 3.32 133.00 oka,

bso ls deta} lat) dostme) dos (e) O.gk 3.08 ah 3.00 0.65

320 1h 35 nen(eis) = oa(ers) —ror(2as) 1291 1.28 4,20 15 3.00 2,38

340107 2h aon(asy = r06(223) ab (e37) serea) Lag 89 - - ~

Power connection — A to°E

405 108 «18 aoa(aah) —agatané) ne(a3h) —13h(273) 1.5092 16 3,00 0.75 2.82
Pover off, strong odor

sho Pover on

32:50 106 ak 67U453)— 66251) 7A(265)Ta(260) 226, - ~ - -
Power off, strong odor

‘Total 60,61

“thermocouple inserted 1 inch (2.5 em) into colum.

164


there was a feed tank holding more than 1500 gallons (5670 liters) of
blow gas condensate, and the feed entered the column at a temperature
of 205°F (96.1°C). At Consolidated a 50-gallon (189 liters) feed drum
was used, and the feed entered the column at a temperature of approxi-
mately 211°F (99.4°c). ,

Figures 5 and 6 show the percentage of methanol removal from Everett
Mill's blow gas condensate as a direct straight-line function of the
amount of stripping steam used. Note that none of the points are more
than the equivalent of 5% methanol removal away from the line drawn,
and both lines go through zero. This indicates the trial runs were
made under ideal operating conditions. Figures 7 and 8 show 90% or
more SO: removal, when using 2% or more weight of feed stripping
steam. The better than 99% SO2 removal in Fig. 7 versus the poor
results on Fig. 8 was due to the following:

1. When the feed entered the column at 205°F (96.1°C), less than
2% by weight of feed stripping steam was not adequate to over~
come the column heat losses and sensible heat required to
raise the liquid in the column to its bubble point and effec-
tively strip-out the SO2.

2. The data plotted in Fig. 7 were the result of samples analyzed
immediately after they had been taken. Analyses in Fig. 8
were conducted hours or even the following day after the
samples were taken. The free SO2 shown in Fig. 8 was believed
to be that regenerated from SO,-OLC which was not removed.
This was verified in future runs. S02-OLC became an important

part of the analyses from August, 1971 to date.

The clusters of points in Fig. 6 at 3 and 6% by weight of feed strip-
ping steam showed very little benefit derived from increasing column
packing height. At 10% stripping steam rate some advantage was shown
by increasing column height. Compare straight-line points in Fig. 5
and 6. However, it was doubtful that the increase would justify the

additional construction costs.

36


LL

2. Operation on Channel B

Sample

Aqua Chem Feed
Aqua Chem Prod.
Rosenblad Feed
Rosenblad #3
Rosenblad #4
Rosenblad #1
Rosenblad #2
Aqua Chem Cond.

Aqua Chem
Scrubber Cond.

Rosenblad
#3 Cond.

Rosenblad
#2 Cond.

Rosenblad
#1 Cond.

Rosenblad
#4 Cond.

Table 9 (cont'd).

EVAPORATOR STUDIES DATA

% by Weight % Solids 802, g/l
Meth. HAc Furf, PH Neut. 24 Hr TI OLc
0.066 0.336 0.032
0.054 0.321 0.029 2.83 11.88 11.53 0.507 4.588
0.028 0.337 0.016 3.59 14.55 14.44 0.181 4.182
0.010 0.328 0.015 3.85 16.86 16.95 0.157 4.305
Trace 0.311 0.016 3.88 22.09 23.03 0.206 5.920
3.98 31.85 34.53 0.281 7.020
4&.45 53.27 54.69 0.583 11.162
0.108 0.273 0.023 3.01 1.15 0.91 0.053 0.375
0,132 0.242 0.028 2.64 0.37 0.09 0.056 0.142
0 3.387 0 2.48 0.59 0.10 0.054 0.140
0.01 0.380 Oo 2.50 6.51 0.04 0.080 0.094
t) 0.293 0 2.80 0.31 0.03 0.013 0.111
0.021 0.284 0 2.25 0.42 0.07 0.452 0.262

Total

4359

3962
3962
4633
6096
7254

2390

2512

4151

3718

2384

2786

HAc

4330

3900
3886
4552
6031
7150

2377

2496

4138

3705

2371

2773

Formic

22

438
58
62
50
80

10
12
10
12
10

10

BODs,
mg/l


SSCF
SSCF
SSCCO
FCO

FCB
FCSC
ACCFE
ACCACE
ACCFRI
ACCFRE
ACCACRI
ACCACRE
FCRF

FCACRB
FCACRSC-1
FCACRSC-2
FCACRO
FCFRSC
FCFRO
FCFRB

GLOSSARY OF ABBREVIATIONS

Steam Stripping Column Feed

Steam Stripping Column Bottoms

Steam Stripping Column Condensed Overhead

Fractionation Column Overhead

Fractionation Column Bottoms

Fractionation Column Side-cut

Activated Carbon Column Furfural Effluent
Activated Carbon Column Acetic Acid Effluent
Activated Carbon Column Furfural Regeneration Inlet

Activated Carbon Column Furfural Regeneration Effluent

Activated Carbon Column Acetic Acid Regeneration Inlet

Activated Carbon Column Acetic Acid Regeneration Effluent

Fractionation Column Regeneration Feed (Furfural Regenera-
tion Effluent, Acetic Acid Regeneration Effluent, or Steam
Stripping Column Overhead)

Fractionation
Fractionation
Fractionation
Fractionation
Fractionation
Fractionation

Fractionation

Column
Column
Column
Column
Column
Column

Column

Acetic Acid Regeneration Bottoms

Acetic Acid Regeneration Side-cut No. 1
Acetic Acid Regeneration Side-cut No. 2
Acetic Acid Regeneration Overhead
Furfural Regeneration Side-cut

Furfural Regeneration Overhead
Furfural Regeneration Bottoms

168 AUS GAVEANMENT PRINTING OFFICE: 1974 546-316/262 1-3


Sulfur Dioxide,

1.0

Steam Stripping, Furfural Activated Carbon and
Acetic Acid Activated Carbon Columns

Feed Rate = 1 gpm (3.78 liters /minute)

09h Stripping Steam = 6% by Weight of Feed

a

0.8.

0.7

0.6
¥
8
3
a
s
6
g Steam Stripping Column © o——o
g 0.5 Feed
ge
g Steam Stripping Column x———-xX———X
a Bottoms
q Furfural Activated Car- 0-——-O-———-0
a bon Column Effluent

oO.

Acetic Acid Activated ©——@—-@
Carbon Column Effluent

0.3

Hours Column Used

Figure 21. Total inorganic sulfur dioxide concentrations —
steam stripping and activated carbon column flows

54


cumulatively. Steam was added to that in Effect 1. Consequently, con-
siderable methanol and furfural were added in Effect 4 to bring the
cumulative condensate to their final concentrations. To verify this,
samples of the condensates made in Effect 4 only were analyzed, with

the following results:

& by Weight S02, g/1
Sample MeOH HAc Furf. EtOH TI OLC
Channel A — 2:30 p.m. 0.18 0.23 0.05 0.02 1.39 0.48
Channel A — 3:30 p.m. 0.19 0.23 0.06 0.01 1.51 0.5%
Channel B — 2:30 p.m. 0.20 0.28 0.08 0O -- --
Channel B — 3:30 p.m. 0.26 0.26 0.06 ie) -- _

Prior composite condensates showed methanol and furfural to be in the
0.04 to 0.05 and 0.01 to 0.02 concentration ranges, respectively. Al-
most 4 times the methanol and furfural concentrations had been con-
servatively predicted.

Since all condensates from Effects 3, 2, and 1 had less methanol and
furfural in them than the majority of the steam stripping column

bottoms, they should be kept separate and out of the steam stripping
column system. Thus, the equipment size in both the steam stripping
and fractionation systems will be substantially lowered, as will the

steam requirement.

The data in Tables 10, 11, and 12 were submitted by one of the coop-
erators and are compared with data from Scott (Table 21) and from
Consolidated (Table 22).

First note the ineffective steam stripping at Scott. This was the
initial work in 1969. Sixteen ft (487.7 om) of packing and 10% steam
were used. Now look at Consolidated in April, 1973 using 4 ft (121.9
cm) of packing and 6% steam. This re-emphasizes what over-design can
do. No problems with scaling or plugging were encountered in this
column, either at Scott or Consolidated, after the screening system
was installed. The figures from the cooperator were sent to demon-

strate little differences in acetic acid concentration in their

78


The individual titles of the figures and the brief calculations are as
follows:

I. Fig. 48 — Equipment flow sheet of the separation process.

II. Fig. 49 — Equipment flow sheet of the activated carbon regen-
eration and furfural recovery.

TII. Fig. 50 — Equipment flow sheet of the activated carbon regen-
eration and ethyl acetate recovery.

Iv. Fig. 42 — Overall mess balances — Basis: 50,000 1b (22,700 kg)
of evaporator condensate. To combine the separation
process and the two recovery-regeneration processes,
the flows shown in Fig. 43 are multiplied by 100,
those in Fig. 44 and 47 by 1, and those in Fig. 46
and 47 by 33.3.

Vv. Fig. 43 —Mass flow sheet of the separation process. ‘The
quantities indicated on this flow sheet are based on

the following calculations:

1. Basis: The total flows shown are based on 500 lb (227 kg) of
evaporator condensate feed. It should be noted that three
significant figures are used for the flow quantities.

2. Evaporator condensate: The following mean analyses taken from an

interim report to sponsors of the project were used.

Acetic acid 1.34 1b (0.61 kg)
Methanol 0.325 1b (0.15 kg)
Furfural 0.0800 1b (0.04 kg)
Total sulfur dioxide 0.490 1b (0.22 kg)
Water 498 1b (226.09 kg)
3. Mass balance around stripping column:
A. In:
a. Preheated feed

Acetic acid 1.34 lb (0.61 kg)

Methanol 0.325 1b (0.15 kg)

Furfural 0.0800 1b (0.04 kg)

113


gTT

Vent

Vent

Vent {
Ethanol 3
LEGEND
8 Pressure Gage a
Recorded Temperati Steam ser
@ a ~ wate Oe pq Ett Acetate
Dt Valve ‘T 7 5
Rotemeter 3 Va \
Q 8 I 48
uli Manometer N
5
@4 3X _@
5 Nav
8 3
pene g Le % Ke E Le
| g TK
Steam
: 8 L— jor Fe
4 i : K 7
Ee g 3
aEE z = steam
i 4
| OH
3
g
i i
Scale: none Sewer
aan

Figure 50.

Activated carbon regeneration and ethyl acetate recovery


be developed in ways which would fit the variety of operating conditions
in the various sulfite pulp mills supporting this project.

The initial pilot plant constructed as per Fig. 2 was not a replica of
the one at Scott's Everett Mill. The flow pattern was more advanced

and tailored to the needs of the Appleton Div. of Consolidated Papers,
Inc. For simplification it will be discussed in five parts: the feed
system, steam stripping column system, fractionation column system, the
activated carbon adsorption system, and the activated carbon regenera-

tion system.

Feed

The evaporator condensate was pumped by means of a transfer pump from
the evaporator area through the pilot plant area to the river through a
2-inch diameter stainless steel pipe. The feed was tapped off this
transfer line and run through a screening system to remove particulate
material (fibers and evaporator scale) to protect the stainless steel
mesh packing in the stripping column. From the screening system it
went into a 55-gallon (208-liter) stainless steel feed drum. From this
drum it was’ pumped by two small Eastern pumps in series through. the
feed preheater to the steam stripping column. Two pumps were required,
because one pump could not constantly deliver the required flow when
back pressures exceeded 15 psig (1.05 kg/om® gage). No effort was made
to determine the scale and fiber content as the amounts varied. It was
established, however, that scale and fiber were in the evaporator con=
densate and had to be removed; Excellent screening performance was
attested to, since the steam stripping column did not require cleaning
for a period extending back over three years of operation in Appleton

and Everett.

Steam Stripping

The steam stripping system consisted of the preheater, steam stripping
column, reboiler, condenser, and receiver. The preheater was used to

bring the evaporator condensate up to its boiling point, 209 to 211°F

23


Heating was continued as shown in Table 22 on the -following morning
with the power connections the same as previously used. After 10
minutes of operation, during which time there was fairly rapid heating,
power was shut off and the column was wet with warm tap water. To
facilitate drainage, air was passed through the column for one-half
hour. Heating was continued on No. 1 rectifier from 10:15 to 3:55, and
during this time the combination of voltages and amperages used repre-
sented an electrical resistance of 0.06 to 0.27 ohms per foot (0.20-
0.88 ohm/m) of carbon. At the last reading at 3:55, the resistance
dropped to 0.18 ohms per foot (0.59 ohm/m). Power was on the No. 2
rectifier from 10:15 to 2:35, at which time the temperature at the No.
3 position suddenly increased from 94°C to 245°C (201°F to 473°F).
Electrical resistances during this time were between 0.14 to 0.28 ohms
per foot (0.46-0.92 ohm/m) of carbon. Twenty-six liters (6.87 gal.)

of water had been vaporized from the column during the 5 3/4 hours of

operation.

The following morning on January 24, both power supplies were activated
before wetting the carbon. No. 1 rectifier was then producing 32 volts
at 50 amps, while No. 2 rectifier produced 47 volts at 50 amps. The
column was flooded and drained with the eid of air pressure, during
which time 17 liters (4.49 gal.) of water were drained from the column
which is the amount of non-adsorbed water in the column when it is ina
flooded state. Current was placed on No. 1 rectifier for 20 minutes
prior to turning on the No. 2 rectifier. Initially, the resistance

was very low, there being 13 volts on Rectifier No. 1 producing 75 amps,
while on No. 2 rectifier there were 100 amps and 37 volts. However,
shortly after the No. 2 rectifier was energized, a sudden drop in
amperage was noted and all power was disconnected. The No. 2 recti-
fier was then connected to the two bottom electrodes between the bottom
foot (30.5 cm) of carbon, the anode being in the D position and the
cathode in the E position. This configuration provided 53 amps at 52
volts. Connections were then changed to the anode in the C position

and the cathode in the E position on Rectifier No. 2 which included 2

148


bt
w 0 F IO

oor nw

10
11

12
13

14
15

16
17

18
19
20
21
22
23
24
25
26
27
28

TABLES

pH, Sulfur Dioxide, and Color Data
COD, BODs, and Acetic Acid and Formic Acid Data

Methanol, Acetic Acid, and Furfural Assays By Gas
Chromatography and Calcium and Sodium Assays

Pollution Potential and Materials Data

Methanol Balance Steam Stripping Runs

Furfural Balance Steam Stripping Runs

Furfural Balance Activated Carbon Adsorption
Acetic Acid Balance Activated Carbon Adsorption
Evaporator Studies Data

Analyses of Evaporator Effects of Cooperator Mill

Carbon Adsorption Work at Scott Paper Company
Oconto Falls Evaporator Condensate

Carbon Adsorption Work at Consolidated Papers, Inc.
Appleton Div. Evaporator Condensate

Typical Activated Carbon Acetic Acid Column Regeneration

Data — Potentially Patentable Process
Typical Pilot-Plant Operating Data

Typical Activated Carbon Acetic Acid Column
Regeneration Data

Typical Activated Carbon Furfural Column Regeneration

Data

Recoverable Values Based on the Condensate of
Consolidated Papers, Inc.

Pollutional Balance Sheet

Lowell Unit — Direct Current
Lowell Unit — Direct Current
Lowell Unit — Direct Current
Lowell Unit — Direct Current
Lowell Unit — Direct Current
Lowell Unit — Alternating Current
Lowell Unit — Alternating Current
Lowell Unit — Alternating Current
Lowell Unit — Alternating Current
Lowell Unit — Alternating Current

ix

10
14
38
Wa
65
67
76
19

19
79

9h
104

105
106

135
136
143
145
17
149
151
154
157
160
162
164


These are the standard heat of combustion with reference con=

ditions of 25°C (77°F), 1 atm. pressure and gaseous substances
in ideal state.

.". Total heat of reaction = =eTO eG 4). = 32,400 Btu
(-8164.8 kg-cal). .
Since the major final products are gaseous carbon dioxide and

liquid water, it is necessary in this case to deduct the latent
heat of vaporization of the liquid water formed.

Latent heat = a (18) (994)

w

25,200. Btu (6350.4 kg-cal)

-'. The net heat of reaction = -7200 Btu (-1814.4 kg-cal).
Fractionation column
a. Reboiler
Assume 390 lb (177.1 kg) reboiling. Heat required to heat
the liquid which is essentially water from 210°F (98.9°C)
to 27°F (119.4°C) = 390 (1) (2) = 780 Btu (196.6 kg-cal).
Heat of evaporation = 390 (970.3) = 378,000 Btu (9526 kg-
cal). :
Heat required to heat the vapor from 212°F (100°C) to 247°Fr
(119.4°C) = 390, (0.482) (35) = 6580 Btu (1658.2 kg-cal).
Total heat required = 385,000 Btu (97020 ‘kg-cal).
b. Heat loss around column.
Use 157°F (69.4°C) as reference temperature.
Heat in:
Heat in with feed = (174-157) [49000 (0.456) + 3900 (1)
+ 124 (0.459)] = 447,000 Btu (112644 kg-cal).
Heat in with reboiled liquid = 390 [(0.482) (1) + 970.3 +
1 (213-157) ] = 400,000 Btu (100800 kg-cal).
Total in = 847,000 Btu (213444 kg-cal).
Heat out with ethanol = (168-157) (49,000) (0.456) =
246,000 Btu (61992 kg-cal).
Heat out with bottom liquid = (3900 + 390) (213-157) (1)
= 240,000 Btu.(60480 kg-cal).

131


were supported on glass laminated strips. Since the Institute had

several direct current power Supply units, previously used on an electro-
dialysis project, it had been decided,

Fabus, to utilize this source of power.

with agreement from Professor

Prior to shipment of the unit
to the Institute, it was tested by Lowell personnel, using a direct cur-

rent rectifier, supplied by the Institute.

A diagrammatrical sketch of the unit as it was initially set up and
connected at the Appleton Division mill of Consolidated Papers, Inc. is
shown in Fig. 51. All materials coming in contact with the condensate
were constructed of 316 stainless steel. Four thermocouples were in-
stalled midway between each electrode which were initially inserted 6
inches (15.2 cm) or to the center of the column. The connectors to the
electrodes, as well as the thermocouples, were insulated from the shell
of the column by means of custom-made ceramic insulators. The two con+

densers used in series consisted of a single tube.

During the adsorption phase the condensate was passed through the con-

densers and entered the column at the top and exited through the bottom.
The column was maintained in a flooded condition by means of a constant
level device. During regeneration the vapors were removed from the top
of the column through the condensers, except during several trials when

the flow was reversed,

As noted in Fig. 51, the three negative electrodes were common to both
power sources, with one positive electrode being connected to each

power unit. Initially, the column was charged with Filtrasorb 300
activated carbon which had been supplied by Lowell Technological Insti-
tute and had been used during their trial period. This was later re-
placed with Filtrasorb 400 carbon. The unit was never operated success-
fully and most of the available time was spent operating repeated dry-
ing and wetting cycles using tap water. Two runs using condensate were
made and the feed for these runs consisted of condensate that had passed

through the stripper and also through the furfural column of Mr.

139


Table 20. LOWELL UNIT ~ DIRECT CURRENT

Water Evaporation
Filtrasorb 300 Carbon
Carbon Bed 1 ft x 4 f (30.5 cm x 1.219 m)

hectifier No. 2 Temperature,
tect er No. °C (°F ‘
Date ‘Time Volts Amps fn Air
Power connection — anode —
cathode — D
One foot (0.3048 m) of air-dried carbon in colum
1-22-73 8:58 at 18 26( 79) on
9:08 eT 12 35( 95) on
9:13 2T 2 37( 99) on
Surface temperature, °C (°F)
Location Right side Front Left side Back
At D 26.1(79) 25.6(78) 25.0(77) 25.0(77)
Between D & E 27.8(82) 27.8(82) 27.2(81) 26.1(79)
At E 27.8(82) 24.4 (76) 27.2(81) 27.8(82)
Below E 26.7(80) - - _
Temperature,
Rectifier No. 2 °c (°F)
Date Time Volts Amps % Air (%)
1-22-73 9:33 50 16 37 99) 50
9:43 50 13 54(129) 50
9:53 50 9 57(135) 25
10:03 50 5 59(138) °
10:30 50 T 35( 95) 50

Surface temperature, °C (°F)
Location Right side ‘ront Teft ei

Between D&C 42.0(107) —36.7( 98) —35.6( 96)

At D 42.5(108) ° 46.8(116) —-42..1(106)

Between E & D 36.7( 98)  35.6( 96) 36.1 97)

ACE 30.0( 86) 28.3( 83) —28.3( 83)
Rectifier No. 1 Rectifier No. 2 ‘Temperature, °C (°F) Air
Date Time ~ Volts Amps ‘Volts Amps 2 3 (03)
1-22-73 10:46 C) ° 50 8 - - 34( 93) 50
10:56 to) oO 50 6 - - 27( 81) 50

Power connection — cathode — D
anode ~ C — Rectifier No. 1
~E-—Rectifier No, 2

Added second foot of air-dried carbon

1:22 50 23 50 18 274 81) 43(109) 21( 70) 50
1:22 503 50.32 +©—48(128) 88(190) 38(100) 50
Surface temperature, °C (°F)
Location Right side Front Left side Back
At E 31.1( 88) 40.0(10%) —26.7¢ 80) 33.9( 93)
Between D & E 33.9( 93) 42.2(108) 32.1 88) 33.9( 93)
At D 44.5(112) 42,2(108) —_38.9(102) 47,8(118)
Between C & D 39.0(102) 42.9(107) 35.6( gh) 45.0(113)
At Cc 39.5(103)  36.7( 98) 30,6( 87) ——45.0(113)

Bac 33.3( 92) 35-6( 96) — 30.6( 87) 33.9( 93)
rae 25.6( 76) 24.4 76) 25.6 78) 25.6( 76)

Removed carbon from column

hss


Table 5. METHANOL BALANCE STEAM STRIPPING RUNS
9-11-72 to 9-20-72

9-11-72

In Feed

4 hr (1.52 gpm) (60 min.) (8.33 1b/gal.) (0.00045) = 1.37 1b (0.622 kg)
In Overhead

4 hr (0.008) (60) (8.33) (0.027) = 0.43 1b (0.195 kg)
% Recovery = (0.43/1.37) 100 = 31.4%

9-12-72

In Feed

4 (1.368) (60) (8.33) (0.000575) = 1.575 1b (0.715 kg)
In Overhead

4 (0.038) (60) (8.33) (0.00385) = 0.290 1b (0.132 kg)
% Recovery = (0.290/1.575) 100 = 18.6%

9-12-72

In Feed

4 (1.215) (60) (8.33) (0.00045) = 1.095 1b (0.497 kg)
In Overhead .

4 (0.049) (60) (8.33) (0.0030) = 0.290 1b (0.132 kg)
% Recovery = (0.290/1.095) 100 = 26.5%

9-14-72

In Feed

4 (0.76) (60) (8.33) (0.00055) = 0.84 1b (0.381 kg)
In Overhead

4 (0.045) (60) (8.33) (0.00355) = 0.32 1b (0.145 kg)
% Recovery = (0.32/0.84) 100 = 38.0%

9-14-72

In Feed
4 (0.608) (8.33) (60) (0.000725) = 0.88 1b (0,
In Overhead (0-399 ke)

4 (0,043) (8.33) (60) (0.004225) = 0.36 1b (0.
% Recovery = (0.36/0.88) 100 = 41.2% (0.163 xg)


39

ho
41

42
43
uy

45
L6
47
48

hg
50

51
52

Figures (Continued)

Suggested Regeneration

Projected Plant — Consolidated Papers, Inc.
Appleton Mill

Suggested Commercial Application Consolidated Papers,
Inc. Appleton Mill :

Overall Mass Balances of the Pilot Plant
Separation Process — Mass Flow Sheet

Activated Carbon Regeneration and Furfural Recovery.
1. Furfural Recovery

Activated Carbon Regeneration and Furfural Recovery.
2. Methanol Recovery

Activated Carbon Regeneration and Ethyl Acetate
Recovery. 1. Draining of Column

Activated Carbon Regeneration and Ethyl Acetate
Recovery. 2. Recovery of Ethyl Acetate and
Recovery of Ethanol

Separation Process
Activated Carbon Regeneration and Furfural Recovery

Activated Carbon Regeneration and Ethyl Acetate
Recovery

Activated Carbon Thermal Regeneration Column

Location of Electrode and Thermocouple Terminals

viii

98
100

101
107
108

109
110
111
112
114
115

116
1ho
1h2


100f-

Methanol Removal, %

Consolidated Papers, Inc.
Appleton Division Mill Evaporator Condensate
90 48-Inch (121.9 em) Goodloe Packing
°
°
°
°
8or-
T0-
éq-
5d-
kde
a¢°
°
oq-
it
() a J i nl 1 fl fl fi j

0 1 2 3 4 5 6 1 8 9 lo ll ie
Stripping Steam, % weight of feed

Figure 9. Methanol removal vs. strippi
. vs. pping steam used —
Consolidated Papers, Inc. — 48-inch (212.9 cm) packing

32


Make-up
Ethanol
7 ip 1.

EtOH 1.94

Ethanol

Feed

Water yo displace ethanol TF, 1b 483.
#30

Scale: none

183

Figure 47.

oF, 1b 170 =P, Yb 1470
‘EtOH 1470 ‘EtOH 1470
OF, Lb 1427
EtOH 1414;
EtOAc 3.71;
H20 0.759
(IF, Ub 2.57
(Poly Matis. 0.000
(MecooH 2.53)
(TF, 1b 483) be
[Heo 483) 3 —
5
j g
3
8
§ , ib 1h19
= EtOH 141k; Tot
6 EtOAc 3.713 peer
3 109-759 Tet one *
8 36715
a ;
g (ar, br 173) iy
= (BtoH 56.0), Matls
z (so u7} 8 ber
a (Poly Matls. 0.00640} .
8
2
5 [BtoH 56.0] « |
- 8
&
~—EROH IEG

Vent

Ethyl Acetate
TF, 1b 3.71
EtOAc 3.71

LEGEND

total flow, 1b

ethanol

water

acetic acid

ethyl acetate

polymerized
materials

to be retained

originally
retained

Fractionation Colum and Condenser

TF, 1b UT sever

HO L175
Poly Matls. 0.06}

Activated carbon regeneration and ethyl acetate recovery.

2. Recovery of ethyl acetate and recovery of ethanol


Mill A cooks all hardwood and the samples submitted were daily compos-
ites taken by sampling at 15-minute intervals. It is not known if the
samples from Mill B are grab samples or composites. However, there is
a distinction between normal condensate and condensate used for wash.
The samples from Mill C were from 100% hardwood and represent 8-hour
composites covering a switching cycle on the Rosenblad evaporator. The
semples from Mill D were from a mill cooking 95% aspen and 5% spruce
by the magnesium bisulfite process. The combined condensate contained
condensate from the second and third effects of a 3-effect evaporator,
along with condensate from a surface condenser. The samples were 22-
hour composites. Of the three samples submitted by Mill E, one is
from a 100% hardwood cook, another from a 100% softwood cook and the
third is a sample of the total condensate discharge. The samples from
Mill F are condensates derived from a non-chemical cook. The four
samples from Mill H were unique in that these condensates were derived
from liquors that had received pretreatment prior to evaporation.
Samples 26, 27, and 28 were derived from liquors that had been pre-
stripped and neutralized, while Sample 29 was derived from a liquor
that was prestripped only. All four samples were grab samples of 100%
softwood origin. The samples from Mills I and J were derived from the

evaporation of magnefite softwood liquors. Both were grab samples.

Table 1 contains pH, SO2, and color data. The COD, BODs, and volatile
organic acids, consisting of acetic and formic acid data, are given in
Table 2. The data for the remainder of the assays, consisting of meth-
anol, acetic acid, and furfural, as determined by gas chromatography,
and assays for calcium and sodium are given in Table 3.

DISCUSSION

The pH of the various samples (Table 1) was between 2.12 and 3.30 for
a spread of about 1.2, except in Sample 5 which had a pH of 1.78 and

Samples 26, 27, and 28 which were preneutralized. There was a large

variation in SO2 content, both total inorganic and organic loosely

combined, from the various mills, and even from samples derived from

il


Color

A Hellige aqua tester was used to determine color. The semple is di-
luted as necessary and the color compared against standards which are
equivalent to the cobalt platinum standards of "Standard Methods for
the Examination of Water and Waste Water" of the American Public Health

Association (APHA).

Chemical Oxygen Demand (COD)

The standard method of APHA was used, which consists of digestion of
the sample with concentrated sulfuric acid and standard dichromate
solution for two hours followed by back-titration with standard fer-
rous ammonium sulfate. Silver sulfate is used as a catalyst since
without it the acetic acid would not be oxidized.

Biochemical Oxygen Demand (BODs)

The five-day BOD was determined by the dilution technique of standard
methods of APHA. In all cases a series of dilutions were set up in
duplicate and the dissolved oxygen determined with a Weston and Stack
meter before and after the five-days incubation. Seeding was accom-
plished by using domestic sewage and BODs was determined on a standard
glucose-glutamic acid standard as a control for all procedures.

Volatile Organic Acids

The volatile organic acids generally present in spent sulfite liquors,
and consequently in the condensate derived from these liquors, are
acetic and formic. For many years the Effluent Processes Group has
used an ether extraction procedure for determining these total vola-
tile organic acids. The procedure consists of extraction with ether
under acidic conditions using a ratio of 9 parts of ether to 1 part of
sample, followed by titration with a standard alkali in the presence of
a small amount of CO2 free water. The volatile organic acids are then
calculated in terms of equivalent acetic acid.


Sections

rT
II
TII

vI
VII
VIII

CONTENTS

Conclusions

Recommendations

Introduction

Assay of Condensate Samples From Supporting Mills

Design, Construction and Operation of Pilot System
At The Appleton Mill of Consolidated Papers, Inc.

Mass, Heat, and BODs Balances

Low Temperature Regeneration of Carbon

Invention Record and Publication

ww wD

16
103
138
167


1. Those gases cooled from 213°F (100.6°C) to 203°F (95.0°C)
without condensing

Water vapor 3.90 lb (1.771 kg)
Sulfur dioxide 24.0 1b (10.896 kg)
Methanol 1.20 1b (0.545 kg)
Furfural 0.900 1b (0.409 kg)

Hg = [3.90 (0.482) + 24.0 (0.234) + 1.20 (0.458) + 0.900
(0.6)] (10) = 61.9 Btu (15.6 kg-cal)

2. ‘Those gases cooled from 213°F (100.6°C) to 212°F (100°C),
condensed, and codled to 203°F (95°C)

Water 2,920 lb (1325.7 kg)
Sulfur dioxide 17.0 lb (7-7 kg)
Methanol 15.3 lb (6.9 kg)
Furfural 3.10 1b (1.4 kg)
Acetic acid 5.60 1b (2.5 kg)

Unaccounted HAc 11.4 1b (5.2 kg)

Hu, = [2920 (0.482) + 17.0 (0.134) + 15.0 (0.458) + 3.10
(0.6) + 5.60 (1.5) + 11.4 (1)] (1) = 1440 Btu (362.9 kg-
eal).

It should be mentioned that the sulfur compounds that condensed into
liquid form are taken as SO2 and that the o of the unaccounted acetic
acid is estimated as 1.
Hye = 2920 (970) + 17.0 (94.9) (1.8) + 15.3 (263) (1.8) +
3.10 (108) (1.8) + 5.60 (96.8) (1.8) + 11.4 (100) (1.8) =
2,850,000 Btu (718,200 kg-cal).

The sulfur compounds are taken as SO2 and the A of the unaccounted
acetic acid is estimated as 100 cal/g (180 Btu/16)
Hys = [2920 (1) + 17.0 (0.5) + 15.3 (0.566) + 3.10 (0.428)
+ 5.60 (0.487) + 11.4 (0.5)] (212-203) = 26,500 Btu (6678
kg-cal)
Hy = Hy: + Hy2 + Hy3 = 2,880,000 Btu (725,760 kg-cal).

12h


by the system developed and patented at Scott Paper Company. These
regeneration systems were not optimized.

A new activated carbon regeneration system was developed using
alcohol and water. This system involves using the activated carbon
column as a distillation column. It varies from the Scott method
in that reflux of alcohol and water is utilized in the carbon col-
umn. It completely regenerated a carbon that had been showing
definite carbon life deterioration, and may be patentable. This
process has not been optimized, although substantial cost reductions
when compared to the Scott process are apparent. Data on this pro~
cess are limited and more work is necessary to establish its full
value.

The urgency required for pollution abatement is the factor most influ-

encing the movement of this project to commercialization in its en-

tirety. The next step is a commercial demonstration unit. Preferably
it should be constructed modularly. The steam stripping and fraction-

ation systems first, and the carbon adsorption and regeneration systems

next. The highest priority pilot plant study should generate data

specifically for this demonstration unit.

102


8000,

Biochemical Oxygen Demand,
mg/liter

700

600q—

500g

7
6
3

T

300g-

200g-

1oog-

Steam Stripping, Furfural Activated Carbon and
Acetic Acid Activated Carbon Colums

Feed Rate = 1 gpm (3.78 liters/minute)
Stripping Steam = 6% by Weight of Feed

Oct. 23, 1972

i L

Steam Stripping Colum

Feed oe —e
Steam Stripping Column
Bottoms X—— Kk
Furfural Activated Car-
bon Column Effluent o——o——0

Acetic Acid Activated
Carbon Column Effluent ©——®—-®

Figure 27.

2 3

x
ee
/, .
°
 —
Nov. 6, 1972
J 1 = 4 1 1 i
5 O 1 2 3 y 5 6 T

Hours Column Used

Biochemical oxygen demand — steam stripping and activated

carbon column flow using regenerated carbon

61


SECTION V

DESIGN, CONSTRUCTION AND OPERATION OF PILOT SYSTEM
‘ AT THE APPLETON MILL OF CONSOLIDATED PAPERS, INC.

PREVIOUS WORK

Initial work in Scott Paper Company's Everett Mill was done using 4
inch D x 4 ft H glass pipe for all operations. Four activated carbon
columns were placed in series to study the selective adsorption of
methanol, furfural, and acetic acid in aqueous solutions by granular

activated carbon. Filtrasorb 400 was used. This work showed that:

1. Methanol came out of Column 1 in 15 minutes, Column 2
in 30 minutes, Column 3 in 45 minutes, and Column 4 in
an hour.

2. Acetic acid came out of Column 1 in 1 hour, Column 2
in 2-1/2 hours, Column 3 in 3 hours 50 minutes, and
Column 4 in 4 hours 50 minutes. Furfural did not come

out of Column 1 after more than 10 hours of operation.

At the start all columns had the activated carbon flooded with water.
It takes approximately 10 minutes for the water to be displaced with
feed in each column (40 minutes for total displacement assuming plug

flow), so only the break through, not full loading, was used for cal-
culating the following carbon loadings.

Methanol Loading — Four Columns

CH30H = 12.6 gph (1 hour) (8.33 1b/gal.) (0.00049)

0.0514 1b 23.3 ¢

CH30H Loading = 0.0514 1b/28.4 1b carbon
0.00181 1b/1b carbon

0.00181 g/g carbon

a

Acetic Acid Loading — Four Columns

CH3COOH = 12.6 gph (5 hours) (8.33 1b/gal.) (0.0053)

2.78 lb 1.26 kg

won

16


Table 17. RECOVERABLE VALUES BASED ON THE CONDENSATE
OF CONSOLIDATED PAPERS, INC.

I. Basis: To process 50,000 (22,700 kg) pounds of the evaporator condensate of the

Appleton Division Mill, Consolidated Papers, Inc.
II. Recoverable Values®

1. Products
1-10 1b (3.22 kg) of furfural, 12¢/1b (26.4¢/kg) 0.8:
AES Riad Sota ales, ey
43.6 1b (19.8 kg) of 802, 0.1¢/1b to.224/kg) 00h
$12.55
2. Savings on BODs reduction
203 1b (92.9 kg) BODs, hg/1b (8.84/kg) 8.06
Total $20.62
III. Estimated Operating Costs
1. Steam
11,700 1b (5311.8 kg), $1.00/1000 1b ($2.20/1000 kg) $11.70
2. Pover
Assumptions:

Capacity = 100,000 1b (45400 kg) of evaporator condensate/hour
Pumps = 100 hp
Power cost = 1¢/kwehr $ 0.38
3. Labor
Assumptions:
Number of operators = 1 operator/8-hr shift
Wage = $10,000/annun

Days operated per year = 350
Other assumptions = same as under Power cost

Labor cost $1.59
4. Ethanol
64.7 1b (29.4 kg), 94/1 (19.84/ke) $5.83

Total $19.50

IV. Estimated Gross Income per Annum = (20.61 - 19.50) (2) (2¢) (350) = $18,600

This net income is based on a plent capacity of 100,000 1b (45400 kg) of condensate
per hour

"No credit has been given to the value of the reusable water or the recovered sulfite liquor.

135


SECTION II

RECOMMENDATIONS

Steam stripping, fractionation, and activated carbon adsorption have
been demonstrated to be commercially feasible, and these unit processes
are considered ready for a commercial demonstration plant. It is
recommended that pilot work be continued on an individual mill basis,
with the unit operations tailored toward establishing design data
specific to each mill's ultimate objective. The data generated to date,
including previous work at The Institute of Paper Chemistry, Scott
Paper Company, and work under this project, should be used as the basis

for future individual mill studies of plant design factors.

Future research work, supported collectively or individually, should
follow the Process Options presented on page 73. These can be
accomplished on laboratory or pilot plant bases. If time permits, a

modular stepwise approach is recommended.

The established and developed analytical techniques can be used and/or

extended in future studies.

The heat and material balances presented should be used as the bases
for individual mill optimization work recommendations and future

economic evaluations.

The newly developed activated carbon regeneration system should be
optimized and fully evaluated with further pilot plant studies.

Finally, the same unit operations can be utilized to treat kraft
evaporator condensates, which are also a potential source of stream

and/or air pollution.


Iv.

Recovery of Ethyl Acetate and Ethanol

1. Heater 19 ,500,000° Btu (4914000 kg-cal)
2. Fractionation Colum 385,000 Btu (97020 kg-cal)
3. Heat of Reaction -7,200 Btu (-1814.4 kg-cal)

Total heat consumption = 31,100 ,000% Btu (7837200 kg-cal).

Heat Removed

A.

Separation Process
i. Stripping Column Condenser 2,880,000 Btu (725760 kg-cal)
2. First Carbon Colum Cooler 3,600,000 Btu (907200 kg-cal)
3. Fractionation Column ;
Condenser 7,240 Btu (1824.5 kg-cal)
Recovery of Furfural and Methanol
1. Furfural Recovery
a. Fractionation Column
Condenser 302,000 Btu (76104 kg-cal)
2. Methanol Recovery
a. Fractionation Column
Condenser 302 Btu (76.1 kg~cal)
Recovery of Ethyl Acetate and Ethanol .
1. Fractionation Column
Condenser 22,800 Btu (5745.6 kg-cal)
Total heat removed = 6,810,000 Btu (1716120 kg-cal).

COST ESTIMATE

With a basis of calculation of 50,000 (22,700 kg) pounds of the Appleton
Division mill of Consolidated Papers, Inc. condensate, the value of the

products potentially recoverable and the economic benefit from the

“This figure is known to be too high due to inefficient pilot plant
operating conditions. According to the latest revised arrangement
and operating conditions the steam consumption for this ‘item should
be 4,000,000 Btu. (1008000 kg-cal)

Fone revised total heat required = 11,700,000 Btu. (2948400 kg-cal)

133


J

Methanol from
Fractionation Column

ist

Heat Exchange
Methanol Vaporizér

Methanol
Feed
Drum
ACCFRI 84
a 3
Ci 3
Methanol 5 5
Water Feed Pump Be ACCFRE
ce ’
23
28 3 8 y
a ca
3 8 'ractionation|
§ £ Column Feed
° Drum
To Fractionation
FCRF Column
Fractionation
Transfer Column Feed
Pump Pump

Figure 3. Activated carbon column furfural regeneration


By 1:40 p.m., however, the temperature at the No. 1 position was at
200°C (392°F) and the power was on intermittently for a period of 1
hour and 15 minutes in an attempt to raise the temperature of the lower
portions of the column without increasing the temperature unduly at the
No. 1 station. The No. 1 thermocouple was then partly removed from the
column so that it was inserted into the column for only 3 inches (7.62
cm) instead of the previous 6 inches (15.24 cm). It immediately regis-
tered a temperature of only 132°C (270°F), indicating that the temper-
ature of the carbon was high only at the center. As the temperatures
increased in the interior at the other stations, these thermocouples
were also brought closer to the periphery of the column, and in this way
the carbon was practically completely dried out without raising the
temperature at the periphery, where excessive high temperatures would

probably damage the teflon insulation.

Following this operation the column was probably packed as good as
possible but it was decided to proceed through one more drying cycle
before applying acetic acid to the carbon. All four thermocouples were
set so that they extended 2 1/2 inches (6.35 cm) into the carbon. Wet-
ting of the carbon was started by passing water into the top of the
column; however, the increased pressure upon the sides of the column
caused one of the small corks, which had been used to close up the open-
ing when the three center electrodes had been removed, to blow out.

This cork was in the B position and the dry carbon being very fluid
rapidly poured through this opening, with the result thet about half

of the top foot (30.5 cm) of carbon flowed from the column. The opening
was again closed and all stoppers tightly secured and the carbon re-
placed and packed as well as possible. Flooding of the column was
continued until all of the carbon was considered to be wetted. As will

be seen later, this was not the case.

With the top flange in place, heating was started at 9:33 a.m. on
February 9, with an electrical resistance of 0.39 ohm per foot (1.28
ohm/m) of carbon. By 10:45 a.m. the No. 1, 2, and 4 thermocouples
registered 100°C (212°F) while the No. 3 thermocouple registered 81°C

158


Activated
Carbon
Column
Acetic

Acid

Ethenol
Storage
Tank

Pump

To Drain

Figure 35. Regeneration — step 1

90


Total heat out = 486,000 Btu (122472 kg-cal).
Heat loss = 361,000 Btu (90972 kg-cal).
It should be noted again that the heat loss shown here
could be either higher or lower depending upon the operat-
ing conditions.

5. Condenser after fractionation column. No vent flow quantity
is available. Heat to be given up in condensing the ethyl
acetate = 124 (102) (1.8) = 22,800 Btu (5745.6 kg-cal).

Summary of Heat Balances

I. Basis: To process 50,000 1b (22700 kg) of evaporator condensate in
the pilot at the Appleton Division Mill of Consolidated
Papers, Inc.
II. Calculations are based on the actual operating conditions of the
pilot plant. It should be noted that:
A. The individual pieces of equipment are not optimized; and
B.. The process may or may not be exactly suitable for the
particular evaporator condensate.
III. Heat Required
A. Separation Process
1. Preheater 4,090,000 Btu (1030680 kg~cal)
2. Stripping Column 3,390,000" Btu (854280 kg-cal)
3. Fractionation Column 34390 ,000° Btu (854280 kg-cal)
B. Recovery of Furfural and Methanol
1. Furfural Recovery
a. Vaporizer 346,000 Btu (87192 kg-cal)
b. Fractionation Colum 9,140 Btu (2303.3 kg~cal)
2. Methanol Recovery
a. Fractionation Colum 30,500 Btu (7686 kg-cal)

"these are based on the actual steam consumptions. This indirect heat-
ing may or may not be desirable in large scale practical operation. If
live steam is used, this quantity could be reduced to 2,750,000 Btu
(693,000 kg-cal). :
Similar to a. This could be reduced to 141,000 Btu. (35,532 kg-cal).

132


£8

Make Up

Ethanol
Feed
Drum

ACCACRI

Ethanol
Feed Pump

Water

end ist
g g
i i
3 |
8 8
a2 ;
az iy
as a3
cP a3
gg sé
oe 23
zi a2
ee g
: :
5 5
3 :
2 4
:
i
S hy
39 sa
ig EE
To Drain

onden=
ser
o
3 FCACRO
2
8
=
S
&
<—
Ethanol — Ethyl Acetate
Fractionation Column
(Methanol ~ Furfural
Fractionation Colum
Modified)
IFCAGRSC-1}
Fs Water
to Drein
SX FCACRB >
Fractionation Column
Recirculation Pump Condensate

Figure 31.

FractionatToén Column

Feed Pump

to Drain

Both activated carbon columns regenerated with ethanol


SECTION III

INTRODUCTION

Five years of research in two separate but complementary projects di-
rected to removal of pollution-contributing materials from sulfite
evaporator condensates have been conducted by The Institute of Paper
Chemistry and by Scott Paper Company. The original studies have been
advanced in this project by installation and operation of the pilot
plant units in the Consolidated Papers, Inc.'s Appleton Division mill
located in Appleton, Wisconsin. The systems developed at Scott

Paper Company incorporated steam stripping, activated carbon adsorption
and fractional distillation as means for removing and recovering sulfur
dioxide, methanol, acetic acid, furfural, and other pollution-contrib-
uting materials, as well as regenerating the activated carbon.

The system previously studied at The Institute of Paper Chemistry
consisted primarily in the removal of BODs and COD contributing
materials from these sulfite condensates by steam stripping and
adsorption on activated carbon. Successful regeneration of the carbon
was attained with low temperature heat (200°C-392°F) and the addition
of superheated steam. Work under this project, herein described,
consisted of the evaluation of a means of heating the carbon during
regeneration by use of a system developed by Messrs. Bela M. Fabuss
and Wilson C. Dubois of Lowell Technological Institute.

Mass, heat and BODs balances are made according to the actual operat-
ing conditions of the pilot plant at the Appleton Division Mill of
Consolidated Papers, Inc. and are based on data taken prior to
January 17, 1973.

As an adjunct to this project, the sponsoring mills were invited to
send samples of their evaporator condensate wastes to The Institute of
Paper Chemistry for evaluation and comparison of their various
constituents. Such a compilation of data would aid the personnel of


> 2nd

Vent

a

Activated
Carbon
Column
Acetic

Acid

|__|

To Drain

Figure 34. Process flow

89


Table 13. TYPICAL ACTIVATED CARBON ACETIC ACID COLUMN REGENERATION |
DATA — POTENTIALLY PATENTABLE PROCESS

Fractionation Column Reboiler, lst Pressure Gage — 21 psig (1.47 ke/om? )
Fractionation Column Reboiler, 2nd Pressure Gage — 20 psig (1.40 kg/em?)
Fractionation Column Bottom Pressure Gage - = 10" Ho (25.4 cm H20)
Fractionation Column Feed Station Pressure Gage — 3" #20 (7.6 cm #20)
Fractionation Column Middle Splitter Pressure Gage - 0" H20
Fractionation Column Top Splitter Pressure Gage - o" #20
Fractionation Column Vent Pressure Gage - 0 to 3s" H20

(0 to 1.8 cm #20)
Acetic Acid Activated Carbon Column Top Pressure Gage ~ 0 psig
Acetic Acid Activated Carbon Column Jacket Pressure Gage ~ O psig
Acetic Acid Activated Carbon Column Bottom Pressure Gage — 1% psig (0.12 kg/cm?)

Acetic Acid Activated Carbon Column Vaporizer Pressure Gage - 16.5 psig (1.16 kg/cm?)
Acetic Acid Activated Carbon Column Rotameter to Vaporizer — 0.05 gpm (0.19 1/min.)
Acetic Acid Activated Carbon Column Rotameter to Fractionator — 0.05 gpm (0.19 1/min.)

Temperatures
Fractionation Colimn Liquid Bottoms — 213°F (100.5°c)
Fractionation Column Bottom Splitter — 212°F (100. 0°¢)
Fractionation Column Feed — 17h°F (78.9°C)
Fractionation Colum Middle Splitter - 173°F (78.3°C)
Fractionation Column at Feed Plate - 17h°F (78.9°c)
Fractionation Column at Top Splitter — 164°F (73.3°¢)
Fractionation Column Vapor after Condenser - 92°F (33.3°C)
Fractionation Column Reboiler Discharge — 213°F (100.5°¢)
Acetic: Acid Activated Carbon Column Top — 115°F (79.4ec)
Acetic Acid Activated Carbon Column Bottom = 207°F (97.2°c)

Ethyl Acetate Removed Top Fractionator Splitter. Periodically
Ethyl Alcohol Removed Bottom Fractionator Splitter to 50 gal. Drain Periodically, 189 liters


TF, hr 0.639
MeOH 0.639 @F, hr 400

Condenser
Receiver

j .
8 :
5 :
3 7 8
5 |
g 8
3 g
ke} TF, hr 309
3 0 308; E
3 MeOH 0.639} °
2 s
a4 2
g
8
2
3
8
FY
&

T, hr 30

TF, 1b total flow
Furf. furfural 7
MeOH methanol cy
Poly Matls. Polymerized materials qd
HeO water 3
C] to be retained &
() originally retained

e :
Figure 45. Activated carbon regeneration and furfural recovery.
- 2. Methanol recovery


Acetic Acid, % by weight

0.4
Steam Stripping, Furfural Activated Carbon and
Acetic Acid Activated Carbon Columns
Feed Rate = 1 gpm (3.78 liters/minute)
Stripping Steam = 6% by Weight of Feed
°
ine,
\
xft}—x
0.3 e o———_—___—_—*
x
/ x . a
x
iz
9
y
0.2L 1
O.1L -
. . Steam Stripping
a
oct. 23, 19 Nov. 6, 1972 Column Fee
et. 23, 1972 * x Steam Stripping
Column Bottoms
o-——-o-—_0 Furfural Activated
Carbon Column
Effluent
@—©—_© Acetic Acia
Activated Carton
Column Effluent
l od n L | 1 j
° o L 1 J +
o 1 2 3 & 5 o 21 2 3 4 5 6 7

Hours Column Used

Figure 23. Acetic acid concentrations — steam stripping and
activated carbon column flows using regenerated carbon

57


Figure 24 shows methanol being adsorbed in both activated carbon columns
over the entire 5-hour operation on October 23, 1972. The run of Novem-
ber 6, 1972 was more normal. Since methyl acetate was recovered during
regeneration, methanol reactions were possible as these chemicals were
allowed to set in the column. Figure 27 is interesting in that no ace~
tic acid appeared in the 2 and 2 1/2-hour samples, and yet the BOD is
almost as high as that in the steam stripping column bottom liquor.

This BOD should be characterized in further studies. If the 700 mg/
liter BOD range that has been attributed to residual methanol is a
problem area of concern, remember that the steam stripping column was
operated utilizing 6% by weight of feed stripping steam. Higher steam
utilization will reduce the methanol. The effluent was to be recycled.
Any recycle problems would have to be evaluated against the cost of

using more stripping steam.

Two more regenerations of the carbon in the column adsorbing acetic
acid were made, but no attempt was made for chemical recovery or
material balances, since the multipoint recorder malfunctioned spoiling
the 3rd regeneration cycle and 4th adsorption cycle. More than 5 weeks

pilot plant operation time was lost, before this unit was repaired.

Since furfural had not broken through the carbon in the first activated
carbon column , that carbon column and the steam stripping column were
operated every day until a breakthrough did occur. This required 70 1/2
hours total operating time. Actually, the furfural was held in the
column from October 9, 1972 until December 21, 1972. The data compiled
in this belated recovery run was plotted in Fig. 29. Graphically inte-
grating the area under the steam stripping column bottoms line indicated
a furfural concentration average of approximately 0.01% by weight. As
shown in the Furfural Balance, Table 7, the furfural adsorbed was cal-
culated to be 3.52 1b (1.6 kg). That recovered was 3.74 1b, (1.7 kg) or
106% of that calculated to be adsorbed. Considering the time it was
held in the column, furfural is quite stable under the operating con-
ditions to which it was subjected.

63


Table 1, pH, SULFUR DIOXIDE, AND COLOR DATA

wu mater Semple {dentification

A 2 Dense hardwood 9/7/72

A 2 Dense hardwood 9/8/72

A 3 Dense hardwood 9/9/72

A 4 Aspen-dense hardwood 9/10/72

B 5 34% Hardwood, 66% softwood

B 6 Seme es No. 5 but used for wash

B 1 93% Popler, 7% spruce

B 8 Same as No. 7 but used for wash

B 18 1Yf Hardwood, 86% softwood

B ag Same es No. 18 tut used for wash

B 32 SSL, 34% Hardwood, 66% softwood

B 33 34% Hardwood, 66% softwood

c 9 100% Aspen 9/19/72

c 10 100% Aspen 9/20/72

c a 100% Aspen 9/22/72

c 12 100% Aspen 9/26/72

D 13 95% Aspen, 5% spruce combined
condensate

D a ‘95% Aspen, 5% spruce second effect

D 2h 95% Aspen, 5% spruce-combined
condensate 1/24/73

D 25 95% Aspen, 5% spruce-second effect

E 15 100% Hardwood

gE 16 100% Softwood

zg y Total discharge including
surface condensate

FP 20 Exploded wood pulp

F 22 Hardboard mill 12/20/72

F 23 Hardboard mill 1/4/73

o a1 Softwood

H 26? Softwood, high solids effect

E are Softwood, low solids effect

q 28 Softwood, 26 and 27 blend

a 29° Softwood, total condensate

I 30 Magnefite softwood 2/2/73

z a2 Magnefite softwood 2/5/73

SAPHA Standard Color Units.
e prestripped neutralized SSL.
Total condensate from prestripped

2.63
2.57
2.50
2.55

2.63

2.38

2.43
2.18
2.38
2.27

2.32
35
3.25
3.30
2.20
6.19
5.5
5469
2.49
2.79
2.37

unneutralized SSL.

8

802, mg/liter
OLG

TT
180
150
160
430
187
6
28
8

13

102
270

2
596

336
2.0
1.0
1.3
1.0

16

430
490
510
490
919
108
270
600
oT
184
3398
575
264
181
4TH
229

uo
269

261
37
212
427

1061

16

Tee

1.0

0.5

343.

ms
107

ColorTM
250
430
600
280

400
90
100
10

20,000

100
500

150

200

as
co

3
Ss

1000
650

300

250
50
150
15
<5
10


The carbon and electrodes were again removed from the column and again
the positive or anode electrodes were found to be corroded. The elec-
trodes were again cleaned by sand blasting, replaced in the column and
the column refilled with Filtrasorb 400 carbon. The column was flooded

with tap water and allowed to drain overnight.

The electrodes were connected as previously and current turned on at .
8:17 a.m. on January 30. The wet carbon showed low resistance, there
being 31 volts and 50 amps on the No. 1 rectifier and 27 volts and 50
amps on the No. 2 rectifier, but within 20 minutes the amperage had
dropped to 6 on both rectifiers. It was found that the surface temper-
ature was hottest at the C electrode. This electrode was then discon-
nected from the system but there was no real improvement. Steam was then
passed through the carbon to dispel any air, but again there was a rel-
atively rapid drop off in amperage. Amperage on the No. 1 rectifier,
however, did increase upon tamping the top one foot (30.5 om) of carbon.
The power was then shut off and the carbon removed from the column. It
was decided that it was useless to continue with direct current using
stainless steel anodes. It would be necessary to use platinized elec-

trodes as anodes in order to successfully use direct current.

In preparation for using alternating current on the unit, the electrodes
were again cleaned. The work using direct current had indicated that
proper carbon packing was very important. This was almost impossible
to do with the electrode supports as originally designed, since all
five electrodes had to be inserted into the column together and tamping
through the electrode slots was next to impossible. Consequently, the
glass laminate electrode supports were cut in two places so that no more
than two electrodes had to be inserted at one time. Using air-dried
carbon, the bottom foot (30.5 cm) of the column was filled and packed
with a small wood ram rod. Following the packing of the earbon, the
leads from one of the direct current rectifiers were connected to the D
and E electrodes. This was done in order to obtain the voltage ana
amperage readings for calculation of the resistance. After packing the
pottom foot (30.5 cm), the voltage was 8 and the amperage 25, for a

152


Bthanol
Storage
Tank

Pump

Vent.

Activated
Carbon
Column
Acetic

Acid

Vaporizer

Receivers

[a

Pump

Conden-|

Ethanol — kthyl

cetate Fractionation
Column

Figure 36. Regeneration — step 2

91



3,885 mg/l, with a color determination of 10 color units. It is quite
obvious that these two latter samples contained a very small amount of

liquor carry-over.

Assays performed by gas chromatography are given in Table 3. The
methanol and furfural varied greatly in samples from various mills, as
well as from samples from the same mill. The data from Mill D which
submitted samples of condensate during normal operation and condensate
that was used for washing, indicates a considerable loss in the meth-
anol and furfural during the washing operation. Calcium levels varied
considerably from mill to mill and from sample to sample within the
mill. The two primary sources of calcium present in the condensate are
from liquor carry-over and from removal of calcium from the evaporator
in the washing cycle. The sodium content was so low that it appears

to be of little or no consequence in these studies.

The data measuring the volatile pollution potential and materials

found in these samples are given in Table 4 under categories of conden-
sate derived from hardwoods and from softwoods. As would be expected,
the acetic acid content of those samples derived from softwoods is
generally lower than those derived from hardwood. There is no real
trend in the methanol, formic acid, or SO2 content of the condensates.
The SO2 content, of course, is mostly affected by the type and method
of cooking the wood. The furfural content of the hardwoods is general-
ly higher than those of the softwoods but there are exceptions. Since
the furfural is derived from the pentoses present in the original liquor,
it would be expected that the hardwoods would contain the higher fur-
fural content, but the level of furfural present is greatly affected by

the type of cook or method of evaporation utilized.

It will be noted that the acetic acid content was determined by two
methods and that the gas chromatography method usually produced higher
results than the ether extraction procedure. Extremely high acetic acid
results by the gas chromatography method are attributable to inter-

ferences by unknown materials present in some of these condensates. No

13


Table 6 (cont'd). FURFURAL BALANCE STEAM STRIPPING RUNS
9-11-72 to 9-20-72

9-15-72

In Feed

4 (0.502) (60) (8.33) (0.0002) = 0.201 1b (0.0912 kg)
In Overhead

4 (0.049) (60) (8.33) (0.000925) = 0.0906 1b (0.0411 kg)
% Recovery = (0.0906/0.201) 100 = 45.0%

9-18-72

In Feed ,

4 (1.52) (60) (8.33) (0.000265) = 0.772 1b (0.351 kg)
In Overhead

4 (0.047) (60) (8.33) (0.001335) = 0.126 1b (0.0571 kg)
% Recovery = (0.126/0.772) 100 = 16.3%

9-18-72

In Feed

4 (1.368) (60) (8.33) (0.000175) = 0.478 2b (0.217 kg)
In Overhead

4 (0.045) (60) (8.33) (0.000885) = 0.0795 1b (0.0361 kg)
% Recovery = (0.0795/0.478) 100 = 16.6% :

9-19-72

In Feed

2 (1.140) (60) (8.33) (0.00015) = 0.171 1b (0.0776 kg)
In Overhead

2 (0.050) (60) (8.33) (0.00091) = 0.0455 1b (0.0207 kg)
% Recovery = (0.0455/0.171) 100 = 27.6%

9-19-72

In Feed

2 (1.215) (60) (8.33) (0.0002) = 0.243 1b (0.110 kg)
In Overhead

2 (0.057) (60) (8.33) (0.00071) = 0.0404 1b (0.
% Recovery = (0.0404/0.243) 100 = 16.6% (0.0183 kg)

9-19-72

In Feed

4 (0.76) (60) (8.33) (0.000125) = 0.190 1b (0.0862 kg)
In Overhead

4 (0.046) (60) (8.33) (0.000635) = 0.0583 1b (0.0265 kg)
% Recovery = (0.0583/0.190) 100 = 30.7%

42


Acetic Acid, % by weight

-———e————e Steam Stripping Column Feed
Xm X—— XX Steam Stripping Column Bottoms
oO Furfural Activated Carbon Column Effluent
O-——0-——6 Acetic Acid Activated Carbon
Column Effluent
0.6f—
March 13, 1973 March 26, 1973
&
x x; e. NN
0.5 — we x
x o—_—_—_——o
°
0.4
0.37
0.2
0.1
‘thanol Trace
i 1 i L J t 1 i |
C) 2 4 6 8 10 0) 2 4 8 10
Hours Column Used
Figure 33. Steam stripping, furfural activated carbon
and acetic acid activated carbon columns

87


splitter and a furfural crude fromthe bottom splitter. Disposal of
the bottoms from the fractionation column was to be studied. In a com-
mercial operation they might be sent back to the evaporators, since the
material they contain were no longer volatile. However, this could in-
volve about a 10% increase in evaporation load. This raised the ques-
tion of how many participating mills could handle a 10% increase in
evaporation load. Plans were to operate this column in conjunction
with the feed and steam stripping column systems, and study the effect

of the steam stripping operation on this column and its product purities.

Activated Carbon Adsorption

The activated carbon adsorption system consisted of a feed pump, heat
exchanger to control the temperature of the steam stripped evaporator
condensate to the carbon columns, and 10 inch I.D. (25.4 cm) stainless
steel columns. The first one was fed up-flow and the second one, which
was jacketed, down-flow. The liquid level in the second column was
controlled above the carbon by running the discharge tubing higher than
the top of the column. Disengaging sections were provided over and
under the columns. Temperature and pressure measurements were taken in
these sections in both columns. In the nonjacketed column there was a
connection for temperature and pressure readings in the middle. The
discharge condensate was piped to the drain. The nonjacketed colum
contained 98 pounds (44.5 kg) of Filtrasorbd 400 granular carbon and the
jacketed one 110 pounds (49.9 kg). The purpose was to study the bene-
fits of selective adsorption of acetic acid, furfural, and polymerized
material in the two carbon columns, and to evaluate the effectiveness

of the developed carbon regeneration. systems.

Activated Carbon Regeneration

The initial activated carbon regeneration systems were built as shown
on Fig. 3 and 4. These systems were identical to those developed and
used in Scott Paper Company's Everett Mill's pilot plant. For recovery
of furfural, polymerized material and that adsorbed portion of spent

25


‘Table 26. LOWELL UNIT — ALTERNATING CURRENT

Water Evaporation
Filtrasorb 400 Carbon
Carbon Bed 1 ft x 4 ft (30.5 cm x 1.219 m)

Temperature; °C (°F) Elec. resistance

Date Time Volts Amps T 2 3 tT cme/t ol ver
Power connection B to E— vibrator installed on shell of column
‘Thermocouple configuration:

1— Wo. 1 position, 2 inches (5.1 cm) into column

2—" position, 6 inches (15.2 cm) into column

27 ¥- 3 position, 2 inches (5.1 cm) into columa

—D' position, 2 inches (5.1 cm) into column

Virgin cerbon — wet

2-16-73 1:35 120 32 42(206) = 42108) = hO(a04) = a(106) 2.15, 3.77
2105 10 10 «41 (106) a(180)-72(162) 75163) 3.67 12.04

Started vibrator and tapped column with mallet

UL ata (06) 86(287) 72162) TH(2G5) 1.76 5.77
mo 86 = THQ65) 8178) = 7(260) 71160) 6.05 19.85

Packed carbon from top

10972 TH(65)-85(285) -79(272)-78(272) O52 1.61
10 k5 Looaa2)— 99{210)—-99(210) 99210) 0.81 2.66
Power off
2-19-73 8:15 108 27 «636. 97) 36 9) 36. 97) 36.97) 1.33 4,36
Packed carbon from top
106 = 83 38(100) 58(136)55(131) 53127) 0.3 1.31
106 54 1oo(z12) 108226) 100(212) © 100(212) 0.65 2.13
108 = 33. g9(210) 110(230) loo(er2) = 98(210) 1.09 3.78
Packed carbon from top
10:35 106 =50 1o0(212) + 120(230) 101(214) —-95(203) oT. 2.33

Sudden temperature rise on No. 2 thermocouple to 143°C (289°F) then: to 181°C (358°F)
Removed top flange — packed carbon — No. 1 thermocouple out of order — flange left off

1:35 «5835 26u3(32T) 128(244) —00(212) 0.55 1.80
ako 657 - 1665(331) 160(320) 105(221)) 0.46 1.51
0 6 59 + 98°(208) 106°(223) 96¢(205) 0.37 1.22

Power off — carbon dry except for 1.(2.5 cm) inch around periphery

Wet carbon — replaced top flange
Pover connection B to E — thermocouple configuration same as for 2-16-73

2-20-73 9:00 88 125 ak 75) 3( 88) 28 82) -35(-95) 0.27 0.88

9350 95 100 97(207)79{274) —-96(205)_-95(203) 0.32 1.05

10:30 10557 = 98(208) —95(203)  98(208) 103(217) 2.00
Vitrator on

20sho 207 =e 98(208) — 97(207) 99210) 105(221) 0.82 2.66

21:30 107-33 98(208) 100(212)  ioL(auk) 157(315) 1.08 3.54
Vibrator off

12:00 108 = 32, 98(208) 102(216) 102(216) 151(30h) 1.16 3.80

1 lot 36 —-99(210) i327) 2os(2e1) 1344273) a.99 3.25

106 56 99(210) rN7b(2g7) 20(ak8) r62°(324) 0.63 2.07

80 53 96(208) 1o1°(21h) —192(378) 192%(378) 0.50 1.64

Pover off — 23k liters (6.2 gal) of water distilled from colum and 5 liters (1.32 gal.)
drained

“mmermocouple inserted 4 inches (10.2 em) into colum.
“mmermocouple inserted 3 inches (7.6 cm) into column.
“Thermocouple inserted 1 inches (3.8 cm) into colum.
Smermocouple inserted 1 inch (2.5 em) into column.
“tmermocouple inserted ¥ inch (1.3 em) into column.

160


D.

Fractionation column

1.

Reboiler — evaporates 3000 1b (1362 kg) of water from 70°F
(21.1°C) to 247°F vapor. Heat required = [(212-50) + 970
+ 0.482 (35)] (3000) = 3,390,000 Btu (854,280 kg-cal)

Estimated amount of heat required by the fractionation

column:

ae

Heat to bring the feed temperature, 166°F (74.4°C) to
its bubble point, say 205°F (96.1°C) = [2920 (1) +
3.10 (0.418) + 15.3 (0.566) + 17.0 (0.5) + 5.60 (0.478)
+ 11.4 (0.5)] (205-166) = 115,000 Btu (28,980 gm-cal)
Heat of vaporization = (15.0 + 0.3) (262.8) (1.8) +
(0.2 + 13.5) (94.9) (1.8) + 0.2 (970) + 3.10 (107.5)
(1.8) = 10,300 Btu (2596 gm-cal)

Heat to bring the bottom stream [(x + 2920 - 0.2) lb of
water, 3.30 SO2, 5.60 HAc and 11.4 unaccounted HAc]
from 205°F (96.1°C) to 210°F (98.9°C) = [(2920 + x)

(1) + 3.30 (0.5) + 5.60 (0.487) + 11.4 (0.5)] (220-
205) = 5(2930 + x) = 14650 + 5x (x = 1b of steam
used).

If live steam is used, and the steam comes in at 73
psig (5.13 kg/cm?) (318°F) (158.9°C) and leaves at
210°F (98.9°C) as liquid, then 115000 + 10300 + 14650
+ 5x [(318-212) (0.482) + 970.3 x + (212-210)] x.

x = 137 1b (62.2 kg)

Total heat required = 141,000 Btu (35532 kg-cal). This
compares with the heat required for the reboiler,

3,390,000 Btu (854280 kg-cal).

Let 149°F (65°C) be the reference temperature. Heat in
with steam which is at 213°F (100.6°C), Hi = 3000 [ (0.482)
(1) + 970 + (1) (63)] = 3,100,000 Btu (781200 kg-cal).
Heat in with the feed which contains:

Water 2920 1b (1325.7 ke)

Furfural 3.10 lb (1.4 ke)

125


Table 2. COD, BODs, AND ACETIC AND FORMIC ACID DATA

tractl
‘Acetic Formic
Semple COD, BOs, WOAY, acid, acid,
Mill number Semple identification mg/l mg/L g/L mg/l mg/1
A 1 Dense hardwood 9/7/72 101k 6090 5998 5875 95
A 2 Dense hardvood 9/8/72 i016 6252587657330
A 3 Dense hardvood 9/9/72 10822 67Th sks Shah 1
A 4 Anpenadense herdvood
9/10/72 8769 = 5870 5326 5308 uy
B 5 66% Hardwood, 34% softwood 12098 8884 66276550 9
3B 6 = Bome a8 No. 5 but used
for wash 9828 = 6480 5680 5570 Bh
B 1 93% Poplar, 7% spruce 12062 7890 65786523 he
B 8 — Game a8 No, 7 but used
for wash loss2 Th 7006 6964 32
3B 18 1% Hardwood, 86% softwood 9h87 7113. ese ar? 4
B19 Same as Mo, 18 but used
for wash 1743 6258 = ks32 sag 2
B 32 SSL, 34% hardwood, 66%
softwood 173425 -37h25 58795550252
B 33 3b Hardwood, 66% softwood 10400 6772 4633 4572 46
c 9 100% Aspen 9/19/72 1268 5586 WT03 4650 a
c 10 100% Aspen 9/20/72 1859 = 5088 4978 ‘960 uw
c a 100% Aspen 9/22/72 1622. Th56 5528 Sura uh
¢ le 100% Aspen 9/26/72 9780 6436 5894 5613 62
D 13 95% Aspen, 5% apruce
combined condensate 5630 bh76 = 2762. 2618. 10

D 1h 495% Aspen, 5% spruce
second effect 3830 4350 3023 2976 6

D> 2k ‘95% Aspen, 5% spruce
combined condensate

1/2h/73 5162 3870 2624 2591 25
D «25 OSH Aspen, 5% 8)

second effect PT/ah/T3 6330 W764 3584 3551 25
E 15 100% Hardwood gee TA3h 7280 7266 nn
g 16 100% Softwood 6152 4506 ho25 woze 2
, u aries musface condensate solve 11100 5803 5800 2
r 20 Exploded wood pulp 32250 «1730-136 967 130
F 22, Hardboard mi11 12/20/72 gus «1332 62h 1301 2hB
Fo 23— Hardboard mi21 1/4/73 3393 22051567 ag 106
2 2 Boftwood 76203718 = 57h 51h Ay
H 26° Softwood, high solids

effect 900 8 6 ho Pu
H at? — Softwood, lov solids effect 2254 1566 36 wr (ub
a 28 Softwood, 26 end 27 blend = =« 16941031 52 33 ro
H 29° Boftwood, total condensate 31912334 «19531896 43
T 30 Magnefite softwood 2/2/73 2982 -15h8 1325 1246 60 ,
a 31 —- Magnefite softwood 2/5/73 3885 2358 akg 2350 60

organic acids (VOA) in terms of acetic acid.
tripped neutral:

a
Spotel condensete from prestrigped unneutralized SSL.

9



Sulfur Dioxide,

Organic Loosely Combined, g/liter

0.8—

Steam Stripping, Furfural Activated Carbon and
Acetic Acid Activated Carbon Columns

Feed Rate = 1 gpm (3.78 liters/minute)
Stripping Rate = 6% by Weight of Feed

0.7.

Steam Stripping Column Feed «¢.

o——e
0.67 Steam Stripping Column a—— X-———-k
. Bottoms

FPurfural Activated Carbon o—_—_o-——_0
Column Effluent

Acetic Acia Activated o—_e—® .

0.5. Carbon Column Effluent

O.uL

Ce

5 6 7 8 9 1 a 22 33

Hours Column Used

1eo— l fi
3 4

Figure 20. Organic loosely combined sulfur dioxide concentrations —
steam stripping and activated carbon column flows

53


process made in this section are also 100 times that of the actual flow
quantity of 500 1b evaporator condensate processed in 1 hour. The
calculations for the regeneration processes are accordingly proportion-

ed.

Since the individual equipment used in the pilot plant is not optimized,
and the flow quantities and conditions vary from case to case, it is
felt that a total energy balance of the pilot plant would not be help-
ful in the economy feasibility analyses. Only enthalpy balances are
made. The calculations are based on the actual operating conditions,

so that estimations of the heat requirements can be made.

Enthalpy balances:

I. Separation process

A. Preheater Sp. Heat
Water 4g ,800 1b (22609.2 kg) 1.05
Furfural 8.08 lb (3.6 kg) 0.418
Methanol 32.5 lb (14.8 kg) 0.66
Acetic acid 134 1b (60.8 kg) 0.54
Sulfur dioxide 49.0 lb (22.2 kg) 0.5 (estimated)

The above heated from 134°F (56.7°C) to 212°F (100.0°C)
Heat required, H, = [49800 (1.05) + 8.00 (0.418) + 32.5 (0.66) +
134 (0.54) + 49.0 (0.5)] (212-134) = 4,090,000 Btu
(1,030,680 kg-cal).
B. Stripping column reboiler

To heat 3000 1b (1362 kg) of water from 70°F (21.1°C) to 2h7°F

(119.4°C) vapor, heat required Hz = 3000 [(2h7-212) (0.482) +

970 + (212-70)] = 3,390,000 Btu (854,280 kg-cal).

Estimated amount of heat required by the stripping column:

1. Assume there is no heat loss from the point the condensate
leaves the preheater to the feed point. ‘The feed is in the
liquid state and at a temperature which is just about the
bubble point. Therefore, no heat is required to bring the
feed up to the bubble point.

122


Table 16. TYPICAL ACTIVATED CARBON FURFURAL COLUMN REGENERATION DATA

Fractionation Column Reboiler, 1st Pressure Gage
Fractionation Colum Reboiler, 2nd Pressure Gage
Fractionation Column Bottom Pressure Gage
Fractionation Column Manometer (Feed to Bottom)
Fractionation Column Top Pressure Gege
Fractionation Column Middle Pressure Gage
Activated Carbon Furfurel Column Top Pressure Gage
Activated Carbon Furfural Column Bottom Pressure Gage
Temperatures
Fractionation Colum Liquia Bottoms
Fractionation Column Bottom Splitter
Fractionation Column Feed
Fractionation Column at Feed Plate
Fractionation Column Middle Splitter
Fractionation Colum Top Splitter
Fractionation Column Vent
Activated Carbon Furfural Column Bottom
Activated Carbon Furfural Column Middle
Activated Carbon Furfural Column Top
Flow Rates to Activated Carbon Column

Flow Rates to Fractionation Column

106

70 psig
67 psig
0 psig
1" #20
24" H20
3" H20
3 psig

0 psig

213°F
19°F
1kg°F
150°F
149°F
1kger
96°F
147°F
UT°F

151°F

(4.92 kg/cm?)
(4.71 kg/m?)
(0.00 kg/cm?)
(2.54 cm H20)
(6.35 cm #20)
(7.62 cm H20)
(0.21: kg/cm?)
(0.00 kg/cm?)

(100.6°¢)
(65.0°C)
(65.0°C)
(65.6°c)
(65.0°C)
(65.0°C}
(35.6°c)
(63.9°C)
(63.9°C)
(66.1°C)

0.10 gpm (0.38 1/min.)

0.10 gpm (0.38 1/min.)


got

LEGEND

TF, 1b 0.152 Methanol

TF, 1b total flow, 1b TF, 1b 30 [iecH 0.150; 50, 0.002 >
Furf. furfural

MeOH methanol OF, 1b 0.033 Furfural

$0, sulfur dioxide = 0.03103 Hg0 0.

a0 vater

MeCOOH acetic acid

t) to be retained

() unaccounted

TF, 1b 500; MeOH
T-HETF 5
0.08005 40 499]
MeCOOH 1.17

tvr, 1b 1.19]
[S02 0.0200]
fMeCooH 1.17}

Stripping Colum

Fractionation Colum

Qnd Activated Carbon Colum

st Activated Carbon Column

|MeCOOH
0.05605
(meCooH
0.114) TF, 1b 499
‘MeOH 0.160
|TF, 2b 500 eo
Furf. 0.0400;
TF, 1b 500 IMeOH 0.160; -
S03 0.0800 ;
3s a0 499 499
i303 3 |MecOOH 1.17 TF, 1b 59.4 MeCOOH 1.17
HO 498; . . 80a 0.03305
MeCOOH 1.3% "F, Hg0 59.25
ge 30) 7 MeCOOH 0.0560;
x 4a (MecooH 0.224)
&
TF, 1b 30
>
t Ha0 30 Sewer

Figure 43. Separation process — mass flow sheet


10

il

12

13

14

15

16

17

18

19

FIGURES

Scott Paper Company Pilot Plant Installation
Everett Mill

IPC Pilot Plant — Consolidated Papers, Inc.
Appleton Mill

Activated Carbon Column Furfural Regeneration
Activated Carbon Column Acetic Acid Regeneration

Methanol Removal vs. Stripping Steam Used — Scott
Paper Company ~ 48-Inch (121.9 om) Packing
Methanol Removal vs. Stripping Steam Used — Scott
Paper Company — Variable Packing

Sulfur Dioxide Removal vs. Stripping Steam Used —
Scott Paper Company — 48-Inch (121.9 cm) Packing

Sulfur Dioxide Removal vs. Stripping Steam Used —
Scott Paper Company — Variable Packing

Methanol Removal vs. Stripping Steam Used — Consolidated
Papers, Inc. — 48=Inch (212.9 om) Packing

Methanol Removal vs. Stripping Steam Used — Consolidated
Papers, Inc. — 12-Inch (30.48 cm) Packing

Sulfur Dioxide Removal vs. Stripping Steam Used —
Consolidated Papers, Inc. — 48-Inch (121.9 cm) Packing

Sulfur Dioxide Removal vs. Stripping Steam Used — .
Consolidated Papers, Inc. — 12-Inch (30.48 om) Packing

Acetic Acid Concentrations ~ Steam Stripping Column
Feed and Bottoms

Acetic Acid Concentrations ~ Furfural Activated Carbon
Column Feed and Effluent

Acetic Acid Concentrations — Acetic Acid Activated
Carbon Column Feed and Effluent

Methanol Concentration — Steam Stripping Column Feed
and Bottoms

Methanol Concentration — Furfural Activated Carbon
Column Feed and Effluent

Methanol Concentration — Acetic Acid Activated Carbon
Column Feed and Effluent

Biochemical Oxygen Demand — Steam Stripping and
Activated Carbon Column Flows

vi

18

20
al
22

28
29
30
31
32
33
3h
35
46
WT
48
4g
50
51

52


Acetic Acid, % by weight

0.6

o——e
x

@ Steam Stripping Column Feed
X——-x Steam Stripping Column Bottoms
o——0——o_ Furfurel Activated Carbon Column Effluent

Acetic Acid Activated Carbon Column
o—o- se] Effluent

Feb. 20, 1973

Mareh 8, 1973

lo 12

Hours Column Used

0 10 12

Figure 32. Steam stripping, furfural activated carbon
and acetic acid activated carbon columns

85


Sulfur Dioxide Removal, %

100

90

70

60

50

ho

30

20

10

r —0-0-0 0 09-59 ono

Scott Paper Company
Everett Mill Blow Gas Condensate
L. 48-Inch (121.9 cm) Goodloe Packing

L 1 1 L a j I L 1 J L J

1 2 3 4 5 6 7 8 9 lo oll. 22
Stripping Steam, % weight of feea

Figure 7. Sulfur dioxide removal v: i
re ¥s.istripping steam
used — Scott Paper Company ~ 48-inch (121.9 em) packing

30


feet (61.0 om) of carbon. Amperage started at 95 and immediately drop-
ped to a very low level. Again the connections were changed so that
only the bottom foot (30.5 cm) of carbon was involved, with the anode
in the D position and the cathode in the E position. With this con-
figuration at 11:14 a.m. the readings were 53 volts and 10 amps and by
11:21 the amperage had dropped to 6. The rectifier was then connected
between the middle 2 feet (61.0 cm) of carbon, with the anode in the B
position and the cathode in the D position. The power readings were
then 52 volts and 12 amps. With the same electrode connections, but to
the No. 1 rectifier instead of No. 2 rectifier, the readings were 62
volts and 35 amps.

These changes indicated that there may have been a separation of the
carbon at some point in the column, so again the carbon was wet with
tap water. All power connections were then replaced as previously,
with the anodes in the A, C, and E position and the cathode for Recti-
fier No. 1 in the B position and for Rectifier No. 2 in the D position.
While in the wet condition, resistance remained low. Prior to dis-
continuing operation for the day, pressure was exerted on the column,
first at 3/4 pounds per square inch (0.052 kg/cm”) and then at 10
pounds per square inch (0.70 kg/cm?) , by closing off all outlet vents.
Each time there was a momentary increase in amperage on Rectifier No. 2.

Operational data for the next day's operation, January 25, are given

in Table 23. Power connections were left the same as the previous day.
The carbon was again wet with tap water and power was applied for one .
hour. During that time there was a rapid heating to near the boiling
point with good conductivity while the carbon was wet. The vapor flow
was then reversed to top to bottom on the assumption that this might
produce some internal pressures that would tend to pack the carbon
rather than loosen it. The amperages on No. 1 rectifier dropped con-
siderably and the application of 3 pounds per square inch (0.21 kg/cm?)
of air pressure did not restore the amperage.

150


Total sulfur dioxide 0.490 1d (0.22 kg)

Water 498 lb _(226.09 kg)
500 To (227.00 kg)
db. Steam 30 lb (13.62 kg)
Total in = 530 1b (240.62 kg).
B. Out:
a. Bottoms — by analysis
Acetic acia 1.17 1b (0.53 kg)
Methanol 0.160 1b (0.07 kg)
Furfural 0.040 1b (0.02 kg)
Total sulfur dioxide 0.0800 1b (0.04 kg)
Water 499 lb (226.55 _k,
500 1b (ee 88 ‘3
b. Volatiles — by difference
Acetic acid 0.0560 1b (0.02 kg)
Methanol 0.165 1b (0.07 kg)
Furfural 0.0400 1b (0.02 kg)
Total sulfur dioxide 0.410 lb (0.19 kg)
Unaccounted acetic acid 0.114 1b (0.05 kg)
Water 29.2 lb (13.26 k
30.0 1b (13.62 es}

Total out = 530 1b (240.62 ke)

It should be noted that since the compositions of the preheated feed,
the gases leaving the receiver, and the fractionation column feed were
all based on actual analyses, the "unaccounted acetic acid" has to be

used here to complete the acetic acid analysis.

4. Around the fractionation column:

A. In:
a. Feed
Acetic acid 0.0560 1b (0.02 kg)
Methanol 0.153 1b (0.07 kg)
Furfural 0.0310 1b (0.01 kg)
Total sulfur dioxide 0.170 1b (0.08 kg)

117


Vent

>
o K
A
Liguid A - Cond
onden:-
ser
| Vapor

2nd
——

Ethanol — Ethyl
po Acetate Fraction-

ation Column

Activated
Carbon
Column
Acetic

Acid

| be

Ethanol
Storage
Tank

Vaporize:

Pump

Receivers

\

Pump

Figure 37. Regeneration — step 3

92


100 -
Consolidated Paper's, Inc.
90 Appleton Division Mill Evaporator Condensate
12-Inch (30.48 cm) Goodloe Packing

80

TOF

60
we
d
i

50.
3
FI
3
2

dob

30

20

°
10 |"
0 J 1 ! 1 L ! i L 1d |
0 1 2 3 4 5 6 1 8 9 lo wm 22

Stripping Steam, * weight of feed

Figure 10. Methanol removal vs. stripping steam used —
Consolidated Papers, Inc. — 12-inch (30.48 cm) packing

33