Boih Emissions 

Sulf.ur capture in combination 

bark boilers 

Arutll V. Someshwar and Ashok K Jain 

ABSTMCT A review of sulfir dioxide emission hta for eight 

com bimtion bark boilers in conjunction with the sulfir contents of 

the fieh reveah significant su@r capture rangingfrom 10% to over 

80% within the soldash phase. Wood ash characteristics simihr to 

activated carbon as well as the significant wood ab alkali ox& and 

carbomte fractions are believed responsible for the su@r capture. 

Su@r emissions from combination bark-fossilfieljring are 

correhted to the su@r inputper ton of bark or wood residue jred 

KEywoRDs: Ash, bark, boilers, emission, gas scrubbing, sulfir 

dioxi&. 

oilers which can burn bark and B other wood residues such as saw 

kerf, sander dust, and wood fines either alone or in combination with fossil fuels find wide use at forest product 

manufacturing facilities. The ashes 

resulting from wood residue combustion typically contain a significant fraction of oxides and carbonates of alkali 

metals such as calcium, potassium, and 

magnesium. Although there is no literature documentation, wood residue 

ash can capture some of the sulfur 

dioxide released with the eo-firing of 

sulfur-containing fossil fuels such as 

coal or fuel oil with wood residue. When 

a wet scrubber follows the combination bark boiler, this sulfur dioxide 

removal by alkaline wood ash becomes 

even more prominent. 

This paper reviews available data 

on sulfur capture in combination bark 

boilers and explores the reasons for 

this capture. During collection of much 

of this data there was no systematic 

effort to identify the mass balance on 

sulfur. The study compares data on 

stack sulfur dioxide emissions from 

combination bark boilers with the sulfur content of fuels eo-fired with bark 

or wood residue to estimate the extent 

of fuel sulfur capture in wood ash. 

There is also supporting data on gassolid sulfur capture by alkaline fractions of other fuels. 

Wood residue composition 

Table I presents the analyses of some 

selected wood residues burned as fuel 

as well as analyses of ashes resulting 

Someshwar is senior research engineer and Jain is regional manager with National 

Council of the Paper Industry for Air and Stream Improvement, P.O. Box 141020, 

Gainesville, FL 32614. 

from wood residue burning (I, 2). Typical wood residues contain nearly 2- 

4% ash. Over 60% of these ashes are 

oxides and carbonates of calcium? potassium, and magnesium. When cofiring with oil, coal, or any other 

sulfur-containing fuel, these alkali oxides and carbonates can react with the 

sulfur dioxide and sulfur trioxide resulting from fuel combustion. 

Figure 1 is a simple material balance which demonstrates the potential for sulfur capture in a combination 

boiler. As an example, consider firing 

a mixture of 30% coal and 70% bark 

(heat input basis) in a 500 x lo6 Btuh 

combination boiler. Assume the coal 

has 1% sulfur and a heating value of 

12,500 Btu/lb, and the bark has 0.025% 

sulfur, 2.0% ash (of which 50% is calcium oxide), and a heating value of 

8600 Btu/lb. The molar ratio of calcium to sulfur in the fuel would be 

approximately 1.9. The alkali metal 

concentration in the coal-bark combination fuel is clearly in excess. As the 

results of this paper will show, there 

will be capture of over 50% of the combined fuel sulfur in the combustion 

ashes. Calcium to sulfur mole ratios 

ranging from 1 to 3 in lime-limestone, 

wet or dry, flue gas desulfurization 

systems have historically yielded well 

over 50% sulfur dioxide capture. 

Sulfur capture in wood residue 

boilers-prior evidence 

The sulfur content of bark and other 

wood residues is very small. One report indicates that the sulfur content 

of 14 different wood samples ranges 

Vol. 76, No. 7 Tappi Journal 179 
1. Sulfur balance for a combination bark boiler 2. Percentage sulfur retention vs. Ca/S ratio for lignite samples 

30% coal, 70% bark 

Coal: 1.0% S 

Bark O.O25%S 

Flue gas 

99,000 dry std. it3 per min @ 4% 0 

120 ppm SOp (60 Ib/h S) 

4 

Economizer & 

ESP ash 

CP 

- (70 Ib/h S) 

Coal: 6 ton& 

(120 lb/h S) 

Bark 20 ton& 4 1 - - - -.C!Bottom ash (10 Ib/h S) 

from 0 to 0.1% on a dry weight basis 

(3). The average is approximately 

0.028%. A field study by NCASI to 

quantify the fate of this small amount 

of sulfur in wood residue, when only 

the residue was fired in four boilers, 

showed that just over 5% of the sulfur 

contained in the residue was emitted 

as sulfur dioxide. The remaining sulfur was in the bottom and fly ash (1). 

Table I also shows that the ash from 

wood combustion typically contains less 

than 3.2% sulfate expressed as sulfur 

trioxide. During several tests on combination bark-fossil fuel boilers, however, analyses for soluble sulfate 

content of particulate matter caught 

on filter papers showed large metal 

sulfate fractions (4,5). EPA Method 5 

was the test procedure. In the case of 

two boilers, both of which fired wood 

residue and oil in various combinations, 

soluble sulfates comprised from 35% 

to 76% of the total particulate catch 

(4). Furthermore, in one of these boilers from 37% to 54% of the soluble 

sulfates were present as metal sulfates, 

the remainder as free sulfuric acid. In 

the outlet of a third oil-bark combination boiler firing a 2.2% sulfur oil, the 

180 July 1993 Tappi Journal 

50' ' 

CalS RATIO OF LIGNITE SAMPLE 

I 

1. Analyses of some selected wood residues burned as fuel 

Item 

Western 

Jack pine Birch Maple hemlock 

Ash 

Volatile 

Fixed carbon 

Carbon 

Hydrogen 

Sulfur 

Nitrogen 

Ash 

Oxygen (by difference) 

Heat value,Btu/lb dry 

TiO, 

Sulfate as SO, 

Proximate analysis, YO 

2.1 2.0 

74.3 78.5 

23.6 19.2 

Ultimate analysis, % 

53.4 57.4 

5.9 6.7 

<0.2 c0.2 

0.1 0.3 

2.0 1.8 

38.6 33.8 

8930.0 8870.0 

Ash analysis, Yo 

16.0 3.0 

6.3 0.0 

5.0 2.9 

51.6 58.2 

4.9 13.0 

5.5 4.2 

1.6 4.6 

2.8 2.9 

4.1 6.6 

3.1 1.3 

0.2 Trace 

2.6 3.2 

4.3 

76.1 

19.6 

50.4 

5.9 

<0.2 

0.5 

4.1 

39.1 

8190.0 

9.9 

3.8 

1.7 

55.5 

1.4 

19.4 

1 .o 

1.1 

5.8 

2.2 

Trace 

1.4 

2.5 

72.0 

25.5 

53.6 

5.8 

<0.2 

0.2 

2.5 

37.9 

8885.0 

10.0 

2.1 

1.3 

53.6 

9.7 

13.1 

1.2 

2.1 

4.6 

1.1 

Trace 

1.4 
Sulfur caDture in bark-coal boilers 

8- 

4- 

P 

!2 

2 

a 

8 

cl 

z 

Y 

K 

a 

a 

m 

LL 

0 

z 

0 

z 

rn 

5 

E 

0 

2 

K 

a 

LL 

4 

a 

rn 

-60 8 

W 

K 

3 

In 

4 

0 

K 

3 

LL 

-I 

-40 2 

d 

12 1 180 

\ 

\ 

\ 

\ 

/ \ 

\ 

\ 

\ 

i 

0' ' 20 

0 10 20 

SULFUR IN COMBINED FUEmON WOOD RESIDUE, Ib 

Sulfur capture in bark-oil boilers 

14 

P 

W 

W 

LL 

- 

d 

d 

P 10 

z 

Y 

K 

m 

a 

a 

B 

5 

3 

52 

z 

O6 

z 

rn 

0 

ur 

K 

a 

a 

fn 

100 

80 

\ 

60 

40 

20 

0 

0 10 20 30 

SULFUR IN COMBINED FUEVTON WOOD RESIDUE, Ib 

total sulfate concentrations ranged 

from 2.9% to 25.5% of the total sulfur 

emissions (5). The metal sulfate fraction of the total sulfate emissions in 

this case ranged from 53% to 92%. 

Clearly, significant sulfur capture in 

bark ash was occurring in these combination boilers. 

One investigator (6) reported that 

the substitution of up to 13% byweight 

of hogged fuel by coal in a boiler with 

emissions controlled by multiclones 

and two parallel wet scrubbers resulted 

in a negligible change in the level of 

sulfur dioxide emissions. At comparable steam production rates of about 

160,000 lbh, the coal substitution increased sulfur dioxide emissions from 

zero to only 6 ppm. Although the coal 

sulfur content and heating value are 

unknown, at 13% by weight coal substitution a coal with sulfur content in 

the range of 0.5 to 3.0% and heating 

value of 12,500 Btu/lb should have resulted in nearly 100400 ppm of sulfur 

dioxide in the stack at 3% oxygen. 

capture ita other bodem 

The literature also documents sulfur 

capture by the alkaline ash of other 

fuels such as coal, oil, and municipal 

refuse. In an analytical study by the 

EPA to assess the potential for sulfur 

retention in various types of coal-fired 

boilers, significant fractions of the sulfur were shown to be bound as calcium 

and sodium salts (7'). For example, Figure 2 shows how a significant sulfur 

retention occurs in lignite coal which 

contained about 20% lime in the ash 

(7). Equation 1 provides the relationship for this curve: 

% sulfur retention = 74.1 (Ca/S)o.22 (1) 

Other investigators (8) showed that 

sulfur retention in coal fly ash was a 

function of the alkali metal oxide content of fly ash. For pulverized coalfired boilers with electrostatic 

precipitators they estimated sulfur dioxide removal due to retention in the 

fly ash to range from near zero for a 

coal with very low alkalinity to greater 

than 40% for a 0.5% sulfur coal with 

10% ash and 35% total alkali metal 

content in the ash. 

From available data on the incineration of municipal refuse which usually contains between 0.10% to 0.15% 

sulfur, one study (9) concluded that 

the stack only released one fourth of 

the sulfur as sulfur dioxide. The remaining sulfur was fixed in the grate 

and fly ashes as alkaline sulfates. 

As mentioned earlier, evidence of 35- 

76% sulfate fractions in ashes resulting from bark or wood residue 

co-combustion with oil, both as free 

sulfuric acid and as alkali metal sulfates have been found(4, 5). These 

sulfates most likely originate as sulfur 

trioxide resulting from oxidation of sulfur dioxide, just as in the formation of 

sulfuric acid during oil or coal combustion(l0,ll). The extent of sulfur trioxide formation required to explain the 

level of sulfates present in combination bark boiler ashes, however, far 

exceeds that typically associated with 

oil or coal combustion alone. There 

must therefore be other mechanisms 

of sulfur dioxide oxidation involving 

the bark ash. 

Vol. 76, No. 7 Tappi Journal 18 I 
_I -> 

II. Combination boiler source and fuel description 

Total Fossil Fossil Yo Heat input Yo Heat input Measured 

heat input, bark or wood fossil Other SO, emissions, 

Code x106 Btu/hr type s, % residue fuel fuels Ib/l O6 Btu 

Mill A 760 

Mill B 461 to 474 

Mill C 274 to 475 

Mill D 239 to 318 

Mill E 190 to 320 

Mill F 231 to 585 

Mill G 179 to 310 

Mill H 198 to 258 

Coal 

Coal 

Oil 

Coal 

Oil 

Oil 

Coal 

Oil 

1 .oo 

0.9!5 

2.1!5 

1 .oo 

2.1!3 

2.1!3 

0.40 

2.20 

45 to 73 

53 to 81 

64 to 84 

9 to 40 

80 to 87 

16 to 79 

9 to 19 

41 to 81 

27 to 55 

19 to 47 

16 to 36 

22 to 86 

13 to 20 

21 to 84 

72 to 86 

19 to 59 

None 

None 

None 

NCG, gas 

None 

None 

Sludge 

None 

0.12 to 0.76 

0.06 to 0.36 

0.13 to 0.44 

0.62 to 1.88 

0.43 to 1.84 

0.43 to 1.84 

0.14 to 0.41 

0.05 to 0.61 

I 

5. Sulfur capture in boilers with venturi scrubber 6. Summary of gas-solid sulfur capture in combination boilers 

tD 

- 

0 40 80 120 

80 

i9 

d 

60 

3 

I0 

40 2 

-I 

3 

rn 

n 

a 

a 

20 

I 

SULFUR IN COMBINED FUEVTON WOOD RESIDUE, Ib 

Judging by the way wood ash forms 

in bark boilers, it is reasonable to expect it to possess properties similar to 

that of activated carbon. Pyrolysis or 

cabonization of several carbonaceous 

materials including sawdust and wood 

forms activated carbon (12). Wood ash 

has a small particle size and low density similar to activated carbon (13). 

The carbon content ofwood ash ranges 

from 1% in fluidized-bed combustion 

to 70% in inefficient burners, a typical 

range being 530% (14). The high degree of carbon in wood ash is further 

evidence of the carbonization process 

12 

-Iw 

3 

u. 

0 

W 

f 

88 

$3 

54 

a 

z 

0 

z 

u) 

0 

u, 

a 

3 

u. 

J 

3 

u) 

0 

100 

80 

i9 

60 $ 

3 

I0 

40 2 

-I 

3 

u) 

n 

a 

a 

20 

0 

0 40 80 120 160 

SULFUR IN COMBINED FUEVTON WOOD RESIDUE, Ib 

- 

111. Best fit curves 

1 

Figure xvs. Y, r2 log x vs. log Y2 r2 

3 Y, = 0.52X - 1.29 0.94 Y, = 155.9X-058 0.56 

4 Y, = 0.44X - 0.174 0.90 Y, = 11 3.9X-044 0.46 

5 Y, = 0.44X + 3.18 0.31 Y, = 80.7X-009 0.08 

6 Y, = 0.45X - 0.55 0.91 Y, = 128.5X-050 0.51 

II I 

that occurs during wood residue corn- properties of several microcrystalline 

bustion. carbonaceous materials including acActivated carbon is averygood cab- tivated carbon. Using experimental relyst for the oxidation of sulfur dioxide sults of several investigators, they 

to sulfur trioxide. One group (15) re- concluded that even at elevated temviewed the absorptive and catalytic peratures (representative of sulfur di182 July 1993 Tappi Journal 
oxide-bearing flue gases) activated 

carbon can absorb a considerable 

amount of sulfur dioxide through catalytic oxidation occurring on the carbon surface. In addition, the presence 

of water vapor and oxygen enhance 

the absorption of sulfur dioxide. Under these conditions, sulfur dioxide 

converts to sulfuric acid and the acid 

remains on the carbon (15). The activated carbon-like wood ash has the 

added advantage of being able to neutralize the acid formed from sulfur dioxide oxidation due to the significant 

concentration of alkaline oxides and 

carbonates in the ash. 

Other potential mechanisms for sulfur capture in wood ash may include 

sulfur dioxide reaction with calcium 

oxide in the ash with concurrent oxidation to sulfate. There can also be 

oxidation of sulfur dioxide to sulfur 

trioxide by metal oxides present in the 

wood ash (in addition to the action of 

carbonaceous materials) and subsequent capture by alkaline wood ash 

fractions. 

Sulfur capture in combination 

bark boilers 

For the study we obtained data on 

sulfur emissions from combination 

bark boilers from mill tests (compliance and otherwise) available to 

NCASI as well as other sources of 

published information. The following 

presentation provides data on capture 

the solid ash phase (pre-scrubber or 

boilers without scrubbers) or into both 

the solid and liquid phases (boilerswith 

scrubbers). Table I1 provides a summary of the eight combination boilers 

used to collect the data including the 

fuel mix in each boiler, fuel sulfur contents, and range of measured sulfur 

dioxide emissions. The percentage sulfur content of bark or wood residue 

when measured, was always below 

0.04%. 

Figures 3-6 are plots of the data in 

units of pounds of sulfur emitted as 

sulfur dioxide per dry ton of combined 

fuel, Y,, vs. pounds of sulfur in the 

combined fuel per dry ton of bark or 

I of volatilized sulfur compounds into 

wood residue (X). In addition, these 

figures provide on the second y axis 

the reduction in potential or stoichiometric sulfur dioxide emissions (alternately, the percentage sulfur 

captured), Y,, as a function of X. Table 

I11 shows the best fit curves for X vs. 

Y, and log X vs. logy, as well as the 9 

values for the regression fits in each of 

these figures. 

One should note that for barks with 

similar calcium contents the inverse of 

X is proportional to the more familiar 

calcium to slllfur mole ratios used 

extensively for correlation in the area 

of flue gas desulfurization. 

Bark-coal combustion 

Mills A, B, and D fired significant 

amounts of coal along with bark in 

their combination boilers. Mill D also 

fired some natural gas and pulp mill 

vent gases (NCG) containing sulfur 

compounds. Figure 3 presents the data 

for sulfur capture in bark-coal boilers. 

Mills A and B boilers had electrostatic 

precipitators (ESP). Data for the Mill 

D boiler corresponded to the inlet to a 

spray dryer absorber. In the case of 

the Mill D boiler, the sulfur input from 

pulp mill vent gases was sigmficant 

(4.). Table 111 shows that Y, in Fig. 3 

correlated rather well with X(9 =0.94). 

In addition, the percentage of captured 

stoichiometric sulfur ranged from over 

20% to about 70%. Note, however, that 

the sulfur contents of coals fired in the 

three boilers fell within a relatively 

narrow range of (see Table 11) approximately 1%. 

Bark-oil combustion 

Mills C, E, F, and H fired fuel oil in 

addition to bark or wood residue in 

their respective combination boilers. 

Figure 4 shows the relationship between the pounds of sulfur in stack 

emissions and the pounds of sulfur in 

the combined oil-bark feed. Mills C 

and E boilers had an ESP for particulate control. The Mill F boiler had a 

dry scrubber. The EPA studied it extensively (5, 16). The data of Fig. 4 for 

the Mill F boiler correspond to the 

boiler outlet location before the dry 

scrubber. The Mill H boiler had a venturi scrubber. There was one test at a 

location before this location, however, 

and this datum is included in Fig. 4. 

This figure also conhs some of the 

trends observed earlier in Fig. 3. Y, 

correlated rather satisfactorily with 

X, especially for low values of X (9 = 

0.90, see Table 111). The percentage of 

sulfur captured ranged from nearly 

10% to over 80%. As in the case of the 

coal-bark boilers, it is necessary to note 

that the sulfur contents of oil burned in 

all four of these oil-bark boilers (see 

Table 111) fell within a fairly narrow 

range of approximately 2.2%. 

*Solid md gadiqdd 

sulfur capture 

Figure 5 presents data for sulfur capture in Mills G and H boilers where 

the information came from locations 

following a wet venturi scrubber. For 

the period of collection of these data, 

there was no alkali addition to the 

scrubbing solution in either instance. 

The Mill G combination boiler burned 

bark and coal in addition to small quantities of sludge. It has a dual-alkali wet 

venturi scrubber. The Mill H boiler 

burned oil with wood residue and used 

a variable throat venturi scrubber to 

control particulate emissions. Sulfur 

removal efficiencies are fairly high 

even at levels of sulfur input that were 

significantly higher than those shown 

earlier in Figs. 3 and 4. Correlations of 

X vs. Y,, however, are rather weak 

(9=0.31, see Table 111). 

S-T 

Figure 6 summarizes all the data corresponding to in-furnace and prescrubber sulfur capture in the three 

coal-wood residue and four oil-wood 

residue combination boilers. In this 

figure, the sulfur in combined fuel included sulfur from various sources 

such as fuel oil, coal, and sludge as well 

as NCG in some cases. The pattern of 

sulfur capture appears independent 

of the origin of the fuel sulfur. As seen 

from Table 111, Y, correlated fairly 

well with X (9 = 0.91). 

Vol. 76, No. 7 Tappi Journal 183 
Boiler Emissions lZ-z-2=--x-x -:= -Y 

In using relationships derived in 

the study for Y, and Yz vs. X for other 

combination boilers, it is necessary to 

note two assumptions that remain. 

First, only the ratio of sulfur to wood 

residue in the combined boiler fuel 

affects the sulfur capture mechanism. 

There was no consideration of other 

parameters of combustion such as excess air, boiler load factor, percentage 

unburned carbon in ash, etc. There 

was also no consideration of the potential sulfur capture capabilities of 

coal ash itself. Second, in using the 

ratio of pounds sulfur in combined fuel 

feed to tons wood residue as an independent parameter, the ashes from 

burning all wood residues were assumed to have about the same amount 

of alkali metal oxides and carbonates 

per ton of wood residue. Obviously, a 

more detailed study would be necessary to determine more precisely the 

influence of these other factors on bark 

ash sulfur capture. 

Conclusion 

Data on gas-solid sulfur capture in 

seven pulp and paper mill combination 

bark boilers showed that a sigmficant 

amount of the sulfur that would otherwise have resulted in sulfur dioxide or 

sulfirr trioxide emissions was captured 

within the boiler. A regression line for 

the data corresponding to these seven 

boilers gave a linear relationship of 

the .form Y= 0.45X - 0.55, where Y is 

the pounds sulfur emitted per ton of 

combined fuel and X is the pounds 

sulfur in combined fuel per ton of wood 

residue. Considering the high carbon 

content and porosity of wood residue 

ash and its mode of generation, the 

The Ha2 Pages published by Emlands Publishing Inc. 

The Haz Pages.. . a yellow-pages style directory exclusively for hazanlous 

and toxic materials management 

With the Haz Pages, you’ll have a comprehensive, easy-to-use source of 

products and services for the control of hazardous materials right at your 

fingertips. 

The Haz Pages brings together waste treatment and disposal, air quality, 

wastewater, groundwater, health and safety, transportation, remediation, 

laboratories, equipment, software, consultants, cleanup for spills, instrumentation, ASTAJST, industrial hygiene, containment, and more - 

all in one easy-to-use volume. 

Order Number: 13HAZP 

Spec/a/ TAPPl Pr/ce: $49 (members and nonmembers) plus shipping 

and handling 

To order call T’APPl’s toll-free 

Service Line at 1-800-332-8686 (US) 

or 1-800-446-9431 (Canada. 

404446-1400. 

Ask about our volume discounts! 

- 

TAPPI PRESS Outside US or Canada, cal 1 

authors postulate that the ash behaves 

similarly to activated carbon at elevated combustion temperatures. 

Thus it absorbs considerable amounts 

of sulfur dioxide from a gas stream 

and catalytically oxidizes it to sulfur 

trioxide or sulfuric acid. Subsequent 

reaction of acid with the high alkali 

content of the ash yields the high levels of metallic sulfates commonly observed in combination boiler ashes. 

Data on simultaneous gas-solid and 

gas-liquid sulfur capture from two 

combination bark boilers equipped 

with wet scrubbers show sigmficant 

capture efficiencies even at high sulfur to bark ratios. 

Literature cited 

1. “Information on the Sulfur Content of Bark 

and Its Contribution to Sulfur Dioxide 

Emissions When Burned as a Fuel,” 

NCASI Atmospheric Quality Improvement 

Technical Bulletin No. 96, NewYork, 1978. 

2. “Steam, Its Generation and Use,” Babcock 

and Wilcox Co., New York, 1963. 

3. Nunn, A. B., “Preliminary Compilation of 

Data for Emissions from Wood-Fired Boilers,” TRW Environmental Engineering 

Div., Report prepared for EPA Contract 

# 68-02-2613, Task no. 30,1979. 

4. “Sulfur Capture in Combination Bark Boilers,’’ NCASI Technical Bulletin No. 640, 

New York, 1992. 

5. Cheney, J. L., Winberry, W.T., Pleasant, 

J. M., Grotecloss, G. B., Analytical Letters 

6. Vosler, G. L., Tappi J. 68(10): 66(1985). 

7. “Sulfur Retention in Coal Ash,” US. EPA600/7-78-153b, Washington, 1978. 

8. Davis, W. J. and Fiedler, M. H., JAPCA 

32(4): 395(1982). 

9. Kaiser, E. R., JAPCA 18(3): 171(1968). 

10. Jaworski, R. J., APCA23 No. 9: 791(1973). 

11. Crocker, B. B., Chem. Eng. Prog. 71(3): 

83(1975). 

12. Hassler, J. W., Activated Carbon, Chemical Publishing Go., NewYork, 1963, Chapter 8, p. 171. 

13. Campbell, A. G., Tappi J. 73(9): 141(1990). 

14. Greene, T. W., Wood Ash Disposal and 

Recycling Source Book, OMNI Environmental Services, Beaverton, 1988. 

15. Hartman, M., Polek, J. R., and Coughlin, 

R. W., 1970, Chemical Engineering 

Progress Symposium Series, McGraw Hill, 

16. Winberry, W. T., “Primary Sulfate Emissions Measurements for a Hogged-Fired 

Boiler,” U.S. EPATechnical Directive 3.3- 

22, Washington, 1978. 

12(A?), pp. 155-167 (1979). 

w, p.7. 

Received for review Sept. 17,1992. 

Accepted Feb. 11,1993. 

184 July 1993 Tappi Journal 
Paul Earl and Paul Rostek 

Sterling Pulp Chernicah, Ltd. 

Kevin Dunn and Jean-Claude Pate1 

Wheelabrator Water Technologies, Inc. 

Editor's reply: 

In piecing together "The pulp mill 

of the future," it was soon obvious 

that a book could be written on the 

topic. The intent was to gather insights from pulp manufacturers, 

consultants, suppliers and researchers worldwide, including the United 

States, Canada and Scandinavia. 

What we ended up with-and presented-was simply one possible 

view. No bias was intended, but it 

was clear there would be differing 

views and that we would not cover 

all possibilities. The Bleach Filtrate 

Recycle (BFRTM) process is certainly 

an innovative technology that will 

likely be an important part of some 

pulp mills in the future. We would 

welcome other comments and views 

on technologies and issues that will 

have a significant impact on the pulp 

mill of the future. 

-Don Meadows 

Editor 

Tappi Journal 

Author recognition 

As an additional acknowledgement 

to my article in the November issue 

(78[11]:121.[1995]) of Tappi Journal 

regarding catalytic oxygen-alkaline 

pulping, I would like to thank my 

friend Dr. Vladimir Leshokhin of 

Chester, NY, for his help in preparing the manuscript. 

-Dr. Emil Germer 

All-Rwsian ScientiJic Research Institute 

of the Pulp and Paper Industry 

St. Petersburg, Rwsia 

Pho.to missing 

Because of a 

printer's error, 

the photo of 

Elliot Rohde 

scheduled to run 

with his editorial 

"Lessons of 

business" on p. 

240-4 of the October 1995 - - 

Tappi Journal 

(78[10]: 240-4[19951) did not appear. 

An editing mistake also occurred in 

the final paragraph of the first page 

of the editorial, which was originally 

titled "Productivity and profitability are today's corrugated watchwords." As submitted, the second 

half of the paragraph should read: 

"Recycling of corrugated combined 

board and of paperboard waste is 

carried on; in addition chemicals 

within the plant are included in the 

proper recycling and waste disposal 

processes." Tappi Journal apologizes for the errors. 

Conference report error 

The August 1995 conference report 

"Chemical Recovery Conference 

emphasizes high solids firing and 

mill system closure" (78[8]:203 

[1995]) contained an error under the 

heading "Recausticizing." Kurt 

Skrifvars, vice president of Ahstrom 

Recovery Inc., was affiliated with 

another company in the report. 

Skrifvars presented results from 

Wisaforest in Finland at the 1995 

Chemical Recovery Conference, 

April 24-27, held in Toronto, ON, 

Canada. 

Figure correction 

A figure in the July 1993 paper "Sulfur capture in combination bark boilers" (76[7]:179[1993]) was incorrectly published. The x-axis in Fig. 

6 should have been the same as in 

Fig. 4. The x-axis, which showed values of 0, 40, 80, 120, and 160 lb for 

sulfur in combined fueVton wood 

residue, should have shown values 

of 0,7.5, 15.0,22.5, and 30.0 lb. 

International Notebook 

clarification 

The September 1995 International 

Notebook (78[9]:48[1995]) reported 

that Champion Papel e Celulose 

(CPC) had approved the building of 

a printing and writing paper mill in 

Mato Grosso de Sul State in Brazil. 

Champion International states that 

reports of this nature are incorrect, 

that the company has made no such 

decision. Champion maintains that 

the goals of debt reduction and increased returns to shareholders 

must be accomplished before new 

major investment is authorized. 

Vol. 78, No. 12 Tappi Journal 13