OAR Box 1851 

Prepped by Keeia Richards 

Document Number: 

35) ll-A-9 

Docket Number: 

A-90-19 

Printed 11/19/2008 11:19:51 AM Sheet 35 of 41 

P.1 
P.2 

i! 

I. 

A-90-19 

ll-A-9 

ENGINEERING

 (II m 

AND COST STUDY _ 

[_EPA A/RT^np^pj 

OF AIR POLLUTION CONTROL 

FOR THE 

PETROCHEMICAL INDUSTRY 

VOLUME 6: ETHYLENE OXIDE 

MANUFACTURE BY DIRECT 

OXIDATION OF ETHYLENE 

by 

v e 

D. E. Field, R. C. Ba/ley , F. B. Higgins, Jr. . 

J. A. Lee, R. Newirth, and J. W. Pervie r 

'•*» 

* Houdry Division 

4

 Air Products and Chemicals, Inc. 

fS P.O . Box 427 

Marcus Hook, Pennsylvania 19061 

Contract No. 68-02-0255 

EPA Project Officer: Leslie B. Evans 

Prepared for 

ENVIRONMENTAL PROTECTION AGENCY 

Office of Air and Waste Management 

Office of Air Quality Planning and Standards 

Research Triangl e Park , North Carolina 27711 

June 1975 
P.3 

This report is issued by the Environmental Protection Agency to report 

technical data of interest to a limited number of readers. Copies are 

available free of charge to Federal employees , current contractors 

and grantees, and nonprofit organizations - as supplies permit - from 

the Air Pollution Technical Information Center, Environmental Protection 

Agency, Research Triangle Park , North Carolina 27711; or, for a 

fee, from the National Technical Information Service , 5285 Port Royal 

Road, Springfield, Virginia 22161. 

This report was furnished to the Environmental Protection Agency 

by Houdry Division/Air Products and Chemicals, Inc. , Marcus Hook, 

Pennsylvania 19061, in fulfillment of Contract No. 68-02-0255. The 

contents o.f this report are reproduced herein as> received from Houdry 

Division/Air" Products and Chemicajs , Inc-. The opinions, findings, 

and conclusions expressed are those*.of the author and not nerfessarily 

those of the Environmental Protection Agency. Mention of company 

or product names is not to be .considered as an endorsement by the 

Environmental Protection Agency.

 3

. 

Publication No. EPA^50/3-73-006-f 

n 

r 
Plant EM Coda No. 

Capacity - Tona EtO/Yr. 

Range of Production - X o f Mas. 

Eaiaalona t o Ataospher e 

Straa a 

Flov - Lba./Hr. 

Flow Characteristic - Continuous or Intermittent 

If Intermittent - Hrs./Yr. 

Composition - Ton/Ton EtO 

Oaygen 

Nitrogen , Argon 

CO, 

Staaai 

HO, 

Ci - C^ & Higher Hydrocarbons 

Particulate s 

Vent Stacks 

Number 

Height - Fee t 

Disaste r - Inche s 

Exit Gas Temperature - °F 

SCFM/Stack 

Emission Control Device s 

Analysis 

Date or Frequency of Sampling 

Tap Location 

Type of Analysis 

Odor Problem 

S__ar y of Ai r Pollutants 

Hydrocarbons - Ton/Ton EtO 

Aerosols - Ton/Ton EtO 

NO, - Ton/Ton EtO 

SO, - Ton/Ton EtO 

CO • Ton/Ton EtO 

Type of Process 

•Fue l 

TABLE EO-3 

NATIONAL EMISSIONS INVENTORY 

ETHYLENE OXIDE BY DIRECT OXIDATION 

o 

'Absorber 

Waste cas 

116,352 

Continuous 

1.704736 

0.049824 

1 

50 

24 

400 

23.167 

13-1 

330,000 

Stripper 

Tail Cae 

1,096 

Continuous 

0.000154 

0.001512 

0.014624 

0.000739 

1 

52 

2 

110 

164 

Continuous for EtO 

Easy, automati c 

GC. MS 

No 

Air Oxidatio n 

Once per year 

Eaay 

GC, MS 

No 

0.03611 7 

Trace* 

Page 1 of 5 

Reabsorber 

Vent Cas 

3,671 

Continuous 

0.000700 

0.137328 

0.002368 

0.006444 

13 

100. 

-2 

000 

Water Scrubber 

Vent C«f 

682 

Cont inuous 

0.001660 

0.004582 

0.015036 

0,000043 

0.005952 

95 

579 

None 

Dally 

Easy, i n lin e 

CC 

No 

0_ Oxidatio n 

114 

None 

Never 

No t4p 

None 

No 

0.01240 3 

< - y I" 1 5 ] V - i | \ 
I J 

Plant EPA Cods No. 

Capacity - Tons EtO/Yr. 

Range of Production - 7 of Mas. 

Emissions to Atmosphere 

Stream 

Flov - Lbs./Hr. 

Flov Characteristic - Continuous or Intermittent 

if Intermittent - Hrs./Yr. 

Composition - Ton/Ton EtO 

Oxygen 

Nitrogen, Argon 

CO2 

Steam 

NO, 

C| - C4 & Higher Hydrocarbons 

Particulates 

Vent Stacks 

Nuaber 

Height - Feet 

Diameter - Inches 

Exit Gas Temperature - °F 

SCFM/Stack 

Emission Control Devices 

Analysis 

Dste or Frequency of Sampling 

Tap Location 

Type of Analysis 

Odor Problem 

Summery of Air Pollutants 

Hydrocarbons - Ton/Ton EtO 

Aerosols - Ton/Ton EtO 

NO, - Ton/Ton EtO 

SO, - Ton/Ton EtO 

CO - Ton/Ton EtO 

Type of Process 

*Fuel gaa. 

•flncludaa .000538 fugitive C2= losses. 

TABLE EO-3 

NATIONAL EMISSIONS INVENTORY 

ETHYLENE OXIDE PY DIRECT OXIDATION 

13-3 

40.000 

Cas Turbine 

Exhaust 

87,223 

Continuous 

0.52380 

6.9775 

1.0871 

0.13390 

1 

48 . y 

450 'si 

18,800 A?: 

Reabsorber 

Vent Cas 

1,239 

Cont inuous-. 

0.00262 

0.020590 

0.094750 

0.000360 

0.005574 

0.000053 0 

1 

150 

4 

110 

200 

Resetor 

Vent 

475.000 

Continuou 

0.045009 

7.04927 

1.23751 

0.000517 

0.001270 

1 

50 

6' x 8' 

440 

100.000 i

J 

Never * 

Difficult^ 

2 per day 

Easy 

Yes \ 

0.005574 

Air Oxidation 

1 per hour 

Easy 

CC 

No 

Page 2 of 5 

13-7 

225 000 

+47. 

Recovery System 

Vent Scrubber 

5.000 

Cont inuous 

0.002362 

0.019858 

0.080533 

0.008046 

1 

45 

4 

95 

1.050 

3 per year 

Bomb - difficult 

MS 

No 

Reactor 

Vent 

52.5 

Cont inuous 

0.000031 

0.000755 

0.000100 

0 000047 

Continuous 

Easy 

CC t6 

No 

Air Oxidation 

Heater 

Vent 

16 

Cont i nuou s 

0.00032 

, None 

None 

Wt Balance 

No 

0.008413 

0.000517 

0.000229* 

13-4 

110 000 

+4"/. 

C02 Purge 

Vent 

69,173 

Cor.tinuouB 

1.1610 

1 5890 

0.003217 

0.003755+ 

Oo Oxidation 
Plant EPA Code No. 

Capacity - Tona EtO/Yr. 

Range of Production - X of Max. 

Emissions t o Atmosphere 

Stream 

Flo v - Lbs./Hr . 

Flo v Characteristi c - Continuous or 

i f Intermitten t - Hrs./Yr . 

Composition - Ton/Ton EtO 

Oxygen 

Nitrogen , Argon 

COj 

Stea a 

HO, 

Cj - C4 & Highe r Hydrocarbons 

Particulate s 

Vent Stack s 

Number 

Migh t - Fee t 

Diameter - Inche s 

Exi t Gas Teaparatur e - «p 

SCTM/Stack 

Emission Contro l Device s 

Analysis 

Dat e or Frequency o f Sampling 

Tap Locatio n 

Type o f Analysis 

Odor Problem 

Suaaary of Ai r Pollutants 

Hydrocarbons - Ton/Ton EtO 

Aeroaols - Ton/Ton EtO 

NO, - Ton/Ton It O 

S O, - Ton/Ton EtO 

CO - Ton/Ton EtO 

Type o f Process 

Intermitten t 

, 

X. 

£••• 

, y 

' 

- -• • • 

Gas Turbine 

Exhaust 

76.00 0 

Continuous 

0.0157 8 

2 2660 

0.7555 0 

0 002764 

1 • 

45 

. 30 

610 

16,55 0 

-

2 per month 

Easy , us e 0 

GC 

No 

I ° 

TABLE E0-3 

NATIONAL EMISSIONS INVENTORY 

ETHYLENE OXIDE BY DIRECT OXIDATION 

13- 5 

100,00 0 

• Recovery 

Sectio n Vent 

3.10 0 

Continuous 

0.00116 4 

0.0138 5 

0.1068 0 

0.00215 5 

1 

35 

4 

100 

4 8 0 

i 2 per month (but 

Oraat bomb Easy , automati c 

GC 

No 

EtO monitor 

Page 3 of 5 

• 

continuously ) 

Absorber 

Cap 

5.500 

Continuous 

0.010748 

0 17920 

0 026284 

0 003768 

Certain conponentu continuousl y 

Easy 

GC 

No 

0 008687 

-' 

EO-12 

Air Oxidation 

I 1 

_ _ " 
I 1 I i 

TABLE EO-3 

NATIONAL EMISSIONS INVENTORY 

ETHYLENE OXIDE BY DIRECT OXIDATION Page 4 of 5 

Plant EPA Code No. 

Capacity - Tons EtO/Yr. 

Range of Production - X of 

Emissions t o Atmosphere 

Stream 

Max. 

Cycl e Gas 

Exhaust 

13-6 

18,000 

Mix Cas Exhaust 

From Scrubber 

Heater and 

Fuel Vent? 

Flo v - Lbs./Hr . 

Flov Characteristi c - Continuous or Intermitten t 

i f Intermitten t - Hrs./Yr . 

Composition - Ton/Ton EtO 

Oxygen 

Nitrogen, Argon 

CO2 

Steam 

NO, 

Ci - C4 & Higher Hydrocarbons 

SO, 

Vent Stacks 

Number 

Height - Feet 

Diameter - Inche s 

Exit Gas Temperature - Fo 

SCFM/Stack 

Emission Control Device s • 

fc 

0.3547 4 

5.8496 0 

0.9197 1 

0.3518 1 

,0.06297 

0.00172 8 

0.0221 9 

0.09472 0 

0.00062 5 

0.003819 O.001301 

0.000004 

Analysis 

Date or Frequency of Sampling 

Tap Location 

Type of Analysis 

Odor Problem 

•ry of Ai r Pollutants 

Hydrocarbons - Ton/Ton EtO 

Aerosols - Ton/Ton EtO 

NO, - Ton/Ton EtO 

SO, - Ton/Ton EtO 

CO - Ton/Ton EtO 

Occasional 

Easy 

Orsat, CH 

No 

Once per month 

Easy 

Orsat, CH. 

No 

0.068090 

0.000004 

Type of Process Ai r Oxidation 
P.8 

EO-14 

TABLE EO-3 

LIST OF ABBREVIATIONS IN ANALYSES Sheet 5 of 5 

' ' '•" m aa, i i| > —- a mi mum ! , i _i .. i . » 

GC - Gas Chromatograph 

MS - Mass Spectroscope 

Orsat - Conventional orsat for CO2, 02 , C2H4 

CH - Ethylene oxide by reaction with MgCl2 to form chlorohydrin 

[ 

[ 

c 

[ 

[ 

[ 
P.9 

EO-15 

TABLE E0-4A 

TYPICAL VENT GAS COMPOSITIONS 

FOR 

200 MM LBS./YR. ETHYLENE OXIDE PRODUCTION 

USING AIR OXIDATION 

MAIN PROCESS VENT GAS 

Component 

Nitrogen 

Oxygen 

Methane 

Ethane 

Ethylene 

Ethylene Oxide 

Carbon Dioxide 

Avg. Mol % 

Reported 

Range in 

Composition 

86.7 

2.9 

0.0 

0.1 

1.6 

0.01 

8.7 

80 - 90 

0.5 - 4.5 

0 - 0.9 

0 - 0.1 

TR - 2.3 

0 - 0.01 

0-1 0 

Average Flow Rate 

Mol/Hr. Lb.s./Hr. 

4,695 

157 

0 

5 

87 

0. 

471 

100.00 5,415.4 

131 

5 

2 

19 

158 

,460 

,024 

0 

150 

,436 

17 

,782 

,869 

32,402 SCFM 29.3 Avg. Mol Wt. 

C02 RICH PURGE GAS 

Component 

Nitrogen 

Oxygen 

Ethylene 

Ethylene Oxide 

Carbon Dioxide 

Avg. Mol 

18 

2 

4.5 

0.5 

75 

100.0 

% 

' 475 SCFM 

Reported 

Range in 

Composition 

13 - 25 

1 - 26 

2.5 - 8.0 

0 - 1.0 

62 - 80 

38.7 Avg. M 

Average 

Mol/Hr. 

14.2 

1.6 

• 3.6 

0.4 

59.3 

79.0 

Flc DW Rate 

Lbs./Hr. 

398 

51 

101 

17 

2,491 

3,058 

] 

NOTE: Both streams on a water free basis. 

"J 
•** • 

E0-16 

TABLE_J0^4B 

200 

MAIN PROCESS VENT GAS 

Component 

Nitrogen, Argon (MW = 

Oxygen 

Methane 

Ethane 

Ethylene 

Ethylene Oxide 

Carbon Dioxide 

TYPICAL VENT GAS COMPOSITIONS 

MM LBS 

(1,3) 

39.2) 

./YR. 

USING 

FOR 

ETHYLENE OXIDE 

OXYGEN FEED 

Mol % 

16.2 

7.3 

1.5 

14.2 

13.5 

0.005 

47.4 

100.0 

114 SCFM 

PRODUCTION 

FL 

Mol/Hr. 

3.09 

1.39 

0.29 

2.70 

2.57 

0.001 

9.02 

19.06 

36.8 Avg. 

ow Rate 

Mol Wt 

Lbs./Hr. 

121 

44 

5 

81 

72 

0.04 ' 

379 

702 

• 

C02 RICH PURGE GAS (1,2,3) 

Component 

Oxygen 

Ethane 

Ethylene 

Carbon Dioxide 

Flow Rate 

Mol 7. 

0.02 

0.12 

0.16 

99.70 . 

100.00 

3,006 SCFM 

Mol/Hr. 

••.••Voti-'. 

0.1 

0.6 

0.8 

500.9 

? 

502.4 

42.0- Avg. Mol Wt:. 

Lbs.VHr. 

n 

~T 

18 

22 

21.038 

21,081 

(1) Based on one questionnaire - other oxygen process does not have any 

appreciable vent other than CO2 and water (one questionnaire). _Me_tharie 

is added after the reactors to build up a background of inert gas in the 

recycle stream at reactor conditions but a combustible gas at boiler 

conditions. 

(2) Composition and quantity adjusted to include future changes as indicated 

on the questionnaire. 

p.10 

t 

[ 

s. 

(3) Both streams on a water free basis. 
P.11 

1 

EO-17 

3. Turbine Exhaust 

Many, if not all of the plants surveyed use natural gas fueled 

turbines to feed air and ethylene to the process. Since the turbines 

whic h drive the compressors are not 100 percent efficient, some 

unburned hydrocarbons escape to the air from this exhaust. It can 

be a considerable portion of the total hydrocarbon emissions . A 

large variation in this stream has been reported (Table EO-3) . 

B. Intermittent Air Emissions 

No dat a given although some plants report flaring or venting gas 

during upsets . One operator reported emptying the system to the flare 

o ne or two times per year for about three hours each time. 

C. Liquid Waste s 

Mainly water , wit h small percentage of organics , all of whic h 

appear to be adequately treated by conventional in-plant biologic 

systems for most respondents . One respondent reported inorganic 

salts (presumably from the CO2 recovery section) in this stream. 

D . Solid Waste s 

None reported although one respondent alludes to the presence of 

about 0.004 lbs. of "sludge'Vlb. EtO leaving the plant as part of, the 

waste water stream. No further data were given. 

E. Odors • 

Not one respondent reported any odor problem on any stream. The 

only reference to odor was the indication that, if there were an odor 

detectable , it would be ethylene. Actually this response is not 

surprising because : 

•J 1. The hydrocarbon content of the vast majority of all the vent 

streams is quite low. ..,-r. ^ 0 

1 "'-.•' • 

! 2 . Ethylene is a colorless sweet smelling gas . In low concentration, i.e., less than two percent, it is doubtful if 

o ne could detect an odor directly in the vent stream. As the 

vent gas mixes wit h the surrounding air, and the ethylene 

— becomes more dilute , the possibility of an odor problem 

fades away. The absence of any detectabl e odor does not 

mean that there are no hydrocarbon emissions . 

Ethylene oxide on the other hand has a pungent irritating odor. 

No one even so much as indicated an ethylene oxide odor problem. 

Again , not surprising. Ethylene oxide is the desired product and 

— the odor of EtO means loss of a valuable commodity. To allow 

continuous loss of EtO would just not make good economic sense and 

any odor problem associated wit h ethylene oxide would be temporary 

«• and most probably du e to a severe upset or equipment failure. 

J 
E0-18 

1 

IV. Emission Control Devices and Systems 

A. Emission Control Devices on Main Process Vent 

1. Absorbers and Scrubbers 

2. Catalytic Conversion Units 

FM2 

L-

[ 

The main ethylene oxide absorber vent gas on all plants is 

recycled to the process. The secondary or purge absorber vent gas T~ 

is normally the main process vent for the air oxidation plants 1^ 

aid the oxygen feed plants. Two air oxidation process respondents 

catalytically convert this dilute hydrocarbon stream to N2 , CO2, 0 2 

and H2O and drive process tubines with the hot compressed gas. The 

other five respondents vent this stream to the air. 

r 

r 

One of these latter plants (also air oxidation) supplied data on j 

their purge absorber and it has been included on Table EO-5 for the 

sake of completeness. Actually all plants have this absorber-scrubber 

but only one gave data on it. Strictly speaking, it is a necessary 

process control device. It is identified as 002 on Table EO-5. Water 

is the absorbing medium. 

Ethylene oxide absorbers/scrubbers do an excellent job in removing 

EtO from the off-gas stream. Efficiencies of 99.9+7. are not uncommon. 

Ethylene oxide is very soluble in water and a well designed scrubber 

should perform well. However, a water scrubber will not remove any 

appreciable ethane or ethylene from the vent gas and as such this 

represents the major source of air pollution for the process. Unless 

this stream is catalytically combusted to CO2 and water, it will 

contribute substantial quantities of hydrocarbons to the air in a 

stream generally too dilute to burn by itself. 

Vent gas scrubbers using water to recover ethylene oxide are 

used by two respondents (see Table EO-5) on the CO2 purge stream of 

air oxidation processes. Here again the efficiency of ethylene oxide 

recovery is good but efficiency is poor in terms of total hydrocarbon 

emissions. This CO2 purge stream is the smaller of the two main 

vent streams. 

r 

r 

1 

These units are designed to convert the ethylene content (about two 

percent) of the absorber vent gas to CO2 and water and to heat the gas j 

stream at 100-200 PSIG from ambient temperature up to 1300° F. The gas 

is then used to drive a gas turbine and exhausts at about 600° F to a 

stack. Data on these units came from two air oxidation processes. [~ 

L 

A typical catalyst would consist of activated precious metals 

(probably platinum) uniformly coated on a matting of high nickel ,_ 

chrome alloy metal ribbins. Self supporting catalyst mats are mounted j 

in a hollow cylindrical configuration. The catalyst tube is surrounded *" 

by a cylindrical baffle that directs the incoming gas to the top of the 

vessel where gas burners preheat the gas to reaction temperature. The |~ 

heated gas then passes over the catalyst where the ethylene reacts with L 

the oxygen in the gas and heats the mass of the gas to about 1300° F. 

The converter outlet temperature controls the firing of the preheat 

burners. 
TABLE EO-5 

CATALOG OF EMISSION CONTROL DEVICES Page I of 2 

ABSORBERS/SCRUBBERS 

EPA Code No. for plan t usin g 

Flow Diagram (Fig . No) Stream I. D. 

Devic e I. D. No. 

Control Emission of 

Scrubbing/Absorbing Liquid 

Type - Spray 

Pscked Column 

Trsy Coluan 

Scrubbing/Absorbing Liquid Rate - GPM 

Design Temperature (Operating Temperature) °F 

Gss Rate - SCFM (lb./hr.) 

T-T Height, Feet 

Diameter - Feet 

Washed Cases to Stack 

Stack Height - Feet 

Stack Diameter - Inches 

Installed Cost - Mat'l. & Labor - $ 

Installed Coat Baaed on '"year" - $ 

Installed Cost - c/lb. 

Operating Coat - Annual - $ (1972) 

Value of Recovered Product - $/Yr. 

Net Operating Cost - c/lb. 

Efficiency - I - SE 

Efficiency - 1 - SERR 

*For total hydrocarbons. 

**For recovered EtO. 

13.6 

(EO-l)-lO 

002 

Ethylene Oxide 

Water 

30 

100 

300 

32 

2 

Yes 

62 

3 

Unknovn 

Not Available 

99.99 

97.05* 

13.6 

(EO-l)-lO 

001 

Ethylene Oxide 

Water 

80 

200 

6500 

57 5 

3.5 

Yes 

38 

8 

Unknovn 

Not Available 

98.5 

56.9* 

13 7 

(EO-l)-lO 

101 

Ethylene Oxide 

Vater 

X 

150 

Ambient 

1167 

4 0 

3 . 5 

Yes 

45 

4 

24.00 0 

1968 

0.005 3 

S2500 

$225,000* * 

(Credi t - 0.049 ) 

95. 3 

66.2 * 
INCINERATION DEVICES 

EPA Code No. for plan t usin g 

Flow Diagram (Fig . No.) Stream I. D. 

Devic e I. D. No. 

Type of Compound Incinerated 

Type of Device 

Material Incinerated, Lb./Hr. (SCFM) 

Auxiliary Fuel Req'd. (excl. pilot) 

Type 

Rate - BTU/Hr. 

Device or Stack Height - Feet 

Installed Cost - Mat'I. & Labor - $ 

Installed Cost Based on "year" - $ 

Installed Cost - c/lb. 

Operating Coat - Annual - $/Yr. 

Operating Coat - c/lb. 

Efficiency - X - CCR 

Efficiency - X - SERR 

TABLE EO-5 

CATALOG OF EMISSION CONTROL DEVICES ( 1) 

13- 3 

(EO-l)-lO 

101 

Hydrocarbons 

Catalyti c Converte r 

(20,000 ) 

CH. 

197 x 

CI 

19 

57 

$74,00 0 

1964 

0.092 5 

(Credit 

(Credit 

100 

100 

1 0 6 

13-4 

(E0-2)- 9 

Hydrocarbons 

Flare Stack 

Normally Zero 

125 

$20,000) 

0.025) 

100 (2) 

100 (2) 

Page 2 of 2 

13-5 

(Eo-l)-lO 

101 

Hydrocarbons 

Catalytic Converter 

76.000 

Natural Gas 

3 x \0b 

45 

S300.000 

1966 

0.15 

$42.000 

0.021 

94.7 

94. 7 

(1) Plant 13-7 also reported (subsequent to their completed questionnaire) a catalytic converter on the reactor vent shovn in Table E0-3. Huwever, they did not give 

coat or perfromance data on the unit. 

(2) Flare shown as burning completely to CO2 and H2O. 

r--~i «- r—\ T \ 1 \ , ^ ^ } 
P.15 

J 

J 

J 

.] 

] 

] 

] 

] 

] 

] 

] 

] 

] 

] 

] 

] 

EO-21 

The above is a description of one type of catalytic converter. 

There are other designs but they follow the general pattern described. 

In some case, it may be necessary to inject small quantities (roughly 

0.4 mol 7«) of methane or natural gas plus some air in order to insure 

complete combustion in the converter. These units are rather large, 

seven to eight feet in diameter and 15 to 20 feet long. 

~]

 ( Table E0-6 gives a material balance for catalytic incineration of 

_j a lean hydrocarbon vent stream. Section VII covers the cost effectiveness of this control. Actual cost data for catalytic converters are 

-» presented, as given by the respondents. 

3. Other Combustion Devices 

For those vent streams which are readily combustible, a steam boiler 

could be used to convert the hydrocarbon content to CO2 and water and 

recover some of the waste heat as steam. Since ethylene oxide plants 

are net steam producers due to the exothermic heat of reaction, it may 

be uneconomical to run yet another steam boiler on a waste stream and 

have to transport the steam from the process area to where it can be 

used. In this case, a thermal incinerator could convert the vent gas 

stream to COo and water and eliminate emissions of hydrocarbons to 

the air. 

Only one respondent indicates use of the main process vent stream 

in a steam boiler but no operating data were given. This, of course, 

is the case where methane is added to the recycle. No one indicated 

use of a thermal incinerator so it is difficult to accurately predict 

equipment performance in these two applications. Table EO-7 and EO-8 

give material and heat balance data for combustion of a fairly rich 

hydrocarbon vent stream. No data are included for thermal incineration 

or steam generation of a lean hydrocarbon stream (below the lower 

flammability limit) because such treatment is impractical and 

uneconomic. 

4. Flare System 

One respondent (oxygen oxidation process) reports on the use of a 

flare system (only during emergencies) and claims 100 percent efficiency. 

It.was not reported whether or not supplemental fuel was used. Generally, 

a "flare system" is understood to mean a combustion stack that does not 

require supplementary fuel except for pilot lights. On the other hand, 

a plume burner is one which is burning a gas that is normally close to 

or below its lower flammable-limit and thus requires a continuous 

supply of supplemental fuel. It is normally assumed that neither a 

flare stack nor a plume burner will achieve more than about 90 percent 

combustion efficiency. 

The oxygen oxidation vent gas shown in Table E0-7 will support 

combustion and could be flared. However, it is unlikely that combustion 

would be complete. It is more likely that about 10 percent of the 

heating value will be lost in the form of carbon monoxide and unburned 

or cracked hydrocarbons. If the plant has an existing flare from 

another process, additional supplemental fuel might not be required, 

depending upon the heating value of total flared gases. In any case, 

however, improper firing could result in NOx formation. 
EO-22 

TABLE EO-6 

AIR FEED PLANT 

CATALYTIC INCINERATION (1) 

MATERIAL BALANCE. LB./HR. 

Combustion Air Flue Gas (3) 

14,663 131,858 

4,457 212 

0 TR 

0 TR 

0 TR 

0 0 

0 30,754 

' 0 -6. 4 

0 3.560 

161,933 • 19,120 181,053 

(1) - Combined combustibles are 1.67 percent by volume vs. 2.7 percent lean lower 

•"limit for ethylene in air. Catalytic incineration is necessary to hold 

• combustion chamber temperature in the 1300° to 1500° range. 

0 . 

(2) Combined process, stream, main vent plus CO2 vent, water free basis. 

(3) Unburned hydrocarbons reported as "trace" in flue gas. One respondent 

reported 200 to 300 ppm in flue< gas- but his vent gas stream differed from 

that shown above. Flue gas has 0.5 percent excess O2 as per respondnet 

experience with catalytic converters. • 

Component 

N2 

°2 

CH4 

C2H6 

C2H4 

EtO 

co2 

NOx (4) 

H20 " 

Process Vent Gas (-

131,858 

5,075 

0 

150 

2,537 

34 

22,273 

6.4 

' 

P. 16 

7 

(4) 40 ppm. 
P.17 

EO-23 

Component 

N2, A 

°2 

CH4 

C2H6 

C2H4 

EtO 

co2 

NOx 

H20 

OXYGEN 

TABLE 

FEED PLANT. 

EO-7 

STEAM GENERATION 

OVERALL MATERIAL BALANCE 

Process Vent Gas (2) 

121 

44 

5 

81 

72 

0.04 

379 

0 

LB. 

Comb 

/HR. 

ustion 

2,102 

639 

0 

0 

0 

0 

0 

0 

0 

Air (D Flue Gas 

2,223 

• 114 

TR 

TR 

TR 

TR 

827 

TR 

250 

702 2,741 3,444 

(1) 20 percent excess 02« 

(2) Water free basis combined combustibles are 27.6 percent well over the 

lower limit for ethylene. This stream will support combustion. 

Other Data - Heat Balance 

a. Heat of combustion of methane, ethane, ethylene in stream- 3,221,078 BTU/Hr. 

b. Less sensible heat, 85° y 570° (stack temperature)- 439,020 BTU/Hr. 

c. Net heat available for steam generation 2,782,058 B>TU/Hr. 

d. Steam available at 750° F, 450 PSIG at 2,261 Lbs./Hr. 

75c/1000 lbs., credit is $14,850 per year 
T 

r 

r 

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P.18 

EO-24 

• TABLE EO-8 

OXYGEN FEED PLANT 

THERMAL INCINERATION 

MATERIAL BALANCE 

This same stream when thermally incinerated with 20 percent excess 02 will 

give the same products of combustion as a steam generator but the heating 

value of the stack gas will be lost. 

An incinerator for this stream will cost less than half of a comparable 

steam generator but the net operating cost is some 25 percent higher. See 

Table E0-7. 
.; A 

" : . P. 19 

E0-25 -1 

B. C02 Rich Purge Gas | 

This stream, which averages around 300 SCFM for a typical 200 L— f 

MM lbs./year plant, is normally vented directly to the air by all I 

respondents. For air oxidation plants, the stream contains about 

70 vol. % C02 and 5-67. hydrocarbons and can be incinerated. The 

best solution would be to combine this vent stream with the main 

process vent stream since it is a small flow and dispose of both 

streams together. One respondent plans to do just this, feeding | 

the C02 rich stream to a catalytic converter along with the main *•• ' 

process vent and virtually eliminating emissions from the plant. 

ii 

For the oxygen feed plants, this stream contains water vapor, 

30-50 percent C02 and only traces of hydrocarbons. Hence, these 

plants probably have no need to treat this stream any further. One 

respondent usually disposes of this stream by selling it to an offsite consumer for its carbon dioxide content, but what is done with 

the hydrocarbon content is un-reported. 

C. By-Product Disposal 

1. Waste Water 

From 0.007 to 0.9 gallons of waste water per lb. ethylene oxide 

are produced with the larger plants consuming the least water/Lb. 

product. Data on contaminants in the waste streams are very sketchy 

but are probably ethylene glycol (mainly) acetaldehyde and miscellaneous 

hydrocarbons. All respondents, save one, treat this stream in plant 

before discharge. This stream is biodegradable and presents no 

unusual operating problems. 

2. Waste Solids 

No waste solids were reported. 

• 3. Miscellaneous * T 

No other by-products were reported. 

D. Best Available Pollution Control System 

The best control system for an air oxidation ethylene oxide plant 

is to feed both the main process vent and the C02 purge vent to a 

catalytic converter and use the hot gases from this unit to power 

feed turbines to the process. With this set-up, emissions from the 

plant vent streams should only be N2, 02, C02 with possible traces ., 

of hydrocarbons and NOx. The questionnaires indicate that several 

plants are planning to install this type of system. Oxygen feed 

plants are different than air feed plants because the CO2 purge vent 

which is reported as essentially hydrocarbon free, is the larger 

stream, and probably can be vented directly to the air with little or 

no effect on the pollution level. It is also apparently pure enough 

to be sold as C02. The main process vent from these plants is small 

but is combustible. It can best be disposed of by burning in a steam 

generator with recovery of the heat as steam. If steam is not needed 

and the gas cannot easily be transported elsewhere, it may be disposed 

of in a thermal incinerator with a similar reduction in emissions as 

the steam generator, but with no energy recovery. 

t 

L 

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P.20 

E0-26 

One of the air oxidation processes features introduction of 

methane as an "inert" background gas in the recycle stream in 

contrast to other oxygen processes which have no methane addition. 

The relatively rich main process vent gas from these plants can 

be sent to the plant boilers as supplemental fuel, even though the 

methane does not oxidize at reactor conditions. 

Whether or not the C02 purge vent from either type of oxygen plant 

can be vented should be dtermined by an EPA sampling program. If not, 

it could constitute a problem because it is too large to be combined 

with the main process vent for incineration either in the plant 

boiler, the steam generator or the thermal incinerator. The dilution 

effect would render the combined stream non-combustible. 

L: 
E0-27 

V. National Emission Inventory 

Based on the emission factors shown in Table EO-3, the total emissions 

from the ethylene oxide plants surveyed were estimated and are summarized in 

Table E0-9. Using Table E0-9, the total approximate emissions from all U.S. 

ethylene oxide plants are as follows: 

Component 

Hydrocarbons 

Particulates 

NOx 

SOx 

Average Emissions 

T/T Ethylene Oxide 

0.02048 

0.000007 

0.000066 

0.000031 

Total = 0.020584 

Total Emissions (1) 

MM Lbs./Year 

85.83 

0.03 

0.28 

0.13 

86.27 

If all air feed plants catalytically converted their main process vent 

gases to C02 and H20 and used the hot exhaust to drive the plant feed turbines, 

(also cutting the turbine emissions about in half) and oxygen feed plants 

incinerated their main process vent in a steam generator, total emissions would 

be reduced to the following approximate values: 

Component 

P.21 

r 

i 

Hydrocarbons 

Particulates 

NOx 

SOx 

Average Emissions (2) 

T/T Ethylene Oxide 

0.0049 

0.000007 

0.0001 

0.000031 

Total Emissions (i 

MM Lbs./Year 

20.53 

0.03 

0.42 

0.13 

Total = 0.005038 21.11 

(1) Basis 4,191 MM lbs. EtO per year in 1972. 

(2) See also Table EO-16. 

• •*•- j_"*?.*"._!r.«-"-
Emission 

Hydrocarbons 

Particulates 

NOx 

SOx 

CO 

Hydrocarbons 

Particulates, 

SOx, CO 

EtO 

Absorber 

Vent Gas 

0.0118 

NOx 

Recovery 

Section 

Vents 

0.0006 

Reabsorber 

0.0064 

Nil 

Nil 

OXYGEN 

' C02 Purge i 

TABLE E0-

EMISSION SOURCE 

9 

SUMMARY 

TON/TON ETHYLENE OXIDE 

AIR OXIDATION 

Source 

Vent Gas 

Scrubber Turbine 

Outlet Exhaust 

0.0023 0.0132 

0.00001 

OXYGEN OXIDATION 

Vent Gas 

OXIDATION PLANTS WITH 

\Jent 

PLANTS 

PLANTS* 

METHANE 

Reactor or 

Heater 

Vent 

0.0006 

0.0001 

0.00005 

C02 Purge 

Vent 

0.00001 

Water Scrubber Vent 

0.0060 

Nil 

Nil 

ADDITION* 

Fugitive Lo sses 

Figitive 

Emissions 

0.00001 

Total 

0.0285 

0.00001 

0.0001 

0.00005 

Total 

0.0124 

Nil 

Nil 

Total 

EO-28 

Hydrocarbons 

Particulates, NOx 

SOx, CO 

0.0032 0.0006 

Nil ° Nil 

Nil Nil 

0.0038 

Nil 

Nil 

*Data from one respondent only. 
P.23 

E0-29 

VI. Ground Level Air Quality Determination 

Table EO-3 presents a summary of air emissions data for various surve ed 

ethylene oxide plants. This table includes emissions from the main process 

vent, C02 purge vent, turbine exhausts, reactor heat transfer fluid vent and 

an estimate of fugitive emissions. Information regarding vapor losses from 

product storage have not been included, but losses from these storage 

facilities should be ld& for the following reasons: 

(a) All plants reporting data on their storage facilities have refrigerated, cooled and/or pressure (inert blanket) storage for 

ethylene oxide. Hence, emissions should be negligible. One 

plant blankets the ethylene oxide with natural gas to prevent 

loss of EtO. The blanketing gas usually goes to a flare when 

the tank "breathes". A loss of blanketing gas is unavoidable 

but will contribute virtually no air emissions if it is flared 

properly. 

(b) Some plants take ethylene oxide directly to a glycol plant and as 

such have no storage facilities for this product. 

Table EO-3 provides operating conditions and physical dimensions of the 

various vent stacks. The EPA will use this information together with the air 

emission data to calculate ground level concentration for later reporting. 
J7 

J 

P.24 

EO-30 

VII. Cost Effectiveness of Controls 

A cost analysis for alternative methods of reducing air pollution from 

the main process vents of a typical 200 MM lbs. per year ethylene oxide plant 

is shown on Tables EO-10 and EO-11. Table EO-10 represents data from plants 

using air feed while Table EO-11 shows similar data for oxygen oxidation plants. 

A. Investment 

Purchased costs of steam generators, thermal incinerators and 

catalytic incinerators were obtained.from current vendor quotes for 

similar packaged type units. Costs for the catalytic converter 

represent actual dollars reported from respondents questionnaire 

-; up-dated to 1973. 

j 

B. Operating Expense 

Unless data were available from the respondent, we used: 

1. Depreciation - 10 year straight line. 

2. Interest - 6 percent on total capital 

3. Maintenance - 3 percent of investment. 

4. Labor - One-quarter of a man assumed for boilers (steam 

generator) and one-eighth man for incinerators. 

5. Utilities - Based on the Gulf Coast area. 

The tables show that if the steam can be used, a steam generator is a 

cheaper method to use than a thermal incinerator for an oxygen oxidation 

tt process. A properly designed thermal incinerator has the advantage over a 

•*• flare in that less NOx should be produced. • It steam could not be used or 

cc. „ V *' transported to othef process areas economically, a thermal incinerator would 

" o b% the best methbd to" use to reduce emissions. 

However, tne air process vent streams are not readily combustible. In 

this case, the best solution appears to be to catalytically incinerate the 

0 vent gas. Two respondents .indi^eatgd that this was done with the main process 

° vent gas. The hot gases from the converter (catalytic incinerator) are used 

to drive the process,, air compressor turbine drives. The literature says that 

almost every manufacturer uses these"-gases to drive turbines for the plants 

but if so, only two respondents so indicated and gave supporting engineering 

data. 

If"one take credit for.the heating value of the gas burned which is ' 

used to power some of the process feed turbines, the analysis shows that this 

cost savings will just about off-set the operating and capital charges for a 

catalytic converter in a 200 million lbs./year ethylene oxide plant. 

All plants reporting store ethylene oxide either under refrigeration 

or pressure (N^ natural gas). All have vapor conservation systems and none 

vent to the atmosphere directly.. As such, there does not appear to be 

anything further necessary for the storage facilities. 
# 

*'. • 

TABLE E0-1U 

COST EFFECTIVENESS OF CONTROLS 

Chemical 

Total U. S. Installed Capacity, Tons/Yr. (a) 

Totsl U. S. Production, Tons/Yr. (a) 

Principal Process 

Percentage of Total U. S. Production, Approximate 

Average Plant Capacity, Tons/Yr. 

Emission Stream 

Emission Control Device 

Flov Rate, SCFM, Basis Average Plant Size 

Ton/Ton Ethylene Oxide Capacity 

N0X 

so2 

CO 

co2 

N2 + Argon 

°2 

H,0 

Hlsc. HC 

Unidentified Particulates 

Ethylene Oxide 

Installed Cost Relative to Emission Control Device 

Delivered Cost 

Installation 

Total capital 

Operating Cost, $/Yr. 

Depreciation (10 years) 

Intereat on Capital (6%) 

Catalyst Replacement (estimated) 

Maintenance (31 of capital) ^ 

Labor ($4.85/man-hour) 

Utilitie s 

Power, lc/KVH 

Fuel, 40c/MM BTU (pilot gas) 

Process Vater, lOc/M Gal. 

Boiler Feed Vater, 30c/M Gal. 

Total utilitie s 

Total Operating Costs 

Heating Value Credit (g) u 

Net Operating Cost 

Main Process 

None 

32,402 

None 

None 

None 

0.86645 

5.75796 

0.22005 

(j) 

0.11327 

None 

0.00074 

0 

AIR OXIDATION PROCESS 

Ethylene Oxide 

2,100,000 

2,100,000 

Air Oxidation 

.76 

100,000 

Vent 

Catalytic (f) Incineration 

None 

None 

None 

1.22255 

6.35093 

0.00858 

0.14962 

TR 

None 

TR 

$158,000 

67,000 

$225,000 

$ 22,500 

13,500 

5,000 

6,600 

. 4,900 (1/8 man) 

200 

500 (c) 

0 

0 

$ 700 

$ 53,400 

50,000 

$ 3,400 

None 

480 

None (b) 

None 

TR 

0.10911 

0.01743 

0.00230 

(j) 

0.00442 

None (d) 

0.00074. 

<o 

C02 Rich Purge Cas 

Catalytic Incinerator fa) 

TR 

None 

None 

0.12448 

0.06675 

0.00070 

0.00631 

TR 

None 

TR 

$12,000 

8.000 

$20,000 

2,000 

1,200 

500 

600 

200 

500 (c) 

0 

0 

700 

5,000 

1,000 

4,000 

,? 

(a) Estimate for 1973. 

(b) Exception - one respondent reports 40 PPM NO in a vent containing no other pollutant vapors. 

(c) Heat exchange incorporated for sustained oxidation; pilot only during portion of start-up sequence. Start-up fuel required. 

(d) Exception - one respondent reports "less than three lbs./hr. (of particulates), primarily carbon, small quantities of Iron and chlorine". 

(e) Incineration figures are estimated for addition of facilities vhere none exist in current practice. The inclusion of these figures is not to be construed aa an 

indication that the facilities Bhould or should not be installed. 

(f) Data from tvo respondents shoved about $85,000 purchased cost in 1964 - 1966, updated to $150,000 in 1973 snd estimated $225,000 installed cost. 

(g) Credit of 0.025c/lb. of EtO/year taken from net heating value of gas burned and used to pover turbines. 

(h) Streams are belov lean lover Limit for combustion. Thermal incineration or Incineration in a steam boiler vould require excessive firebox 

temperatures for complete combustion, 

(i) Installed cost based on data from tvo respondents. Corrected to 200 million lbs./year via the "0.6 factor" and up-dated from 1965 costs using O&CJ Construction Coat Index. 

(j) Main Process Vent and C02 Vent on vater free basis. , " 

I01 
TABLE EO-U 

COST EFFECTIVENESS OF CONTROLS 

OXYGEN OXIDATION PROCESS 

Chemical 

Total U. S. Installe d Capacity, Tons/Yr. va) 

Total U. S. Production, Tons/Yr . (a ) 

Principal Process 

Percentage of Total U. S. Production, Approximate 

Average Plant Capacity , Tons/Yr. 

Emission Stream 

Emission Control Devic e 

Flov Rate, SCFM Average Plant Siz e 

Ton/Ton Ethylene Oxide Capacity 

N0X 

S0-

CO 

co2 

N2 + Argon 

°2 

H2 0 

Misc. HC 

Unidentified Particulates 

Ethylene Oxide 

C02 Rich Purge Gas 

None 

5,782 

None 

None 

None 

0.92147 

None 

0.00013 

(e) 

0.00096 

None 

None 

Ethylene Oxide 

0 

0 

Oxygen 

5 MM 

5 MM 

Oxidation 

24 

100,000 

None 

699 

None 

None 

None 

0.01660 

0.00530 

0.00193 

(e) 

0.00692 

None 

TR 

Main Process Vent 

Steam Generator (c) 

(b) 

TR 

None 

TR 

0.03622 

0.09737 

0.00499 

0.01095 

TR 

None 

None 

The rma 1 

702 

(b) 

TR 

None 

TR 

0.03622 

0.09737 

0.00499 

0.01095 

TR 

None 

None 

Incinerator (c) 

Installed Cost Relative to Emission Control Device 

Delivered Cost 

Installation 

Total Capital 

Operating Cost, $/Yr. 

Depreciation (10 years) 

Interest on Capital (6%) 

Catalyst Replacement (Estimated) 

Maintenance (3% of capital) 

Labor ($4.85/man-hour) 

Utilities 

Power, lc/KWH (estimated) 

Fuel, 40c/MM BTU (pilot gas) 

Process Water, 10c/M Gal. 

Boiler Feed Vater, 30c/M Gal. 

Total Utilities 

Total Operating Costs 

Steam Generation, 75c/M Lbs. (credit) 

Net Operating Costs 

20,000 

20,000 

40,000 

4,000 

2,400 

0 

1,200 

9,700 (^ man) 

200 

1,500 

0 

700 

2,400 

19,700/Yr. 

($13,800/Yr.) 

5,900/Yr. 

8,000 

8,000 

16,000 

1,600 

1,000 

0 

500 

4,900 (1/8 man) 

100 

1,500 

0 

0 

1,600 

9,600/Yr. 

9,600/Yr. 

(a) Estimated for 1973. 

(b) Basis 20% "excess air". 

(c) Steam generation and incineration figures are estimated for addition of facilities vhere none exist in current practice. The inclusion of these figures is not to 

be construed as an Indication that the facilities should or should not be installed. 

(d) Cost of steam generator and thermal incinerator from A.P.C.I. (Catalytic, Inc.) company files. 

(e) Vents on vater free baa is. 
EO-3 3 

VIII. Source Testing 

Plants 13-3 and 13-5 were the only plants that reported a catalytic 

converter in operation when the questionnaires were completed. Data from 

these two plants indicate that a catalytic converter is an excellent pollution 

control device. If the data presented by these respondents can be substantiated 

by a sampling program and if the hydrocarbon emission reduction is as complete 

as is claimed, this device could be classified as the best demonstrated 

emission control system. It has since been reported by an official of plant 

13-7 that they also have a catalytic converter, although this was not clear 

from the questionnaire. 

P.27 

L 

Respondent 13-4 shows one stream which is quite rich in hydrocarbons u 

as going to a steam generator. (No data on operation of this unit were 

given.) The stream is burned to generate steam used elsewhere. It would not 

be valuable to source test this stream as it represents a unique process, •-

because methane is fed into the process streams to build up an inert background 

gas in the recycle. However, since this plant is an oxygen feed plant and r 

reports very low hydrocarbons in the CO2 purge gas vent, a sampling program (_ 

to verify this could be of value. 
P.28 

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EO-34 

IX. Industry Growth Projection 

Current U.S. capacity for ethylene oxide production is estimated at 

4,191 MM lbs./year and is projected to increase to 6,800 MM Lbs./year by 

1985. (See Figure EO-3) 

By far, the largest use for ethylene oxide is in the production of 

ethylene glycol. Probably two-thirds of all the ethylene oxide produced 

goes into glycol manufacture. Ehylene glycol's largest, but slowest growing 

end use is anti-freeze which accounts for about 70 percent of the ethylene 

glycol produced. Another area of increased use of glycol is in polyester 

fiber and film production. 

The second largest market for ethylene oxide is nonionic surface-active 

agents which consume 10-15 percent of the ethylene oxide production. Ethoxylated 

mixed linear alcohols (components in biodegrabable detergents) have been the 

major contributor to this use of ethylene oxide in recent years. 

Glycol ethers, the third largest end use of ethylene oxide has exhibited 

the fastest rate of growth as a consumer of the oxide. Most of this growth 

can be attributed to the use of ethylene glycol monomethyl ether as a jet 

fuel additive. 

Ethanolamines follow glycol ethers as the next largest consumer of 

ethylene oxide. The fastest growing use for these ethanolamines has been 

in the manufacture of surface active agents, e.g., diethanolamine condensates 

of conconut oil acids and lauric acid. 

Fifth in size of ethylene oxide consumption is diethylene glycol whose 

major end use is in polyurethane and unsaturated polyester resins. 

Ethylene oxide is also consumed in the manufacture of numerous other 

chemicals such as ethyl acrylate, choline and choline chloride, acrylonitrile 

(probably not being used commercially now), hydroxyethyl cellulose, hydroxyethyl starch, polyethylene oxide resins, fumigants and food sterilants. 

A conservative growth rate for ethylene oxide through 1985 of four percent 

per year has been estimated. It is based mainly on Figure EO-3 which shows 

the growth of ethylene oxide production since 1940. In the early 1970s, by 

far the dominant process has been direct oxidation as opposed to the older 

chlorohydrin process. All new growth has been projected to be via the 

direct oxidation route. A good average plant size is 200 MM lbs./year and as 

such about. 15 new units will have to be built between now and 1985. (See 

Table EO-12) 

The price history of ethylene oxide is interesting. From 1940 to the 

mid fifties, it showed a small increase each year until the direct oxidation 

process really began to catch on. From 1955 to the present, there has been 

a steady drop in price from 15c/lb. to 7.5c/lb. in mid 1973 despite a general 

rise in prices in the economy. 

The chlorohydrin process is only economic when the price of ethylene is greater 

than six times that of the chlorine price and is also more economical when ethylene 

oxide prices are high. At low ethylene oxide prices, the direct oxidation route 

gives a better return on ethylene and with low ethylene prices, the direct 

oxidation process has completely taken over the production of ethylene oxide. 
P.29 

E0-35 

, FIgURE EG^l 

c 
Current 

Capacity 

4,191 

Marginal 

Capacity 

356 

Current 

Capacity 

On-Stream 

in 1975 

3,835 

TABLE 

NUMBER OF NEW 

Demand 

1985 

6,800 

EO-12 

PLANTS BY 1985 

Capacity 

1985 

6,800 

Capacity 

to be 

Added 

2,965 

Economic 

Plant 

Size 

200 

Number 

of New 

Units 

15 m 

o 

i 

to 

ON 

NOTE: All capacitie s i n million s of pounds per year. 

CO 
P.31 

EO-37 

X. Plant Inspection Procedures 

The largest source of emissions from an ethylene oxide plant would be 

hydrocarbons, chiefly ethylene. These hydrocarbon emissions are sometimes 

vented as a very dilute stream of hydrocarbons in a large amount of nitrogen, 

CO2 and some oxygen. The vented gas stream should be below the lower explosive limit of ethylene in air. 

A. There is no easy way to test for the presence of hydrocarbons in an 

air-C02 stream other than a chromatograph and this is not generally 

a portable instrument. A quick, albeit rather qualitative test for 

the presence of ethylene is odor. There should be no odor detectable. 

Ethylene has a sweet odor and taste but it is not a strong odor. 

Ethylene has no local or chronic irritant rating. If the odor of 

ethylene is detectable, the unit is probably upset and venting 

improperly. The normal two percent ethylene + one percent in the 

vent gas probably will not be detectable by smell. The absence of 

any sweet odor does not mean that there are zero emissions. 

B. Ethylene oxide, on the other hand, is quite detectable by odor. It 

is irritating to the eyes and nose and is classified as an acute 

local irritant. In high concentrations, it numbs the sense of smell. 

It is toxic and should not be inhaled although it is non-cumulative 

in the body and is not a chronic poison. If the odor of ethylene 

oxide is detectable, chances are that the purge reactor absorber (or 

the secondary absorber/scrubber) is upset and not functioning properly. 

If would be advisable to discuss the following with plant officials. 

1. Proper flow of absorbing medium - water. 

2. Proper temperature of the absorbing medium and the scrubber. 

3. Deposits of material on the packing of the absorber which could 

foul the scrubber internally and cause by-passing. 

4. Markedly different temperature and pressure of the feed gas to 

the scrubber than design. 

Since ethylene oxide is the desired product and is being recovered in 

rather dilute form from the reactor effluent gases, prudent management 

of the plant would insist that every bit of ethylene oxide be recovered. 

It is just not economical to lose ethylene oxide due to improper 

scrubber operations so these instances should be rare. 

C. Stacks should be checked for particuTate emission and NOx by opacity. 

All stacks should be practically colorless but again a clear stack 

does not mean no hydrocarbon emissions because ethylene and related 

compounds are colorless. 

D. Flares, if any, should be smokeless and only a rather substantial upset 

should cause smoke here. However, putting a dilute stream of hydrocarbons through a flare below the lower combustible limit of the stream 

will result in a clean flare but no reduction in hydrocarbon emissions. 

E. Incinerators - If thermal incinerators are provided on any of the 

vent streams, a visual check of the stack gas should be made. The 
P.32 

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EO-3 8 

stack should be nearly clear, if not completely clear. Since the 

feed stream to the incinerator is liable to be below its combustible 

limit, one should check to see if adequate supplemental fuel is being 

burned to properly combust the vent gas. Design specifications should 

be compared to actual operating conditions since there probably will 

be no visible clue in the stack effluent. Some check points would be: 

1. Burner in the combustion zone should be operating. 

2. Combustion zone temperature in the design range. 

3. Stack gas temperature in the design range. 

4. Process gas valves open to the incinerator. 

A catalytic incinerator or converter may also be used. In fact, this 

type of device is more likely to be encountered than a thermal 

incinerator. Generally, the off-gas from the converter will be used 

to power a turbine before exhausting to the air. The same points 

should be checked on the catalytic converter as on the thermal 

incinei tor. Supplemental fuel may or may not be used on a catalytic 

incinerator. 

Log data on operation of both types of incinerators should be 

reviewed, especially if stack gas analyses are available via a 

chromatograph and recorded intermittently or continuously. Hydrocarbons in the stack gas should be virtually nil (say 0.2 percent or 

less and zero if possible). 
P.33 

EO-39 

XI. Financial Impact 

Table EO-13 presents an estimate of the cost of ethylene oxide manufacture 

by both an air oxidation process and by an oxygen oxidation process. The 

difference in manufacturing cost may not be as great as the table shows at 

200 MM lbs./year (i.e., the 0.48c/lb. may be on the high side) but the 

literature indicates a small advantage for the" air process at capacities 

over about 100 MM lbs./year, a break even at 60-70 MM lbs. and a small edge 

for the O2 process in smaller plants. The minimum economical plant size is 

reported to be about 25 MM lbs./year. 

Table EO-14 was calculated by using the air oxidation process as outlined 

in Table E0-13, but adding emission control facilities to reduce hydrocarbon 

venting to near zero with a catalytic converter on the two main process 

streams. This represents the most feasible new air oxidation facility at 

200 MM lbs. per year production and virtually no emissions. Credit for 

power derived from the incinerator gases was taken as 0.25c/lb., based on 

data in the questionnaires. Cost of building a new 200 MM lbs./year air 

oxidation ethylene oxide plant with good pollution control facilities would 

reduce profits after taxes by about 1.5 percent. 

Table EO-15 was calculated by using the oxygen oxidation process as 

outlined in Table E0-13, but adding emission control facilities to reduce 

hydrocarbon venting to near zero with an incinerator and steam generator. 

This represents the most feasible new oxygen oxidation facility at 200 MM 

lbs./year production and virtually no emissions. Net operating cost is only 

$5,900/year. Cost of building a new 200 MM lbs./year oxygen oxidation 

ethylene oxide plant with good pollution control facilities would reduce 

profits after taxes by about eight percent. 

A sensitivity analysis was performed for the catalytic incineration 

installation in the air oxidation process (Table E0-14b). Installed cost 

of the pollution control facility was varied + 50 percent and its effect on 

the R.O.I, calculated. The 6.8 percent R.O.I, was found to vary from 6.5 

to 7.1 percent. 

A comparable calculation on the operating cost sensitivity would result 

in variations of similar magnitude because the savings in operating costs 

through the addition of a catalytic converter are approximately equal to 

the increased capital charges. If both sensitivities were applied simultaneously, 

they sould nearly off-set each other. 

Sensitivities were not calculated for the oxygen oxidation process because 

the extra capital involved is only $40,000 on a $5,200,000 plant and the extra 

operating cost is only $20,000/year on a $14,540,000/year total. Thus, it was 

judged that the sensitivities are not significant. 

Table E0-16 is a pro-forma balance sheet for the two above cases. A 

constant selling price of 7.5c/lb. for ethylene oxide was used. Capital 

requirements for the most feasible new plants are about $225,000 higher with 

air oxidation and about $40,000 higher with oxygen oxidation than for 

existing type plants. 

In addition to the financial impact of the proposed most feasible new 

plants a definite positive environmental impact would result. Not only 

would 2,050 tons of hydrocarbons per 200 MM lbs./year plant not be vented 

to the atmosphere (for 1985, 15 new plants would vent 30,750 tons of hydrocarbons per year if not controlled) but an energy savings.could be realized 
P.34 

J 

] 

.] 

.] 

.] 

.] 

] 

] 

1 

] 

1 

1 

1 

1 

EO-40 

if the hot gases were used to drive some of the process turbines or generate 

steam. i 

~ For 1985, installation of emission control facilities and utilization of 

j the power generated would be equal to a savings of about three billion cubic 

—' feet of gas per year. 
EO-41 

u 

TABLE EO-13 

ETHYLENE 

EXISTING 

PROCESS 

DIRECT MANUFACTURING COST 

Raw Materials 

Ethylene (4.0c/lb.) 

Oxygen ($15/ton) 

Catalyst & Chemicals 

Labor 

Maintenance @ 5% of Investment 

Utilities 

INDIRECT MANUFACTURING COST 

OXIDI 

FOR 

200 

: MANUFACTURING COST* 

A TYPICAL 

MM LB./YR. 

o2 

C/LB. 

3.8 

1.0 

0.2 

0.31 

0.13 

0.60 

6.04 

FACILITY 

S/YR. 

AIR 

C/LB. $/YR. 

3.8 

0.0 

0.2 

0.31 

0.25 

0.60 

. 5.16 

0.34 

0.26 

0.06 

0.32 

6.70 

520,000 

0.34 

0.50 

0.11 

0.61 

6.11 

1,000,000 

Plant Overhead @ 1107. of Labor 

FIXED MANUFACTURING COST 

Depreciation - 10 year str. line 

Insurance & Prop. Tax 2.37. of Inv. 

MANUFACTURING COST 

GENERAL EXPENSES 

Administration (37. of Mfg. Cost) 

Sales (17, of Mfg. Cost) 

Research (27. of Mfg. Cost) 

Finance (67, of Investment) 

TOTAL COST 

PRODUCT VALUE 

Ethylene Oxide @ 7.5c/lb. 

Profit before Taxes 

NPAT (527.) 

Cash Flow 

ROI 

*Taken from literature "Petrochemical Industry: Markets & Economics" up-dated 

and scaled up to 200 MM lbs./year using "0.6 Factor" on capital for both 02 

and Air Feed Plants. Based on 1973 dollars. 

0.20 

0.07 

0.13 

0.15 

7.25 14,500,000 

15,000,000 

500,000 

240,000 

760,000 

4.67. 

0 

0 

0 

0_ 

6 

18 

06 

12 

_30 

77 13,540,000 

15,000,000 

1,460,000 

700,800 

1,700,800 

7.07.