DEQ-CFW_00086197

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AIR EMISSIONS INVENTORY SUPPORTING DOCUMENTATION
Emission Source ID No.:
I-137
Emission Source Description:
Butacite® Plasticizer Storage Tank
Process Description:
This tank is used to store triethylene glycol bis (2-ethylhexanoate) or 3GO. Emissions from this
tank would be exclusively from the diurnal temperature change. Because the delivery railcar is
closed -loop vented with the tank, the displaced headspace associated with the unloading of the
railcar is vented back to the railcar, thereby resulting in no emissions to the atmosphere. The
tank vents to the atmosphere through a conservation vent, so there are normally no emissions
from the tank unless the tank is heating up from the sun.
Basis and Assumptions:
- Venting to atmosphere occurs only from daytime heating.
- Tank volume = 60,000 gallons or 8021 ft3
- 3GO vapor pressure = <0.0075 mm Hg @ 20°C (see Note 1)
5 mm Hg @ 219°C (see Note 2)
- Molar volume of an Ideal Gas @ 0°C and 1 atm = 359 ft3/(lb-mole)
- Molecular Weight of 3GO = 403 (403 lb 3G01 lb -mole 3GO)
- Assume one complete tank volume turnover per day for point source emissions.
- Assume DuPont Good Emission Factor on Equipment Leaks for fugitive emissions
(See Appendix A).
- Flange emissions were used for all equipment except valves and pumps.
Note 1: Vapor pressure reference from Celenese EC Safety Data Sheet
2001/58/EG revised on February 16, 2007.
Note 2: Vapor pressure reference from March 6, 1991, Federal Register Volume
56, Number 44, Page 9571
DEQ-CFW 00086197

Triethylene glycol bis (2-ethylhexanoate) CAS No. 94-28-0
3GO
Point Source Emissions Determination:
Assume a diurnal temperature change from a nighttime low of 50°F (10°C or 283°K) to a
daytime high of 11YF (45°C or 318°K).
Assume the entire tank volume (8021 ft3) is nitrogen saturated with 3GO.
Assume the ideal gas law applies:
Pressure x Volume = lb -moles x Gas Constant x Temperature
At a temperature of 10°C (510°R):
(1 atm ) x (8021 ft) = (n lb -moles) x (0.73 atm ft3 °R-1 lb -mole 1) x (510°R)
n lb -moles = 21.55 lb -moles of gas inside the tank
At a temperature of 45°C (573°R):
(1 atm ) x (8021 ft) = (n lb -moles) x (0.73 atm ft3 °R-1 lb -mole 1) x (573°R)
0 n lb -moles = 19.18 lb -moles of gas inside the tank
Therefore, if the tank heats from 10°C to 45°C, then 2.37 lb -mole (21.55 minus 19.18) of gas per
day is lost through the conservation vent.
Vapor pressure of 3GO = <0.0075 mm Hg at 20°C
Mole fraction 3G0 in vapor (using Dalton's law):
Mole fraction 3 GO = Vapor pressure 3GO = 0.0075 mm H = 0.0000099 mole 3GO
Total pressure in tank 760 mm Hg mole gas in tank
Pounds of 3GO emissions from tank from diurnal temperature change:
2.37 lb -mole x 0.0000099 lb -mole 3GO x 403 lb 3GO = 0.0095 lb 3GO
day lb -mole gas in tank lb -mole 3GO day
Total 3GO emissions per year from the diurnal temperature change:
0.0095 lb 3GO x 365 days x 1 ton = 0.002 ton 3GO
day year 2000 lbs year
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DEQ-CFW 00086198

0 Fugitive Emissions Determination:
Equipment
Component
Number of
Components
Good Factor
(lb/hr/com onent)
Emissions
(lb/hr)
Emissions
(ton/ r)
Pump Seal
1
0.0075
0.0075
0.033
Heavy Liquid Valve
20
0.00352
0.0704
0.308
Open-ended Line
1
0.0215
0.0215
0.094
Flange/Connection
9
0.00031
0.00279
0.012
Total
0.447
Good factor (lb/hr/component) x Number of Components = Emissions (lb/hr)
Emissions (lb/hr) x 1 ton / 2000 lbs x 24 hr/day x 365 days/year = Emissions (ton/yr)
Total fugitive 3GO emissions per year = 0.447 ton 3GO / year
Total Emissions Summary:
Point Source Emissions + Fugitive Emissions = Total Emissions
0.002 ton 3GO / year + 0.447 ton 3GO / year = 0.45 ton 3GO / year
= 0.45 ton VOC / year
DEQ-CFW 00086199

Which factors should I use?
The factors suggested above represent DuPont "experience" and more accurately reflect
OVERALL fugitive emissions from DuPont facilities, i.e. the DuPont culture. The comparisons
were made with a limited database and the factors suggested here reflect a comparison of overall
or aggregate emission levels to those predicted by EPA SOCMI factors. It should be pointed out
that individual DuPont factors did vary from specific source service factors suggested by EPA,
i.e. light or heavy liquid service. For the "Superior" category, the individual factors are
extremely small numbers, and therefore, it is suggested to calculate the emission estimate with
EPA SOCMI factors, and then divide the total by the 10,000 factor. Since there is considerable
variability in ANY individual component leak rate due to type, age, size, service, etc., it is also
suggested to check overall predicted emissions from the "Excellent" and "Good" categories in
the same way, i.e. use EPA factors and then divide by 20 or 3, respectively.
In order to determine which factors to use, a series of questions were developed to index a
facility into one of the three categories. These are general guidance, and not definitive in the
sense of black or white. Additionally, use of the DuPont Factors may be challenged by State
Environmental Agencies since they do vary from EPA prescribed factors. However, past
validation efforts gave overall estimates within 10-20% of those based on DuPont factors. For
additional information and assistance, please call Tom Kittleman, Ducom 366-4718.
Superior factors should only be sued by facilities that use extremely hazardous materials, i.e.
phosgene, chlorine or HF. The maintenance culture of these operations is to detect and repair
leaks immediately due to the inherent toxicity of the chemicals. Most other processes/facilities
will be either excellent or good.
The "Excellent" factors listed above should be used only after HONESTLY answering the list of
questions attached, and at least 4 or 5 answers are "Yes." otherwise use "Good".
QUESTIONS FOR DETERMINING UNIT -SPECIFIC FACTOR CATEGORY
1. Are techniques available and used to routinely locate specific leaks? Examples include SO2
bombs, ammonia solution, special detectors (such as those for HCN or phosgene), chemical
badges, and sniff testers.
2. Do you perform leak checks in this process area at least once per day?
3. Are specific procedures used on each start-up to minimized fugitive emissions? Examples
include hydrostatic tests, special leak tests, etc.
4. Do you have.a documented check list startup procedure that helps locate routine leaks?
5. Do you have a formal procedure that requires leaks be repaired in a timely manner, including
use of overtime if necessary?
DEQ-CFW 00086200