Document Qkm3vryGB45DaBN6K02MeoDo7
June 18, 1982
Conoco Chomfeols Company
Conoco Inc. P. O. Box 91. Naw Highway 28 AbaiOaan. Mitl--ippi 39730 (001) 399-9111
Mr. Jerry B. Banks, P.E. Mississippi Department of Natural Resources Bureau of Pollution Control P. 0. Box 10385 Jackson, MS 39205
Dear Mr. Banks:
At approximately 10:45 a.m. on June 10, 1982, our plant experienced a minor emergency relief valve discharge from two relief valves. Pursuant to the National Emission Standard for Vinyl Chloride (40 CFR, Part 61, Subpart 6, paragraph 61.55 (a)) we are reporting this incident to your office. This release has also been reported to the National Response Center under the Comprehensive Environmental Response and Liability Act of 1980.
The vessels involved were the East and West Recovered Monomer Condensers in reactor module No. 2. Each condenser is protected by a 1" x IV' relief valve with a 2 inch diameter rupture disc between it and the condenser. The relief valves were both set to relieve at 150 psig and rupture discs both had a rated burst pressure of 150 pslg at 150F.
At approximately 10:45 a.m. on June 10, 1982, an operator noticed a liquid leak coming from the second floor of the VCM recovery in reactor module No. 2. Upon investigation the operator found that liquid vinyl chloride was coming from the weepholes in the discharge piping of the east and west recovered monomer condenser relief valves. The operator notified his supervisor for help and instructed the panel operator to shut down the monomer recovery system. The relief valves on the East and West Recovered Monomer Condensers were isolated at approximately 11:00 a.m. There were no vapors observed coming from either of the relief valve stacks. No personnel were overexposed to vinyl chloride.
Reactor module #2 was then shut down to find the source of the overpressure to the condensers that caused the relief valves to discharge liquid vinyl chloride. The line from the discharge of the condensers to the recovered monomer receivers was taken out of service and evacuated. This line was found to be plugged with polyvinylchloride resin, which is believed to be the cause of the overpressure of the condensers. This line was thoroughly cleaned before reactor module #2 was started up again. This is the first time this line has ever plugged with polymer since startup in early 1978.
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Mr. Jerry Banks 6/18/82 Page 2
The eetlaeted aaount of vinyl chloride discharged is approximately 57 pounds. This aaount is estimated from the accounts of those who observed the discharge. The accounts rangad from a quart of total liquid discharged to a pint of liquid eyery 30 seconds. The most conservative account waa used to calculate the discharge. Attached are the calculations used to estimate the amount of the discharge. This aaount differs from the amount reported to the National Re sponse Center shortly after the incident. The estimated amount reported to the National Response Center waa in the low hundreds of pounds.
To minimize the possibility of future discharges of this type, the plant has instituted a procedure to check the pressure drop using pressure gauges between the discharge of the condensers and the recovered monomer receivers during re actor recovery. This check will be made weekly. If an abnormally high pressure drop is experienced between the discharge of the condensers and the recovered monomer receivers, the line will be taken out of service and cleaned. As a long term measure, the plant will install a high pressure alarm on the dis charge of the recovery system compressors. Upon high compressor discharge pressure, the source the high pressure will be found and corrected. When the high pressure alarm is installed, the weekly check of the pressure drop between the condensers and the receivers will be discontinued.
The reporting requirements of the Standard pertaining to the relief valve discharge are summarized below:
Source:
East and West Recovered Monomer Condensers, Reactor Module No. 2
Nature:
Discharge through relief systems on the East and West Recovered Monomer Condersers
Cause:
Overpressure of Recovered Monomer Condensers which is believed to be caused by pluggage of the liquid discharge line
Date:
June 10, 1982
Time:
10:45 a.m.
Approximate Discharge: 57 pounds of vinyl chloride
Method of Determining Discharge: Calculation based on account of personnel who observed the discharge.
Action Taken to Prevent
Discharge:
1. Monomer Recovery System shut down. 2. Relief valves isolated. 3. Module No. 2 shut down 4. Liquid line from the discharge of the Recovered Monomer
Condensers was evacuated and cleaned.
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Mr. Jerry Banks 6/18/82 Page 3
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CONFIDENTIAL
Measures Taken To Prevent Future Discharges:
1. Weekly pressure readings will be taken to determine pressure drop between the discharge
of the Recovered Monomer Condeneers and the
Recovered Monomer Receivers. If an abnormally high pressure drop is observed, the discharge line of the condensers will be taken out of
. service and cleaned.
2 A. high pressure alarm will be installed on the compressor discharge. Upon high
compressor discharge pressure, the source of the high pressure will be found and corrected
The weather conditions at 11:00 p.m. on June
1982
Barometric Pressure Wind
Wind Speed Temperature Clear
29.88 inches of mercury
From Northwest
0--1 miles 83F
hour
Sincerely,
any questions concerning 1, extension 2331.
ns at
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Veldon E. Messick Senior Process Engineer
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