Document 0qmxN2yoaapEOeRaJKEv7d2O

CHEMICALS INDUSTRIES TO See Below FROM Don Metzger b> -b HINTEROFFICE / LAKE CHARLES DATE April 27, 1971 subject CtJNFIDC^LU Attached is your copy of the Hazard Review report for the Per-Tri Expansion, including the new TCE Plant. DM/jg Distribution List: D. L. Duncan R. E. Baker O. L. Cromeans R. Richard T. Taylor J. M. Davis C. L. Payne File ^ SL 050568 INDUSTRIES INTEROFFICE / LAKE CHARLES TO C. L. Payne FROM Don Metzger DATE April 27, 1971 SUBJECT Hazard Review of Per-Tri Expansion, Including New TCE Plant Hazard Review Team: Richard, O'Neal, Carley, Carter, Gorton, Metzger Summary This report summarizes the Hazard Review of the Per-Tri expan sion, including the new TCE Plant. Two groups of questions have been formulated as a result of the review. The first group is composed of unresolved questions which require further consideration. The second set of questions are resolved, or at least partially answered. Some of this second set of questions involve procedures which are adequate, but are presented for future reference. In general, the plant is very well engineered. The ma}or questions deal with further back-up on instrumentation and the possible need for further overpressure protec tion. Discussion The Hazard Review of the Per-Tri Expansion included equipment design, fire protection and process safety. The reviews were conducted by using the Hazard Review Manual and associated checklists. The review of the expansion project by the team members in meetings con sumed approximately 44 manhours. The existing Per-Tri equipment which will be reused in the expanded plant has been reviewed and will be discussed in the Hazard Review report for the existing Per-Tri plant. Unresolved Questions A. New TCE Plant 1. The EDC to be used in the AIBN tank will have some unsaturated light components from the OHC-EDC. Will these light compo nents be polymerized by the AIBN? 2. High liquid level in the TCE Reactor Condensate Surge Tank could result in overpressure of the TCE Reactor (design HCl flow is 234,500 sch), subsequent operation of the TCE Reactor SRV and loss of HCl flow to OHC. Is a back-up level trans mitter and alarm needed? 3. The cooling tower basin could be pumped empty between opera tor rounds in the event of loss of tne make-up level control system. Is a back-up level alarm needed? SL 050569 Page 2 April 17, 1971 4. The chlorine supply line isolation block valve to the new TCE plant area is not accessible. Should a valv be installed at a readily accessible location? B. Per-Tri Plant Expansion 1. Does the increased volume of flammables created by two Tri Still Reflux systems and the Tri Reflux Dryers warrant fire protection in this area? 2. Is overpressure protection needed on the oxygen preheater or TCE preheater? 3. The DH Stills cannot be isolated from the Secondary Condenser. Are isolation valves needed? 4. The design pressure of the Degassers and Reactor Secondary Condensers are 50 psig, while the operating pressure will be 40 psig. A foreseeable upset in pressure could blow the rupture disc. Also, the graphite rupture discs have ques tionable reliability at settings this close to operating pressure. Should SRV's mounted over rupture discs or some other type of rupture disc be considered? Resolved Questions A. New TCE Plant 1. Question: The original prints show an automatic shutdown of HCl feed to the OHC plant if the chlorine content exceeds a certain level. Is the probability of substantial chlorine breakthrough great enough or is the chlorine analyzer reliability good enough to warrant automatic shutdown? Answer: This analyzer will be used to indicate and alarm only. 2. Q: The original prints show a two-position vent pressure control valve to the Scrubber coming off downstream of the system PCV. This type of control and take-off point could result in serious upsets both in the TCE plant and in OHC. Should other methods of control be considered? A: The take-off point has been relocated upstream of the system PCV and a proportional mode of control will be used. 3. Q: The steam PCV to the Chlorine Vaporizer fails in the closed position with loss of supply air. Should failure in the open position be considered? A: This PCV will be changed to allow failure in the open position. SL 050570 Page 3 April 27, 1971 4. Q: Should an alarm b provided on vaporized chlorine temperature? A: An alarm will be added. 5. Q: Failure of the chlorine PCV in the open position could result in operation of the Chlorine Surge Drum SRV. Are means provided for working on the SRV without requiring a plant shutdown? /L > ^ -W' A: .6 Q: The Surge Drum can be bypassed to allow SRV main tenance. The HCI temperature to OHC is not alarmed. In the event of loss of steam to the heater, could enough liquid condense in the line to give problems at OHC? A: The temperature will be checked routinely by the opera tor, and the surge drum at OHC will remove any fore seeable condensate. 7. Q: Is overpressure protection needed on the Lights Still Feed Heater or the cool side of the Crude TCE Cooler? A: .8 Q: No. These exchangers would be isolated only during shutdowns. Is a steam snuffing line needed on the Scrubber Vent Stack? A: No; this vent will normally be non-flammable. 9. Q: The overhead streams from the OHC Lights Still and the Tri Stills will be fed to the new TCE Reactor. Are any components present in these streams which could lead to problems? A: .10 Q: These streams contain some unknown or doubtfully identified lights. These components should be identified. Are excess flow valves needed on sight glasses? A: All vessels containing flammable mixtures or operating at about 20 psig or more will have excess flow valves. 11. Q: The mechanical flow sheet shows a block valve in the vent off the acid tank. Is this acceptable? A: .12 Q: This valve is not needed and will not be installed. Are all steam lines protected by steam traps? A: The piping drawings will be checked and traps installed as needed. SL 5057l pri 7, 1971 * B. Per-Tri Plant Expansion 1. Q: What are the consequences of getting oxygen in the steam condensate? Should the Oxygen Preheater steam condensate be sewered? A: Oxygen in the condensate could lead to corrosion and the condensate will be sewered. 2. Q: Can the Oxygen Preheater enter the hazardous temperature range under foreseeable circumstances? A: The temperature is alarmed and only 30 psig steam Is used. This should provide adequate protection. 3. Q: Is overpressure protection needed on the new filters or the Heavies Still Bottom Dryers? A: No overpressure protection is needed because the filters are small and the material in the Heavies Still Bottoms Dryer has a very high boiling point. 4. Q: Is fire protection needed for the new refrigeration unit? A: FIA classified the unit as non-hazardous, requiring no fire protection. 5. Q: A desuperheater will be used on the 170 psig steam system in order to meet the pipeline and valve specifications. Will use of the desuperheater cover all foreseeable circumstances? A: The line has two SRV's to protect against overpressure, and the steam temperature is alarmed. Foreseeable circumstances have been considered and appear to be covered. 6. Q: Are spare parts being set up? A: Recommended spare parts lists are being obtained from all manufacturers. The appropriate spare parts will be set up by the project team. 7. Q: Do the discharges of the safety relief devices on the DH Still, Tri Reflux Dryer or refrigeration unit present personnel safety hazards? A: The discharge point will be checked on these devices. DM/jg SL 05057!