Document xzeRMOkmEVvQz03dry5rJBjk1

EDC PLANT SAFETY STUDY RESULTS HANDOUT SLIDE AND CHECKLIST T. M. SNOW EUROPEAN VINYLS CORPORATION VINYL CHLORIDE SAFETY ASSOCIATION 1990 CONFERENCE CTL019633 1 --,-r; PREMISE NO. I: i *' '"K'hL r? i ff.. ,- ITED FEEDSTOCKS ARE REASONABLY CONSTANT MPOSmON. PREMISE NO. IT 5LANT GAS MIXTURES ARE NOT EXPLOSIVE IF CONTAIN NO OXYGEN. CTL019634 Oxygen --Based 0Mlchlorination 2 Purge Crude EDC H2O C2H4 + 2HCI + i02 EDC + H20 Feed Stream c,h4 HCI 02 N, Potential Impurity c2h6 vcm n2 02 CTL019635 LOW -- temperature Direct Ltiiormation 6 Vent To T reatment C2H4 + Cl2 EDC Feed Stream N? Cl2 Cl2 c?h4 Potential Impurity o2 o2 h2 c2h6 Crude EDC Cooling Water CTL019636 Vapor--Phase Chlorination Reactions 4 AH' 25*C. kcal/a mole CH4 + 4CI2 ecu + 4HCI -104 W C2H4 + 6CI2 hy 2CCI4 + 4HCI -167 C2H6 + 7CI2 "-h-'W 2CCI4 + 6HCI -179 C2H4CI2 + 5CI2 (EDC) hv m 2CCI4 + 4HCI For Reference : -124 CTL019637 Caustic gashing 5 2NaOH + C12 NaOCI + NaCI + H 2 0 (At High pH) NaOCI + 2HCI --- NaCI + H 2 0 + Cl 2 1 (At Low pH) CTL019638 RECOMMENDATIONS 6 I. PROTECTION AGAINST EXCURSIONS IN FEEDSTOCK COMPOSITION - EVALUATE POSSIBLE DEVIATIONS AND THEIR POTENTIAL EFFECT ON THE PROCESS (SEE CHECKLIST). - INSTALL ANALYZERS ON CRITICAL FEED STREAMS, n. PROTECTION AGAINST CHLORINE-FUEL EXPLOSIONS - GENERAL: 1. REVIEW CHLORINATOR AND DOWNSTREAM UNITS FOR POTENTIAL Cl 2 BREAKTHROUGH OR GENERATION (SEE CHECKLIST). 2. ELIMINATE SIGHT GLASSES. 3. INSTALL Cl 2 ANALYZERS AT VULNERABLE POINTS. 4. EXERCISE PARTICULAR CARE WHERE HYDROCARBON GAS IS USED FOR BLANKETING. - IN DIRECT CHLORINATOR: 1. REGULATE COOLING WATER PRESSURE TO AVOID WATER INGRESS. 2. PROVIDE LEAK DETECTION DEVICES. 3. INSTALL ALARMS/TRIPS ON HIGH PRESSURE AND/OR HIGH VENT FLOW. - IN EDC WASHING: 1. REVIEW INTEGRITY OF pH CONTROLS. 2. EXAMINE SPENT CAUSTIC TREATMENT SYSTEM FOR HYPOCHLORITE DECOMPOSITION HAZARDS. 3. EXAMINE EDC SYSTEM FOR CHLORINE BREAKTHROUGH HAZARDS. CTL019639 EDC PLANT FEEDSTOCK'PURITY HAZARD CHECKLIST IF THIS STREAM: HAD A LARGE AND UNEXPECTED INCREASE IN CONTENT OF: WHAT POTENTIAL HAZARDS MIGHT RESULT? C2H4 TO OXYCHLORINATION c2h6 HC1 TO OXYCHLORINATION VCM O2 TO OXYCHLORINATION n2 N2 TO VARIOUS LOCATIONS 02 C2H4 TO DIRECT CHLORINATION C2H6 CI2 TO DIRECT CHLORINATION 02 Cl2 TO DIRECT CHLORINATION H2 HOW CAN THESE BE AVOIDED? CTL019640 EDC PLANT FUEL-CHLORINE MIXTURE HAZARD CHECKLIST I. DIRECT CHLORINATION REACTOR a. Is the vent stream normally diluted with natural gas or fuel gas? If so, could an instrument failure or process upset give rise to a fuel gas-chlorine mixture in the vent system? B. Could loss of cooling lead to an EDC vapor-chlorine mixture in the reactor or vent system? C. Could water ingress "kill" the reaction, giving rise to an ethylene-chlorine gas mixture in the reactor or in the vent system? D. Could any other process upsets (e.g., low level in the reactor vessel) cause incomplete reaction? II. CAUSTIC WASHING/SPENT CAUSTIC TREATMENT A. Would a loss of pH control in the caustic washing unit produce "springing" of free chlorine from dissolved hypochlorite? If so, could this form an explosive gas mixture, either with a fuel gas blanket or with chlorcarbon vapors? B. Follow the path of the spent caustic. Is there any point downstream where it might be acidified, releasing chlorine in the presence of hydrocarbon or chlorocarbon vapors? C. Follow the path of the washed EDC. If, due to loss of pH control, dissolved chlorine were not removed from the EDC, where would it eventually concentrate? Could this be in a place (e.g., the azeotrope drying column overhead system) where it could form an explosive mixture with light ends vapors or with blanketing gas? CTL019641