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• • <br />EXHIBIT A <br />DESCRIPTION OF THE PROJECT <br />LA PORTE FACILITIES <br />I. BLOWDOWN SYSTEM <br />• Project No. A-43 <br />PURPOSE: <br />To provide caustic scrubbing systems capable of absorbing phosgene and <br />hydrochloric acid from various sources in the La Porte Site and destroy- <br />ing them by chemical reaction. <br />PROCESS DESCRIPTION: <br />The project consists of five complete, independently operated, scrubber <br />systems located at appropriate locations in the La Porte Site. Each <br />system consists of two caustic solution feed tanks, two knockout drums, <br />two absorption columns, two heat exchangers and ten (10) pumps. One <br />dispersion stack will service all scrubbers. <br />Phosgene and hydrochloric acid from pressure relief devices or from <br />equipment clearing systems are transferred by pipeline through one or <br />two knockout drums and then through an absorption column containing a <br />circulating, dilute caustic solution. Here the phosgene and hydro- <br />chloric acid are first absorbed and then reacted with sodium hydroxide <br />and water to produce sodium chloride, sodium carbonate, carbon dioxide <br />and water. Heat liberated by the absorption and reaction process is <br />removed by a heat exchanger in the caustic solution stream circulating <br />about each column. Fresh caustic solution is made up on demand to each <br />column from 24,000 gallon storage tanks which are maintained at constant <br />level by diluting a 502 solution. <br />Vents from each scrubber system are passed by pipeline to an air <br />injected dispersion tower and exposed to an ammonia/stream environment <br />before release to the atmosphere. The spent caustic and ammonia solu- <br />tions released from the scrubber systems or vent stack are collected by <br />pipeline and passed through an existing wastewater treatment system <br />before discharging to the La Porte Site outfall. <br />A-1 <br />