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Integrated Design of Alternative Technologies for Bulk-Only Chemical Agent Disposal Facilities Appendix B Process Description for the Newport Chemical Agent Disposal Facility The following excerpt is accompanied by a simplified flow diagram for the NECDF (Figure B-1 ) and mass balance tables of input and output streams (Table B-1 and Table B-2 ). The numbered streams in Table B-1 and Table B-2 correspond to the numbered diamonds in Figure B-1 (U.S. Army, 1998). 1. VX PROCESS OVERVIEW The Newport Chemical Agent Disposal Facility is designed to destroy the stockpile of nerve agent VX stored in ton containers at the Newport Chemical Depot. The overall process employed in the facility design is divided into three major process steps: Ton Container Cleanout (TCC) - removal of agent from ton containers and decontamination of the ton containers prior to shipment Neutralization - destruction of VX resulting in a non-agent product (hydrolysate) Post Treatment - oxidation of organic compounds in the hydrolysate through supercritical water oxidation (SCWO) and removal of inorganic salts through evaporation 1.1 Ton Container Cleanout (TCC) The ton container cleanout process consists of draining agent from ton containers, decontaminating the containers to a 3X condition, and preparing the containers for off-site shipment. The draining of bulk agent is accomplished in the Bulk Drain Station by punching two holes in each ton container and inserting a drain tube into one hole. Liquid agent remaining after draining is removed with a vacuum nozzle inserted through one hole. After removal of liquid agent, any residual agent is washed from the surface of the ton container by halving the container and spraying it with hot process water directed through high pressure spray nozzles. Each container is steamed and air dried, monitored to verify that a 3X condition has been achieved, and readied for shipment to offsite smelting. Agent drained from the ton containers is referred to as drained agent, while the effluent from the washing of ton containers is termed TCC effluent. All vent gases from the TCC area are passed to the building cascade ventilation system where they are filtered prior to release to the atmosphere. 1.2 Neutralization Drained agent is neutralized through batchwise reaction with caustic at 194°F. The neutralization reaction converts VX to several non-agent organic products, and the resulting mixture is referred to as drained agent hydrolysate. After reaction, the drained agent hydrolysate is combined with TCC effluent. The combined mixture is reacted to destroy agent in the TCC effluent, and the resulting mixture is called hydrolysate. The hydrolysate is sampled and held until it is confirmed that the VX is 99.9999% destroyed (no more than 330 ppb VX) and cannot be detected. The concentration of EA 2192 must be below 20 ppm. Vent gases from the reactors are contained during the reaction, but are vented and partially condensed during the initial filling of each reactor. The vent condensate is returned to the reactors, and the vapor effluent ultimately routed to the building cascade ventilation system. 1.3 Post Treatment Non-agent organic compounds in the hydrolysate are destroyed with supercritical water oxidation (SCWO), which mineralizes the organics at high temperature and pressure to form water, innocuous gases, and inorganic salts. Water is added to the hydrolysate prior to the SCWO reaction to adjust the heating value of the feed. Oxygen, the oxidant for the reaction, is injected directly into the SCWO reactor. A quench stream of water is added to the reactor effluent to cool the effluent below its critical temperature. After separation of the product gases, the pH of the SCWO aqueous effluent is adjusted with sodium hydroxide and the stream is evaporated to remove salts. The evaporator condensate is recycled to supply SCWO feed and quench water and process
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Integrated Design of Alternative Technologies for Bulk-Only Chemical Agent Disposal Facilities FIGURE B-1 Simplified flow diagram for the NECDF. Source: U.S. Army, 1998. water for washing ton containers and diluting caustic. The salt-concentrated evaporator bottoms are crystallized and filtered, then sent to a properly permitted offsite landfill. The excess evaporator condensate is sent to a sewage treatment plant (STP). Post treatment vent gases are passed through carbon filters prior to discharge to the atmosphere. Since the SCWO package is vendor-supplied, the final configuration may differ from what is described. The process description of SCWO provided in this document represents a typical configuration. SUPPLEMENTAL PROCESS INFORMATION Operation of Supercritical Water Oxidation Two independent supercritical water oxidation (SCWO) reactor trains are located in separate rooms in the SCWO building. Normally, one train is in operation and the other on standby. The SCWO reactors are plug-flow tubular reactors about 10 inches in diameter and 15 feet long. At the start of each batch run, fuel oil is used as a start-up feed to bring the unit up to operating temperature and pressure. The feed is then switched to hydrolysate at a rate of 2,092 lbs/hr, along with 937 lbs/hr of water. Oxygen is introduced separately at a rate of 1,313 lbs/hr, 150 percent of the stoichiometric requirement. The unit operates under severe conditions of 1,200°F and 4,000 psig. Residence time is about 60 seconds. The reaction stream is quenched with 7,555 lbs/hr of water as it leaves the reactor, the pressure is let down, and vapor streams totaling 1,170 lbs/hr are mixed with air and sent through a carbon filter before being released to the atmosphere. The 10,727 lb/hr liquid-solid outlet stream is mixed with caustic to maintain a pH of 9 before it is fed to an evaporator feed tank.
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Integrated Design of Alternative Technologies for Bulk-Only Chemical Agent Disposal Facilities Evaporator/Crystallizer Material in the evaporator feed tank goes to an evaporator/ crystallizer. The SCWO product contains about 4 weight percent salt. The evaporator system can handle about 125 percent of the 11,122 lbs/hr of caustic-treated feed from each SCWO reactor. It operates continuously, producing 24,870 lbs/hr of condensate and 574 lbs/hr of solids. TABLE B-1 Process Inputs for VX Neutralization/Posttreatment Stream number 1 2 3 4 5 Description Agent NaOH (aq) N2 to Reactors N2 to Hydrolysate Tanks Oxygen Total Inputs Total flow Pressure (psia) 1197.00 5.78 0.89 3,500.00 3,500.00 5,703.67 Temperature (° F) Physical state (solid (S), liquid (L), gas (G)) 70 L 80 L 70 G 70 G 70 G Components CH3P(O)(OEt)(SR) VX Water 956.50 956.50 598.50 NaOH Air 598.50 0.00 Oxygen Nitrogen 5.78 0.89 3,500.00 3,500.00 6.67 Agent impurities Diisopropylamine Diisopropylcarbodiimide (stabilizer) 0.03 11.90 0.03 11.90 O-ethyl methylethylphosphinate Diethyl methylphosphonate 0.21 0.41 0.21 0.41 2-(diisopropylamino) ethane thiol O,O-diethyl methylphosphonothioate 6.50 0.98 6.50 0.98 O,S-diethyl methylphosphonothioate 2-(diisopropylamino) ethyl ethyl sulfide 0.46 0.81 0.46 0.81 Diethyl dimethylpyrophosphonate (Pyro) O,O-diethyl dimethylpyrophosphonothioate 7.20 1.24 7.20 1.24 O-(2-diisopropylaminoethyl) O-ethylmethylphosphonate 1.70 1.70 1,2-bis(ethyl methylphosphonothiolo)ethane Unknowns 4.50 7.56 4.50 7.56 Ton containers (No./1,000kg) 1.47 Ton container valves (No./1,000kg) 3.06 Ton container plugs (No./1,000kg) 9.19 Source: U.S. Army, 1998. WASTE STREAMS Air Emissions The ton container clean-out (TCC) system, neutralizers, and hydrolysate storage sections all produce small amounts of vent gas, totaling about 2.7 lbs/hr. In the cascade ventilation system, these gases are passed through two-stage carbon filters and are then exhausted to the atmosphere. A separate gas-handling system with carbon filters processes the 1,170 lbs/hr of posttreatment gases. Liquid Waste No liquid waste is produced under normal operating conditions. Although most of the requirements for the SCWO operation are met by the evaporator/crystallizer condensate, some supplemental plant water is required. Solid Waste Salt produced in the evaporator/crystallizer is sent to a suitable hazardous waste treatment, storage, and disposal facility. The clean ton containers and various metal parts exiting the TCC are sent to the Rock Island Arsenal for
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Integrated Design of Alternative Technologies for Bulk-Only Chemical Agent Disposal Facilities Table B-2 Process Outputs for VX Neutralization/Posttreatment Stream number 101 102 103 104 105 Description Neutralization Vent Hydrolysate Vent SCWO/Evaporation Vent Solid Effluent TC Cleanout Parts Liquid Effluent Total Output Total flow (kg/1,000kg) Pressure (psia) 5.80 0.93 3,121.00 1,535.00 See below 1,042.00 5,704.73000 Temperature (°F) 46 40 80 95 100 Physical state (solid (S), liquid (L), gas (G)) G G G S L Components CH3P(O)(OEt)(SR) NaOH VX Water 0.0317 0.00345 70.22 462.00 1,042.00 1,574.25520 NAOH Air Oxygen 1,165.22 1,165.22000 Nitrogen 5.74 0.922 6.66200 CO2 1,803.44 1,803.44000 N2O 82.11 82.11000 Nox 0.022 0.02200 CO 0.0089 0.00890 Volatile organic compound 0.00056 0.00056 (NO3)− 0.691 0.69100 Ethyl methylphosphonic acid 0.277 0.27700 Methylphosphonic acid 0.137 0.13700 Thiols 0.00778 0.00778 (HCO3)− 9.45 9.45000 Total organic carbon 0.113 0.11300 Na2SO4 531.26 531.26000 Na2HPO4 531.04 531.04000 Total Metals 0.0702 0.07020 O,O-diethyl methylphosphonothioate O,S-diethyl methylphosphonothioate 2-(diisopropylamino) ethyl ethyl sulfide Diethyl dimethylpyrophosphonate (Pyro) O,O-diethyl dimethylpyrophosphonothioate O-(2-diisopropylaminoethyl) O-ethylmethylphosphonate 1,2-bis(ethyl methylphosphonothiolo)ethane Unknowns Ton containers (No./1,000kg) 1.47 1.47 Ton container valves (No./1,000kg) 3.06 3.06 Ton container plugs (No./1,000kg) 9.19 9.19 Source: U.S. Army, 1998. smelting and recycling. Spent filter carbon is checked for detectable agent before being sent to an outside contractor for disposal. Demilitarization protective ensembles, which are at the 3X level after normal decontamination procedures, will be packed in 55 gallon drums, stored in a solid waste storage area, and shipped off site. REFERENCE U.S. Army . 1998 . Acquisition Design Package, Vol. 2 . Newport Chemical Agent Disposal Facility. February 1998 . CD-ROM prepared by Stone and Webster Engineering Corporation for the Department of the Army . Aberdeen Proving Ground, Md. : Office of the Product Manager for Alternative Technologies and Approaches .
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