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Suggested Citation:"System Considerations." National Research Council. 1993. Alternative Technologies for the Destruction of Chemical Agents and Munitions. Washington, DC: The National Academies Press. doi: 10.17226/2218.
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Page 200
Suggested Citation:"System Considerations." National Research Council. 1993. Alternative Technologies for the Destruction of Chemical Agents and Munitions. Washington, DC: The National Academies Press. doi: 10.17226/2218.
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Page 201
Suggested Citation:"System Considerations." National Research Council. 1993. Alternative Technologies for the Destruction of Chemical Agents and Munitions. Washington, DC: The National Academies Press. doi: 10.17226/2218.
×
Page 202
Suggested Citation:"System Considerations." National Research Council. 1993. Alternative Technologies for the Destruction of Chemical Agents and Munitions. Washington, DC: The National Academies Press. doi: 10.17226/2218.
×
Page 203
Suggested Citation:"System Considerations." National Research Council. 1993. Alternative Technologies for the Destruction of Chemical Agents and Munitions. Washington, DC: The National Academies Press. doi: 10.17226/2218.
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Page 204

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APPLICATION OF ALTERNATIVE TECHNOLOGIES TO THE DESTRUCTION OF THE U.S. CHEMICAL WEAPONS 200 STOCKPILE Energetics, as well as metal parts and containers, are heated to a high temperature. The vapors from the decomposition and vaporization of these materials are then oxidized and cleaned before release. Metals are detoxified to the 5X level to allow recycling, and salts are rendered suitable for landfill disposal. All waste streams are tested to ensure their suitability for release. System Considerations As Figures 8-1 and 8-2 show, unit processes and technologies must be combined to form a system that meets all demilitarization requirements. The two demilitarization strategies provide a framework for examining the potential roles of alternative technologies. Strategy 1, which delays or avoids local disposal, is discussed first. Alternative processes for Strategy 1 (disassembly and agent detoxification). The only major agent conversion process required for Strategy 1 is detoxification (Figure 8-1). However, decontamination of the disassembled weapon parts and containers will probably be necessary as well for achieving agent demilitarization and acceptable agent emissions during storage or transportation. Table 8-2 shows the alternative processes that might be used in this strategy. Because high-temperature processes to mineralize agent are similar in effect to the baseline incineration technology, these processes are considered as part of Strategy 2 (mineralization). The low-temperature, liquid-phase chemical detoxification processes are particularly suited for Strategy 1. It is assumed that the same process equipment can be used for all three agents and, taken as a whole, this approach is at the laboratory data-gathering stage of development. Because each agent may require different reagents, three separate laboratory and pilot plant programs would be required. Although each of these programs might normally require 12 years to progress through demonstration, they could be run in parallel and use common equipment. One of the processes (NaOH hydrolysis of GB) could form the basis for early demonstration. With skilled management and adequate talent and resources, the time to application of these processes probably could be significantly shortened. An attractive feature of the low-pressure, liquid-phase detoxification processes is their production of little or no gas. The high-pressure oxidation processes, however, produce a waste gas stream, which could be largely eliminated by capture of CO2 by lime. There would probably be few significant differences in the equipment requirements for the three agents for these high-pressure processes, apart from those related to corrosivity.

APPLICATION OF ALTERNATIVE TECHNOLOGIES TO THE DESTRUCTION OF THE U.S. CHEMICAL WEAPONS 201 STOCKPILE TABLE 8-2 Low-and Moderate-Temperature Agent Detoxification Processes Process Special Gas Treatment Needed Number of New Processes (Development Status) Low-temperature, liquid-phase No 3 (laboratory) detoxification Wet air or supercritical water oxidation Yes 1 (pilot plant) Removal of agent from metal parts and No 1 (pilot plant) containers, and agent detoxification with decontamination fluid The drainage of agent from weapons and containers is never complete. The amount of agent remaining might normally be between 1 and 5 percent. Thickened or degraded mustards, however, can leave larger residues. In all cases these residues must be removed and detoxified to meet demilitarization requirements and to be suitable for storage or transportation. The baseline technology does not require this step because the residual agent is immediately destroyed in the high-temperature kilns. Using this alternative strategy, additional facilities to clean out the residual agent would need to be added to the current disassembly procedure. Agent removal by water jets, solvent, or decontamination fluids should produce a stream that can be processed in the detoxification step. Such residual agent removal processes could be developed and demonstrated in parallel with development of the detoxification processes. Alternative processes for Strategy 2 (mineralization). As shown in Figures 8-1 and 8-2, drained agent is generally treated separately from the energetics, metals, and other solids resulting from weapons disassembly. Table 8-3 indicates the processes that might be used for agent mineralization and their development status.

APPLICATION OF ALTERNATIVE TECHNOLOGIES TO THE DESTRUCTION OF THE U.S. CHEMICAL WEAPONS 202 STOCKPILE TABLE 8-3 Agent Mineralization Processes Number of New Processes (Development Status) Case/Process Using Air Using Oxygen 1. Baseline incineration 0 (operational) 1 (demonstration) 2. Baseline incineration plus gas storage and certification 0 (operational) 1 (demonstration) 3. Fluidized bed or molten salt combustion 1 (demonstration) 1 (pilot plant) 4. Molten metal or plasma arc plus burner 1 (pilot plant) 1 (pilot plant) 5. Steam gasification plus burner 1 (pilot plant) 1 (pilot plant) 6. Supercritical water oxidation or wet air oxidation 1 (pilot plant) 1 (pilot plant) 1 (pilot plant) 1 (pilot plant) 7. Low-temperature, low-pressure oxidation 1 (laboratory) 1 (laboratory) 8. Biological oxidation 1 (laboratory) 1 (laboratory) For agent treatment, the liquid-phase detoxification processes mentioned under Strategy 1 could be followed by incineration (such as the baseline incineration technology) or by some combination of the pyrolysis and oxidation alternatives to complete the oxidation process. If supercritical water or wet air oxidation is chosen for detoxification, these follow-on processes might be unnecessary; however, some treatment of unoxidized organics might be necessary for wet air oxidation.

APPLICATION OF ALTERNATIVE TECHNOLOGIES TO THE DESTRUCTION OF THE U.S. CHEMICAL WEAPONS 203 STOCKPILE Cases 1 and 2 in Table 8-3 incorporate the baseline technology, which uses air and additional fuel in a two- step burner and afterburner system. This process is operational at Johnston Island without storage and certification of the flue gas stream. It is believed that addition of the storage and certification feature (Case 2) would not require demonstration beyond the normal startup and testing programs for a new installation. About an 85 percent reduction in flue gas volume can be achieved by substituting oxygen for air. Removal of CO2 by reaction with lime would give a large additional reduction in flue gas volume. Such systems could be designed and built based on current experience but would require demonstration. If the current incineration process is not chosen, a number of alternatives could be developed. For these technologies, development could be based on the use of oxygen without adding appreciably to technological risk or development time. In all these cases, at the least a pilot plant program would be needed, and in some cases additional laboratory data would be needed as well. Cases 3 to 5 in Table 8-3 are high-temperature, atmospheric pressure oxidation systems that, combined with appropriate afterburners, may be capable of mineralizing agent. Case 6, high-pressure, supercritical water or wet air oxidation, has the potential, with additional pilot plant work, to oxidize agent at relatively low temperatures. The water streams from both processes may require additional oxidation for complete mineralization. Cases 7 and 8 axe low-temperature, liquid-phase oxidation processes that could potentially be used to complete the oxidation of agent detoxification products. Both axe in a very early laboratory stage. However, they axe similar enough to oxidation processes used for other waste streams for the committee to be optimistic about their chances of success. Gas treatment would be necessary for these processes and, with biological oxidation, a waste sludge stream would be produced. For final disposal of energetics and metal parts and containers, destruction of energetics and heat treatment of metal parts and containers is required to eliminate any residual agent. The alternatives for carrying out these operations, in contrast to those for agent destruction, all require high temperatures. Table 8-4 lists these processes. The baseline system (Case 1 in Table 8-4) makes use of an internally fired rotary kiln to destroy energetics and small metal parts. An internally fired traveling-grate kiln is used for the larger metal parts, such as drained ton containers and drained 155-mm artillery shells. The mixture of pyrolyzed organic compounds and combustion flue gas from these kilns then enters a secondary burner for completion of combustion. As in the agent incinerator, the volume of gas in this system could be reduced by using pure oxygen rather than air. This modification again would require demonstration. Case 2 (Table 8-4)

APPLICATION OF ALTERNATIVE TECHNOLOGIES TO THE DESTRUCTION OF THE U.S. CHEMICAL WEAPONS 204 STOCKPILE TABLE 8-4 Processes for Treatment of Energetics and Metal Parts and Containers Number of New Processes (Development Status) Case/process Using Air Using Oxygen 1. Baseline kilns 0 (operational) 2 (demonstration) 2. Baseline kilns plus gas storage and certification 0 (operational) 2 (demonstration) 3. Electrically heated kilns 2 (demonstration) 2 (demonstration) 4. Molten metal furnace 1-2 (pilot plant) 1-2 (pilot plant) indicates a modification to the baseline that allows certification of gas emissions before release to the environment. The volume of gas can be further reduced by replacing internal firing with electrical heat (Case 3 in Table 8-4). Use of electrical heating and oxygen for oxidation would, after CO2 removal, almost eliminate flue gas. Any air leakage into the system would be discharged after cleanup and analysis. In Case 4 (in Table 8-4), a molten metal furnace could destroy energetics and all metal pieces (ton containers might need to be cut into smaller pieces). Combining the function of the baseline rotary kiln and the traveling-grate furnace could be a useful simplification. Energetics could probably be destroyed in other alternative processes (supercritical water oxidation, molten salt, fluidized-bed combustion, and plasma arc processes) if separated from their metal containers and broken into small particles. Complete removal of energetics from metal containers is expected to be difficult, and high- temperature treatment of metals would still be required. No large advantage is seen for these variations. All the high-temperature systems shown in Table 8-4 require afterburners and similar gas cleanup and handling technologies. The main difference between these systems and the baseline technology is substitution of electrical heating for internal firing. All of these processes also have the potential to destroy bulk agent. Treatment of all streams in one device, as in

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The U.S. Army Chemical Stockpile Disposal Program was established with the goal of destroying the nation's stockpile of lethal unitary chemical weapons. Since 1990 the U.S. Army has been testing a baseline incineration technology on Johnston Island in the southern Pacific Ocean. Under the planned disposal program, this baseline technology will be imported in the mid to late 1990s to continental United States disposal facilities; construction will include eight stockpile storage sites.

In early 1992 the Committee on Alternative Chemical Demilitarization Technologies was formed by the National Research Council to investigate potential alternatives to the baseline technology. This book, the result of its investigation, addresses the use of alternative destruction technologies to replace, partly or wholly, or to be used in addition to the baseline technology. The book considers principal technologies that might be applied to the disposal program, strategies that might be used to manage the stockpile, and combinations of technologies that might be employed.

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