Alternative Technologies for the Destruction of Chemical Agents and Munitions (1993)
Chapter: THERMAL TREATMENT
THERMAL TREATMENT
Many processes require heating or cooling steps before or after the destruction operation. Conventional heat exchange methods are assumed to be available for most of these needs. Chemical agents can be destroyed by simple thermal decomposition through indirect heating without their reaction with oxygen in combustion or with other chemicals.
Simple thermal decomposition results in the release of less exhaust gas, representing only the products of agent decomposition without the larger volume of additional fuel combustion products, excess oxygen, and nitrogen present in the baseline processes. However, the products of thermal decomposition would still require oxidation (in an afterburner) before release.
This alternative approach is dearly applicable to the treatment of energetics and contaminated metal parts and containers. For bulk agent, the use of combustion heat provides a self-sustaining flame, and there appears to be less advantage to the two-step process of thermal decomposition followed by oxidation.
Several indirect heating methods are available for heating contaminated metal parts to the required time and temperature conditions for achieving the 5X level of decontamination (i.e., 1000°F for 15 minutes; see Chapter 4). These methods include indirect gas firing and electrical resistive heating. (Plasma arc and molten-metal heating are discussed as principal alternative processes in Chapter 7.) Gas burners, electric heating elements, and heating chamber equipment are commercially available, although special designs would be required for chemical demilitarization.
Special factors that would require consideration for the use of indirect heating include the following:
remote operation: required for solids handling because of the presence of both agent and explosives;
uniform heating: distribution must be ensured to treat all material to 5X criterion time and temperature;
molten aluminum: provisions would be required to handle molten aluminum when decontaminating M55 rockets; and
decomposition products: available data on the thermal decomposition of agents do not describe the quantities or nature of by-products. However, if oxygen is not present, the decomposition products must include a variety of only partially oxidized hydrocarbons (only two atoms of oxygen are present in the molecule of the agent GB). A subsequent oxidation process (afterburner) will still be required to transform the decomposition products, which can include hazardous organic chemicals, into wastes that are suitable for disposal.
