OCR Text |
Show • A controlled-temperature packed bed reactor , where the diffusion of contaminants through the voids of the bed structure to the bed surface and the rate of energy transfer within the solid phase are characterized and defined. The results of these experiments are used to understand the evolution and volatilization of the contaminant out of a bed of solid. Since these results focus on phenomena on a particle and/or bed basis, they are only dependent on combustion environment and type of contaminant and solid. Hence, the data from these frrst two reactors are relevant to a number of primary combustor systems. The third reactor, however, focuses specifically on a realistic rotary kiln environment, where large beds are being slowly stirred: • A pilot-scale rotary kiln simulator, where contaminant evolution, in the presence of realistic heat transfer and solid phase mixing, is characterized. The experimental studies are supported by computer modeling of the desorption and diffusion processes within the bed and of the radiant, convective, and conductive heat transfer within the kiln. A variety of organic contaminants including xylene, toluene, and naphthalene and solid phases including commercial sorbents, sand, peat, and clay are currently under investigation. This paper focuses specifically on one portion of a study which is being conducted in conjunction with Louisiana State and Dow Chemical Company. The overall goal of this study is to develop a rudimentary understanding of and a predictive capability for rotary kiln design. It is a multifaceted experimental and theoretical project involving: 1. basic studies of contaminant evolution to characterize the hydrocarbon release rate in the primary combustor, 2. measurements with laboratory and intennediate scale rotary kiln incinerators to define the rate controlling steps, 3. numerical modeling of the chemical and physical processes that occur during the operation of a rotary kiln incinerator, and 4. insitu sampling in a full scale industrial rotary kiln incinerator to characterize actual incinerator perfonnance. This paper explicitly examines the results obtained to date in the fundamental and laboratory scale studies which have focused on the evolution of toluene from a sorbent material (Supersorb). Experimental Facilities Particle Characterization Reactor The high temperature particle characterization reactor, which can operate up to 1200°C, was designed to provide evolution rate data in a dispersed phase environment where the controlling resistances are largely intrapartic1e. The reactor, shown in Figure 1, is constructed in two major cylindrical assemblies, a soil bed and a heat exchanger, which are placed in a circular furnace. Desorbent gas is preheated in the annular heat exchanger |