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Show recovered is taken into accoun4 as much as 47 MMT per year could be incinerated. Due to federal and state regulations on existing and new landfill facilities, e.g. ground water monitoring and the exclusion of landfilling for an increasing number of hazardous compounds (3), landfill options are expected to decrease. In addition, the EPA estimates that from 1400 to 2200 existing waste sites could require some type of cleanup (2). The projected increase in the generation of hazardous waste, the reduction of landfill disposal options, and the required cleanup of existing landfill sites require the development of new alternatives for hazardous waste disposal. To date incineration has proven to be a permanent solution for many waste disposal problems, minimizing future "cradle-tograve" liabilities. A typical incinerator system consists of two parts: the primary combustor and the secondary combustor. In the primary combustor - a rotary kiln, fluidized bed, multiple heanh, or other type of incinerator - the contaminants are volatilized from the solid. Some initial decomposition may take place, but the majority of the thermal destruction occurs in the secondary combustor. The temperature and time of combustion are such that the solid from the combustor is relatively free of organics and can often be delisted. The rate limiting steps in the primary combustor are mass transfer and heat transfer. In the secondary combustor, or afterburner, the hazardous off-gas is decomposed, and in principal no products of incomplete combustion (PICs) are formed. The primary limitations in the afterburner are usually chemical kinetics, controlled by the time, temperature, turbulence, and excess oxygen in the afterburner system. Research is currently exploring the destruction of principle organic hydrocarbons (POCHs) and PICs in the afterburner system (4,5). The data available on primary combustor phenomena, particularly on the transient evolution of contaminants from a solid sorbent, are limited; however, recent work (6) has demonstrated the importance of transient puffs in a rotary kiln environment As delisting requirements become more stringent, it will become more imponant to understand, optimize, and predict the phenomena occurring in the primary combustor. The research described herein attempts to qualify the controlling transfer steps and quantify the release of contaminants from solids in the primary combustor. Objectives and Approach The University of Utah, Department of Chemical Engineering, has a major research effon under way to characterize the rate limiting steps and optimize the incineration of hazardous solid waste materials including incinerable solids, spent sorbents, and contaminated soils in a rotary kiln environment. Rotary kilns were selected as the primary combustor since they accommodate a diversity of waste forms -solids, liquids, sludges - and represent a common system for solid waste incineration; approximately 12% of existing incinerators in 1983 were rotary kilns (1,7). The overall research approach is based on the concept that the solid charge in a rotary kiln can be viewed as a bed composed of many layers of panicles that are being slowly stirred. The particles are assumed to have varying size distributions and some internal pore structure. Typical contaminants may exist: 1) adsorbed onto the internal pore structure of the particles, 2) adsorbed onto the external surface of the panicles within a bed, or 3) as a liquid phase within a bed. The approach simplifies the complicated effects of a rotary kiln environment by frrst exploring the fundamental transfer phenomena within panicles and then within beds in two reactors: • An isothermal particle characterization reactor (PCR), where the evolution of hydrocarbons from within the pore structure of the solid, and subsequent diffusion to the particle surface are investigated and defined, and |