Stabilization of spent sorbents from coal gasification. Final technical report, September 1, 1992--August 31, 1993

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The objective of this investigation was to determine the rates of reactions involving partially sulfided dolomite and oxygen, which is needed for the design of the reactor system for the stabilization of sulfide-containing solid wastes from gasification of high sulfur coals. To achieve this objective, samples of partially sulfided dolomite were reacted with oxygen at a variety of operating conditions in a fluidized-bed reactor. The effect of external diffusion was eliminated by using small quantities of the sorbent and maintaining a high flow rate of the reactant gas. The reacted sorbents were analyzed to determine the extent of conversion as a function of operating variables including sorbent particle size, reaction temperature and pressure, and oxygen concentration. The results of sulfation tests indicate that the rate of reaction increases with increasing temperature, increasing oxygen partial pressure, and decreasing sorbent particle size. The rate of the sulfation reaction can be described by a diffuse interface model where both chemical reaction and intraparticle diffusion control the reaction rate. The kinetic model of the sulfation reaction was used to determine the requirements for the reactor system, i.e., reactor size and operating conditions, for successful stabilization of sulfide-containing solid wastes from gasification of high sulfurmore » coals (with in-bed desulfurization using calcium based sorbents). The results indicate that the rate of reaction is fast enough to allow essentially complete sulfation in reactors with acceptable dimensions. The optimum sulfation temperature appears to be around 800{degrees}C for high pressure as well as atmospheric stabilization of the spent sorbents.« less