Steam Pyrolysis of Coal for Two-Stage Gasification

摘要

In a series of pyrolysis experiments prior to this program, it was shown that up to 80% of the carbon in coal could be liberated as volatile matter in less than 100 msec. The objective of this program was to maximize the yield of product gas produced by steam pyrolysis of coal in a flow reactor at residence times less than 0.1 sec. Experiments were carried out in a high-throughput (1/2 - 1 ton coal/hr) flow facility consisting of a combustor (operating on fuel oil) with outlet temperature 2450 - 2600K followed by a pyrolyzer section into which pulverized coal was injected. Product composition (with axial and radial resolution) and gas temperature were measured, and char samples were obtained for subsequent analysis. Particle size, coal loading, steam loading and CO sub 2 /H sub 2 O ratio in the background gas were varied. The results show that the pyrolysis reactions are very rapid, with most of them completed within 10 msec. The results are in agreement with our coal gasification model at low coal loadings. At high coal loading, the char analysis remains consistent with the model, but the gas analysis data diverge, indicating the possibility of cracking reactions, stabilization vs cracking, to maximize the yield of useful products. 8 refs., 58 figs. (ERA citation 10:045940)