Optimal Control Of Reaction And Products Of Oil Shale Pyrolysis

To tackle with the technical problems in oil shale pyrolysis process to produce shale oil with high yield as well as high quality,this article puts forwards the idea of optimally controlling the process of radical generation and volatile reaction in order to promote the product yield and quality.This work deeply investigates rapid pyrolysis and the mechanism of moving bed with internals in controlling pyrolysis reaction and products.By using two-stage fluidized bed,oil shale rapid pyrolysis and in-bed oil upgrading by shale char were studied to obtain the pyrolysis condition for producing shale oil at total and light fraction(boiling point<350?)yields higher than those of Fischer-Assay.By coupling a drop tube reactor and a moving bed with internals,their matching conditions were investigated and the optimal condition for drop tube fast pyrolysis was obtained.Shale oil product with high yield and high quality was realized.The following summarizes the main results of this study.(1)Rapid pyrolysis and upgrading characteristics in fluidized bed.Rapid pyrolysis of oil shale in one-stage fluidized bed obtained shale oil yield higher than the Fischer Assay oil yield at temperatures of 500-600?.The highest yield was 12.7 wt%at 500? and was 1.27 times of the Fischer Assay oil yield.The heavy fraction(boiling point>350?)in shale oil at all temperatures of fluidized bed rapid pyrolysis was above 50%.Adding an upper fluidized bed of secondary cracking over oil shale char,found that the optimal pyrolysis and secondary cracking temperatures in such a two-stage fluidized bed were 600?,where the shale oil yield decreased by 17.74%but its light fraction yield was 7.07 wt%and increased by 86.11%in comparison with the light fraction yield of shale oil from the Fischer-Assay.(2)Rapid pyrolysis in a drop tube and its coupling to a moving bed with internals.Using a drop tube realized rapid pyrolysis of continuous-fed oil shale particles and the highest shale oil yield was 9.59 wt.%at 600?,it was close to 90%of the Fischer Assay yield.Further coupling to a moving bed with internals for volatile reactions,the highest shale oil yield was 9.20 wt.%at 600? of moving bed,which again was close to 90%of the Fischer Assay yield.Its highest light fraction yield was 8.21 wt.%,above the light fraction yield from the Fischer Assay.The internals mounted in the moving bed control the pyrolysis volatile to flow in the char layer from high temperature to low temperature so that heavy fraction in volatile can be selectively adsorbed and further cracked on char particles.This process ensures the high shale oil yield and high light fraction content in oil.Meanwhile,such a flow of volatile in char bed allows dust with the volatile to be filtered to produce shale oil with low dust contamination.