Experiments on pyrolysis of coal hydroliquefaction residue by solid heat carrier technology

To extract oil from coal hydroliquefaction residue ( CHR),the basic properties and pyrolysis of CHR in a dual loop reaction system ( DLRS) were investigated in this study. The DLRS was designed to solve the problems caused by the easily softening characteristics and high caking property of CHR such as feeding,caking and dust sepa- ration. It consists of a fluidized bed pyrolyzer,a radial-flow moving bed filter and a riser combustor followed by a parti- cles grading cyclone. These reactors form a pyrolysis loop between the pyrolyzer and the combustor and a filtration loop between the filter and the combustor with small and big inert particles as circulating bed materials,respectively. CHR mixed with the inert material is injected into the pyrolyzer by a gas driven feeder,which makes it possible to dispose the CHR continuously. The dust entrained in the pyrogas from the pyrolyzer would be captured in the filter to get a dust-free tar. The results show that the CHR contains over 50% extractable matter,which leads to its high caking prop- erty. The caking property tends to be weaken after blending a certain amount of inert additives. With the quartz sands as bed materials and the quartz sands-CHR blends (in a volume ratio of 4 ∶ 1) as feedstocks,at a pyrolysis temperature of 500 ℃ and with the nitrogen gas of a superficial velocity about 2. 8 Umf as fluidizing medium in the pyrolyzer, the pyrolysis of CHR on the DLRS has obtained a tar yield of 23% ,which is about two times of the Fischer Assay val- ue.