Synergistic Effects And Sulfur Transformation During Co-pyrolysis Of Lignite And High-sulfur Swelling Coal

Co-pyrolysis of a lignite coal (L) and a bituminous coal (YST) was carried out on a fixed-bed reactor. The lignite was enriched with calcium, and the bituminous coal featured in high sulfur and strong swelling. This paper mainly includes three aspects:First, pyrolysis of two coals was observed by the effect of acid-washing. The influence effects of demineralization differ from the rank of coals and the coal particles aggregate increasingly by acid-washing.Secod, the co-pyrolysis at different temperatures of two coals with various ratios was examined. The tar yield obtained experimentally was lower than the calculated value, while the char yield obtained experimentally waw larger than the parent value. The results were reversed with demineralization. The gas compositions detected by GC—TCD were effected by the co-pyrolysis, the tar compositons detected by GC—MS were found that the aromatic were reduced, the surface structure and the cohesiveness of the char/coal were analyzed by the SEM and Arnu-Audibert's dilatometer. The synergetic effects appeared different aspects, mainly deserve from the calcium in the lignite and the swelling of the bituminous coal.Third, the sulfur transformation of co-pyrolysis was investigated by the sulfur gas compositions and the char quality. The contribution of sulfur-retention mainly happened on the elevated temperature, about 19% of the char increasing; Coal/char of lignite, bituminous coal and blends was analyzed by XRD and XANES. Calcium in lignite was devided into calcium sulfate and organic calcium; sulfur in YST coal was exsited by pyrite and thiophene and was decomposed to pyritic and a little R-S-S-R'; the blend char at 900℃with different ratios contained different sulfocompounds.