Process Analysis on Co-Pyrolysis of Lignite and Residue from Shendong Coal Direct Liquefaction

摘要

In order to upgrade the yield and quality of lignite pyrolysis tar and utilize coal direct liquefaction residue in a more clean and highly efficient way, the concept of co-pyrolysis of lignite and coal direct liquefaction residue was proposed in this paper. The experimental studies on co-pyrolysis were conducted using a fixed-bed reactor under atmospheric pressure in high purity nitrogen. In situ micro-Raman experiments, thermogravimetric analysis (TGA), Soxhlet extraction and scanning electron microscope (SEM) analysis were also performed to explore the interaction mechanism during the co-pyrolysis process. Results indicated the interactive effect between lignite and the residue during co-pyrolysis. This interaction was not from the enriched mineral or remained liquefaction catalyst (Fe_(1-x)S), but was likely to come from hydrogen-rich components in the residue. Moreover, hydrogen-rich components had positive and negative effects on the pyrolysis - supply hydrogen to free radicals and gelatinous body mass transport limitations. Hence, based on the interactive effect, optimization of experimental conditions was suggested as the ratio of the residue to coal, pyrolysis temperature and particle sizes of coal and residue are 0.15, 550°C and 0.425 - 0.85mm, respectively. Under the optimal operational conditions, co-pyrolysis tar yield was 8.75% and the hexane insoluble content of the tar was 38.56%.