Experimental study on co-pyrolysis and gasification behaviors of petroleum residue with lignite

Co-processing of petroleum residue (deoiled asphalt, DOA) with lignite was investigated in this paper. The co-pyrolysis of three lignite with DOA was studied by a fixed bed reactor and the gasification reactivity of the co-pyrolysis chars was evaluated by a thermogravimetric analyzer. The results showed that no synergetic effect was observed on the char yield during co-pyrolysis of the lignite and DOA, while the DOA melted and stuck to the lignite surface and caused the agglomeration of the co-pyrolysis char. The XRD analysis reflected that the graphitization degree of the co-pyrolysis char's became higher than that of pure lignite, but the mineral form did not changed. The gasification reactivity of the DOA in the co-pyrolysis char increased greatly with the addition of the lignite. Among the three lignites, Wenshan lignite which is rich in Ca and Fe and poor in Si and Al showed the best catalytic effect on DOA gasification. The co-gasification of lignite char with DOA char showed that only Wenshan char had an obvious catalytic effect on DOA gasification though the catalytic effect is lower than that in the co-pyrolysis char. For the co-processing of DOA and lignite, it's better to mix the raw materials together before they are pyrolyzed, since the co-pyrolysis char shows higher gasification reactivity than that of the pure char blends.