Synergistic Effects In Pyrolysis And Gasification Of Lignite/High-sulfur Petroleum Coke System

The coking product high-sulfur petroleum coke has problems such as low reactivity,high sulfur content and difficulty in utilization.By mixing with lignite with high calcium and iron content,it can make full use of high-carbon and low-carbon raw material resources,and at the same time reduce pollution caused by the utilization process of high-sulfur petroleum coke.In this paper,low-order lignite with calcium and iron content above 20%are selected as gasification raw materials.The synergies in co-pyrolysis and co-gasification of lignite/high sulfur petroleum coke were studied by thermal analysis.Based on the analysis of the basic properties of lignite and petroleum coke,the synergistic effect of co-pyrolysis and co-gasification was determined by thermal analysis,and the synergistic mechanism was analyzed.The morphology of sulfur during co-pyrolysis was further explored.The main contents were summarized as follows:Thermal analysis technology was used to study the synergetic effect of lignite/high-sulfur petroleum coke system on pyrolysis and gasification.In addition,X-Ray Diffraction(XRD),Raman and Scanning electron microscope and energy spectrometer(SEM-EDX)were used to reveal the synergetic mechanism of co-pyrolysis of lignite and high-sulfur petroleum coke.The results show that the actual value of weight loss and weight loss rate of pyrolysis of ML and PC are both higher than the theoretical weighted values,and it indicate that there is a significant synergistic effect in the co-pyrolysis process of lignite/high-sulfur petroleum coke.The reactivity index of co-gasification of ML and PC increases with the increase of the proportion of ML.In addition,the gasification synergetic factors are all higher than 1.Thus,the synergetic effect of gasification is obvious.Adding ML coal ash,Fe₂O₃,and Ca O into PC,respectively,PC gasification reactivity is significantly improved.Therefore,the synergistic effect of lignite/high-sulfur petroleum coke is due to the increased reactivity of ML ash wrapping on the PC surface.The graphitization degree and aromatization degree decrease with the increase of the proportion of ML in co-pyrolysis coke,and thus the reactivity is increased.The arrangement of carbon microcrystalline structure becomes more regular with the increased of temperature,and the order degree and aromatic degree of carbon structure of co-pyrolysis coke samples increase.Thus,the reactivity is reduced.XRD,Fourier Transform Infrared Spectrometer(FT-IR)and SEM-EDX were used to study the morphology of sulfur during co-pyrolysis process,and the influence of minerals in lignite on the sulfur fixation of high sulfur petroleum coke was investigated.The results show that the content of Fe S and Ca S sulfide increased with the increase of the amount of coal ML added;with the increase of pyrolysis temperature,Fe S₂and organic sulfur(sulfyl bond-SH,sulfoxide sulfur-S=O functional group)in PC are decomposed,and the decomposition products react with Ca O generated from ML to form Ca S.Thus,the sulfur-fixing effect enhances with the increases the content of coal ML and pyrolysis temperature.Figure[42]table[16]reference[82]...