Study On Combustion And Gasification Reaction Performance Of Semi-coke From Lignite

China's energy structure has been moving toward low carbon in the past few years,but the situation in which coal dominates China's energy structure will continue for several years.Due to the excessive use of high-quality coal in the past,the current supply of high-quality coal in China is tight.Therefore,it is necessary to pay attention to the utilization of low-rank coal such as lignite.The clean and efficient use of lignite is of great significance for optimizing the energy utilization mode in China.Low-temperature pyrolysis is one of the important ways for efficient and low-polluting utilization of lignite.Semi-coke is its main product.Therefore,studying the semi-coke properties of different coals under different conditions can provide a basis for the industrial utilization of lignite.In this paper,we selected lignite from Wulagai area in eastern Inner Mongolia and Zhaotong lignite from Yunnan.Firstly,different semi-cokes were obtained by changing the pyrolysis parameters on the tube furnace.The obtained semi-coke was analyzed for particle size and comprehensive coal quality analysis.The results show that:After lignite pyrolysis,the particle size decreases and the calorific value increases.In the low temperature pyrolysis range,the pyrolysis atmosphere and heating rate have little effect on the coal quality characteristics of the semi-coke.With the increase of pyrolysis temperature,The ash content and fixed carbon content of the semi-coke increased,and the volatile matter decreased.With the increase of the size of the raw coal,the ash content of the two lignite semi-cokes decreased,but the volatile matter of Mengdong lignite semi-coke was greatly changed by the particle size.The particle size of the raw coal increases,and the content of volatiles in the semi-coke increases.The combustion characteristics of two lignite semi-cokes were studied on a thermogravimetric analyzer.The effects of pyrolysis temperature,pyrolysis rate and raw coal particle size on the combustion characteristic index of the semi-coke and the activation energy of the gasification reaction are mainly considered in the test.The results show that the pyrolysis temperature and the size of raw coal have great influence.With the increase of pyrolysis temperature,the combustion characteristics of the two semi-cokes deteriorate and the activation energy increases.As the particle size of the raw coal increases,the combustion characteristics of Mengdong semi-coke become better and the activation energy is reduced,but the properties of Zhaotong semi-coke are not obvious.The Mengdong lignite semi-coke sample was prepared by different pyrolysis conditions,and its gasification reaction performance with CO₂ was studied.The results show that with the increase of pyrolysis heating rate,the decrease of pyrolysis final temperature and the decrease of pyrolysis residence time The gasification reaction activity of Mengdong lignite semi-coke is improved.Therefore,it is suggested that when Mengdong lignite semi-coke is used as gasification raw material,the choice of pyrolysis process should choose low temperature rapid pyrolysis,and pyrolysis does not have to stay too much time.