Clean Coal Technology

2022, v.28;No.142(06) 44-53

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Co-combustion and sulfur oxide release characteristics of typical sludge and coal slime

WANG Xin;LING Peng;AN Xiaoxue;HAN Hengda;XU Jun;JIANG Long;WANG Yi;SU Sheng;HU Song;XIANG Jun;State Key Laboratory of Coal Combustion,Huazhong University of Science and Technology;

Abstract:

The output of sludge and coal slime is increasing year by year, which affects the ecological environment and human life, and it is urgent to deal with them reasonably. Combined with the respective fuel characteristics of sludge and coal slime, the co-combustion of the two can produce a certain synergistic effect and form an effective complementarity in different combustion stages, and finally realize the efficient co-combustion and comprehensive reduction of the two, which is of great significance for the efficient disposal of sludge and coal slime. The co-combustion characteristics and sulfur oxide release characteristics of sludge/coal slime and typical fuels(coal, biomass, etc.) have been studied, but there are few studies on the co-combustion characteristics and sulfur oxide release characteristics between the two. Therefore, on the self-built fixed-bed combustion reaction system, the co-combustion experiments were carried out on a typical dried sludge(Dali sludge) and two types of coal slimes(Lingshi coal slime and Shanxi coking coal slime) after drying. The influence mechanism of fuel type, temperature, mixing ratio and other factors on co-combustion characteristics and sulfur oxide release characteristics was analyzed. The results show that the combustion reaction can be accelerated by increasing the temperature and sludge mixing ratio when sludge and coal slime are mixed for combustion. During the combustion process, the conversion rate of SO_2 firstly decreases and then increases with the increase of combustion temperature. High temperature can promote the secondary release of sulfur fixed in inorganic matter. There is an obvious interaction in the co-combustion of sludge and coal slime, which will significantly affect the generation and release of SO_2. At 800 ℃,the sulfur fixation is strengthened and the release of SO_2 is inhibited due to the formation of sulfur-containing compounds between ash and SO_2. However, when burning at 1 000 ℃,the decomposition of inorganic sulfur is accelerated due to the accelerated combustion reaction, which leads to the increase of SO_2 release. The experimental results show that the combustion with 30% sludge/70% coal slime mixture at 800 ℃ can achieve lower SO_2 emission and higher fuel burnout characteristics.

Key Words: sludge;coal slime;co-combustion;combustion characteristic;sulfur oxide

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Foundation: 国家自然科学基金资助项目(U1910214)

Authors: WANG Xin;LING Peng;AN Xiaoxue;HAN Hengda;XU Jun;JIANG Long;WANG Yi;SU Sheng;HU Song;XIANG Jun;State Key Laboratory of Coal Combustion,Huazhong University of Science and Technology;

DOI: 10.13226/j.issn.1006-6772.CC22013003

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