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Research progress of thermal treatment and utilization technologyof coal gasification fine ash and slag

2023 No. 07
438
214
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Authors:
ZHOU Li
LIANG Chen
QI Xiaobin
LI Wei
REN Qiangqiang
Unit:
Institute of Engineering Thermophysics,Chinese Academy of Sciences
University of Chinese Academy of Sciences
Abstract:

Coal gasification, as the leading technology in coal chemical industry, is an important pathway to achieve clean and efficient uti⁃lization of coal. However, the gasification process generates a large amount of gasification ash and slag,which is difficult to achieve re⁃source utilization. Currently, the treatment of gasification ash mainly relies on storage, causing serious environmental and soil pollution is⁃sues, which becomes a bottleneck in the development of the coal chemical industry. Therefore, it is urgent to develop large-scale utiliza⁃tion technologies for gasification ash and slag. The thermal treatment technologies for fluidized bed coal gasification fine ash and entrainedflow coal gasification fine slag were highlighted, and the disposal principles, disposal capabilities, and research stages of various thermaltreatment technologies were summarized. The disposal methods for fluidized bed coal gasification fine ash include steam activation, com⁃bustion, gasification, and melting. In order to fully utilize the developed porous structure, abundant amorphous carbon structure, and ac⁃tive sites of gasification ash, a scheme for steam activation to produce activated carbon was determined. The enhanced preheating combus⁃tion technology, which prolongs the residence time of gasification ash in the furnace through material leg feeding, achieves a combustionefficiency of over 98% for gasification fine ash. The preheating combustion technology based on circulating fluidized bed can not onlyachieve stable decarbonization of gasification ash, but also control the emission of NOx. The coupled regasification of fluidized bed and en⁃trained bed makes up for its poor reactivity by increasing the gasification reaction temperature. The fluidized-melting gasification processutilizes a circulating fluidized bed to fluidize and modify the coal gasification ash, and the modified product and secondary gasifying agentare simultaneously fed into the melting gasification unit to achieve high-temperature melting gasification of the modified fly ash, therebyobtaining synthesis gas from gasification fly ash as a single fuel under atmospheric pressure. The thermal treatment methods for entrainedflow gasification fine slag are blending combustion and fluidized-melting combustion. The blending combustion materials mainly consist ofraw coal and biomass, but the blending ratio is low, and the large amount of ash in the gasification fine slag presents new challenges toash conveying systems and other components. The fluidized-melting combustion adopts a technical route of combining thermal modificationand high-efficiency incineration of gasification slag, as well as mineral phase reconstruction and high-value utilization of slag, to achievethe separate utilization of organic carbon and inorganic ash components in coal gasification slag. Currently, the thermal treatment technolo⁃gies for coal gasification ash slag mainly focus on the removal and utilization of organic carbon, while the inorganic ash components, afterthermal treatment, still remain as solid waste, without achieving the harmless disposal and resource utilization of coal gasification ash.Therefore, in order to truly achieve large-scale treatment and resource utilization of coal gasification ash and slag, the correspondinghigh-value utilization technologies must be developed based on the characteristics of inorganic mineral components after thermal treatment,which will be the main research direction in the future.

Keywords:
coal gasification fine ash and slag
thermal treatment
activate
combustion
gasification
melting
Citation format:
周丽(1996—),女,甘肃平凉人,博士研究生。E-mail:zhouli@iet.cn
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Citation format:
ZHOU Li,LIANG Chen,QI Xiaobin,et al.Research progress of thermal treatment and utilization technology of coal gasification fine ash and slag[J].Clean Coal Technology,2023,29(7):65-77.

About Journal

  • Executive director

    China Coal Science and Industry Group Co., Ltd

  • Sponsored by

    Coal Science Research Institute Co., Ltd
    Coal Industry Clean Coal Engineering
    Technology Research Center

  • Editor in Chief

    XIE Qiang

  • Vice Editor-in-Chief

    YU Chang
    SHI Yixiang
    ZHAO Yongchun
    DUAN Linbo
    CAO Jingpei
    ZENG Jie

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    Monthly

  • ISSN

    1006-6772

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    11-3676/TD

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