Application of hydrothermal pretreatment during thermal conversion of hydrocarbon solid fuels

Nowdays, coal and biomass are the most widely used hydrocarbon solid fuels in the world. The utilization of hydrocarbon solid fuels in China mainly depends on thermal conversion, the most representative of which is thermal power generation. In addition, thermal conversion utilization also includes pyrolysis, gasification, and liquefaction produces chemical products and liquid fuels. Pretreatments are important ways to improve thermal conversion efficiency, especially the most economical and widely used hydrothermal pretreatment. This paper reviews the effects of hydrothermal pretreatment on coal and biomass structure and examines the matching relationship between hydrothermal pretreatment and the thermal conversion process. The relationships between hydrothermal pretreatment and pyrolysis, gasification, liquefaction, and combustion of coal/biomass are discussed. Future studies on HTP should focus on environmentally friendly, high-efficiency, and low-energy consumption technology for coal/biomass thermal conversion. The treatment and utilization of effluents from the HTP systems, catalysis technologies and preparing high-quality materials by HTP are meaningful. [Display omitted] •HTP removes oxygenate groups and increases aromatization degree and porosity.•HTP increases crystalline structure order and decreases alkali metal content.•HTP improves coal conversion and tar yield by destroying cross-linked structure.•HTP reduces pollution, corrosion, ash slagging of conversion by demineralizing.