Gas-pressurized torrefaction of biomass: A review

Gas-pressurized (GP) torrefaction has the advantages of mild reaction conditions, low energy consumption, high deoxygenation efficiency, high energy recovery efficiency, and semi-coke fuel quality similar as subbitumiunous coal. It is one of the novel technologies promising to replace the traditional torrefaction. This review introduces the development of GP torrefaction, reviews the optimization of GP torrefaction conditions (including the raw biomass type, temperature, pressure and time) and product composition and physicochemical properties, explains the macroscopic reaction pathways and microscopic reaction mechanisms, focuses on the combustion, pyrolysis and gasification utilisation pathways of semi-coke, reviews the reactor design and expansion in solid waste treatment such as chlorinated solid waste, sludge, etc. Finally, the GP torrefaction technology converting biomass into high fuel quality solid fuel which can directly replace coal is summarised and prospected. © 2024 Chemical Industry Press Co., Ltd.. All rights reserved.