In-situ torrefaction-densification approach for pelletizing of rice hull/rice stalk and the combustion behavior analysis.

The utilization of biomass resources could optimize the energy consumption structure and achieve the goal of carbon neutrality. Torrefaction and densification pretreatment could improve the defects of high oxygen content, low energy density, and low bulk density of biomass. In this work, high-density and hardness pellets were prepared by torrefaction coupling densification (in-situ torrefaction-densification without binders). In-situ torrefaction-densification significantly reduced the pressure required for the densification process. In-situ torrefaction-densification lowered the pressure required to prepare RH pellets with a bulk density of 1000 kg/m3 from 88.23 MPa to 30.95 MPa. The effects of the in-situ torrefaction-densification method and pelletizing pressure on the pellet combustion process were investigated by non-isothermal and isothermal combustion. The volatile and carbon of TCDP could be burned intensively during combustion, and the emissions of CO and C x H y were reduced during combustion. The original structural strength of TCDP was still maintained in the combustion process. The alkali metal K in TCDP was difficult to escape, effectively reducing the emission of K in the flue gas. In-situ torrefaction-densification could not only improve the quality of biomass solid fuel but also facilitate the storage and transportation of biomass solid fuel. [Display omitted] • The volatile and carbon of pellets could be burned intensively by in-situ torrefaction-densification pretreatment. • Emissions of CO and C x H y were reduced during TCDP combustion. • The in-situ torrefaction-densification inhibited the release of K during combustion. [ABSTRACT FROM AUTHOR]