The Innovation Team of Development and Utilization of Urban Agricultural Growing Substrate of the Institute of Urban Agriculture, Chinese Academy of Agricultural Sciences (IUA, CAAS), proposed a novel torrefaction technology recently. This research has been published in Bioresource Technology with a title "Superheated steam as carrier gas and the sole heat source to enhance biomass torrefaction".

Superheated steam (SHS) is superior in thermal capacity and heat transfer coefficient resulting in even heating and fast heating rates. Therefore, SHS was taken as the sole heat source for torrefaction at ambient pressure.

Garden waste is common and abundant all over the world. The disposal of garden waste has been a problem for decades. Nowadays, carbon neutrality is a world-wide mission. The recirculation of carbon from garden wastes could reduce carbon emission and benefit carbon neutrality.

From this study, a setup was specially designed and capable of heating wood shavings at a rate > 120 °C•min-1. Solid products were analyzed in many aspects and demonstrated the enhanced organic conversion owing to SHS torrefaction. Torrefied biomass was comparable to slow pyrolysis char in fuel quality and superior to that of conventional torrefactions. Moreover, it was found that SHS torrefaction was super-timesaving. A coal-like product (HHV of 27.84 MJ•kg-1) was achieved in only 15 minutes at 350 °C. This technology could save 1/2— 3/ 4 of the treatment time compared to the conventional process. Overall, SHS torrefaction boosted biomass densification and gave rise to greater production efficiency.

The research was supported by the Science and Technology Innovation Project of CAAS.

The link of the paper: https://doi.org/10.1016/j.biortech.2021.124955

By Zhang, Dongdong (zhangdongdong@caas.cn)