Engineering

Char

Biology

Pyrolysis

Materials science

Heat of combustion

Steam explosion

Geology

Coal

Oceanography

Waste management

Torrefaction

Organic chemistry

Biomass (ecology)

Agronomy

Combustion

Superheated steam

Chemistry

Boiler (water heating)

Pulp and paper industry

Solid fuel

Bioresource Technology

Superheated steam (SHS) has been used as a carrier gas for pressurized steam torrefaction, steam explosion or pyrolysis, but is barely used as a heat source. However, SHS is superior in thermal capacity and heat transfer coefficient resulting in even heating and fast heating rates. Therefore, this work applied SHS as the sole heat source for torrefaction at ambient pressure. 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 organics conversion owing to SHS torrefaction. Torrefied biomass was comparable to slow pyrolysis char in fuel quality and superior to that of conventional torrefactions. Moreover, SHS torrefaction was super-timesaving. A coal-like product (HHV of 27.84 MJ•kg−1) was achieved in only 15 min at 350 °C. Overall, SHS torrefaction boosted biomass densification and gave rise to greater production efficiency.

Superheated steam as carrier gas and the sole heat source to enhance biomass torrefaction