Oxidative torrefaction for pulverized palm biomass using air

Abstract

Torrefaction is one of the promising ways to utilize abundant amount of empty fruit bunch (EFB) and palm kernel shell (PKS) while upgrading the combustion properties of both types of palm biomass. However, the supply of costly inert gas during torrefaction process such as nitrogen in large industrial sector may not be economical. Therefore, in the present study, air is used instead of nitrogen for the torrefaction process. The EFB and PKS were torrefied separately in a 60 mm diameter and 300 mm length of horizontal tubular reactor under various temperatures of 150°C to 190°C and 210°C to 250°C, respectively for 30 minutes using air. The torrefaction with nitrogen was also performed for comparison purpose. At the respective maximum temperature, energy yields of the torrefied EFB for the case of oxidative (air) torrefaction and nitrogen torrefaction are around 95% and 88%, respectively while energy yields of PKS for the case of oxidative(air) and nitrogen torrefaction are around 69% and 83%, respectively due to the weight loss after removal of volatile matter during torrefaction process. Besides that, the calorific values are enhanced after being torrefied with air (mere 4% for EFB and 18% for PKS when the respective maximum temperature was used).