TORREFACTION OF BIOMASS FOR THE REDUCTION OF CHLORINE AND SULPHUR

Afifa Moeen, Centre for Coal Technology University of the Punjab

  Hassan Zeb* (corresponding Author) Hassanzeb.cct@pu.edu.pk

Abstract

Biomass is a sustainable and renewable source of energy. It can either be used indirectly after converting to different biofuels or directly to produce heat through its combustion in power sector. This study relates to the torrefaction of wheat straw as biomass. the effect of two parameters such as temperature (200, 250 and 300 °C) and time 20,35 and 50 minutes were optimized for torrefaction at inert atmosphere of N₂. Torrefaction of wheat straw biomass for the reduction of chlorine and Sulphur was investigated. After torrefaction at 300 ^oC the maximum amount of reduction was observed. Torrefaction temperature and residence time are the two important parameters that should be considered in torrefaction process. Even though some studies stated that residence time only has a slight effect in torrefaction, further study is required to investigate the effects of residence time on solid char, energy yield and determination of their optimum values. This is because shorter residence time will make the torrefaction process cost-effective and yet able to produce a superior solid char to be further used in power generation sector. It is also worth mentioning that investigation of residence time varies between individual biomass from different origin either for lignocellulosic or non-lignocellulosic biomass. Chlorine is present in biomass in the form of HCl, CH₃Cl, Cl₂ and alkali salts. Chlorine releases in the form of HCl from the biomass. Torrefaction reduces the moisture content, increases the calorific value and grindability. In torrefied biomass, HCl emission after combustion of fuel was lower 2-5 times lower than raw biomass. Sulfur releases in the form of SO₂ when exposed in air, reacts with it and form sulphuric acid which causes acid rain.

Keywords: Torrefaction, Mohr’s titration,