BRIQUETTING OF BIOMASS RESIDUES AND THEIR CHARACTERIZATION

Abstract

Biomass densification refers to the . process whereby biomass in the form of small particles, like straw, sawdust or chips, is concentrated by machines into small pellets or briquettes. Depending on the particular machine used, this process increases the bulk density of the biomass by about 1.0 to 12 times of its original bulk density. The moisture content of the compacted biomass generally should be between 7% and 14%. If it is higher, the biomass will not compact easily, if lower it will not bind together as well. Densification is an important strategy for the biomass market because it improves the convenience and accessibility of biomass: densification reduces the bulkiness of biomass products and therefore increases their transportability (an important selling point for biomass use, as the farms and forests biomass is harvested from are often far away from its consumers). Currently, the challenge the biomass industry faces is developing a cost effective way to produce biomass fuel pellets. Densification of loose biomass (viz., agricultural and agro-industrial wastes) is called biomass briquetting. It facilitates easy transportation, better handling and storage besides being efficient in use as an alternative fuel to coal and firewood. The high temperature developed during the high-pressure densification process assists the inherent lignin present in the biomass to bind the biomass and form a densified fuel called briquettes In India, briquettes are mostly manufactured from groundnut shell, saw dust, coffee husk, bagasse, mustard stalk, cotton stalk and press mud. Briquettes find applications in process industries of any scale using either coal or firewood and in commercial and domestic sectors. In addition, briquettes are widely used in brick kilns in the northern region. Recently, briquettes have also been successfully tried in steel rolling mills and for gasification for power generation.