Biomass to briquettes

Biomass to briquettes INDIAN scientists, in collaboration with Dutch researchers, have developed the technology to convert agricultural residues -- like rice husk and groundnut shell -- into briquettes for use as an efficient, economical and a non-polluting fuel. The screw press technology for briquetting biomass compacts low-density agricultural residues into cylinders with a hole in the centre. The hole serves to enhance the combustion characteristics of the briquette.

The technology marks the fruition of the efforts of scientists from the Biomass Conversion Laboratory at the Chemical Engineering Department of the Indian Institute of Technology (IIT), Delhi, who worked in collaboration with the Technology and Development Group, University of Twente, The Netherlands.

A major problem in using agricultural residues as fuel is their low density, which makes their handling, transport and storage both difficult and expensive. Says S K Mishra, senior scientific officer with the Indo-Dutch project, "These problems can be overcome by compacting the loose biomass into briquettes."

Although there are several briquetting technologies that are commercially available, they are expensive and produce briquettes that burn badly or generate lot of smoke.

The new technology is less problematic. It works as follows: dried biomass is crushed and preheated to a temperature of 100-120 0 C. Preheating softens the biomass and also reduces the load on the screw. This material is then fed into a screw extruder press where a revolving screw compacts the material, which is then forced through a heated die to harden the briquettes.

Says Mishra, "Since most developing economies are still predominantly based on agriculture, they produce huge quantities of agro-residues which are a potential untapped fuel resource. For instance, in India there is a large, underutilised supply of agro-processing residue; around 49 million tonnes per annum. This technology can be of immense use in both sustainable biomass fuel production and utilisation in the country."

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