'Smokeless' stove

A solid-fuel stove has been devised that produces less smoke

Published: Saturday 31 January 1998

british researchers have developed a solid-fuel stove that produces the same amount of smoke as generated after burning costly "smokeless" fuels. The stove can burn wood, peat and coal. It could be of immense use for those who are forced to depend on solid fuel and those who want to have fires in smoke-controlled areas (New Scientist , Vol 156, No 2108).

Manufacturers had earlier been using expensive catalysts in the chimney of smokeless stoves. Glyn Hughes, a consultant who worked on the stove with cre Group laboratories in Cheltenham, Gloucestershire, uk , says that it is easier to design the new stove than old ones.

In the stove, the fuel is placed in a bed in the front chamber. Primary air enters through a sliding vent which is at the top of the front door. It passes through the bed into a second chamber which is called as afterburner. The smoke and gas is mixed with fresh secondary air in the afterburner. Several holes at the back of the stove help draw the mixture. The faster the gases flow through the afterburner, the more air they suck in.

The six-kilowatt stove cuts particulate emissions from burning peat and brown coal, or lignite, from the usual 25-30 grammes (g) per hour to between two and three grammes. This is within the seven-gramme-per-hour limit which is permissible in smokeless zones in Britain. When wood is burnt in the stove, it produces emissions between 10 and 15 g per hour. The new design reduces emissions from bituminous coal by 75 per cent to a mere 10 g per hour.

Due to small size, it is difficult to design a domestic stove, says Hughes. According to him, mathematical modelling has always been improving in case of industrial installations. This is the reason that Hughes and his collaborators Dave Cownburn and Roy Holtham sought help from Leaun Owen of the University of Liverpool, uk. The researchers built and tested several physical flow models of the domestic stove to design an efficient model. The new stove substantially reduces levels of carbon monoxide in the emissions. The us, Poland and the Czech Republic are soon expected to start production of the new design.

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