Part I: experimental studies on a pulverised fuel stove

Abstract

This paper is concerned with development of a pulverised fuel stove with improved conversion efficiency and minimal emissions at near constant power level without the use of external power. The design originates from a cylindrical sawdust stove with a central porthole being lit from the bottom. Such a stove will have a flame in port with enhanced sooting tendency. For similar configuration, stable premixed combustion behaviour of the combustible gases from the port of the fuel block (known as the gasification mode) has been achieved by use of air supply through a thin slot at the bottom, for at least 30 min of stove operation. In order to ensure stable combustion of the gases at exit, a metal device is used. In an attempt to extend gasification duration, studies are conducted in single port configuration having air entry from the bottom with a horizontal baffle to control the flow rate. This configuration worked in gasification mode for about 20 min but there have been problems of flame extinction. To overcome these drawbacks multi-port design with vertical air entry is employed with success. The stove has exhibited conversion efficiency in excess of 37% due to well focused nature of flame at exit. CO emission factors are about 12 g (kg fuel)^-1, a performance superior to conventional biomass stoves (~45 g kg^-1). NO_x emission factors are about 1 g kg^-1 fuel which falls in the range of reported data for NO_x. Studies with different pulverised leafy fuels have indicated these fuels have lower volatile release rates and therefore exhibit lower power level operation for a given port configuration compared to sawdust fuel.