Increasing the efficiency of burning solid fuel in the layer

Abstract

he main directions of increasing the efficiency of solid fuel heat generators are analyzed. It is noted that in industrial designs of heat generating installations depending on their class technological schemes of burning of solid fuel are applied at various levels on capital and operational expenses. The most expensive are the technologies of combustion of pre-prepared high-quality fuel in heat generators with complex mechanization at all stages of the combustion process, which provide high thermal and environmental performance. Cheaper combustion technologies are widespread, according to which the normative performance of heat generators is achieved due to the rational ratio of design and mode parameters of the combustion zone with the thermophysical characteristics of the burned fuel, including low-grade. Examples of realization of such technological schemes of combustion on the basis of results of theoretical and experimental researches in designs of solid propellant heat generators are resulted. The paper proposes a constructive scheme of a small-capacity heat generator with a combined technology of two-chamber solid fuel combustion, in which a layered (or shaft-layered) combustion process with combustion in volume is combined: in the primary combustion chamber above the burning fuel layer on the grate, and in the secondary cyclone chamber (or cameras). Due to the vortex motion in the lined secondary chamber of high-temperature gases containing solid particles carried by the flow from the combustion zone of the primary chamber, there is both afterburning of combustible substances and separation of ash particles with their discharge into the ash generator. This combustion technology also allows increasing the forcing of the combustion layer on the grate, increasing the stability of the process and reducing the dimensions of the structure. Improving the efficiency of a solid fuel heat generator with a two-chamber furnace is achieved by reducing heat loss with mechanical incomplete combustion of carbon particles in the exhaust gases, as well as reducing the concentration of ash particles in the gas stream at the inlet of convective heat exchange surfaces and increase their thermal efficiency. This is confirmed by the calculated dependences of the efficiency of the mechanized solid fuel heat generator under different technological schemes of solid fuel combustion