Secondary Air in the Scheme of Combustion of Solid Fuel in the Layer

. Various methods of stream combustion in layer furnaces are considered with the analysis of their influence on the efficiency of mixing of overlayers combustible gases with air for the formation of necessary combustion conditions to ensure the completeness of combustion of the gas-air mixture. The expediency of using in the solid fuel low power heat generators the system of air (secondary) blast with low pressure of blast air is shown. The analysis of secondary air flow circuits in classical technological schemes of solid fuel combustion in a layer (flow, direct flow, transverse) and their im-plementation in the structures of common mechanical furnace devices (with a retort, with a poke plank and with a chain grill) are presented. The paper deals with different schemes of secondary air supply in combined technological schemes of solid fuel combustion. The technical solutions for the main structural units of the secondary air systems in the furnace are presented. For the shaft type of a furnace, there are profile muzzles on the secondary air nozzles at the outlet of the fuel shaft. For the shaft-layer type of a furnace, there is a water-cooled air collector with blast nozzles in the gasification zone of the fuel. Due to the rational organization of the secondary air supply, depending on the quality of the combusted fuel (volatile yield, humidity, ash content, fractional composition), a mixture of over-gases with air is formed. The concentra-tion and temperature conditions of it should ensure its reliable ignition, stable combustion and complete combustion of combustible substances. The paper substantiates the choice of an effective air blowing system for mechanical furnaces in low-power shaft boilers (up to 4 MW). Effective burning of over-gases rises the efficiency of boilers and decreases atmo-spheric pollution.