SU1132110A1 - Furnace for burning wood waste - Google Patents

Abstract

BURNING BOILING OF WOOD WASTE, mainly wood dust, containing a bunker, a combustion chamber with a slit gas distribution grille and a layer of inert dispersed material, nozzles of secondary and tertiary air, coaxially mounted in the combustion chamber of the pups and a pipe, in the lower part of which a slot is made, that, in order to ensure complete combustion of toxic gases, the screw and the pipe are installed in the layer of inert particulate material, the secondary air nozzle is in the upper part of the pipe, and the slot is made on the expanding dust in the feed direction.

Description

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4 The invention relates to the incineration of waste mainly in woodworking enterprises, and more specifically to the incineration of wood dust containing burning substances, which is formed during grinding of chipboard. The known furnace for burning coal in a fluidized bed, in which coal is fed by means of a screw into the superlayer space 1. The disadvantage of this furnace is the incomplete combustion of toxic gases released during thermal decomposition of burning substances in wood dust. When wood dust is burned in a firebox, only a small amount of dust (due to its small size and particle density) enters and burns in a fluidized bed. The bulk of the dust from the feeder enters the over-bed space, is picked up by the air coming out of the fluidized bed and burns in the pneumatic transport mode in the over bed space. But since the residence time in the supra layer of the furnace of wood dust and toxic gases is short, they, together with the combustion products, are emitted into the atmosphere, contaminated with it. Closest to the proposed is a furnace for burning coal in a fluidized bed, containing a bunker, a combustion chamber with a slotted gas distribution grid, a layer of dispersed material, such as dolomite, coaxially installed pipes and screws, which extend along the entire length of the furnace a layer of dispersed material, secondary air nozzles, located under the cheek. Along the entire length of the horizontal pipe in its lower part, a constant profile slot is made. Primary air is fed through a gas distributor grille, fluidized bed dispersed material, and coal is burned, which is fed by means of the screws from a bunker through horizontal pipes. The coal moving through them falls through the slots, gets into the jets of secondary air, falls into the fluidized bed, where it burns. Tertiary air 2 is supplied through nozzles to burn out combustion products. A disadvantage of the known furnace is incomplete combustion of toxic gases when wood dust is burned in it, because a small portion of dust enters the dust and burns in a boiling layer. The bulk of the dust from the screw feeder enters the overlayer space, where it burns during upward movement. Consequently, the combustion processes of wood dust and toxic gases released from it due to thermal decomposition of the burning substances occur not in the fluidized bed, but above it, which leads to deterioration of the burning processes and reduction of the residence time of dust particles and toxic gases in the furnace. This leads to incomplete combustion of toxic gases that are emitted into the atmosphere, polluting it. In addition, as established experimentally, through a slot of a constant profile, dust does not evenly distribute along the length of the combustion chamber: most of it falls out of the screw at the beginning of the slot, and smaller, at the end, which worsens the combustion processes and, therefore, further contributes to incomplete combustion gases. The purpose of the invention is to ensure complete combustion of toxic gases. The goal is achieved by the fact that in the furnace for burning wood waste, mainly wood dust containing a bunker, a combustion chamber with a slit gas distribution grille and a layer of inert particulate material, nozzles of secondary and tertiary air, coaxially mounted in the combustion chamber of the screw and pipe, in the bottom the parts of which are slotted, the pins and the tube are installed in the layer of inert particulate material, the secondary air nozzles are in the upper part of the tube, and the slot is made expanding in the flow direction yly. FIG. 1 shows a longitudinal section of a wood burning furnace; in fig. 2 shows section A-A in FIG. one; in fig. 3 - a slot in the pipe. The wood waste burning furnace contains a bunker 1, for wood dust 2, a combustion chamber 3, a slit distribution grid 4 for supplying secondary air through the nozzle 5, a layer of inert particulate material 6 (for example, river sand with a particle size of at least 1.5 mm) , a coaxially mounted screw 7 and a pipe 8, in the lower part of which there is an expanding slot 9, made in the form of an equilateral triangle, nozzles 10 for supplying secondary air by a downward vertical flow, placed in the upper part of the pipe 8, a branch pipe 11 for The supply of secondary air to the nozzles 10; an outer pipe 12, which, together with the pipe 8, forms an annular channel for uniform supply of secondary air to the nozzles 10; the box 13, the nozzle 14 and the slit nozzles 15 for supplying tertiary air into the over-bed space; igniter 16; the duct 17 for removal from the furnace products of combustion. The firebox for burning wood waste works as follows. Pre-burned in the furnace natural gas. To do this, primary air is supplied through the pipe 5 and the gas distribution grid 4, the igniter 16 is turned on, natural gas is fed into the fluidized bed through the pipe 11 and the nozzles 10, which ignites from the ignition valve 16. The gas heats the inert dispersion material to 400 ° C , which is higher than the ignition temperature of wood dust. Stop the flow of gas, serves through the pipe 11 and the nozzle 10 secondary air, and through the pipe 14, the box 13 and the slot nozzles 15 - tertiary air. Then the screw drive 7 is turned on. Because the slot 9 is made expanding in the direction of dust supply, the wood dust is evenly distributed throughout the volume of the pipe 8, and since the nozzles 10 for supplying secondary air are installed in a downward vertical flow at the top of the pipe 8, This produces a dust and gas mixture of the same concentration along the entire length of the furnace, which moves down through the slit 9 and then moves with the inert particulate material 6. Since the temperature of the latter is higher than the ignition temperature of wood dust, then the dust burns. The amount of secondary air is maintained so that its coefficient of discharge is less than one, which ensures explosion safety. The spreading of the screw 7 and the pipe 8 in the fluidized bed, as well as the outflow of the downward vertical stream of dust-air mixture of the same concentration over the entire length of the furnace, ensures reliable ignition of the dust in the lower part of the combustion chamber 3, thereby increasing the burning time in the fluidized bed as wood dust, and emitted from it due to thermal decomposition into burning substances, toxic gases, which in turn causes complete combustion of these. The mixture of combustible wood dust 2 and inert particulate material b is directed downwards, spreading along the upper formations of the slit gas distribution grill 4 to the walls of the combustion chamber 3. Then the mixture is connected to the streams of primary air flowing out of the slit gas distribution grill 4, rises up and fluidizes along the way, the remaining inert particulate material 6, and evenly distributed throughout the volume of the fluidized bed. Fluidization, contributes to the intensive burning of wood dust and the toxic gases generated in the process. The temperature of the fluidized bed is maintained at 900 ° C. The smallest dust particles and toxic gases leave the fluid bed. For their complete combustion, tertiary air is supplied to the supralayer space through slot nozzles 15. Its coefficient of discharge is supported by more than one. The combustion process is carried out at a temperature of 1300-1400 ° C, ensuring complete combustion of toxic gases. The products of combustion through the duct 17 are removed for technological needs, for example for drying the crushed wood from which particle boards are made. Large dust particles with inert particulate material 6 from the upper part of the fluidized bed along the outer walls of the box 13 and the outer pipe 12 are lowered into the lower part of the fluidized bed, where they are again mixed and raised again by air flows and gaseous products of combustion, carrying out internal circulation to those until, as a result of burning, their mass is reduced to a value at which they will not be carried by the flows of the ascending gases from the fluidized bed. The design of the proposed furnace saves fuel, ensures complete and safe burning of toxic gases, which contributes to the protection of the environment.

Claims (1)

HEATER FOR COMBUSING WOODEN WASTE, mainly wood dust, containing a hopper, a combustion chamber with a slit gas distribution grid and a layer of inert dispersed material, nozzles of secondary and tertiary air, a screw and a pipe coaxially mounted in the combustion chamber, in the bottom of which a slot is made, characterized in that that, in order to ensure complete combustion of toxic gases, the screw and pipe are installed in a layer of inert dispersed material, the secondary air nozzle is in the upper part of the pipe, and the slot is made widening towards dust supply.