RU2383822C1 - Method to process solid household and industrial wastes - Google Patents

Abstract

FIELD: heating.

SUBSTANCE: invention relates to integrated processing of household and industrial wastes and can be used in production of construction materials. Proposed method comprises preparing sold wastes and loading them into shaft furnace together with carbonate materials, for example limestone, and feeding fuel and air therein. It comprises also withdrawing fume gases and outputting ready product out from furnace bottom. Two-shaft limestone calcining kiln can be used as shaft furnace. Prepared wastes and carbonate materials are loaded into one shaft operated in direct-flow conditions, while fuel and air are fed into top part of two-shaft furnace for combustion. The other shaft operated in counter-flow conditions receives carbonate material for producing lime, while fuel and air are fed into shaft bottom. Fume gases from first shaft are forced into second shaft and, further on, removed therefrom with the help of fume-gas pump.

EFFECT: higher efficiency and ecological safety.

2 cl, 1 dwg, 1 tbl, 1 ex

Description

The invention relates to the field of integrated processing of solid household and industrial waste and can be used in the construction materials industry.

A known method of processing waste by thermal decomposition and chemical interaction of unsorted waste with additives, in which the processing is carried out without air at a temperature of at least 700 ° C and a pressure of at least 0.2 MPa, and crushed calcium carbide is used as an additive, which is fed into the reaction zone in a separate stream (see SU 1143931 A, 03/07/1985).

The disadvantage of this method is the need for additional purification of gases released as a result of pyrolysis of organic substances of the processed waste, and solid coal residue with an uncontrolled composition from various toxic compounds.

A known method of processing solid household and industrial wastes, including their preparation and loading into a vertical shaft furnace, the supply of fuel and hot air to the lower part of the shaft furnace, the output of generator gas and vapor components in its upper part and the output of slag and liquid metal in the lower part of the shaft the furnace, while the processing of waste is carried out in a sealed shaft furnace with the addition of limestone, low-grade solid fuels and flux-containing materials, and the waste is compacted in advance cutting and cutting into dimensional pieces, which are loaded into the shaft furnace in layers with these additional components with a limestone fraction of 0.05-0.25 of the waste mass, and in the furnace top zone below the loading device, overpressure of gaseous products of processing in the range of 1.1 -1.5 ata (see RU 2105245 C1, 02.20.1998).

This method is adopted as a prototype.

The disadvantages of the prototype include high values of the removal of harmful substances with pyrolysis gases removed from the shaft of the furnace in the system for use by the consumer. This drawback is due to the fact that when the shaft furnace is operating in countercurrent mode, the recyclable waste passes through temperature zones where conditions are created for the sublimation of volatiles, pyrolysis, the formation of complex organic compounds, as well as CO by reaction

CO ₂ + C + Q = 2CO,

where C is the carbon of low-grade solid fuel.

The combustible gases obtained by this method before their secondary use require serious purification from the vapor of volatile metals Zn, Hg, Pl, Cd, as well as dioxins, furans, benzopyrenes and other organic compounds.

The problem to which this invention is directed, is the creation of an effective and environmentally friendly method of disposal and disposal of solid household and industrial waste in a wide range of their starting components.

The problem is solved in that in the method of processing solid household and industrial waste, including their preparation and loading into a shaft furnace together with carbonate material, supplying fuel and air to the furnace for combustion, removing flue gases and removing the finished product from the bottom of the furnace, a feature consists in the fact that a double shaft furnace for calcining limestone is used as a shaft furnace, and the prepared waste together with the carbonate material is loaded into one shaft operating in the direct-flow mode and into its upper part fuel and air are supplied for combustion, carbonate material is loaded into another mine operating in countercurrent mode for lime production, and fuel and air are fed to its lower part, and flue gases from the first mine are sucked into the second mine through the smoke channel and using a smoke exhauster remove from the top of the second shaft.

In addition, solid fuel is additionally loaded into a mine operating in a direct-flow mode, together with waste and carbonate material.

The inventive combination of essential features allows to obtain the following technical result.

Using a double shaft limestone kiln as a shaft furnace, loading the prepared waste together with carbonate material into the upper part of the mine, operating in the direct-flow mode, and supplying fuel and air to its upper part for combustion, followed by suction of the flue gases through the smoke channel from this mine into the mine, working in countercurrent mode, allows you to expose the processed waste to prolonged exposure to high temperatures, at which the amount of gaseous hazards in these waste reduces to a minimum, and compounds of heavy metals Pb, Zn, Cd, Hg, etc., entering into a chemical interaction, for example, with CaO go into a neutral state.

Loading carbonate material to produce lime into the counter shaft of the kiln operating in the counterflow mode, supplying fuel and air to the lower part of the furnace, as well as sucking the flue gases from the first shaft through the smoke channel into the second shaft, followed by removal of the flue gases using a smoke exhauster from the top parts of the second shaft contributes to the complete thermal decomposition of waste products and pyrolysis products. In addition, due to the heat recovery from burning the combustible component of the processed waste, carbon-containing fuel is saved in the process of lime production in a double shaft furnace.

Additional loading of solid fuel together with waste and carbonate material into the direct-flow mode shaft optimizes the firing process and allows the use of low-energy fuel in the decarbonization process, as well as increasing the degree of desulfurization of the processed material.

The proposed method for processing solid domestic and industrial waste is based on the fact that the recyclable waste is exposed to high temperatures, while solid domestic and industrial waste is considered as low-calorie fuel.

An example of the implementation of the proposed method is considered according to the structural diagram of the installation for processing solid household and industrial waste, presented in the drawing.

The solid domestic and industrial waste to be processed, after appropriate preparation, is loaded into the shaft 1 of a two-shaft furnace operating in the direct-flow mode. Simultaneously with the waste, carbonate material, for example limestone, is loaded into mine 1. The amount of loaded waste is 20-50% of the loaded limestone, depending on the morphological and chemical composition of the processed waste. The supply of fuel and combustion air is carried out in the upper part of the mine 1. The materials loaded into the mine 1 are fired at a temperature of -1200-1250 ° C in the direct-flow mode, in which flue gases from fuel combustion, flue gases generated from the combustion of solid household and industrial waste, limestone and lime are moving in one direction - down.

An additional introduction of solid fuel in the mine 1 together with waste and limestone in an amount of not less than 1.5 kg per 1 ton of lime increases the degree of desulfurization of the processed material by 15-20%.

Coke, various types of coal, as well as shale, wood waste, straw, etc. can be used as solid fuels.

Lime is discharged through a sealed discharge device of mine 1, and flue gases having a temperature of 1000-1100 ° C are sucked into mine 2 by a smoke exhaust fan 3 installed in the upper part of mine 2 through a smoke channel 4. Mine 2 operates in a counterflow mode, in which limestone is loaded into the upper part of the mine 2, and the supply of fuel and combustion air is carried out in its lower part.

Passing through a layer of limestone and lime, located in the mine 2, flue gases give their heat to the calcined material. In this case, additional afterburning and neutralization of flue gases occurs by forming inert compounds with lime. The finished product is unloaded through the discharge device of the mine 2.

The increase in the environmental cleanliness of the process of processing solid domestic and industrial waste is due to the fact that flue gases and a gas mixture of sulfur compounds, heavy metals, H ₂ S, Hcl, furan dioxins and other organics, when moving through both mines of the furnace, repeatedly come into contact with heated to 1300 ° With limestone and lime, the surface of which is huge due to their continuous movement.

The table shows the efficiency of cleaning flue gases after removing them from a twin shaft furnace in the process of implementing this method.

Component HC1 Hf SO ₂ Cd, pb, zn Hg Dioxins and furans The cleaning efficiency,% 80 98 75 > 99 90 99.8

Thus, the concentration of harmful substances in the flue gases removed from the twin shaft furnace does not exceed the MPC.

Solid household and industrial wastes in the proposed method are considered as low-calorific fuel with a calorific value of 1000-1300 kcal / kg, which allows to reduce the specific consumption of carbon-containing fuel during calcination of limestone to 70-75 kg of equivalent fuel. per ton of lime produced.

In addition, moving limestone and lime play the role of a movable top grid, which is constantly cleaned of ash and ensures complete combustion of waste.

It is advisable to use the lime obtained in the process of implementing this method as follows: from a mine operating in countercurrent mode - for the production of gas silicate, silicate brick, etc .; from a direct-flow mine working for the production of paving slabs, curbs, slabs for roads.

Claims (2)

1. A method of processing solid household and industrial waste, including their preparation and loading into a shaft furnace together with carbonate material, supplying fuel and air to the furnace for combustion, removing flue gases and removing the finished product from the bottom of the furnace, characterized in that as In a shaft furnace, a double shaft furnace is used for calcining limestone, and in one shaft, operating in the direct-flow mode, the prepared waste is loaded together with carbonate material, and fuel and air are supplied to its upper part for combustion, to another the countercurrent mine is loaded with carbonate material to produce lime and fuel and air are supplied to its lower part, and the flue gases from the first mine are sucked into the second shaft through the smoke channel and removed from the upper part of the second shaft with the help of a smoke exhaust. 2. The method according to claim 1, characterized in that solid fuel is additionally loaded into the mine operating in the direct-flow mode, together with the waste and carbonate material.

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