RU2524231C2 - Heat processing of ash-rich and/or low-calorie solid fuel - Google Patents

Abstract

FIELD: oil-and-gas industry.

SUBSTANCE: invention can be used in coal, petrochemical industries and construction. Proposed method comprises drying of solid fuel by exhaust flue gases, heating and burning of dried fuel to produce gas mix and solid residues. Solid fluid as charge is formed to hollow blocks to be piled at conveyors and, after drying, fed into heated tunnel kiln. Here, they are carried via heating zone, combustion zones and cooling zone. In heating zone, said blocks are gradually heated to carbon ignition temperature, i.e. 600°C and higher, and held at ignition zone at 750-1200°C. Excess heat released at carbon burning is derived from combustion zone and recovered. Blocks as finished construction blocks are cooled and discharged from the kiln. Said fuel represents the charge from coal concentration wastes.

EFFECT: wasteless production, maximum heat release from processed solid fuel.

5 cl, 1 ex

Description

The invention relates to the thermal processing of high-ash and / or low-calorie fuels, mainly coal processing waste, and can be used in coal, oil shale, petrochemical industries, in the energy sector, in the energy-technology use of high-ash and other low-calorie (low-grade) fuels in power plants, and, at the same time, in construction (obtaining building blocks).

A known method of thermal processing of high-ash fuels, such as oil shale, including pyrolysis performed using a circulating solid carrier with the formation of gas-vapor products and a high-ash residue, burning the latter with the formation of a gas suspension, stepwise separation of the latter into a circulating solid coolant returned to the pyrolysis stage, a gaseous drying agent directed to the drying stage and the ash mixture, cooling this mixture and separating it into ash and fumes removed from the process gases, while part of the flue gas is recycled to the stage of cooling the ash mixture, and the concentration of solid particles in the cooled ash mixture is maintained by changing the flow rate of recirculated gases, and the remaining part of the flue gas is burned together with the spent drying agent and the temperature in the drying stage is maintained by changing the flow rate directed to the combustion of flue gases [RF Patent for the invention No. 21118979, cl. СВВ 53/06, published on September 20, 1998].

The disadvantages of this method are the impossibility of waste-free processing of high-ash and low-grade fuel, an insufficient amount of released thermal energy, environmental pollution.

The closest in technical essence to the claimed method is a method for the technical processing of high-ash solid fuel, for example oil shale, including drying the crushed fuel with exhaust flue gases, heating the dried fuel with a solid heat carrier to form a gas-vapor mixture and a coke-ash residue, burning the latter in an air blast stream to form a gas suspension , separation of a solid phase from a gas suspension with its return to the heating stage as a solid coolant, separation of the remaining gas suspension to the solid phase, with its removal in the form of ash, and flue gases, followed by the return of the flue gases to the drying stage, while part of the solid phase extracted from the gas suspension stream is additionally fed to the combustion stage, and it is cooled before being fed to the combustion stage to a temperature of 250-600 ° C [RF patent for the invention No. 2088633, class. СВВ 53/06, published on August 27, 1997].

The disadvantages of this method include the impossibility of processing low-grade high-ash coal production wastes, such as coal preparation waste, a small amount of heat released, which is used only at the stage of drying the fuel, clogging the environment.

The basis of the invention is the task of improving the method of thermal processing of high-ash and / or low-calorie solid fuel, in which molding into hollow blocks of solid fuel in the form of a charge, stacking blocks in stacks on conveyors, feeding them, after drying, in a heated tunnel furnace, where the blocks pass three zones: the heating zone, the combustion zone and the cooling zone, the gradual heating of the blocks to the ignition temperature of carbon (600 ° C and above), keeping them in the combustion zone at a temperature of 750-1200 ° C, removal of the hut Single thermal energy released during combustion of the carbon burning zone and recycling provide wastelessness production in the mining industry, this ensures maximal release excess thermal energy from the feed of the solid fuel and its use for conversion into other forms of energy, including into electrical, obtaining solid residues in the form of building blocks, improving the environment.

The problem is solved in that in the method of thermal processing of high-ash and / or low-calorie solid fuels, including drying solid fuels with flue gases, heating and burning dried fuel to form a gas mixture and a solid residue, according to the invention, the following differences are provided:

- solid fuel in the form of a charge is molded into hollow blocks;

- hollow blocks are stacked on conveyors;

- carry out the drying of the blocks in the drying unit;

- hollow blocks on conveyors are fed into the heating zone of the heated tunnel kiln;

- in the heating zone, the blocks are gradually heated to the ignition temperature of carbon (600 ° C and above);

- after the heating zone, the blocks are fed into the combustion zone of the tunnel kiln;

- the blocks are kept in the combustion zone at a temperature of 750-1200 ° C;

- the excess thermal energy released during the burning of carbon is removed from the combustion zone and disposed of;

- in the cooling zone of the tunnel furnace, the blocks, in the form of finished building blocks, cool down;

- after cooling, the blocks are unloaded from the furnace.

In addition, solid fuel is taken in the form of a mixture from coal preparation waste, the excess thermal energy is disposed of in waste heat boilers; excess heat is disposed of using heat exchangers; heat exchangers are mounted in a tunnel kiln.

The method is as follows.

The mixture, for example, coal-rich waste with a low carbon content, is dehydrated to a moisture content of 30-50% to 18-25%, formed into hollow blocks, which are stacked on conveyors and sent to a separate drying unit in which part of the heat is used, removed from the combustion zone of the tunnel kiln. After drying the mixture to a moisture content of 2-6%, the blocks laid in stacks on conveyors are fed through the loading zone to the heated tunnel furnace, where they pass the heating zone, the combustion zone and the cooling zone, while in the heating zone the blocks are gradually heated to temperatures of 600 ° C and above - the ignition temperature of carbon, from where they are sent to the combustion zone, where the blocks are kept at a temperature of 750-1200 ° C for 5-24 hours (depending on the composition of the shift plate), but the thermal regime must be maintained in the combustion zone required for firing pus total blocks - 300 kcal / kg, so excess heat (from 2000 kcal / kg to 2500 kcal / kg) is removed from the combustion zone and disposed of in the form of flue gases in waste heat boilers, or in heat exchangers with coolant or gas mounted in the tunnel oven. The resulting blocks, in the form of building blocks, through the cooling and unloading zones, are discharged from the furnace, and the extracted heat energy, in the form of hot gases, liquid or steam, is supplied for further use:

heating of buildings and structures, hot water supply, conversion of thermal energy into other types of energy, including - electric, for other purposes.

The method is illustrated by an example.

Example

At the Svyatovarvarinskaya concentrator, flotation waste with an ash content of 76% and carbon content of 24%, the calorific value of which is 2500 kcal / kg, was used for the production of ceramic wall blocks. For drying and calcining the formed hollow blocks, the required heat energy consumption is 300 kcal / kg, and the generated thermal energy after burning carbon from the charge is 2200 kcal / kg. This amount of excess thermal energy does not allow to control the required firing mode, as a result of which there is a need to remove excess heat from the combustion zone of the furnace. The tests of the method showed that the removal of excess thermal energy can be carried out either by direct removal of flue gases from the combustion zone through a special hole in the furnace body, or by using heat exchangers with a cooling liquid or gas, while the liquid or gas passing through the heat exchanger is heated, removing part of the thermal energy from the furnace.

The application of the proposed method of thermal processing of high-ash and / or low-calorie solid fuels will allow waste-free processing of coal waste, such as rock, batch, cake, which pollute the environment, and at the same time produce significant amounts of thermal energy that can be sent to heat buildings and structures, hot water supply, and superheated steam from heat exchangers to be supplied to turbogenerators for generating electricity, and other purposes, and from the solid residue to receive ready-made itelnye blocks, it does not pollute the environment.

Claims (5)

1. The method of thermal processing of high-ash and / or low-calorific solid fuel, including drying solid fuel with exhaust flue gases, heating and burning dried fuel to form a gas mixture and a solid residue, characterized in that the solid fuel in the form of a charge is molded into hollow blocks that are laid in stacks on conveyors and after drying, they are fed into a heated tunnel kiln, where the blocks pass the heating zone, the combustion zone and the cooling zone, while in the heating zone the blocks are gradually heated until carbon ignition temperatures (600 ° C and higher), then they are kept in the combustion zone at a temperature of 750-1200 ° C, and the excess heat energy released during the carbon burnout is removed from the combustion zone and disposed of, and the blocks are in the form of finished building blocks after the cooling zone is discharged from the furnace. 2. The method of thermal processing of solid fuel according to claim 1, characterized in that the solid fuel is taken in the form of a mixture from coal preparation waste. 3. The method of thermal processing of solid fuel according to claim 1, characterized in that the excess thermal energy is disposed of in waste heat boilers. 4. The method of thermal processing of solid fuel according to claim 1, characterized in that the excess thermal energy is disposed of using heat exchangers. 5. The method of thermal processing of solid fuel according to claim 1, characterized in that the heat exchangers for disposing of excess thermal energy are mounted in a tunnel furnace.