RU2661881C1 - Method of coal briquetting - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention discloses a method for coal briquetting, including drying with flue gases, crushing, heating of coal, pressing and cooling of the briquettes obtained, characterized in that the drying of the coal is conducted in three stages, in a first step, the feedstock is dried in a whirling flow to a moisture content of 5–23 %, in the second stage, the drying is combined with the process of crushing the feedstock to 1 mm, in the third – drying to a moisture content of 1.5–5 % is combined with transportation through a pipe made in the form of a coil, with simultaneous heating to 170–370 °C, then perform briquetting in a roll press at a pressure of 19–25 MPa for 5–7 s with the supply of superheated steam at a temperature of 105–130 °C in the pressor, cooling briquettes are carried out by spraying fine water on top of briquettes and blowing air from below, while simultaneously taking air to combustion in a heat and smoke generator.

EFFECT: technical result consists in simplifying the production technology, reducing costs and obtaining briquettes with good performance at the lowest cost.

1 cl, 1 dwg, 1 tbl

Description

The invention relates to the field of briquetting minerals, in particular to the technology of briquetting brown and hard coal, and can be used in the coal processing industry.

A known method of briquetting brown, bituminous coal and the like, including grinding, heating and drying the source coal, grinding dry coal, pressing and sifting breakage and fines from finished briquettes (DE 102010053593 (A1), IPC C10L 5/08 from 14.06.2012).

The disadvantage of the known invention is that the need to use several crushing and averaging systems, storage bins and other equipment, as well as high pressing pressure greatly complicate and cost the process of briquetting coal.

Closest to the proposed invention is a method of briquetting coal, including crushing and sorting, heating coal and drying with flue gases, preparing binders and mixing them with coal, pressing and cooling finished briquettes [Elishevich A.T. "Technology of briquetting of minerals", M .: "Nedra", 1989, p. 86-114].

The disadvantage of the known fact is that the need to prepare feedstock by size, the use of binders, the presence of stagnation of raw coal in the lowest part of the dryer pipe significantly complicates and increases the cost of coal briquetting, as It provides for the use of size averaging systems, storage of the binder and mixing systems, elimination of stagnation of the dryer pipe, in addition to the cost of the binder, a universally applicable binder has not yet been found.

The present invention is to reduce costs and simplify the technology of production of coal briquettes.

This is achieved in that in the method of briquetting coal, including crushing, heating coal and drying with flue gases, pressing and cooling the obtained briquettes, according to the invention, the drying of coal is carried out in three stages, in the first stage, the feedstock is dried in a vortex stream to a moisture content of 5-23% , at the second stage, drying is combined with the process of crushing the feedstock to 1 mm; at the third, drying to a moisture content of 1.5-5% is combined with transportation through a pipe made in the form of a coil, with simultaneous heating to 170-370 ° C, then briquetting is performed into the shaft the main press under a pressure of 19-25 MPa for 5-7 s with the supply of superheated steam with a temperature of 105-130 ° C to the prepress, the briquettes are cooled by spraying finely dispersed water on top of the briquettes and pumping air from below, while simultaneously taking combustion air into the heat and smoke generator .

Depending on the brand, the moisture content of coal can be up to 45%, crushing of coal at this humidity will not be effective, therefore it is necessary to first reduce the moisture content of the initial coal, depending on the brand, to 5-23%, for this, preliminary drying of coal is used at the first stage.

Coal drying in the second stage continues during crushing, which will undoubtedly reduce the costs associated with preparing the feedstock for briquetting.

It is necessary to crush the initial coal to a particle size of 1 mm, since the humidity of the larger particles is always much greater than the fine ones, which requires equalization of humidity and increased pressure during pressing and leads to a rise in price and complication of the briquetting process.

The third stage of drying is also aimed at achieving the desired moisture content of the crushed coal and is carried out during transportation to the press equipment via a pipe made in the form of a coil, which carries out drying and regrinding of large particles to the required values and, accordingly, reduces the cost of production.

For the best effect of drying the coal, a swirl movement of the flue gas stream is used, and to eliminate the “failure” in the dryer pipe, the loading of raw coal is carried out in the upper part of the dryer pipe, and the direction of movement of coal and the flue gas stream coincides, which also reduces briquetting costs .

Coal is heated to 170-360 ° C depending on the brand and properties of coal, this temperature of the pressed coal eliminates the use of a binder, and for better adhesion of coal particles during pressing and briquette production, superheated steam is supplied with a temperature of 105-130 ° C prepresser, other indicators of the temperature of coal and steam do not lead to a high-quality briquette.

Getting steam is carried out by heating the water supplied to the steam generator 5, the heat of the flue gases going to the drying of crushed coal, which leads to energy savings.

The pressure, equal to 19-25 MPa, and the time of 5-7 s briquetting depend on the brand of coal and are the most optimal.

The spent drying agent (flue gas), after the intermediate dust collectors, is partially returned for recycling to the heat generator with fine coal dust, which is the fuel for the heat and smoke generator, and for supplying fuel to the heat and smoke generator, partial separation of the fine coal sent for drying is provided, this leads to lower costs for briquettes.

Combustion air is taken into the heat generator in the cooling zone, above the mesh conveyor with finished briquettes, which reduces the cost of drying the raw materials and cooling the finished product, and hence the cost of briquettes in general.

The combination of finely dispersed water spraying and intensive air blowing allows efficient briquette cooling to the required temperature.

Coal and brown coal of various grades, anthracite, as well as their combination and waste from enrichment and processing can be used as feedstock for the production of briquetted fuel, which significantly expands the raw material base for the production of briquetted coal fuel.

The invention is illustrated by the scheme for the production of briquette coal fuel.

In the diagram, the initial coal with a grain size of up to 25 mm and humidity up to 45% from hopper 1, after sorting out impurities, is dosed into a shelf-type tube dryer 2, into which a swirling stream of flue gas with a temperature of 600-800 ° C, created by a heat and smoke generator, is introduced 3. Passing through the dryer, the coal is heated and dried to a moisture content of 5-23%, depending on the type of coal and together with the flue gases it enters the grinder 4, where it is crushed to a size of 0-1 mm and is simultaneously dried. At the outlet of the crusher, coal and flue gases are connected to an additional vortex flue gas stream, with the same temperature, and transported to the briquetting site via pipeline 6, made in the form of a coil, where it is dried to a moisture content of 1.5-5%, depending on the type of raw material .

Heated to a temperature of 170-370 ° C, depending on the brand, the coal from the pipeline 6 enters the dust pre-sedimentation apparatus 7, from which it is dosed via a tubular conveyor 9 into the prepress 10 of the roller press 11. To improve the pressing and binding of coal particles to the prepress 10 superheated steam with a temperature of 105-130 ° C. is supplied. Steam is produced by passing the flue gases going to dry the crushed coal through the steam boiler 5, into which cold water is supplied.

The pressure of pressing coal dust is 19-25 MPa, the residence time in the press of coal mass is 5-7 s. To better separate the finished briquette from the working surface of the press, it is preheated.

After pressing, the briquettes are discharged onto the mesh conveyor 12, in the initial part of which the fine fraction is screened and the briquettes are sifted, for return and re-briquetting, finely dispersed water is sprayed on the upper part of the conveyor to the upper surface of the briquette, and in the final part, the intake of ambient air pumped from below combustion in a heat and smoke generator. The amount of cooling water is balanced with the total amount of heat that should be removed to achieve the required temperature of the finished briquette.

Cooled briquettes in bulk arrive at the warehouse or are packed in bags of various sizes.

The spent drying agent (flue gas), after the intermediate dust collectors 7, is partially returned for recycling to the heat and smoke generator with fine coal dust, which is the fuel for the heat and smoke generator, and is also partially discharged into the atmosphere through the fabric gas purification filter 8 and the chimney 13.

To adjust the heat output of the heat generator, it is possible to control the efficiency of dust collection. Gas recirculation is also necessary to reduce the temperature at the outlet of the heat generator.

To eliminate spontaneous combustion of coal, the entire system from the receiving hopper of the raw materials to the exit of the finished briquettes to the cooling conveyor is sealed, flue gases are used as the medium for transporting coal.

The application of the proposed method allows to produce briquette coal fuel without a binder from a wide base of raw materials with significantly reduced production costs.

Table 1 presents the test results obtained by the proposed method of briquettes from brown coal brand 2BV

Claims (1)

The method of coal briquetting, including flue gas drying, crushing, heating coal, pressing and cooling the obtained briquettes, characterized in that the coal is dried in three stages, in the first stage, the feedstock is dried in a vortex stream to a moisture content of 5-23%, in the second stage drying is combined with the process of crushing the feedstock to 1 mm, drying to a moisture content of 1.5-5% is combined with transportation through a pipe made in the form of a coil, with simultaneous heating to 170-370 ° C, then briquetting in a roller press under pressure 19-25 psi for 5-7 to feed the superheated steam temperature 105-130 ° C in the pre-press, cooling is carried out by spraying the fine briquettes top briquettes water and air injection from the bottom, while the air intake for combustion in the heat-smoke generator.

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