RU2401295C1 - Method of coal conversion - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: coal crushed to 10 mm-size is subjected to thermal-oxidative treatment at 700-950°C via partial oxidation of coal by air and separation coal mineral part heavier than coal. Blast for layer quasi-liquefaction is fed in amount of 2500-4200 m³/(m²×h). Finely dispersed coal, vapor-gas products of coal thermal decomposition products and coke gasification products are partially burnt in boiling layer to provide for its operating temperature. Heavier rock particles are deposited in quasi-liquefaction layer and removed from the apparatus through fire grate. Combustion products are sent into exhaust heat boiler to recover heat power.

EFFECT: producing low-ash-content thermally treated fuel; without dressing initial coal.

Description

The invention relates to the field of coal processing, in particular to the production of thermal energy from coal and high-calorie heat-treated solid fuel for metallurgy, energy and other industries.

There are a number of methods for heat treatment of coal using the fluidized bed (fluidized bed) technique, designed to produce high-calorie solid fuel (semi-coke). A typical example is the “Method for the production of semi-coke from brown and bituminous coals” (RF patent No. 2073061, priority dated 02/10/1997). This method consists in the heat treatment of coal in a fluidized bed at a temperature of 600-700 ° C with the addition of water vapor to the air blast and removal of materials deposited from the gas distribution grid from the fluidized bed.

The disadvantage of this method is the increased ash content of semi-coke, due to the fact that the effective separation of the mineral part of the source coal is not provided. This essentially eliminates the possibility of obtaining a semi-coke suitable for metallurgy from ordinary (unenriched) coal, because the ash content of semi-coke does not meet the technical requirements for coke breeze (class 0-10 mm): according to TU 14-7-115-89, the ash content should not exceed 16% by dry weight.

Closest to the claimed method according to the technical nature and the achieved result is the "Method of producing metallurgical medium-temperature coke" (RF patent No. 2285715, priority dated July 29, 2005). This method consists in thermo-oxidative coking of coal with a grain size of 0-15 mm in a fluidized bed at a temperature of 800-900 ° C to produce high-calorie solid fuel - medium-temperature metallurgical coke.

The main disadvantage of this method is that to obtain high-quality heat-treated solid fuels with low ash content (for example, A ^d not higher than 16% for coke breeze according to TU 14-7-115-89), either low-ash coal should be used as a raw material, which narrows the raw material base for applying the method, or the initial raw coal having an increased ash content, must first be enriched (for example, to an ash content of 7–9% per dry weight), which complicates and increases the cost of coal processing.

The objective of the invention is to eliminate the above disadvantages of known methods, namely to increase the efficiency and simplify the processing of coal by eliminating the stage of preliminary enrichment of the original raw coal.

The technical result of the invention is to obtain from high-ash ordinary coals of high-calorific (specific heat of combustion - 6300-7000 kcal / kg) low-ash heat-treated solid fuel without preliminary enrichment of the source coal.

The specified technical result is achieved by thermo-oxidative treatment of coal crushed to 10 mm in a fluidized bed (fluidized bed) at a temperature of 700-950 ° C using air blasting, while blasting air is supplied to the fluidized bed in an amount of 2500-4200 m ³ / (m ² × h), which provides both maintaining the temperature regime in the fluidized bed and efficient separation of the mineral part of coal, heavier than coal, with a reduction in the ash content (enrichment) of the obtained heat-treated solid fuel.

The method is as follows. In a device with a fluidized bed of coal, which, depending on the assigned mode, determined by the ratio of air blast to coal consumption and specific heat of combustion of coal, has a temperature of 700 to 950 ° C, pre-ground coal is continuously fed by the feeder. Coal particles, heated to the temperature of the layer and moving in the horizontal direction, successively pass through the stages of drying, pyrolysis and are discharged from the apparatus by natural overflow through a selective pipe. Fine coal, vapor-gas products of thermal decomposition of coal, as well as gasification products of coke are partially burned in the fluidized bed, ensuring its working temperature, are removed from the fluidized bed and burn out in the superlayer space by supplying secondary air blast. Heavier particles of rock contained in a high-ash ordinary angle are deposited in the lower part of the fluidized bed and, as they accumulate, are removed from the apparatus through a failed grate. The combustion products are fed to a recovery boiler for the generation of thermal energy - hot water or steam.

In the examples illustrating the method, a fluidized bed apparatus with a coking chamber size of 540 × 55 mm in plan and selection of a solid product at a height of 560 mm was used.

Example 1:

=5020 ккал/кг и следующий технический и элементный состав:As raw materials used Kuznetsk coal brand DR (long flame ordinary), crushed to 5 mm, having a specific heat of combustion per working mass

= 5020 kcal / kg and the following technical and elemental composition:

W ^r _t = 8.8%; A ^d = 24.3%; V ^daf = 41.2%; C ^daf = 78.3%; H ^daf = 5.5%; N ^daf = 2.1%; O ^daf = 13.6%; S ^daf = 0.37%.

100 kg / h of coal and 75 nm ³ / h of air are fed into the apparatus.

The temperature in the fluidized bed is 910-950 ° C.

The specific air flow rate is 2525 m ³ / (m ² × h).

The yield of coke residue is 41% by weight of the initial coal.

=6490ккал/кг и следующий технический и элементный состав:The resulting coke residue has an ash content lower than the initial coal, the ash content meets the requirements of TU 14-7-115-89 for coke breeze (A ^d not more than 16%), has a specific heat of combustion per working mass

= 6490 kcal / kg and the following technical and elemental composition:

W ^r _t = 0.5%; A ^d = 15.4%; V ^daf = 4.0%; C ^daf = 92.5%; H ^daf = 1.3%; N ^daf = 1.9%; O ^daf = 3.9%; S ^daf = 0.4%.

Example 2

=3275ккал/кг и следующий технический и элементный состав:As raw materials used coal grade 2BR (brown, ordinary) deposits "Baganuur" (Mongolia), crushed to 10 mm, having a specific heat of combustion per working mass

= 3275 kcal / kg and the following technical and elemental composition:

W ^r _t = 33.0%; A ^d = 14.6%; V ^daf = 45.0%; C ^daf = 70.0%; H ^daf = 5.0%; N ^daf = 0.7%; O ^daf = 23.7%; S ^daf = 0.52%.

170 kg / h of coal and 124 nm ³ / h of air are fed into the apparatus.

The temperature in the fluidized bed is 700-730 ° C.

The specific air flow rate is 4175 m ³ / (m ² × h).

The yield of coke residue is 26% by weight of the source coal.

=6700ккал/кг и следующий технический и элементный состав:The resulting coke residue has an ash content lower than the initial coal, the ash content meets the requirements of TU 14-7-115-89 for coke breeze (A ^d not more than 16%), has a specific heat of combustion per working mass

= 6700 kcal / kg and the following technical and elemental composition:

W ^r _t = 1.3%; A ^d = 12.7%; V ^daf = 10.7%; C ^daf = 92.8%; H ^daf = 1.5%; N ^daf = 1.0%; O ^daf = 4.2%; S ^daf = 0.44%.

Example 3 (comparative of the patent of the Russian Federation No. 2073061, priority of 02/10/1997).

As raw materials, dried coal of a fraction of 0.5-7 mm of grade 3B (Lermontovskoye deposit, Sakhalin) with the following technical and elemental composition was used:

W ^r _t = 6.25%; A ^d = 31.2%; V ^daf = 44.9%; C ^daf = 73.4%.

75 kg / h of coal and 106 nm ³ / h of air and 8.5 kg / h of water vapor are supplied to the apparatus with a cross section of 0.075 m ² .

The temperature in the fluidized bed is 680-720 ° C.

The specific air flow rate is 1413 m ³ / (m ² × h).

The yield of coke residue is 63% by weight of the initial (dried) coal.

The ash content of semicoke A ^d = 54.2% - does not meet the requirements of TU 14-7-115-89 for coke breeze (A ^d not more than 16%). The semi-coke has an ash content significantly higher than the initial coal, which is due to the lack of effective separation of the mineral part of the coal.

Thus, the proposed method allows to process high-ash raw coal into low-ash high-calorie heat-treated solid fuel with the simultaneous production of thermal energy without preliminary enrichment of the source coal.

Claims (1)

A method of processing coal to produce heat-treated solid fuel and thermal energy, including thermo-oxidative treatment of crushed coal in a fluidized bed, characterized in that the processing is carried out by simultaneous thermal-oxidative treatment of coal at a temperature of 700-950 ° C due to the partial oxidation of coal by air and the separation of the mineral part of coal heavier than coal, with a decrease in the ash content of the heat-treated solid-treated fuel, and coal, crushed to 10, is used as the feedstock mm, moreover, blast air is supplied to the fluidized bed in an amount of 2500-4200 m ³ / (m ² × h).