RU2287011C1 - Method of the layerwise coal gasification - Google Patents

Abstract

FIELD: coal industry; power industry; chemical industry; methods of the layerwise coal gasification.

SUBSTANCE: the invention is pertaining to production of the power station coal or gas and may be used in coal industry, power industry, chemical industry. The method of the layerwise coal gasification is conducted in the mine type apparatus with the dry blast feed from below and firing of the coal layer from above. Process is conducted in two stages, at the first of which feed the dry blast in amount of 150-600 m³/(m²·h), and at the second stage - the dry blowing is added with the steam in amount of up to 100 kg/(m²·h). The method provides for simultaneous utilization of no less than four apparatuses working with the equal phase shifts of the process realization. The invention allows to exercise the complete gasification of the raw and to produce the gas having the heightened specific heat of combustion and is free from the condensable products of pyrolysis.

EFFECT: the invention ensures the complete gasification of the raw, production of the gas with the heightened specific heat of combustion and free from the condensable products of pyrolysis.

2 cl, 2 ex

Description

The invention relates to the field of producing energy or process gas from coal and can be used in the energy and chemical industries.

There are a number of known methods for layer-by-layer gasification of coal using air and steam-air blasting. For example, in the Wellman-Galusha process (Schilling G.-D. Gasification of coal / G.-D. Schilling, B. Born, U. Kraus. - M .: Nedra, 1986. - 175 p.) Pre-ignited coal filling in a mine-type apparatus, it is blown up with a steam-air mixture.

The main disadvantage of this method is that the resulting gas is saturated with coal pyrolysis products and contains up to 0.1 kg of resin per 1 nm ^{3 of} gas. Such a gas has limited use. Approximately every 3-4 months, the pipelines must be cleaned of condensate and resin deposits, which impedes long-term continuous operation of the equipment. Gas cooling and its washing from resinous substances significantly increase capital and operating costs and reduce the efficiency of the gasification process.

Closest to the claimed method according to the achieved result is a method for producing semicoke and associated combustible gas (RF patent No. 2169166, 06/20/2001), which is a variation of the method of layer gasification of the angle. The method involves blowing a layer of coal filling with a mixture of air and combustible gas (approximately 8-10% of the volume obtained in a vertical shaft type apparatus). The blast is fed from the opposite side of the coal ignition with a specific flow rate of 100-400 m ³ / (m ² · h) so that the temperature of the coal in the carbonization front is 920-950 ° C. Coal pyrolysis products formed in the carbonization front are burnt in the air stream, forming mainly carbon dioxide and water vapor. Further, these gases are reduced to carbon monoxide and hydrogen on the hot surface of the semicoke. Thus, the resulting gas does not contain condensable products of coal pyrolysis and can be used in further processing without intermediate stages of cooling and washing from the resin.

The disadvantage of this method, from the point of view of the production of gas that does not contain condensable products of coal pyrolysis, is the incomplete gasification of the carbon-containing part of coal. About 50-60% of the organic part of the coal is converted into gas, and the rest is discharged in the form of semi-coke. The relatively low temperature in the carbonization front (up to 920–950 ° C) limits the rate of endothermic reactions of carbon with carbon dioxide and water vapor; therefore, the volume content of carbon monoxide and hydrogen in the gas does not exceed 33%, and its specific calorific value is 600–900 kcal / nm ³ , which limits the scope of such a gas as an energy carrier.

Closest to the claimed method according to the technical essence is a two-stage gasification of a moving layer of solid fuel in a shaft type gas generator (Fedoseev S.D. Semicoking and gasification of solid fuel / S.D. . In the gas generator, the upper part of the fuel layer is horizontally purged with a gas coolant obtained by burning part of the product gas. The semi-coke formed as a result of pyrolysis is transported to the lower part of the mine, where it undergoes complete gasification with a steam-air mixture. The gas flows after the first and second stages are mixed and enter the stage of cooling and purification from the resin.

The disadvantage of this method is that the resulting gas contains pyrolysis products.

The objective of the present invention is to obtain a gas that does not contain condensable pyrolysis products, expanding the scope of gas, increasing efficiency and efficiency.

The technical result of the invention is to increase the specific heat of combustion of a gas not containing condensable pyrolysis products, provided that the organic mass of the source coal is completely gasified.

The technical result is achieved due to a two-stage layer gasification of coal in a vertical shaft-type apparatus, including the first stage - heating, drying, carbonization of the initial coal and partial gasification of carbon, and the second stage - the complete gasification of carbon contained in the coke residue. In the first stage, the supply of air blast in an amount of 150-600 m ³ / (m ² · h) is carried out from the side opposite to the ignition of the layer, in the second stage (after the front of the reaction reaches the side of the coal layer opposite to the ignition), water vapor in the amount of up to 100 kg / (m ² · h), necessary to maintain the temperature in the gasification front no higher than 1100-1200 ° С (the limitation is the softening temperature of ash).

To achieve a technical result, the method is as follows. Crushed coal of a class of 5-50 mm is loaded into a vertical shaft type apparatus to the entire height, air blasting with a specific flow rate of 150 to 600 m ³ / (m ² · h) is fed, and a layer of coal is ignited from the side opposite to the blast feed. The formed reaction front with a constant speed is shifted towards the air flow, and behind the front there is a layer of hot coke residue. When passing through the reaction front, coal is subsequently subjected to heating, drying, and pyrolysis. The combustible components of the pyrolysis products are completely oxidized by atmospheric oxygen to form carbon dioxide and water vapor, and then, by reduction on the hot surface of the coke residue, they turn into combustible components of the gas (carbon monoxide and hydrogen), which does not contain condensable pyrolysis products. The temperature in the front of the reaction reaches 1000-1200 ° C, and the specific heat of combustion of the gas is 1000-1200 kcal / nm ³ .

After the reaction front reaches the side of the layer opposite to the ignition side, water vapor in the amount of up to 100 kg / (m ² · h) is added to the blast and complete vapor-oxygen gasification of the carbon contained in the coke residue is carried out, and the gasification front moves towards the primary ignition of the layer. The resulting combustible gas does not contain condensable products of coal pyrolysis, and the specific heat of gas combustion is 1000-1200 kcal / nm ³ . The amount of water vapor in the blast is selected so that the temperature in the gasification front does not exceed the softening temperature of the ash for a given coal (1100-1200 ° C).

After the end of the process, the slag is unloaded from the bottom of the vertical apparatus.

To equalize the composition of the product combustible gas and the specific gas productivity, it is preferable to simultaneously use at least four devices operating with equal shifts in the phase of the process.

In the examples illustrating the method, a vertical shaft-type apparatus was used with an internal diameter of 0.5 m and a height of 1.5 m. Coal of fraction 5-20 mm of grade B2 (Berezovsky open pit of the Kansk-Achinsk coal basin) was used as raw material, having the following technical and elemental composition:

A ^d = 5.0%; V ^daf = 48%;

With ^daf = 71.7%; H ^daf = 4.9%; N ^daf = 0.8%; O ^daf = 22.3%.

Example 1

The specific air supply is 235 m ³ / (m ² · h).

The specific steam supply in the second stage is 61 kg / (m ² · h).

The temperature in the reaction zone is 1100-1150 ° C.

The composition of the gas (vol.%):

CO = 13.8; H ₂ = 15.6%; CO ₂ = 16.0%; CH ₄ = 2.4%; N ₂ = 46.5%; H ₂ O = 5.92%.

.Specific heat of gas

.

The carbon content in the solid residue is 1.9%.

Example 2 (comparative).

The specific air supply is 107 m ³ / (m ² · h).

The temperature in the reaction zone is 900-930 ° C.

The composition of the gas (vol.%):

CO = 8.5; H ₂ = 12.5%; CO ₃ = 17.5%; CH ₄ = 2.9%; N ₂ = 51.6%; H ₂ O = 7.0%.

.Specific heat of gas

.

The carbon content in the solid residue is 81.5%.

Claims (2)

1. The method of layer-by-layer gasification of coal in a mine-type apparatus by supplying air blast from below and igniting a layer of coal from above, characterized in that the process is carried out in two stages, the first of which is supplied with air blast in an amount of 150-600 m ³ / (m ² · h), and on the second - to the blast water vapor is added in an amount of up to 100 kg / (m ² · h). 2. The method according to claim 1, characterized in that it provides for the simultaneous use of at least four devices with equal shifts in the phase of the process.