RU2278254C1 - Method for electrical power production by underground coal combustion - Google Patents

Abstract

FIELD: mining, particularly electrical power generation by underground coal combustion.

SUBSTANCE: method involves forming isolated coal blocks in seam to be burned-off by driving down-dip uprise drifts for the full seam thickness and connecting the drifts with each other by ignition drift isolated from lower coal bed with fire-resistant coating; creating fire-resistant partition walls for the full uprise drift lengths so that the partition walls are arranged in drift centers, wherein fire-resistant coating and fire-resistant partition walls are deepened in rock massif for depth equal to coal-containing rock thickness; forming sluices provided with gates in uprise drifts; forming air-supply hole and ignition drift in each coal block; drilling gas-discharge holes in uprise drift roofs so that gas-discharge holes communicate with each sluice; laying rails in each uprise drift and arranging heat-exchangers on the rails; connecting the heat-exchangers with steam turbine of electric generation plant and heat-transfer material vessel through flexible and rigid heat-resistant pipelines; combusting coal in ignition drift and supplying heat-transfer material into heat-exchangers arranged near fire front line and moved through uprise drifts from ignition drift to surface, wherein heat-exchanger movement speed is regulated on the base of heat-transfer material temperature; forming additional uprise drifts between two adjacent ones in coal block, wherein the additional uprise drifts are adapted to supply air and to move heat-exchangers in the case of heat-exchanger contact with fire front line from both sides thereof. Isolated coal block is formed by filling extreme uprise drifts with non-combustible rock. Coal is ignited from end uprise drift parts. Air is supplied to fire front line zone and gas is discharged from the zone via pipelines laid in uprise drifts.

EFFECT: increased efficiency of gas-coal deposit potential usage for marketable product obtaining and reduced product production cost.

3 cl, 2 dwg

Description

The invention relates to mining, in particular to the generation of electricity from underground coal combustion.

Various methods are known for underground burning coal and generating electricity. So, for example, there is a known method of underground mining of coal deposits and production of electricity (Application No. 94023017, published on June 10, 1996), including the burning of produced coal in stationary underground furnaces and the delivery of high-temperature products to the surface of the mine in a steam-powered circuit of thermomechanical equipment for electricity production .

The disadvantages of the method are the high resource intensity of the coal-energy complex due to the cost of coal mining, the high risk of work for people underground, the plant is stationary, and the need to deliver coal to it. All this determines the high cost of the received electric energy.

The closest technical solution to the proposed method is a method of generating electricity during shaftless coal gasification and / or underground coal burning (RF Patent No. 2100588, IPC 6 E 21 V 43/295, publ. 1997.12.27), including the formation of coal blocks (panels) in the formation, drilling from the surface of air supply and gas outlet wells, sequential degassing and gasification of coal blocks, removal of methane and generator gas through the wells to the gas generator’s gas turbine, while the heat of the generator gas is diverted to the steam generator turbine iterator, and the received electric energy is transmitted through power lines to consumers.

The disadvantages of this method are:

- the seam panels are separated by interpanel pillars of coal with a width of 3-5 m, which can also catch fire, which will lead to an uncontrolled spread of the fire front, premature arson of an undrained panel from methane and disruption of the technological process;

- the abandonment of coal in the roof and soil of wells in formations with a thickness of more than 1.2 m and, as a consequence, the presence of conditions for a fire to go beyond the boundaries of the burned panel;

- the heat of the burnt coal is removed only with the generator gas and is largely lost on heating the rocks, dispersing in the array, heating the interpanel pillars;

- generator gas is a low-calorific energy carrier, which determines the high cost of electricity produced;

- low efficiency of the energy complex in obtaining energy contained in coal seams, and a large consumption of coal matter in the process of electricity production;

- low level of use of resources of a gas-coal deposit subjected to underground burning, due to the lack of opportunities for efficient use of burnt rock mass.

The objective of the invention is to increase the efficiency of use of resources of a gas-coal field for the production of marketable products with a decrease in its cost.

This task is achieved by the fact that in the method of generating electricity during underground coal burning, which includes the formation of coal blocks in the formation, drilling from the surface of air supply and gas extraction wells, sequential degassing and gasification of coal blocks, the removal of methane and generator gas to a gas turbine, and the heat of the generator gas - to a steam turbine of an electric generator, the transmission of electricity to consumers, according to the invention, coal blocks are formed by holding the slopes connected to the entire thickness of the formation by its falling x ignition drift, insulated from the underlying coal layer with a refractory coating, throughout the slopes along their center create refractory dividing walls, while the refractory coating and refractory dividing walls create with deepening into the rock mass by the amount of coal-bearing rocks, then locks are formed in the slopes, equipped with lock gates, in each coal block from the surface one air supply hole is drilled into the roof of the pilot drift at an equal distance from the slopes, and into the roof of the slopes in each slope s gas wells are drilled, rail roads are laid on slopes on both sides of the refractory dividing walls and heat exchangers are placed on them, which are connected by a system of flexible and rigid heat-resistant pipelines with a steam generator turbine and a coolant reservoir, after which coal is ignited from the ignition drift and the coolant is fed into heat exchangers, which are located in the zone of the front of fire, moving along the slopes from the firing drift to the surface, and the speed of movement of the heat exchanger The sensors are controlled by the temperature of the coolant. In addition, between two adjacent slopes in the coal block, additional slopes are formed along which heat exchangers are moved under conditions of bilateral contact with the fire front. After cooling the array through the slopes of the scorched blocks of coal, the miners are fed to the surface, and the air and gas wells are used to ventilate the underground space.

The claimed technical solution is illustrated by drawings, where figure 1 presents a schematic process diagram of underground coal burning and power generation; figure 2 is a section along aa in figure 1.

A method of producing electricity during underground coal burning is as follows. By the fall of the coal seam, slopes 1 successively pass through its entire thickness and depth of 600-800 m, which are then connected by a horizontal working - firing drift 2 (Fig. 1). The width of the coal blocks 3 cut in this way is 30-60 m and is determined by the required capacity of the heat exchangers 4 (steam generators), the thickness of the coal seam, its calorific value, combustion temperature, etc. To reduce the complexity of tunneling with a large thickness of loose loose sediments, slopes can be formed not from the day surface, but from a horizontal drift, passed along the strike of the formation under sediments. In order to prevent the movement of the fire front 5 outside the blocks of coal 3, the soil of the drift 2 is insulated with a refractory coating 6 of brick, concrete, and other modern non-combustible materials, as shown in Fig.2. Throughout the slopes 1 along their center create refractory dividing walls 7, which divide the worked out space of the slopes 1 into two parts. To increase safety, the refractory coating 6 and the refractory dividing walls 7 are created by deepening into the rock mass by the amount of power of coal-bearing rocks. This is due to the fact that layers of siltstones and mudstones with a thickness of 0.3-0.7 m lie in the roof and soil of most coal seams. These rocks contain coal matter (up to 20-40%) and can act as conductors of the fire front 5 beyond the limits of the burned coal block 3 .

In the slopes 1 through 100-150 m, locks 8 are formed, equipped with lock gates 9 controlled by a dispatcher from the surface, which creates conditions for controlling the gas flow in the underground space and maintaining the high temperature mode. Thus, insulated coal blocks 3 are formed in the bowels, which subsequently act as thermogas generators or dynamic underground furnaces.

In each insulated block of coal 3, at an equal distance from the slopes 1, an air supply 10 is conducted into the firing drift 2. This may be a surface well, a well or a gradient along the formation, etc. Gas outlet wells 11 are drilled into the roof of slopes 1 into each gateway 8. On the first prepared blocks of coal 3, methane is drained through all these wells and diverted to an electric generator 12. The electric generator 12 is equipped with two turbines - gas and steam - with the possibility of generating electricity in a combined cycle . To transfer the generated electricity to consumers, an electric generator is connected to existing power line networks.

Then, on the basis of slopes 1, rail roads are mounted on both sides of the fire-resistant walls 7 to move the heat exchangers 4. The heat exchanger 4 is a cylindrical boiler on wheels (like a railway tank), moved from a surface control station by, for example, a winch and converting the water entering it in high pressure steam.

To increase the safety level of energy production, it is possible to organize a contour (cascade) removal of thermal energy of coal burned when heavy liquids (liquid potassium or glycol) with a boiling point of about 600 degrees Celsius are used in the primary circuit, in the underground heat exchanger 4, which transfer heat to the water coolant through another heat exchanger located in a safer area, such as on a surface or in a buried chamber.

On rails in the slopes 1 of the first two blocks of coal 3, heat exchangers 4 (MOT 1, 2, 3 and 4) are lowered to the level of the firing drift 2 and connected by a system of rigid and flexible pipelines to the electric generator 12 and the coolant reservoir 13. Steam generators (heat exchangers), pipelines, rails, cables, chains, etc. made from materials that withstand the heat generated underground. As a means of monitoring the process of burning coal on the refractory dividing walls 7, temperature sensors and other monitoring devices are installed.

Upon completion of the preparation of several isolated coal blocks 3, their preliminary degassing and removal of the front of tunneling in the first isolated coal block 3 from the firing drift 2, the coal mass is ignited. This is achieved, for example, by setting fire to several wood bonfires laid out in the ignition drift 2 along its coal wall, or by removing arson of oil products (diesel fuel, fuel oil) deposited on the coal wall of the ignition drift 2 or launched through the air supply hole 10.

Simultaneously with the ignition of the first insulated coal block 3, they organize the supply from the coolant reservoir 13 to the heat exchangers 4 (TO 1 and TO 2), which are located in the zone of the fire front 5, moving (for example, using winches) along the slopes 1 from the firing drift 2 to the surface and controlling the speed of their movement according to the temperature of the coolant. When the temperature decreases (which means the heat exchanger leaves the zone of the fire front), the heat exchanger is accelerated or slowed down the slope 1, providing maximum removal of heat generated by the burned coal.

Underground steam production is monitored at a ground control station, where, using a computer program, the compliance of the actual process parameters with the required ones is monitored. The temperature readings are monitored at various points of the coal blocks 3 burned, the pressure and temperature in the heat exchangers 4 are controlled, thermal imaging imaging of the massif is carried out using modern monitoring tools, etc. From there, they control the process of energy production by regulating the air supply to the wells 10, moving heat exchangers (steam generators) 4 along the slopes 1 upwards after the fire front 5, closing the lock gates 9, regulating the flow of water, etc. The creation of locks 8 in the slopes 1 provides the conditions for maintaining a high temperature regime in the zone of placement of heat exchangers 4, and drilling gas outlets 11 into each lock 8 creates the conditions for controlling the movement of gas flows with minimal loss of heat generated. Gas exhaust wells 11 of the lower locks 8 are used to supply air into the underground space after the fire front 5 has moved to the level of the upper locks 8. Thereby, the compactness of the coal burning work area is maintained, the supply of air is reduced and the heat energy is lost.

As you burn one block of coal 3, the next is brought into action. At the same time, all preparatory and degassing work on the coal block 3 adjacent to the ignition unit must be completed, heat exchangers 4 (TO 5 and TO 6) are installed at the level of the firing drift 2, and people from it should be transferred to the following coal blocks 3.

Thus, in addition to methane and generator gas entering the gas turbine of the electric generator 12, a powerful additional stream of high pressure hot steam from underground heat exchangers 4 also comes to its steam turbine from the cooling of the generator gas. This helps to increase the power of the steam generator installation of the electric generator 12, increase electricity production and reduce its cost.

The electric generator 12 is mobile and is moved in the direction of the prepared coal blocks 3 along the strike of the formation with the corresponding remounting of the pipelines.

The heat exchangers 4 (TO 1-6), located on the flanks of the burned coal blocks 3, operate under conditions of one-sided contact with the fire front 5. As a result, the walls of the heat exchangers 4 removed from the fire warm up less than the walls located close to the fire front 5. Increase heat removal levels are ensured by forming in the coal blocks 3 between two adjacent slopes 1 additional slopes along which heat exchangers move under conditions of bilateral contact with the fire front 5 and uniform heating of the heat exchangers with both sides. This ensures the issuance on the surface of the coolant with high temperature, and when using water - the issuance of steam with high pressure.

Favorable conditions for the implementation of the proposed method have areas of coal deposits worked out by drilling coal with wells or slopes from a split trench (for example, American HWM drilling machines). After the completion of coal mining operations, such sections are a combination of slopes up to 300 m long and 2-2.5 m wide and pillars of coal between them with a width of 0.3-0.9 slope widths. In such conditions, the formation of isolated blocks of coal is carried out by laying the extreme of the inclinations outlined by the block as non-combustible rocks. The remaining slopes are used to supply air to the zone of the fire front and move the heat exchangers. In this case, the pilot drift can be formed by the destruction of pillars in the dead ends of slopes (for example, by drilling into the pillars of holes and blasting them).

Reducing the number of wells and the volume of drilling work in the field can be achieved by organizing the supply of air to the front of the fire and the removal of gases from it through pipelines laid on slopes.

As a result of underground burning of blocks of coal 3 in the bowels of the horizon formed of burned rocks. At the place of application of the proposed technology for extracting energy from coal, a technogenic deposit of building material - a burner - is formed with lightened conditions for its subsequent mining: a burnt coal seam is not susceptible to gas emissions and its emissions into the workings, the roof of the formation and workings as a result of sintering of rocks under the influence of high temperatures has high stability and is not prone to collapse, the massif has low water saturation, there are prepared wells for ventilation and production for ransportirovaniya product on the surface, etc.

After burning coal and cooling the array through slopes 1 of burned blocks of coal 3, the miners are fed to the surface, and air supply 10 and gas outlet 11 wells are used to ventilate the underground space and create favorable conditions for people to work. Thus, they ensure the comprehensiveness and safety of the development of mineral deposits.

The proposed method provides a comprehensive development of coal deposits using the gas, organic and mineral components of the coal mass for the production of commercial products. This allows you to expand the product range and reduce the costs of operating the production complex operating the field. An increase in the efficiency of the use of thermal energy and a reduction in the cost of the produced electric energy are achieved by reducing heat loss during underground coal combustion by creating isolated coal blocks and efficiently controlling the movement of gas and air flows in the underground space, as well as by organizing additional active removal of thermal energy of coal material burnt underground. In addition, the technogenic load on the environment is sharply reduced, which is relevant for the territories of coal-energy complexes. In the process of burning coal, a technogenic deposit of burners is formed with lightened conditions (lack of gas emission from the massif, availability of prepared workings, ventilation wells, etc.) for their extraction for construction needs.

The social effect of the invention is achieved by the possibility of withdrawing from a hazardous working environment a large number of personnel of machinists of underground combine harvesters, burrows, electrical fitters, etc. and releasing them for other creative activities.

Underground coal burning is a breakthrough solution to the problem of doubling Russia's GDP by 2010, avoiding the extraction and transportation of energy raw materials from coal seams at TPPs and ensuring the release of environmentally friendly, transportable and valuable products from the coal field - electricity, as well as building material with a sharp reduction in resource consumption the entire energy production system and reducing the cost of final goods.

The proposed method can be applied in a wide range of geological conditions, namely, on coal seams with a thickness of 1.0-1.5 m and above, any gas abundance, strength, ash content, on undeveloped sections of mine fields, as well as areas with substandard reserves for well-known mining technologies.

Claims (3)

1. A method of generating electricity during underground coal burning, including the formation of coal blocks in the formation, drilling from the surface of air supply and gas extraction wells, sequential degassing and gasification of coal blocks, removal of methane and generator gas to a gas turbine, and heat of the generator gas to a steam turbine of the generator, transmission of electricity to consumers, characterized in that the coal blocks are formed by holding the slopes connected to the ignition drift isolated from of the underlying coal seam with a refractory coating, throughout the slopes along their center create refractory dividing walls, while the refractory coating and refractory dividing walls are created by deepening into the rock mass by the amount of coal-bearing rocks, then in the slopes form locks equipped with lock gates, in each a block of coal passes the air supply to the pilot drift, and gas outlet wells are drilled into the roof of slopes in each airlock, rail tracks are laid in slopes and placed on them heat exchangers that connect the system of flexible and rigid heat-resistant pipelines with a steam turbine of the electric generator and a coolant reservoir, then they ignite the coal from the ignition drift and supply heat to the heat exchangers located in the zone of the fire front, moving along slopes from the ignition drift to the surface, and the speed the movement of the heat exchangers is controlled by the temperature of the coolant. 2. The method according to claim 1, characterized in that between the two adjacent slopes in the coal block additional slopes are formed along which air is supplied and heat exchangers are moved under conditions of bilateral contact with the fire front. 3. The method according to claim 1 or 2, characterized in that the formation of an isolated coal block is carried out by laying the extreme slopes of non-combustible rocks, ignition of coal is carried out from the dead ends of the slopes, and air is supplied to the front of the fire area and gases are removed from it through pipelines laid in biases.

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