CN103670361B - Gas injection device, coal underground gasification system and coal underground gasification method - Google Patents

Abstract

One aspect of the present invention relates to a gas injection device for underground coal gasification, comprising: a water injection pipe, a cylindrical atomizer, and a nozzle is arranged on the wall of the device around its axis. In another aspect, an underground coal gasification system is provided, which is provided with the above-mentioned gas injection device. The present invention also provides an underground coal gasification method using the above-mentioned gas injection device. The gas injection device sprays water mist into the air intake channel to absorb heat in the air intake channel and form water vapor to enter the gasification channel. middle. The nozzle of the atomizer of the gas injection device sprays the liquid water in the form of atomization to the inner wall of the air intake channel, and after exchanging heat with the inner wall of the air intake channel, it is further vaporized to form water vapor to participate in the gasification of coalbed methane in the working face reaction. Thus, it is effectively ensured that water vapor enters the gasification channel, the temperature of the gasification working face is controlled, and the component content of effective gas in the coal gas is increased. The underground coal gasification system can realize the effective recycling of the sewage produced by the gasification.

Description

Gas injection device, underground coal gasification system and underground coal gasification method

technical field

The invention relates to a gas injection device, an underground coal gasification system and an underground coal gasification method.

Background technique

Underground coal gasification is an energy conversion technology that efficiently and cleanly utilizes low-quality coal resources. It is a process in which underground coal is directly burned in a controlled manner, and combustible gas is generated through thermal and chemical effects on coal. Due to the difference in hydrogeological conditions of different coal seams, the effect of underground coal gasification technology after implementation is different. Especially in coal seams rich in water, because the coal seam gasification process is a chemical process of self-expansion in volume, a large amount of heat is released during the coal seam combustion process, and the heat released makes a large amount of water in the coal seam vaporize to form water vapor, and in the During the volume expansion process, the water vapor is driven out of the gasification furnace along the gasification channel, so that all the converted water vapor cannot effectively participate in the coalbed gasification reaction, thereby reducing the hydrogen content in the coal gas, thereby reducing the gas quality.

In addition, due to the long gasification channels of industrial gasifiers, the general length ranges from tens of meters to hundreds of meters. When the water vapor travels along the gasification channel, due to the cooling effect of the channel wall, the water vapor has formed condensed sewage when it reaches the gasifier outlet, and the formed condensed sewage is discharged out of the gasifier along with the coal gas, and separated by water and gas on the ground After the equipment is separated, it enters the sewage tank. The scale of industrial gasification furnace is large, and a large amount of condensed sewage is discharged from the gasification furnace every day, and the sewage contains a large amount of organic pollutant components. If several large sewage pools are installed to purify the condensed sewage, it will not only increase the production costs of coal gas, and is contrary to laws and regulations to protect groundwater resources.

Patent CN102587884A discloses a utilization process for underground gasification gas condensate, which cools the high-temperature gas with a large amount of water by setting a high-temperature gas cooling device in the gas outlet to obtain relatively purified dry gas and gas condensation Liquid, and part or all of the gas condensate is converted and collected. After being treated by the purification equipment, the condensed water is converted into low-pressure saturated steam by the steam generator, and transported to the underground coal gasifier through the steam pipeline to Adjust the effective gas composition of the gas. Since the core reaction space of the underground coal gasification furnace is 300 meters deep from the surface, any gasification agent must be transported through pipelines buried deep in the ground. In the journey to the coal seam, it needs to pass through several aquifers. Based on the above reasons, the gasification agent must exchange heat with the pipe wall when it flows through the pipe. Therefore, when the low-pressure steam reaches the coal seam reaction zone through the gasifier inlet, it will be re-cooled and turned into water, which cannot realize the original function of steam, and consumes a lot of electric energy to generate low-pressure steam.

Patent CN102606127A discloses a groundwater prevention and control method and device for an underground coal gasification gasifier. This process directly collects the condensed water cooled by the coal gas, and then uses the conveying equipment to directly discharge the condensed water through the pipeline to the underground gasifier. Bottom of stomata. In this method, a large amount of water is directly passed into the gasifier, which will have a certain negative impact on the gasifier, affect the normal combustion and gasification of the gasifier, and in serious cases will cause the gasifier to go out. In the case of a small flow rate, due to the pressure film produced in the reaction space of the underground gasifier, water with a small flow rate cannot participate in the gasification reaction under the action of the pressure film. To sum up, the method of this patent does not send water vapor into the gasification channel, and thus does not achieve the effect of improving the gas composition.

Contents of the invention

The purpose of the present invention is to provide a gas injection device that can effectively send water vapor into a gasification channel, an underground coal gasification system and an underground coal gasification method with the gas injection device.

In order to achieve the above object, on the one hand, a gas injection device for underground coal gasification is provided, comprising: a water injection pipe; A plurality of nozzles are arranged on its wall around its axis; wherein, the outlet of the water injection pipe is in fluid communication with the open end of the cylindrical atomizer.

According to the present invention, at least one ring of nozzles is arranged along the axial direction of the cylindrical atomizer, and the nozzles in the same ring are evenly arranged around the axis of the cylindrical atomizer and located in the same plane, and the plane is perpendicular to the axis of the cylindrical atomizer. axis.

According to the present invention, a plurality of nozzles are arranged in at least two circles around the axis of the cylindrical atomizer, and in each adjacent upper and lower circles of nozzles, all nozzles in the lower circle are relative to the upper circle of nozzles around the axis of the cylindrical atomizer Rotate by a constant angle.

According to the present invention, a plurality of nozzles are spirally arranged on the wall of the cylindrical atomizer, and every two adjacent nozzles form a constant angle around the axis of the cylindrical atomizer.

According to the invention, the constant angle is greater than 5° and less than 15°.

According to the present invention, the nozzle is a through conical hole, tapering along the direction from the inner peripheral wall of the cylindrical atomizer to the outer peripheral wall thereof.

According to the present invention, it also includes: a centralizer arranged on the outer peripheral wall of the cylindrical atomizer.

On the other hand, an underground coal gasification system is provided, including: an air inlet channel, an air outlet channel, a gasification channel connecting the air inlet channel and the air outlet channel; and also includes: a water-gas separator communicated with the gas outlet of the air outlet channel, The water-gas separator is provided with a drain port; a sewage pool connected to the drain port; a gas injection device extending into the air intake channel, and the gas injection device is any one of the gas injection devices mentioned above; Sewage pump for water pipes.

According to the present invention, it also includes: a casing arranged in shape with the inner wall of the air intake channel, the gas injection device extends into the casing, and the space between the casing and the water injection pipe in the gas injection device forms an air chemical agent injection channel; wherein, one end of the casing protrudes from the air intake channel and is provided with a first flange; the outer peripheral wall of the inlet of the water injection pipe is sleeved with a second flange, and the first flange is connected to the first flange. Two flanges.

In addition, the present invention also provides an underground coal gasification method using any one of the above-mentioned gas injection devices, comprising the following steps: a. Establishing an inlet channel, an outlet channel and communicating the inlet channel with the outlet channel the gasification channel; b. extend the gas injection device into the air intake channel; c. inject the combustion aid through the air intake channel and ignite the coal seam; d. pass the gasification agent through the air intake channel E. spray water mist into the air intake channel through the nozzle in the gas injection device to absorb the heat in the air intake channel to form water vapor, and the water vapor is sent into the gasification channel by the injected gasification agent middle.

According to the present invention, in the step b: the distance between the closed end of the cylindrical atomizer and the bottom of the gasification channel is within the range of 300 mm to 1000 mm, and is determined according to the geological conditions of the coal seam and the thickness of the coal seam Choose the appropriate distance value within the above range.

According to the present invention, the following steps are also included: collecting water vapor in the coal gas discharged from the gas outlet channel; condensing the water vapor into liquid water; injecting the liquid water into the gas injection device and spraying it through the nozzle.

Compared with the prior art, the beneficial effects of the present invention are:

The gas injection device used in the underground coal gasification process of the present invention uses the potential energy from the ground to the closed end of the cylindrical atomizer to spray liquid water into the intake air in the form of atomization through the nozzle of the cylindrical atomizer. The inner wall of the passage, and after exchanging heat with the inner wall of the intake passage (that is, absorbing the heat of the inner wall of the intake passage), further vaporizes to form water vapor. The water vapor formed above enters the gasification channel along with the gasification agent, and participates in the coal seam gasification reaction of the gasification working face. Therefore, on the one hand, the endothermic reaction between water and coal seam can reduce the reaction temperature of the gasification working face, so that the ash layer attached to the coal seam will not be formed due to the high reaction temperature of the gasification working face, which will hinder the formation of coalbed methane. change. On the other hand, water vapor and coal seam generate hydrogen to increase the content of effective gas components in the gas, thereby improving the quality of the gas. In addition, in the hydrolysis reaction between water and coal seam, carbon atoms are fixed in the form of carbon monoxide molecules. With the increase of liquid water participating in the reaction, the carbon in the coal seam is also effectively utilized, thereby improving the utilization rate of the coal seam and realizing the coal seam. Maximize the use of resources.

In the underground coal gasification system of the present invention, the water vapor in the coal gas discharged from the gas outlet channel is condensed and circulated through the gas injection device to spray into the intake channel in the form of water mist, and absorb heat to form water vapor and enter the gasification channel to participate in the process. The gasification reaction of the coal seam, and the water vapor contained in the generated coal gas is condensed again and injected into the gas injection device, thereby realizing the resource utilization of coal seam water and improving the energy efficiency of the underground gasification system, especially in reducing production costs Under the premise, improve the gas composition and improve the efficiency of the underground gasification system.

In the underground coal gasification method of the present invention, the water mist sprayed by the gas injection device on the inner wall of the air intake channel absorbs the heat on the inner wall of the air intake channel to form water vapor, and the water vapor enters the gasification channel together with the gasification agent. Thus, it can effectively ensure that the water vapor reaches the gasification working face in the gasification channel and participates in the combustion of the coal seam. Since the combustion of water vapor and coal seam is an endothermic reaction, the temperature of the gasification working face can be effectively controlled by water vapor, preventing the ash from ash from adhering to the coal seam and hindering gasification due to the high temperature of the gasification working face. In addition, the reaction of water vapor and coal seam produces carbon monoxide and hydrogen, thereby improving the effective components in the gas and improving the quality of the gas.

Description of drawings

Fig. 1 is the schematic diagram that an embodiment of the gas injection device of the present invention is used in the underground coal gasification process;

Fig. 2 is a cross-sectional view of setting the atomizer shown in Fig. 1 in the casing;

Fig. 3 is the schematic diagram of the first embodiment of underground coal gasification system of the present invention;

Fig. 4 is the schematic diagram of the second embodiment of underground coal gasification system of the present invention;

Fig. 5 is a schematic diagram of an embodiment of the underground coal gasification method of the present invention.

detailed description

Specific embodiments of the present invention will be described below in conjunction with the accompanying drawings.

Referring to Fig. 1, an embodiment of the gas injection device 12 for underground coal gasification of the present invention includes: a water injection pipe 1 and a cylindrical atomizer 2, the two ends of which are respectively set as open open ends and closed A closed end, and a nozzle is provided on its wall around its axis, wherein the outlet of the water injection pipe 1 is in fluid communication with the open end of the cylindrical atomizer 2 .

As shown in Figure 1, the gas injection device 12 is used in an exemplary stratum, which consists of an upper overburden 18, an aquifer 17, a roof rock stratum 16 and a coal seam 15 downwards from the ground, and the gas inlet channel 5 It penetrates from the ground into the coal seam 15 and communicates with the gasification passage 7 in the coal seam 15. The coal seam in the gasification passage 7 burns to form a gasification working face, that is, the area where the coal seam undergoes gasification and combustion. The inner surface of the channel 5 may be snugly provided with a sleeve 13 .

The gas injection device used in the underground coal gasification process of the present invention uses the potential energy from the ground to the closed end of the cylindrical atomizer to spray liquid water into the intake air in the form of atomization through the nozzle of the cylindrical atomizer. The inner wall of the channel (when the above-mentioned sleeve 13 is provided, the inner peripheral wall of the sleeve 13) is further vaporized after exchanging heat with the inner wall of the intake channel (that is, absorbing the heat of the inner wall of the intake channel) to form water vapor. The water vapor formed above enters the gasification channel along with the gasification agent, and participates in the coal seam gasification reaction of the gasification working face. Therefore, on the one hand, the endothermic reaction between water and coal seam can reduce the reaction temperature of the gasification working face, so that the ash layer attached to the coal seam will not be formed due to the high reaction temperature of the gasification working face, which will hinder the formation of coalbed methane. change. On the other hand, water vapor and coal seam generate hydrogen to increase the content of effective gas components in the gas, thereby improving the quality of the gas. In addition, in the hydrolysis reaction between water and coal seam, carbon atoms are fixed in the form of carbon monoxide molecules. With the increase of liquid water participating in the reaction, the carbon in the coal seam is also effectively utilized, thereby improving the utilization rate of the coal seam and realizing the coal seam. Maximize the use of resources.

Further, in this embodiment, the cylindrical atomizer 2 is provided with at least one ring of nozzles 3 along its axial direction, and the nozzles 3 in the same ring are evenly arranged around the axis and their axes are located in the same plane, which is perpendicular to the cylindrical atomizer. Axis of atomizer 2. Moreover, a plurality of nozzles 3 are arranged in at least two circles around the axis, and in each adjacent upper and lower circles of nozzles, all the nozzles in the lower circle rotate around the axis at a constant angle relative to all the nozzles in the upper circle. For example, among two adjacent circles of nozzles, along the direction from the closed end of the cylindrical atomizer 2 to the open end, the circle closest to the closed end is the upper circle, and the circle farthest from the closed end is the lower circle, and all the nozzles in the upper circle are Baseline, all nozzles in the lower circle turn to a constant angle relative to all nozzles in the upper circle. More specifically, along the direction from the closed end to the open end, based on the first layer of nozzles (the layer of nozzles closest to the closed end), the second layer of nozzles has exactly the same number of nozzles as the first layer of nozzles, and the second layer of nozzles is opposite to each other. The first layer of nozzles is formed by turning an angle. The third layer of nozzles is based on the second layer of nozzles. The number of nozzles set by the third layer of nozzles is exactly the same as that of the second layer of nozzles. The third layer of nozzles rotates an angle with the first layer and the second layer of nozzles relative to the second layer of nozzles. The same angles are formed. And so on until the last layer of nozzles. Thus, the nozzles 3 are arranged in a plurality of helical lines on the wall of the cylindrical atomizer 2 . The nozzle 3 arranged in a helical shape can more evenly absorb the heat on the inner wall of the air intake passage, ensuring that there is enough heat to evaporate all the water mist into water vapor and enter the gasification passage. In addition, when a casing is provided in the air intake channel, the water mist sprayed out by the nozzles arranged in a spiral shape can evenly absorb the heat on the casing, avoiding only one or several vertical stripes on the casing. Tube wall cooling. Of course, it can also be directed along the direction from the opening end of the cylindrical atomizer 2 to the closed end, the circle closest to the opening end is the upper circle, and the circle farthest from the opening end is the lower circle. In addition, preferably, the constant angle is larger than 5° and smaller than 15°.

Further referring to FIG. 1 , the gas injection device further includes a centralizer 4 disposed on the outer peripheral wall of the cylindrical atomizer 2 . The centralizer 4 can ensure that there is a gap between the outer peripheral surface of the cylindrical atomizer 2 and the inner wall of the air inlet passage 5, that is, an annular gap is formed between the outer peripheral surface of the cylindrical atomizer 2 and the inner wall of the air inlet passage 5 (Fig. 2 clearly shown in ), so that the gasification agent passed into the intake channel can enter the gasification channel through the annulus, and bring the water vapor formed by the vaporization of the water mist in the annulus to the gasification channel.

Referring to FIG. 2 , in this embodiment, each layer of nozzles is provided with four nozzles 3 , and the four nozzles 3 are evenly arranged around the axis of the cylindrical atomizer (in FIG. 2 , the axis is the center point of the circle). That is, the included angle between every two adjacent nozzles 3 among the four nozzles 3 is 90°. In addition, as shown in FIG. 2 , the nozzle 3 is a through conical hole, tapering along the direction from the inner peripheral wall of the cylindrical atomizer 2 to its outer peripheral wall, that is, along the direction from the inner peripheral wall of the cylindrical atomizer to the outer peripheral wall. In the direction of the wall, the cross-sectional area of the nozzle 3 gradually becomes smaller.

Of course, the arrangement of the nozzles 3 on the wall of the cylindrical atomizer 2 is not limited to the above-mentioned method. Optionally, the nozzles 3 are spirally arranged on the wall of the cylindrical atomizer 2, and every adjacent The two nozzles 3 form a constant angle around the axis of the cylindrical atomizer 2 . Preferably, the constant angle is greater than 5° and less than 15°. In other words, there is only one nozzle 3 in each spaced plane perpendicular to the axis of the cylindrical atomizer, and the nozzles 3 on the wall of the cylindrical atomizer 2 form a helical line. Therefore, it can also be understood that when there are multiple nozzles in each layer in this embodiment, the nozzles 3 on the wall of the cylindrical atomizer 2 form a plurality of spaced, identical helical lines.

In addition, when the nozzles of each layer are rotated 90° in the same direction around the axis of the cylindrical atomizer 2, the nozzles 3 will form multiple straight lines parallel to the cylindrical atomizer 2 on the wall of the cylindrical atomizer 2. shape settings. Of course, the nozzles 3 can also be arranged irregularly on the surface of the cylindrical atomizer 2 .

Preferably, the cylindrical atomizer 2 and the water injection pipe 1 are connected by flanges or threads.

Referring to Fig. 3, an embodiment of an underground coal gasification system of the present invention includes an air inlet channel 5, an air outlet channel 6, a gasification channel 7 communicating with the air inlet channel 5 and the air outlet channel 6, and also includes a The gas injection device 12 of any one of the above-mentioned channels 5, the water-gas separator 9 communicated with the air outlet of the gas outlet channel 6, wherein the water-gas separator 9 is provided with a drain, and the drain is connected to the sewage tank 10, and the sewage The pump 11 connects the sewage tank 10 with the inlet of the water injection pipe 1 in the gas injection device 12 .

As shown in Figure 3, the underground coal gasification system of this embodiment will be established in an exemplary stratum, which is successively down from the ground to the upper overburden layer 18, aquifer layer 17, roof rock layer 16 and coal seam 15 , the air intake passage 5 penetrates into the coal seam 15 from the ground, and communicates with the gasification passage 7 in the coal seam 15, the coal seam in the gasification passage 7 burns, and forms the gasification working face, that is, the area where the coal seam undergoes gasification combustion, In addition, a sleeve 13 can be fitted on the inner surface of the air intake channel 5 .

In this embodiment, it also includes: a casing 13 that is fitted in shape with the inner wall of the air inlet passage 5, the gas injection device 12 extends into the casing 13, and the gap between the casing 13 and the water injection pipe 1 in the gas injection device 12 The space forms a gasification agent injection channel (annulus between the water injection pipe 1 and the casing 13). Wherein, one end of the casing 13 protrudes relative to the air inlet passage 5, and is provided with a first flange; the outer peripheral wall of the inlet of the water injection pipe 1 is provided with a second flange; the first flange is connected to the second flange. Orchid plate. The underground coal gasification system of this embodiment also includes a gasification agent supply device, which is connected to the wall of the casing 13 to pass the gasification agent 8 into the gasification agent injection channel.

Specifically: put the water injection pipe 1 with the cylindrical atomizer 2 in the air intake channel 5, wherein the cylindrical atomizer 2 is connected to the lower part of the water injection pipe 1, and configure the water injection pipe 1 according to the needs of the process. Steel will do. Because the air inlet channel 5 is relatively long, many pipes can be connected by flanges to form a longer water injection pipe 1. The total length of the water injection pipe 1 depends on the buried depth of the coal seam and the depth of the roof rock formation. The length of the atomizer 2 depends on the thickness of the coal seam and the thickness of the roof rock formation, that is to say, preferably, when the cylindrical atomizer 2 is placed in the air intake channel 5 for use, the open end of the cylindrical atomizer 2 is located on the roof rock layer middle position. Because the temperature of the region above the middle of the roof rock layer is relatively low, the temperature of the inner peripheral surface of the casing 13 that is attached to the inner wall of the air inlet channel 5 is relatively low, and the water sprayed by the nozzle 3 of the cylindrical atomizer 2 When the mist encounters the low-temperature inner wall here, no heat exchange will occur to form water vapor.

The lowering depth of the water injection pipe 1 connected with the cylindrical atomizer 2 in the casing 13 depends on the thickness and depth of the coal seam. The closed end of the cylindrical atomizer is 300 mm to 1000 mm away from the bottom of the gasification channel 7. In this embodiment, According to the geological conditions and the difference in the thickness of the coal seam, the distance between the closed end of the cylindrical atomizer and the bottom of the gasification channel 7 is selected as 500 mm. Specifically, the geological conditions and coal seam thickness of the coal seam in this embodiment are shown in Figure 3, and the strata are successively from bottom to top respectively coal seam 15, roof rock layer 16, aquifer 17, and upper overburden layer 18. The depth of the coal seam 15 in the example is 280 meters, and the average thickness of the coal seam is 8 meters. In order to ensure that the heat of the coal seam 15 is fully utilized, the axial length of the cylindrical atomizer 2 is determined to be 9 meters. Considering that when the cylindrical atomizer 2 is lowered into the coal seam 15, its open end is preferably flush with the middle position of the roof rock layer 16, and the closed end of the cylindrical atomizer 2 is selected to be 500mm away from the bottom of the gasification channel 7. From this, it can be calculated that the total axial length of the water injection pipe 1 and the cylindrical atomizer 2 is 279.5 m. Of course, it can be understood that when the thickness of the coal seam 15 is greater than the thickness of the coal seam in this embodiment and the thickness of the roof rock layer 16 is greater than that of the roof rock layer 16 in this embodiment, the length from the closed end of the cylindrical atomizer 2 to the gasification channel 7 can be appropriately increased. The distance from the bottom. Conversely, reduce the distance. Of course, according to different geological conditions and coal seam thickness, as long as the opening end of the cylindrical atomizer 2 is located in the middle of the roof rock layer 16 and the distance that can fully absorb the heat of the coal seam 15 is the appropriate distance value. After determining the lowering depth, that is, when it is placed at a position 500mm away from the bottom of the gasification channel 7, pass the top of the water injection pipe 1 (the end away from the cylindrical atomizer 2) through the pre-processed second flange, the second flange One end of the disc is reserved for connection with the ground water injection pipeline, and then the second flange is welded to the water injection pipe 1 and connected to the first flange on the casing 13 . In addition, a centralizer 4 is installed at the bottom of the cylindrical atomizer 2 to ensure that the annular space between the water injection pipe and the casing 13 is even and the flow of the gasifying agent is stable.

After the water injection pipe 1 is lowered to the designated position, the inlet of the water injection pipe 1 is connected to the water injection pipe 1 and the casing 13 by a flange, and the inlet is connected to the sewage pool 10 through a pipe. A gasification agent inlet is arranged on the top, and the inlet is communicated with the gasification agent supply device. The gasification agent flows along the annular gap between the water injection pipe 1 and the casing 13 (that is, the gasification agent injection channel), and is connected with the atomization agent. The final sewage is mixed and enters the coal seam reaction zone with the gasification agent.

After the water injection pipe is firmly connected with the sewage pool, after the sleeve pipe 13 is connected with the gasification agent supply device, the valve of the water injection pipe can be opened, and the sewage in the sewage pool 10 can be pumped into the water injection pipe 1 by the sewage pump 11, and the water can be pumped into the water injection pipe 1 by the self-weight of the water. The water injection pipe 1 flows down to the cylindrical atomizer 2. Since the closed section of the cylindrical atomizer 2 is closed, after the sewage reaches the closed end of the cylindrical atomizer 2, it is transformed into lateral flow by the potential energy of water. The kinetic energy of the water uses the direct jet flow of the nozzle 3 to atomize the sewage and spray it onto the inner peripheral wall of the casing 13 .

The atomized sewage reaches the inner peripheral wall of the hot casing 13 under the condition of high-speed jetting. The atomized sewage absorbs the heat of the casing 13 and then vaporizes to form steam. Because the continuous atomized sewage absorbs a large amount of heat, the casing The temperature of the pipe 13 is cooled, which eliminates the thermal expansion and contraction of the casing 13, and avoids the phenomenon of cracks in the cement cement caused by the thermal expansion of the casing 13, thereby ensuring the normal and stable operation of the underground gasification. In addition, the service life of the sleeve 13 can also be extended. The vaporized steam is mixed with the gasification agent flowing from the annulus of the water injection pipe 1 and casing 13, and driven by the gas pressure, it is sent to the coal seam combustion oxidation reaction zone together with the gasification agent to participate in coal seam gasification The participation of water vapor in the reaction can not only adjust the temperature of the gasification working face, but also promote the optimization of the effective components of the gas.

In addition, the coal gas discharged from the gas outlet channel 6 enters the gas-liquid separator 9, and the gas-liquid separator 9 condenses the water vapor in the gas to form liquid water (sewage) and imports it into the sewage tank 10 for storage. Sewage is pumped into the water injection pipe 1 in the gas injection device 12, sprayed out from the nozzle on the atomizer 2 to form atomization and then absorb heat to become water vapor, which is carried by the gasification agent into the gasification channel 7, and a process is completed so far. cycle. As a result, the resource utilization of coal seam water is realized, the energy efficiency of the underground gasification system is improved, especially on the premise of reducing production costs, the gas composition is improved, the efficiency of the underground gasification system is improved, and the resource utilization of sewage is realized.

Of course, the underground coal gasification system can also establish two air intake passages 5 as shown in Figure 4, and gas injection devices can be installed in the two air intake passages respectively, or a gas injection device can be provided in one of the air intake passages , when the combustion of the coal seam in the vicinity of the air inlet passage is completed, the gas injection device is taken out and put into another air inlet passage. In addition, a directional channel 14 with a horizontal section and an inclined section can also be provided, and the horizontal section of the directional channel 14 communicates with the inlet channel 5 and the gas outlet channel 6 , that is, the horizontal section of the directional channel 14 is the gasification channel 7 .

In addition, a pressure gauge 21 and a flow meter 22 are provided on the pipeline connected between the sewage pump 11 and the inlet of the water injection pipe 1 .

Referring to Fig. 5, an embodiment of the underground coal gasification method of the present invention, comprises the following steps: a. establishes the gasification channel 7 of inlet passage 5, outlet passage 6 and communication inlet passage 5 and outlet passage 6; b. Extend the gas injection device into the air intake channel 5; c. inject the combustion aid and ignite the coal seam through the air intake channel; d. pass into the gasification agent through the air intake channel 5; e. Water mist is sprayed into the air intake channel 5 to absorb the heat in the air intake channel 5 to form water vapor, and the water vapor is sent into the gasification channel 7 by the injected gasification agent. Wherein, the combustible agent is optionally air.

Optionally, in step b: extend the gas injection device into the air inlet channel 5 until the distance between the closed end of the cylindrical atomizer and the bottom of the gasification channel 7 is in the range of 300mm to 1000mm, and according to the coal seam Due to the differences in geological conditions and coal seam thickness, select an appropriate distance value within the above range. In this embodiment, the distance value is selected as 500mm. It should be understood that the appropriate distance is that the cylindrical atomizer lowered to this position can fully utilize the heat of the coal seam, and its open end is located in the middle of the roof rock layer 16 . In addition, it may also include collecting water vapor in the coal gas discharged from the gas outlet channel 6, condensing the water vapor into liquid water, injecting the liquid water into the gas injection device, and spraying the liquid water through the nozzle. Thus, the recycling of the sewage discharged from the air outlet channel 6 can be realized.

Further referring to Fig. 5, in particular, in the present embodiment, step a is performed, and an air inlet channel 5 for injecting gasifying agent, an air outlet channel 6 for discharging gas and connecting the air inlet channel 5 and The gasification channel 7 of the gas outlet channel 6, the coal seam in the gasification channel 7 is gasified and burned to generate coal gas. In addition, a sleeve 13 is provided on the inner wall of the intake passage 5 , that is, the gasification agent does not contact the inner wall of the intake passage 5 after injection, but contacts the inner peripheral wall of the sleeve 13 . Before performing step b, according to the geological conditions of the coal seam on site (in this embodiment, the strata are respectively as shown in Figure 5 from bottom to top: coal seam 15, roof rock formation 16, aquifer 17, upper overburden layer 18), The depth of the coal seam 15 in this embodiment is 280 meters, the average thickness of the coal seam is 8 meters, and the axial length of the cylindrical atomizer 2 is determined to be 9 meters. Considering the above geological conditions and preferably the middle position of the roof 16 at the open end of the cylindrical atomizer 2 is level, the cylindrical atomizer 2 is lowered to 500 mm from the bottom of the gasification channel 7 through the air inlet channel 5 . From this, it can be calculated that the total axial length of the water injection pipe 1 and the cylindrical atomizer 2 is 279.5 m. In addition, the cylindrical atomizer 2 in this embodiment is set as follows: 18 circles of nozzles are arranged on its wall, and 4 nozzles are evenly arranged in each circle of nozzles. In every two adjacent circles of nozzles, all the nozzles in the lower circle are opposite to each other. All nozzles in the upper circle are rotated by 10° (the circle closest to the closed end is the upper circle, and the circle farthest from the closed end is the lower circle). By analogy, a total of 18 circles of nozzles are arranged, a total of 72 nozzles, and the nozzles are conical nozzles penetrating through the wall of the atomizer 2.

Therefore, after determining how to determine the size of the gas injection device and the structure of the cylindrical atomizer according to the geological conditions, step b is performed, that is, using a hoist to connect a plurality of pipes used to form the water injection pipe 1 through flanges in sequence Afterwards, they are lowered one by one, and after being lowered to the designated position (that is, when the closed end of the cylindrical atomizer 2 is 500 mm from the bottom of the gasification channel 7), the flange connected to the water injection pipe 1 is connected to the flange of the casing 13. , and the inlet of the water injection pipe 1 is communicated with the surface sewage pool 10 through the sewage pump 11, and the gasification agent inlet of the casing 13 is connected with the gasification agent supply device (not shown in FIG. 5 ). The gasification agent 8 can enter the air intake channel 5 through a pipe between the gasification agent inlet and the gasification agent supply. Of course, the gas outlet channel 6 needs to be communicated with the water-gas separator 9, so that the gas discharged from the gas outlet channel 6 can be cooled by the water-gas separator 9, so that the water vapor therein is condensed into liquid water, and the gas 20 after removing the water vapor Proceed to the next device collection (not shown).

Step c is executed, the gasification agent is introduced through the air intake channel 5, and the gasification agent introduced at this time is air.

Execute step d to ignite the coal seam. After the gasification furnace is stabilized, pure oxygen (O ₂ ) and carbon dioxide (CO ₂ ) are used as gasification agents to continue to flow into the intake channel 5 . The two gases are mixed in a certain proportion to form the gasification agent of the gasifier, and a certain proportion of nitrogen (N ₂ ) can be properly added to adjust the concentration of pure oxygen and carbon dioxide. After the above-mentioned gasification agent is mixed in a certain proportion in the mixer, it can be passed into the air intake channel 5 according to the industrial production scheme. After the gasification agent passes through the reaction coal seam in the gasification passage 7, it first performs a combustion-oxidation reaction with the coal seam, which releases a large amount of heat and generates coal gas. After the combustion-oxidation reaction of the coal seam occurs, the heat released evaporates the water in the coal seam to form water vapor. The water vapor is cooled by the channel wall during the process of traveling along the gasification channel 7 and gathers at the bottom of the gas outlet channel 6, and is discharged to the ground along with the gas After being separated by the water-gas separator 9 on the ground, the gas is sent to the purification and desulfurization section through the pipeline for processing. The separated sewage is firstly stored in the sewage tank 10 .

When sewage that can be injected into the gas injection device is stored in the sewage pool 10, step e is performed, and water mist is sprayed into the air intake channel 5 through the gas injection device to absorb heat in the air intake channel 5 to form water vapor and enter the gasification channel 7 in. Specifically, after the sewage enters the water injection pipe 1 through the sewage pump, it flows into the cylindrical atomizer 2 along the axial direction of the pipe. The bottom of the pipe is sprayed out to the side through the nozzle, and all of it is converted into the kinetic energy of the water.

Due to the combustion and oxidation reaction of the coal seam, the inner wall of the casing 13 is heated and reaches a hot state. After the sewage atomized by the nozzle meets the hot inner wall of the casing 13, the sewage absorbs heat and is vaporized, reducing the wall temperature of the casing 13. The casing forms a cooling protection function, which protects the casing from the influence and damage of high temperature, realizes the resource utilization of sewage at the same time, and ensures the long-term operation of the underground gasifier.

In addition, this method can effectively ensure that the water vapor reaches the gasification working face in the gasification channel 7 and participates in the combustion of the coal seam. Since the combustion of water vapor and coal seam is an endothermic reaction, the temperature of the gasification working face can be effectively controlled by water vapor, preventing the ash from ash from adhering to the coal seam and hindering gasification due to the high temperature of the gasification working face. In addition, the reaction of water vapor and coal seam produces carbon monoxide and hydrogen, thereby improving the effective components in the gas and improving the quality of the gas.

The above are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (12)

1. a kind of gas injection device for underground coal gasification(UCG) is it is characterised in that include：

Water injection pipe (1)；

Tubular atomizer (2), its two ends is respectively set to unlimited openend and the blind end of closing, and in its wall upper measurement Its axis is provided with multiple nozzles (3)；

Wherein, the described openend of the tubular atomizer described in communication (2) of described water injection pipe (1)；

Described water injection pipe (1) and tubular atomizer (2) are arranged in inlet channel (5).

2. gas injection device according to claim 1 it is characterised in that

Axis direction along tubular atomizer (2) is provided with least one described nozzle of circle (3), and the nozzle (3) in same circle is uniformly In ground is arranged around described axis and is generally aligned in the same plane, described plane is perpendicular to the axis of tubular atomizer (2).

3. gas injection device according to claim 2 it is characterised in that

The plurality of nozzle (3) is arranged at least two circles around described axis, in often adjacent two circle nozzles up and down, in lower circle All nozzles are around described axis with respect to all nozzle rotary constant angles of upper circle.

4. gas injection device according to claim 1 it is characterised in that

The plurality of nozzle (3) is spirally arranged on the wall of described tubular atomizer (2), and often two neighboring described Nozzle (3) folds constant angle around described axis.

5. the gas injection device according to claim 3 or 4 it is characterised in that

Described constant angle is more than 5 ° and is less than 15 °.

6. gas injection device according to any one of claim 1 to 4 it is characterised in that

Described nozzle (3) is the bellmouth of insertion, along the direction pointing to its periphery wall from described tubular atomizer (2) internal perisporium Tapered.

7. gas injection device according to claim 1 is it is characterised in that also include：

It is arranged at the centralizer (4) on the periphery wall of described tubular atomizer (2).

8. a kind of underground coal gasification system, including：

Inlet channel (5), the gasification tunnel of outlet passageway (6), the described inlet channel of connection (5) and described outlet passageway (6) (7)；

It is characterized in that, also include：

The moisture separator (9) connecting with the gas outlet of described outlet passageway (6), described moisture separator (9) is provided with draining Mouthful；

The cesspool (10) connecting with described discharge outlet；

Stretch into the gas injection device (12) in described inlet channel (5), described gas injection device (12) is in the claims 1-7 Gas injection device described in any one；And

Connect the sewage pump (11) of water injection pipe (1) in described cesspool (10) and described gas injection device (12).

9. underground coal gasification system according to claim 8 it is characterised in that

Also include：The sleeve pipe (13) ordinatedly arranging with the inner wall shape of described inlet channel (5), described gas injection device (12) is stretched Enter in described sleeve pipe (13), in described sleeve pipe (13) and described gas injection device (12), between water injection pipe (1), space forms gasifying agent Injection channel；

Wherein, one end of described sleeve pipe (13) projects from described inlet channel (5) and is provided with first flange disk；

It is arranged with second flange disk on the periphery wall of entrance of described water injection pipe (1),

Described first flange disk is connected to described second flange disk.

10. the coal underground gasification method of gas injection device any one of a kind of use the claims 1-7, including following Step：

A. set up inlet channel, outlet passageway and connect described inlet channel and the gasification tunnel of described outlet passageway；

B. described gas injection device is stretched in described inlet channel；

C. pass through described inlet channel to inject combustion adjuvant and light coal seam；

D. gasifying agent is passed through by described inlet channel；

E. by nozzle in described gas injection device to water spray in described inlet channel, to absorb the heat shape in inlet channel Become vapor, described vapor is sent in gasification tunnel by the gasifying agent spraying into.

11. coal underground gasification methods according to claim 10 it is characterised in that

In described step b：The distance of the bottom apart from described gasification tunnel for the blind end of described tubular atomizer, is located at In the range of 300mm to 1000mm, and according to residing for coal seam geological conditions and coal seam thickness difference, select within the above range Suitable distance value.

12. coal underground gasification methods according to claim 10 are it is characterised in that also comprise the steps：

Collect the vapor in the coal gas discharged by described outlet passageway；

Described water vapor condensation is become aqueous water；

Described aqueous water is injected in gas injection device and sprays via described nozzle.