CN103711471B - Underground gasification furnace and the starting method of ground corollary system - Google Patents

Abstract

The invention relates to a start-up method of an underground gasification furnace and a matching system on the ground. The start-up method of the underground gasifier and the supporting system on the ground includes the following steps in sequence: injecting gasification agent into the underground gasifier and igniting the coal seam; when the oxygen consumption of the underground gasifier corresponds to the minimum start-up load of the air separation unit When the amount of oxygen produced is consistent, the air separation unit will be started, and the oxygen-enriched air composed of the mixture of oxygen and air discharged from the air separation unit will be sent to the underground gasifier as a gasification agent; adjust the total load of the underground gasifier After reaching the set load, the gas pretreatment device and the low-temperature methanol washing device are started, and the crude gas discharged from the underground gasification furnace is purified by the gas pre-treatment device and then sent to the low-temperature methanol washing device; The crude gas purified by the device is sent to the synthesis ring; the underground gasifier is adjusted to run at full load. The start-up method of the underground gasifier and the ground matching system of the present invention is highly efficient and low in consumption.

Description

Start-up method of underground gasifier and supporting system on the ground

technical field

The invention relates to the field of underground coal gasification, in particular to a method for starting up an underground gasification furnace and a ground supporting system.

Background technique

Underground coal gasification technology can produce air gas, water gas, semi-water gas and synthetic gas, etc., which can be applied to IGCC (integrated coal gasification combined cycle power generation system) power generation, industrial/civil gas, etc. Further underground coal gasification furnaces can match the ground The chemical plant is used for chemical synthesis to produce chemical products such as methanol and methane.

The underground gasifier produces chemical synthesis gas, usually using enriched oxygen or pure oxygen as the gasification agent. For a continuous production chemical system, it is necessary to ensure a continuous gasification agent supply during the start-up phase of the underground gasifier. However, the characteristic of underground gasifier is that the initial demand for gasification agent is relatively small, and the ground air separation unit and boiler usually need to have a certain load to operate normally. If it is too low, it will not be able to establish stable operation. The demand cannot meet the minimum start-up load requirements for air separation unit and boiler start-up. In addition, at the same time, for the production process that uses carbon dioxide and oxygen-enriched (composed of carbon dioxide and oxygen) as the gasification agent, carbon dioxide generally comes from the gas in the purification process (the gas is generally purified by a gas pretreatment device and a low-temperature methanol washing device in turn), while Only when the gas volume reaches a certain scale can the start-up requirements of the gas pretreatment device and the low-temperature methanol washing device be met, so that the carbon dioxide removed by the low-temperature methanol washing device can be used to provide carbon dioxide and oxygen enrichment for the underground gasifier. In addition, it should be pointed out that after the normal production of the underground gasifier, it is usually not possible to adjust the large load like the ground gasifier, especially the load cannot be adjusted from a large value to a small value, because this will cause gas The chemical process is unstable, and the produced syngas cannot meet the process requirements.

It can be seen that for a continuous production chemical system, it is necessary to combine the characteristics of the underground gasifier and the supporting system on the ground, and reasonably plan the start-up sequence of each device and the adjustment of the load of each device. Because it not only involves how to match with the supporting equipment on the ground, but also involves how to optimize the materials, personnel and funds of the entire process system on the ground. Therefore, how to start up and put into operation the underground gasification furnace in conjunction with the supporting surface system is a technical problem that needs to be solved urgently for the large-scale application of underground gasification technology.

Contents of the invention

In view of the problems existing in the related art, the object of the present invention is to provide an efficient and low-consumption method for starting up the underground gasifier and ground matching system.

In order to achieve the above purpose, the present invention provides a method for starting up an underground gasifier and ground supporting system, which includes the following steps in sequence: (s1) injecting gasification agent into the underground gasifier and igniting the coal seam; (s2) when the underground gasifier When the oxygen consumption of the furnace is consistent with the amount of oxygen produced corresponding to the minimum start-up load of the air separation plant, the air separation plant is started, and the oxygen-enriched air composed of oxygen and air discharged from the air separation plant is used as gasification (s3) After adjusting the total load of the underground gasifier to the set load, the gas pretreatment device and the low-temperature methanol washing device are started, and the crude gas discharged from the underground gasifier is pretreated After the device is purified, it is sent to the low-temperature methanol washing device; (s4) the synthesis loop starts up, and the crude gas purified by the low-temperature methanol washing device is sent to the synthesis loop; (s5) the air separation unit is adjusted to enter full-load operation to adjust the underground gas The chemical furnace is running at full load, and the gas pretreatment device, low-temperature methanol washing device and synthesis ring are adjusted to run at full load.

According to the present invention, the carbon dioxide removed by the low-temperature methanol washing device is mixed with the oxygen generated by the air separation device to form carbon dioxide-enriched oxygen; the carbon dioxide-enriched oxygen is sent to the underground gasification furnace as a gasifying agent.

According to the present invention, the volume concentration of oxygen in the carbon dioxide oxygen enrichment is 55%-80%.

According to the present invention, the minimum start-up load of the air separation plant is 30%.

According to the present invention, in step (s2), the load of the air separation unit is maintained within the range of 30%-70%.

According to the present invention, in step (s3): set the load within the range of 30%-50%.

According to the present invention, the total load of the underground gasifier is adjusted to the set load by adjusting the load of the air separation unit to the range of 30%-50% and adjusting the amount of gasification agent injected into the underground gasifier.

According to the present invention, after step (s3) and before performing step (s4), by increasing the load of the air separation unit and adjusting the amount of gasification agent injected into the underground gasifier, the total load of the underground gasifier is maintained at 50%- 70% range.

According to the present invention, when the air separation unit is operating at full load, its load is within the range of 70%-100%; when the underground gasifier is operating at full load, its total load is within the range of 70%-100%; When the processing device, low-temperature methanol washing device and synthesis ring are operating at full load, their loads are respectively in the range of 70%-100%.

According to the present invention, before the start-up of the gas pretreatment device, part or all of the crude gas discharged from the underground gasification furnace is sent to the flare for combustion.

According to the present invention, the air separation compressor in the air separation plant is a steam turbine compressor; and/or the crude gas compressor in the gas pretreatment device is a steam turbine compressor; and/or the low temperature methanol washing The carbon dioxide compressor is a steam turbine compressor.

According to the invention, part or all of the steam generated by the boiler is used to drive the steam turbocompressor.

According to the present invention, the carbon dioxide removed by the low-temperature methanol washing device, the oxygen generated by the air separation device and the steam generated by the boiler are mixed as a gasification agent and sent to the underground gasifier.

According to the present invention, before the start-up of the gas pretreatment device, part or all of the crude gas discharged from the underground gasification furnace is sent into the boiler as a blended fuel.

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

The start-up method of the underground gasifier and the ground supporting system of the present invention starts up each device in the ground supporting system successively, and gradually adjusts the load of each device in the underground gasifier and the ground matching system during this process, thus It can reduce the investment in the initial start-up of each device, the consumption of manpower and raw materials, thereby reducing the cost of operation and maintenance of the underground gasifier, and improving the efficiency and benefits of chemical production in cooperation between the underground gasifier and the ground supporting system. Specifically, start the air separation unit according to the oxygen demand of the underground gasifier, adjust the total load of the underground gasifier to meet the set load, start the gas pretreatment device and the low-temperature methanol washing device, and then start the synthesis loop to utilize The purified crude gas is used to produce gases such as methanol. After the above-mentioned devices are started up, the underground gasifier and the above-mentioned devices are adjusted to full-load operation to improve production efficiency.

The carbon dioxide removed by the low-temperature methanol washing unit is mixed with the oxygen generated by the air separation unit to form carbon dioxide enriched oxygen and sent to the underground gasifier as a gasification agent, which effectively recovers and utilizes carbon dioxide and reduces system carbon emissions The quantity improves the environmental benefits of the production process. In addition, before the start-up of the gas pretreatment device, part or all of the crude gas discharged from the underground gasifier can be used as the fuel for the boiler, which can improve energy utilization efficiency and reduce environmental pollution and production costs.

Description of drawings

Fig. 1 is the process flow chart of the first embodiment of the start-up method of applying the underground gasifier of the present invention and the supporting system on the ground;

Fig. 2 is a process flow diagram after the execution step (s2) is completed in the start-up method shown in Fig. 1;

Fig. 3 is a process flow diagram after the execution step (s3) is completed in the start-up method shown in Fig. 1;

Fig. 4 is the process flow diagram of the second embodiment of the start-up method applying the underground gasifier and the ground matching system of the present invention;

Fig. 5 is the schematic diagram of the underground gasifier of the third embodiment of the start-up method of the underground gasifier and the ground supporting system of the present invention;

Fig. 6 is the schematic diagram of the underground gasifier according to the fourth embodiment of the start-up method of the underground gasifier and ground supporting system of the present invention;

Fig. 7 is the schematic diagram of the underground gasifier according to the fifth embodiment of the start-up method of the underground gasifier and ground matching system of the present invention;

Fig. 8 is the process flow diagram of the sixth embodiment of the start-up method of the underground gasifier and ground supporting system of the present invention;

Fig. 9 is a process flow diagram after step (s2) is executed in the start-up method shown in Fig. 8;

FIG. 10 is a process flow diagram after step ( s3 ) is executed in the start-up method shown in FIG. 8 .

detailed description

First, each device used in the following examples will be briefly described.

Underground gasifier: the underground gasifier used in the present invention is coal with at least one inlet channel for injecting gasification agent, at least one gas outlet channel for discharging raw coal gas, and a gasification channel connecting the inlet channel and the gas outlet channel Underground gasifier. Among them, crude gas is produced by the combustion, gasification and pyrolysis of underground coal seams and gasification agents. Its main components are carbon monoxide, carbon dioxide, methane, hydrogen, nitrogen and hydrogen sulfide, and it also contains dust, tar, water vapor, phenol ammonia and other ingredients. In addition, the total load of the underground gasifier is the percentage of the crude gas output from the underground gasifier to the design capacity of the underground gasifier. The volume calculation, that is, the output unit is Nm ³ /h. If the underground gasifier has only one gas outlet channel, the total load of the underground gasifier is the output of crude gas discharged from the gas outlet channel. If the underground gasifier has multiple gas outlet channels, it is the sum of the output of crude gas discharged from all gas outlet channels. The designed production capacity is the designed crude gas output, which is the volume of crude gas that can be produced by the underground gasifier per unit time during the gasification process, which can be calculated according to the hydrogeological conditions and the structure of the underground gasifier.

Air separation unit: The air is pressurized by the air separation compressor of the air separation unit, and then part or all of the air is cooled and purified, and then enters the air separation rectification tower for separation, and finally oxygen and nitrogen are obtained. When air is needed as a gasification agent, it is only necessary to pressurize the air without cooling, purification and separation; when oxygen-enriched air (air and oxygen) is needed as a gasification agent, part of the air can be separated to obtain Oxygen is then mixed with another portion of air to obtain oxygen-enriched air. In the present invention, the start-up of the air separation unit starts the production process of sending compressed air to the rectification tower for the air separation compressor in the air separation unit to separate oxygen. Wherein, the air separation unit used in the present invention is an air separation unit known to those skilled in the art, utilizes this air separation unit to separate oxygen from the air as a part of the gasification agent for the underground gasifier to use, when the gasification agent When air is needed, use the air separation compressor in the air separation unit to generate compressed air and send it to the underground gasifier. The load of the air separation plant refers to the production capacity of the air separation plant. In this embodiment, the load of the air separation plant is the percentage of the volume of oxygen produced per unit time (in ^Nm3 /h) and the production capacity of the air separation plant , where, the production capacity of the air separation plant is the volume of oxygen that can be produced per unit time (unit: Nm ³ /h) according to the working conditions adopted in the design when the air separation unit leaves the factory. Of course, the unit of the above two numerical values may also be Nm ³ /min. Gas pretreatment device: the gas pretreatment device used in the present invention is a gas pretreatment device known to those skilled in the art, optionally, it includes crude gas washing and compression process, gas water separation process, phenol recovery process, mainly used It is used for dust removal, tar removal, and washing of some impurity gases (such as phenolic components). Specifically, the crude gas containing dust, tar, phenol ammonia and other impurity components discharged from the underground gasification furnace first enters the washing tower to contact with fresh water and reused waste water in countercurrent for washing and cooling, and the cooled tar water flows out from the bottom of the tower to be sent to the washing tower. To the gas-water separation process, the crude gas obtained from the top of the tower is sent to the activated carbon filter to capture a small amount of tar, and the crude gas after the tar is fully removed is separated by the gas-liquid separator and sent to the crude gas compressor after pressurization sent to the downstream purification unit. Among them, the load of the gas pretreatment device is the percentage of the volume of crude gas processed per unit time (unit: Nm ³ /h) and the design capacity of the gas pretreatment device for processing crude gas. The design capacity is based on the working conditions adopted in the design, The volume of crude gas that can be processed by the gas pretreatment device per unit time. The unit of the design capacity of the gas pretreatment device is Nm ³ /h. For example, if the design capacity is 120000Nm ³ /h (dry basis), when the volume of raw gas processed per unit time is 100000Nm ³ /h (dry basis), the load of the gas pretreatment device is 83%. The unit of the above two numerical values may also be Nm ³ /min.

Low-temperature methanol washing device: the low-temperature methanol washing device used in the present invention is a low-temperature methanol washing device known to those skilled in the art, which has the function of removing acid gases (such as hydrogen sulfide, carbon dioxide), and it may optionally include an ammonia washing tower , coolers, scrubbers. Specifically, the crude gas that has been preliminarily purified by the gas pretreatment device is first washed in the ammonia washing tower to fully remove the ammonia, and the ammonia-washed crude gas is heat-exchanged and cooled by a cooler to separate water. After the water is separated from the crude gas, it enters the lower section of the scrubber, which includes a desulfurization section and a decarbonization section. In the desulfurization section, the crude gas from which the water has been separated is washed with methanol to remove components such as hydrogen sulfide and part of carbon dioxide, and then enters the decarbonization section. The crude gas entering the decarbonization section does not contain sulfur, and the carbon dioxide component in the crude gas is washed with methanol at the top of the tower to be fully removed. The purified crude gas is drawn from the top of the tower and sent to the synthesis circle. Among them, the load of the low-temperature methanol washing device refers to the percentage of the volume of crude gas purified by the gas pretreatment device per hour (in Nm ³ /h) and the design capacity of the low-temperature methanol washing device. The design capacity refers to the volume of crude gas that can be processed per unit time according to the working conditions adopted in the design (referred to as working conditions), and the unit is Nm ³ /h. The unit of the above two numerical values may also be Nm ³ /min.

Synthetic coils: The synthetic coils used in the present invention are well known to those skilled in the art, which in the following examples optionally produce methane, methanol, dimethyl ether, olefins. For example, the carbon monoxide and a small amount of carbon dioxide and hydrogen in the crude gas purified by the low-temperature methanol washing device are generated by methanation under the action of a methanation catalyst. The reaction equation is: CO+3H ₂ =CH ₄ + H ₂ O; CO ₂ +4H ₂ =CH ₄ +2H ₂ O. If methanol is produced, the main reaction equation is: CO+2H ₂ =CH ₃ OH; CO ₂ +3H ₂ =CH ₃ OH+H ₂ O. Among them, the load of the synthesis circle refers to the percentage of the volume of the target product produced per hour (unit: Nm ³ /h) and the design capacity of the synthesis circle, and the design capacity of the synthesis circle refers to the production of the target product according to the working conditions adopted in the design volume, in Nm ³ /h. For example, the design capacity for producing methane is 40000Nm ³ /h. Of course, the units of the above numerical values may also be Nm ³ /min or ton/d.

Torch: The torch used in the present invention is well known to those skilled in the art. It is an important safety and environmental protection facility in a chemical plant, and is mainly used to deal with combustible gases that cannot be effectively recovered under production equipment shutdown, abnormal production and emergency conditions. .

Boiler: The boiler used in the present invention is well known to those skilled in the art. It is an energy conversion device that inputs fuel into the boiler, converts it through the boiler, and outputs steam with certain heat energy. The load of the boiler is the percentage of the volume of steam produced per hour (in Nm ³ /h) and the design capacity of the boiler. Among them, the design capacity of the boiler refers to the volume of steam produced by the boiler per unit time according to the working conditions adopted in the design, and the unit is Nm ³ /h. The above numerical units may also be Nm ³ /min, ton/h, ton/d.

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

Referring to Fig. 1 , an embodiment of the method for starting up the underground gasifier and ground supporting system of the present invention includes the following steps in sequence.

Executing step (s1): injecting a gasifying agent into the underground gasifier and igniting the coal seam. Wherein, the underground gasifier is an underground gasifier that has been established in a gasification area to be developed before step (s1) is performed. The specific layout of the underground gasifier depends on the specific geological and hydrological conditions such as the direction, tendency, development of cracks, and water inflow of the coal seam in the gasification area to be developed. In the layout area of the underground gasifier, drilling is carried out from the ground to the coal seam to establish the inlet channel, the gas outlet channel and the gasification channel, etc. According to the coal seam structure, the ignition area is selected, and the underground gasifier is ignited to ignite the coal seam. During the ignition process of the underground gasifier, the injected gasification agent is, for example, air or oxygen, and after the coal seam is ignited, the combustion of the coal seam can be regulated by adjusting the oxygen content in the gasification agent. Optionally, air is used as the gasification agent when igniting the coal seam. After the coal seam is ignited, the oxygen-enriched air that gradually becomes air and oxygen is used as the gasification agent. In this embodiment, the air and oxygen mentioned above are provided by equipment known to those skilled in the art.

Execution step (s2): When the oxygen consumption of the underground gasifier is consistent with the amount of produced oxygen corresponding to the minimum start-up load of the air separation plant, the air separation plant is started. Specifically, the "start-up load of the air separation unit" is equal to the percentage obtained by dividing the "amount of oxygen produced by the air separation unit" by the "capacity of oxygen production by the air separation unit". When the "start-up load of the air separation unit" is equal to the "minimum start-up load of the air separation unit (for example, 30%)", there is a corresponding "amount of oxygen produced by the air separation unit". Further, for the air separation plant, the amount of oxygen produced by the air separation plant is the volume of oxygen produced per unit time. When it reaches a certain value, the stable operation of the air separation plant can be established, and due to the production of the air separation plant The capacity (the ability to produce oxygen) is known, so the volume of oxygen produced by the air separation plant per unit time corresponds to the load of the air separation plant. In addition, the gasification agent sent to the underground gasifier is configured according to a certain ratio, that is, the volume percentage of oxygen and air in the gasification agent is known, when the total consumption of gasification agent (gas consumed per hour After determining the volume of the chemical agent, the unit is Nm ³ /h), the oxygen consumption and air consumption can be calculated and determined. Among them, the oxygen consumption is the volume of oxygen consumed per hour (the unit is Nm ³ /h), and the air Consumption is the volume of air consumed per hour (in Nm ³ /h). It can be understood that the oxygen consumption of the underground gasifier is how many standard cubic meters of oxygen are consumed per hour, and the volume of oxygen produced by the air separation unit per unit time is how many standard cubic meters of oxygen can be produced per hour. When the air separation unit per hour When the volume of oxygen produced meets the volume of oxygen needed by the underground gasifier per hour, the air separation unit will be started, thereby ensuring the stable operation of the air separation unit.

In addition, in this embodiment, when the air separation unit is started, the compressed air produced by the air separation compressor in the air separation unit and the oxygen-enriched air composed of oxygen separated from the rectification tower are injected into the underground gasification as a gasification agent In the furnace, it can be understood that at this time, the gasification agent fed into the underground gasifier is provided by the air separation unit. The gasification agent injected into the underground gasifier before the start-up of the air separation unit. Optionally, the compressed air produced by the air separation compressor and the oxygen separated from the rectification tower are first sent to the gas mixer, mixed in a certain proportion to form a gasifying agent, and the gasifying agent can be injected into the ground with a flow rate controllable In the intake channel of the gasifier. Of course, according to the operating conditions of the underground gasifier, the ratio of oxygen and air in the above-mentioned oxygen-enriched air can be adjusted. In an optional embodiment, only air or oxygen may be introduced according to the operating conditions of the underground gasifier.

In this embodiment, the air separation compressor in the air separation plant is a steam turbine compressor, and steam is provided to the steam turbine compressor through a boiler. Therefore, before the start-up of the air separation unit, the steam boiler is started up to provide steam for the steam turbine of the air separation compressor.

Further, after the start-up of the air separation unit in step (s2), before the start-up of the gas pretreatment unit and the low-temperature methanol washing unit in step (s3), some or all of the crude gas produced by the underground gasifier can be sent to the flare for combustion and emission Or part or all of it is sent to the boiler as a co-firing fuel. Since the underground gasification furnace is not operating at full capacity at this time, and the underground gasification furnace is in the initial stage of operation, the effective component content of the crude gas is low, so introducing it into the torch combustion can effectively prevent its emission from polluting the air. And using crude gas as the dye for boiler blending can improve energy utilization efficiency and reduce environmental pollution and production costs.

In addition, after the air separation plant is started, the load of the air separation plant is maintained within the range of 30%-70%. In this embodiment, the load of the air separation plant is maintained within the range of 30%-50%. Among them, the amount of gasification agent in the underground gasification furnace can be adjusted, or the number of sub-gasification furnaces put into operation in the underground gasification furnace. Of course, other methods can also be used to control the load of the air separation unit, for example, adjusting the load of the boiler.

In summary, with reference to Fig. 2, after step (s2) is performed, the start-up method of the present invention forms the process flow shown in Fig. 2, that is, the boiler provides steam for the air separation unit, and the oxygen produced after the start-up of the air separation unit The oxygen-enriched air composed of air is used as a gasification agent and sent to the underground gasifier through the pipe network, and a part of the crude gas produced by the underground gasifier is sent to the flare for combustion and emission, and the other part is sent to the boiler as a blended fuel.

Execution step (s3): Based on the water inflow of the gasifier, the thickness of the coal seam, the composition and calorific value of the crude gas, and the gasification efficiency, adjust the injection flow rate of the gasification agent, thereby increasing the total load of the underground gasifier until its equal to the set load. Specifically, in the process of underground coal gasification, the water inflow of the gasifier, the thickness of the coal seam and the injection flow rate of the gasification agent have a certain functional relationship, that is, under a certain thickness of the coal seam and water inflow, there is an optimal gasification Chemical injection flow. In the actual gasification process, the composition and calorific value of the crude gas discharged from the gas outlet channel of the underground gasifier and the gasification efficiency can be used to determine whether the injection flow rate of the gasification agent is appropriate. Thus, the injection flow rate of the gasification agent can be adjusted to promote the combustion of the coal seam through the crude gas composition, calorific value and gasification efficiency, thereby increasing the total load of the underground gasifier.

In this embodiment, the aforementioned set load is 50%. Specifically, by adjusting the load of the air separation unit to 50% and adjusting the amount of gasification agent injected into the underground gasifier, the total load of the underground gasifier is adjusted to the set load. Thus, by adjusting the load of the air separation unit to 50%, the amount of oxygen provided by the air separation unit can be controlled to meet the oxygen demand in the process of increasing the total load of the underground gasifier. The amount of the agent can control the combustion status in the underground gasifier, thereby gradually increasing the combustion of the coal seam and increasing the output of crude gas.

When the total load of the underground gasifier reaches the above-mentioned set load, the gas pretreatment device and the low-temperature methanol washing device are started, and the crude gas discharged from the underground gasifier is passed into the gas pretreatment device for purification, namely dust removal, tar removal, Part of the impurity gas is washed, such as phenolic components, and the crude gas purified by the above process is dehydrated and pressurized, and then sent to a low-temperature methanol washing device for further purification to remove acid gas hydrogen sulfide and carbon dioxide. The carbon dioxide removed by the low-temperature methanol washing unit is mixed with the oxygen generated by the air separation unit to form carbon dioxide enriched oxygen, and the carbon dioxide enriched oxygen is sent to the underground gasifier as a gasification agent. It can be understood that the above-mentioned carbon dioxide enriched oxygen replaces the oxygen-enriched air composed of air and oxygen provided by the air separation unit before the start-up of the gas pretreatment unit and the low-temperature methanol washing unit as the gasification agent, in other words, the gasification of the underground gasifier The agent is carbon dioxide enriched with oxygen. Optionally, the volume concentration of oxygen in the carbon dioxide enriched oxygen is 55%-80%. Of course, it is not limited to this embodiment, and it can be understood that whether to use carbon dioxide to enrich oxygen and when to use carbon dioxide to enrich oxygen is based on the actual operation of the underground gasifier. When there is no need to use carbon dioxide to enrich oxygen, oxygen-enriched air can continue to be used as gasification agent.

In this embodiment, a steam turbine compressor is used as a crude gas compressor in the gas pretreatment device to pressurize the crude gas. And, steam is supplied to the steam turbocompressor using the above-mentioned boiler. The low-temperature methanol washing device includes a carbon dioxide compressor, which compresses the removed carbon dioxide and sends it to the underground gasifier. Preferably, the carbon dioxide compressor is a steam turbine compressor, and the above-mentioned boiler is used to provide steam for the steam turbine compressor. Therefore, before the start-up of the gas pretreatment device and the low-temperature methanol washing device, a step of adjusting the load of the boiler is also included to provide steam for the crude gas compressor and the carbon dioxide compressor.

In summary, with reference to Fig. 3, after step (s3) is executed, the start-up method of the present invention forms the process flow shown in Fig. 3, that is, the boilers are respectively the air separation compressor and the gas pretreatment device in the air separation plant The crude gas compressor in the low-temperature methanol washing unit and the carbon dioxide compressor in the low-temperature methanol washing unit provide steam to drive the turbine, and the oxygen produced by the rectifying tower in the air separation unit and the carbon dioxide removed by the low-temperature methanol washing unit form carbon dioxide and oxygen-enriched gas. The chemical agent is sent to the underground gasifier. The crude gas produced by the underground gasifier is purified by the gas pretreatment device and the low-temperature methanol washing device and then discharged. The purified crude gas mainly contains hydrogen and carbon monoxide.

Optionally, after step (s3) and before step (s4), by increasing the load of the air separation unit and adjusting the amount of gasification agent injected into the underground gasifier, the total load of the underground gasifier is maintained at 50%— 70% range. That is, by increasing the amount of oxygen provided by the air separation unit and adjusting the flow rate of the gasification agent injected into the underground gasifier, the combustion of the coal seam in the underground gasifier is promoted, thereby gradually increasing the crude gas output of the underground gasifier until the load Reach the range of 50%-70%, and maintain it no more than 70%.

Execution step (s4): When the total load of the underground gasifier is stable within the range of 50%-70%, the synthesis loop starts up, and the crude gas purified by the low-temperature methanol washing device is sent into the synthesis loop. Among them, if the volume change rate of gas components is less than or equal to 0.5% and the change rate of gas production is less than 15% within 24 hours, it means that the operation of the underground gasifier is stable.

In summary, continue to refer to Fig. 1, after step (s4) is executed, the boilers are respectively the air separation compressor in the air separation unit, the crude gas compressor in the gas pretreatment unit and the carbon dioxide compressor in the low temperature methanol washing unit Steam is provided to drive the turbine, and the gasification agent is composed of oxygen produced by the rectification tower in the air separation unit and carbon dioxide removed by the low-temperature methanol washing unit, and sent to the underground gasifier, and the crude gas produced by the underground gasifier is passed through The gas pretreatment device and the low-temperature methanol washing device are purified and discharged to the synthesis circle. The purified gas mainly contains hydrogen and carbon monoxide. In the synthesis cycle, the production of methane, methanol, dimethyl ether or olefins can be done.

Step (s5): Adjust the full load operation of the air separation unit to adjust the full load operation of the underground gasifier, and adjust the full load operation of the coal gas pretreatment device, low temperature methanol washing device and synthesis ring. Among them, when the air separation unit is operating at full load, its load is within the range of 70%-100%; when the underground gasifier is operating at full load, its total load is within the range of 70%-100%; the gas pretreatment device When running at full load, its load is in the range of 70%-100%; when the low-temperature methanol washing device is running at full load, its load is in the range of 70%-100%; In the range of 70%-100%.

To sum up, in this embodiment, during the process from step (s1) to step (s3), the total load of the underground gasifier is gradually increased to 50%, and after step (s4) is completed, the underground The total load of the gasifier is gradually increased to the range of 50%-70%, and it maintains a stable operation. In performing step (s5), the total load of the underground gasifier is increased to a range of 70%-100%. In the process of gradually increasing the total load of the underground gasifier, the boiler, air separation unit, gas pretreatment unit, low-temperature methanol washing unit, and synthesis loop will be gradually started up, and the load of each unit will be gradually increased accordingly.

Therefore, through the above start-up method, each device in the ground supporting system is started up successively, and the load of each device in the underground gasifier and the ground supporting system is gradually adjusted during this process, thereby reducing the initial cost of starting up each device. Investment, manpower and raw material consumption, thereby reducing the cost of operation and maintenance of underground gasifiers, and improving the efficiency and benefits of chemical production in cooperation between underground gasifiers and ground supporting systems. Specifically, start the air separation unit according to the oxygen demand of the underground gasifier, adjust the total load of the underground gasifier to meet the set load, start the gas pretreatment device and the low-temperature methanol washing device, and then start the synthesis loop to utilize The purified crude gas is used to produce gases such as methanol. After the above-mentioned devices are started up, the underground gasifier and the above-mentioned devices are adjusted to full-load operation to improve production efficiency.

In addition, the carbon dioxide removed by the low-temperature methanol washing unit is mixed with the oxygen generated by the air separation unit to form carbon dioxide-enriched oxygen, which is sent to the underground gasifier as a gasification agent, which effectively recovers and utilizes carbon dioxide and reduces the system cost. Carbon emissions, improving the environmental benefits of the process.

Referring to FIG. 4 , the second embodiment of the present invention, the similarities with the above-mentioned first embodiment will not be repeated. In this embodiment, in order to obtain better effective components of the coal gas, water vapor can be appropriately added to the gasification agent according to the differences in the melting point of coal seam ash, water content, and temperature of the gasifier. When it is necessary to adjust the effective components in the crude gas produced by adding steam, the carbon dioxide removed by the low-temperature methanol washing unit, the oxygen generated by the air separation unit and the steam generated by the boiler are mixed and fed into the gasification agent. Underground gasifier. It can be understood that the gasification agent composed of oxygen, carbon dioxide and water vapor replaces the previously used gasification agent, that is, the gasification agent composed of oxygen, carbon dioxide and water vapor replaces the carbon dioxide enriched with oxygen. In other words, at this time, all the gasification agents injected into the underground gasifier are gasification agents composed of oxygen, carbon dioxide and water vapor. Of course, it can be understood that whether the gasification agent contains water vapor and when to use the gasification agent with water vapor is based on the actual operation of the underground gasifier.

Referring to Fig. 5, it schematically shows the underground gasifier of the third embodiment of the start-up method of the underground gasifier and the ground matching system of the present invention.

Before step (s1) is performed, an underground gasifier is set up. Specifically, in this embodiment, n sub-gasifiers are established in the mine area where gasification is scheduled, and n depends on the coal reserves in the mine area, the design size of the underground gasifier, and the production scale of syngas. As shown in Figure 4, each sub-gasifier is composed of one directional borehole and one vertical borehole. The directional borehole is composed of coiled tubing and supporting devices and is used as the inlet channel a, and the vertical hole is used as the outlet channel b. The inlet passage a and the outlet passage b communicate through the gasification passage c. In this way, the establishment of a sub-gasifier is completed. In this embodiment, n sub-gasifiers constitute an underground gasifier. And in Fig. 4, there is an isolated coal pillar between the first sub-gasifier 1, the second sub-gasifier 2, and the nth sub-gasifier n.

Execution step (s1): Lower the ignition device from the gas outlet channels of the n sub-gasifiers, use silane and methane to ignite and inject gasification agent to ignite the coal seam, and use thermocouples to detect the temperature to confirm the coal seam is ignited. The production is carried out by the controlled retreat of the injection point (CRIP) gasification process, which injects oxygen (i.e. gasification agent) through the coiled tubing to maintain the combustion and gasification of the coal seam, and retreats through the coiled tubing in a controlled manner (from the gas outlet channel to the The direction of the air intake channel) to control the position of coal seam combustion and gasification, and the distance of one retreat depends on the size of the expansion of the combustion space and the gas injection capacity of the gasification agent. In this embodiment, the aforementioned oxygen is provided by equipment known to those skilled in the art.

Execute step (s2): When the oxygen consumption of the underground gasifier is consistent with the amount of oxygen produced corresponding to the minimum start-up load of the air separation unit, the boiler starts up and provides the ventilation for the air separation compressor in the air separation unit. Ping provides steam, after which the air separation unit starts. , in this embodiment the minimum driving load is 30%. The air separation compressor is started, and the air pressurized by the air separation compressor and the oxygen separated from the rectification tower are composed of oxygen-enriched air. Then it is transported to the fire area through the coiled oil pipe, and the crude gas produced by each sub-gasifier is sent to the flare for burning and discharging through the gas outlet channel. Wherein, after the air separation unit is started up, the oxygen-enriched air composed of the air pressurized by the air separation compressor in the air separation unit and the oxygen separated by the rectification tower replaces the above-mentioned oxygen as the gasification agent, that is, at this time The gasification agent injected into each gasification furnace is only the air pressurized by the above-mentioned air separation compressor. Preferably, in the oxygen-enriched air, the volume concentration of oxygen is 35%.

Executing step (s3): adjusting the load of the boiler and the air separation compressor so that the load of the air separation unit can be adjusted within the range of 30%-50%. And according to the water inflow of the gasifier, the thickness of the coal seam, the calorific value of the coal gas, the gasification efficiency, etc., adjust the amount of gasification agent injected into the underground gasifier, so that the total load of the underground gasifier gradually reaches the range of 30%-50% Inside. After the commissioning operation is stable, that is, within 24 hours, when the volume change rate of the gas component is less than or equal to 0.5% and the change rate of the gas output is less than 15%, adjust the steam load of the boiler to be the crude gas in the gas pretreatment device The compressor provides steam to drive the turbine, and the gas pretreatment device starts up. The gas pretreatment device washes the gas to remove impurities such as tar, dust, phenol and ammonia in the gas, and then separates the water from the crude gas and pressurizes the crude gas by the crude gas compressor. After the gas pretreatment device is started up, the low-temperature methanol washing device is started up, and the raw gas sent in after being purified by the gas pre-treatment device is removed by the low-temperature methanol washing device to remove acid gases such as hydrogen sulfide and carbon dioxide. Among them, adjust the steam load of the boiler and start Carbon dioxide compressor, which pressurizes carbon dioxide and transports it to the underground gasifier, mixes it with the oxygen delivered by the air separation unit to make carbon dioxide enriched with an oxygen volume concentration of 55%-80%, and replaces oxygen-enriched air as a gasification agent. In other words, in this embodiment, in order to adjust the combustion of the coal seam in the underground gasifier and increase the content of effective components in the crude gas produced, carbon dioxide and oxygen are used as the gasification agent instead of the air used as the gasification agent before , that is, the gasification agents passed into the underground gasifier are carbon dioxide and oxygen.

After the boiler, air separation unit, gas pretreatment unit, and low-temperature methanol washing unit start up, gradually increase the load of the air separation unit, increase the oxygen supply, and adjust the flow rate of gasification agent injected into each sub-gasifier accordingly (ie, air intake), so as to increase the load of part or all of the sub-gasifiers, and maintain the total load of the underground gasifier within the range of 50% to 70%. Specifically, in the actual operation process, each sub-gasifier can optionally use an independent air intake control system, such as adjusting the opening of the air intake drilling valve, to change the intake air volume of each sub-gasifier, thereby controlling the air intake of each sub-gasifier. The production load of sub-gasifiers, and then control the total load of underground gasifiers. Execution step (s4): After the commissioning operation is stable, that is, within 24 hours, when the volume change rate of gas components is less than or equal to 0.5% and the change rate of gas production is less than 15%, the synthetic circle starts. The crude gas produced by the underground gasifier is sent to the synthesis circle after being purified by the gas pretreatment device and the low-temperature methanol washing device. So far, the entire underground gasifier and the ground supporting system have been started and put into operation, and the production process has been opened, that is, the production of the above-mentioned methanol and other gases.

Execution step (s5): gradually adjust each sub-gasifier, air separation unit, gas pretreatment unit, low-temperature methanol washing unit and synthesis ring to full-load operation. Among them, when the air separation unit is operating at full load, its load is within the range of 70%-100%; when each sub-gasifier is operating at full load, its load is within the range of 70%-100%; the gas pretreatment device When running at full load, its load is in the range of 70%-100%; when the low-temperature methanol washing device is running at full load, its load is in the range of 70%-100%; In the range of 70%-100%.

Referring to Fig. 6, it schematically shows the underground gasifier of the fourth embodiment of the start-up method of the underground gasifier and ground supporting system of the present invention.

Before step (s1) is performed, an underground gasifier is established. In this embodiment, an underground gasifier is built on the selected gasification coal field. The size of the underground gasifier and its structural layout depend on the coal reserves, the daily output of crude gas, and the exhaust volume of each borehole. , The designed production period of the underground gasifier and the hydrological and geological conditions of coal seam occurrence. The number of drill holes in each row is determined according to the output of crude gas (unit: Nm ³ /h) and the hourly exhaust capacity of each drill hole; according to the design service period of the underground gasifier, it is decided to drill several rows of drill holes. If the crude gas output of one underground gasifier cannot reach the designed output, more than two underground gasifiers can work in parallel to produce crude gas at the same time. Figure 6 shows an underground gasifier, which is composed of several rows of boreholes, all of which are vertical holes, generally 10 to 12 holes per row, depending on the scale of crude gas production and the per hour per hole. exhaust capacity. The first three rows of drilling shall be constructed first, and the construction of the supporting pipe network on the ground shall be completed. After the above-mentioned vertical holes are established, the boiler is started to provide steam for the turbine of the air separation compressor. Afterwards, the air separation compressor is started, and the pressurized air is transported to the underground gasifier through the pipe network, and the 11' and 12' holes are coldly fractured to establish communication between the two holes, and 11' is selected as the gas outlet channel , 12' is used as an air intake channel, and ignition is carried out in the 11' borehole to ignite the coal seam. After the ignition is successful, use reverse fire penetration to form a gasification channel after reaming between the 11' and 12' boreholes, and simultaneously perform fracturing in the 13' and 12' boreholes. According to this method, other vertical holes on the row are gradually penetrated, and this row of drilled holes is used as the gas outlet channel of the underground gasifier.

Afterwards, the second row of boreholes is cold-fractured, and the reverse fire penetration method is used to establish passages connected with the gas outlet boreholes of the above-mentioned underground gasifier, such as 21' and 11', 22' and 12' boreholes, etc. . Thus, the communication between the second row of boreholes and the first row of boreholes is established in turn, and the second row of boreholes are used as air intake passages, so that each borehole in the first row is connected with the corresponding second row of boreholes in the first row. Each borehole constitutes a sub-gasifier. During the establishment of the two rows, the air separation compressor in the air separation unit is powered on to provide it with pressurized air through it, and provides air as a gasification agent when it is reversed through. During this process, the rectification tower of the air separation unit has not started to operate, that is, the production process of sending the compressed air discharged from the air separation compressor to the rectification tower to separate oxygen has not started, so the air separation unit has not been started. Among them, cold fracturing is an operation method to establish a gas flow connection between two vertical boreholes. Specifically, it refers to pressing high-pressure air into a vertical borehole. Since the coal seam has certain pores and cracks, when the air pressure reaches a After that, air can flow in the coal seam and out the other borehole, so that the two boreholes are connected in the coal seam.

Execution step (s1): In this embodiment, the penetration and gasification process of the underground gasifier are carried out continuously, so the flame during the penetration process can continue to ignite the coal seam while injecting air, so that it enters the forward gasification. That is, the compressed air discharged from the air separation compressor is used as the gasification agent along the intake pipe, and the gasification agent is sent into the gasification channel through the branch pipe along the intake pipe, and the forward gasification begins. During the gasification process, oxygen and air are gradually mixed and sent into the gasification channel. The crude gas produced is sent into the gas outlet pipeline through the branch pipe along the gas outlet borehole. In this embodiment, the aforementioned oxygen is provided by equipment known to those skilled in the art.

Execution step (s2): When the oxygen consumption of the underground gasifier is consistent with the amount of produced oxygen corresponding to the minimum start-up load of the air separation unit, the air separation unit starts up. Oxygen and air produced by the air separation unit are injected into the underground gasifier as gasification agents. Among them, in order to maintain the continuity of the gasification process, while the gasification is being carried out, the third row of boreholes is synchronously penetrated, and the second row of boreholes establishes a channel in the coal seam to communicate with each other; while the subsequent rows of boreholes are carried out simultaneously. Drilling or construction preparation stage. In this embodiment, the minimum start-up load is equal to 30%.

Execute step (s3): adjust the boiler load and the load of the air separation compressor (the load of the air separation compressor is the volume of compressed air produced per hour, in Nm ³ /h), so that the load of the air separation unit is adjusted to 30 %—50%. According to the water inflow of the gasifier, the thickness of the coal seam, the calorific value of the coal gas, and the gasification efficiency, etc., the amount of gasification agent injected into the underground gasifier is adjusted so that the total load of the underground gasifier gradually reaches 30%-50%. After the commissioning operation is stable, that is, within 24 hours, when the volume change rate of the gas component is less than or equal to 0.5% and the change rate of the gas output is less than 15%, adjust the load of the boiler to provide a drive for the crude gas compressor. Flat air, gas pre-conditioner to drive. The gas pretreatment device washes the gas, removes impurities such as tar, dust, phenol and ammonia in the gas, and pressurizes after separating the water. After the gas pretreatment device is started up, the low-temperature methanol washing device is started up, and the raw gas sent in after being purified by the gas pre-treatment device is removed by the low-temperature methanol washing device to remove acid gases such as hydrogen sulfide and carbon dioxide. Among them, adjust the steam load of the boiler and start The carbon dioxide compressor transports carbon dioxide to the underground gasifier after pressurization, and mixes it with the oxygen delivered by the air separation unit to make carbon dioxide enriched with an oxygen volume concentration of 55%-80%, replacing oxygen-enriched air as a gasification agent. After the boiler, air separation unit, gas pretreatment unit, and low-temperature methanol washing unit start up, gradually increase the load of the air separation unit to 50% to increase the oxygen supply, and adjust the air intake of each sub-gasifier accordingly (gas Injection flow rate of gasification agent), so as to increase the load of part or all of the sub-gasifiers, so that the total load of the underground gasifier can be maintained at 50% to 70%.

Execution step (s4): After the commissioning operation is stable, that is, within 24 hours, when the volume change rate of gas components is less than or equal to 0.5% and the change rate of gas production is less than 15%, the synthetic circle starts. The crude gas produced by the underground gasifier is sent to the synthesis circle after being purified by the gas pretreatment device and the low-temperature methanol washing device. So far, the entire underground gasifier and the ground supporting system have been started and put into operation, and the production process has been opened up.

Execution step (s5): gradually adjust each sub-gasifier, air separation unit, gas pretreatment unit, low-temperature methanol washing unit and synthesis ring to full-load operation. Among them, when the air separation unit is running at full load, its load is 70%-100%; when each gasifier is running at full load, its load is 70%-100%; when the gas pretreatment device is running at full load, Its load is 70%-100%; when the low-temperature methanol washing device is running at full load, its load is 70%-100%; when the synthesis ring is running at full load, its load is 70%-100%.

Referring to Fig. 7, it schematically shows the underground gasifier of the fifth embodiment of the start-up method of the underground gasifier and the ground matching system of the present invention.

Before step (s1) is performed, an underground gasifier is set up. In this embodiment, the underground gasifier is a multi-column gasifier, which is composed of a plurality of directional boreholes, generally 4 to 6, and the directional boreholes are arranged in parallel, and the ends are connected by another directional borehole , the end of the directional drill includes at least one vertical borehole, and the number of boreholes depends on the design capacity of the underground gasifier and the exhaust capacity of the borehole. First construct the 1st column, the 2nd column directional drilling, and the vertical drilling; after that, lower the ignition device in the vertical drilling to ignite the coal seam. After the ignition is successful, first, start the boiler, start the air separation compressor, and transport the air to the underground gasifier through the pipe network. The vertical drilling is used as the air outlet channel b'', and the directional drill is used as the air intake channel a''. Carry out reverse fire penetration, process directional drilled horizontal channel as the gasification channel c'' of the gasifier, and use the gas outlet channel to send the crude gas produced by the underground gasifier to the flare for combustion and discharge. After the construction of the channel is completed, the compressed air discharged from the air separation compressor is used as the gasification agent, and it is sent to the underground gasification furnace to start the forward gasification, and in the process, oxygen and the above air are gradually mixed as the gasification agent The gas is sent to the underground gasifier, and the gas produced is sent into the main gas pipeline through the branch pipe along the gas outlet borehole. In order to maintain the continuity of the gasification process, while the gasification is in progress, the second directional drilling is constructed synchronously; and the subsequent directional drilling is simultaneously carried out in the drilling or construction preparation stage. In this embodiment, the aforementioned oxygen is provided by equipment known to those skilled in the art.

In this embodiment, step (s2) to step (s5) are the same as those in the third embodiment, and will not be repeated here.

Referring to FIG. 8 , it shows a process flow diagram of the sixth embodiment of the start-up method of the underground gasifier and ground matching system of the present invention.

Executing step (s1): injecting a gasifying agent into the underground gasifier and igniting the coal seam. Wherein, the underground gasifier is an underground gasifier that has been established in the gasification area to be developed before step (s1) is performed. The specific layout of the underground gasifier depends on the specific geological and hydrological conditions such as the direction, tendency, development of cracks, and water inflow of the coal seam in the gasification area to be developed. In the layout area of the underground gasifier, drilling is carried out from the ground to the coal seam to establish the inlet channel, the gas outlet channel and the gasification channel, etc. According to the coal seam structure, the ignition area is selected, and the underground gasifier is ignited to ignite the coal seam. During the ignition process of the underground gasifier, the injected gasification agent is, for example, air or oxygen, and after the coal seam is ignited, the combustion of the coal seam can be regulated by adjusting the oxygen content in the gasification agent. Optionally, air is used as the gasification agent when igniting the coal seam. After the coal seam is ignited, the oxygen-enriched air that gradually becomes air and oxygen is used as the gasification agent.

Execution step (s2): When the oxygen consumption of the underground gasifier is consistent with the amount of oxygen produced corresponding to the minimum start-up load of the air separation plant, the air separation plant is started. In this embodiment, the air separation plant’s The minimum driving load is equal to 30%.

In addition, when the air separation unit is started up, the oxygen-enriched air composed of the mixture of oxygen and air discharged from the air separation unit is sent to the underground gasifier as a gasification agent. In this embodiment, the pressurized air produced by the air separation compressor in the air separation unit and the oxygen-enriched air composed of oxygen separated by the rectification tower are injected into the underground gasifier as a gasification agent. It can be understood that, At this time, the gasification agent fed into the underground gasifier is provided by the air separation unit. Gasification agent for underground gasifier. Optionally, the compressed air produced by the air separation compressor and the oxygen separated from the rectification tower are first sent to the gas mixer, mixed in a certain proportion to form a gasifying agent, and the gasifying agent can be injected into the ground with a flow rate controllable In the intake channel of the gasifier. Of course, according to the operating conditions of the underground gasifier, the ratio of oxygen and air in the above-mentioned oxygen-enriched air can be adjusted. In an optional embodiment, only air or oxygen may be introduced according to the operating conditions of the underground gasifier.

In this embodiment, the air separation compressor in the air separation plant is a steam turbine compressor, and steam is provided to the steam turbine compressor through a boiler. Therefore, before the start-up of the air separation unit, the steam boiler is started up to provide steam for the steam turbine of the air separation compressor.

Further, after the start-up of the air separation unit in step (s2), before the start-up of the gas pretreatment unit and the low-temperature methanol washing unit in step (s3), some or all of the crude gas produced by the underground gasifier can be sent to the flare for combustion and emission Or part or all of it is sent to the boiler as a co-firing fuel.

In addition, after the air separation unit is started, the load of the air separation unit should be maintained within the range of 30%-50%. Among them, the amount of gasification agent in the underground gasification furnace can be adjusted, or the number of sub-gasification furnaces put into operation in the underground gasification furnace. Of course, other methods can also be used to control the load of the air separation unit, for example, adjusting the load of the boiler.

In summary, with reference to Fig. 9, after step (s2) is executed, the start-up method of the present invention forms the process flow shown in Fig. 9, that is, the boiler provides steam for the air separation unit, and the oxygen produced after the start-up of the air separation unit The oxygen-enriched air composed of air is used as a gasification agent and sent to the underground gasification furnace through the pipe network, and the crude gas produced by the underground gasification furnace is sent to the flare for combustion and discharge, and sent to the boiler as a blended fuel.

Execution step (s3): Mix the oxygen separated by the air separation unit with the boiler steam to form water vapor enriched with oxygen as a gasification agent and send it to the underground gasifier, and adjust the load of the air separation unit to 50%, adjust the underground The total load of the gasifier reaches 50%. It can be understood that in this embodiment, the above-mentioned water vapor enriched with oxygen replaces the above-mentioned oxygen-enriched air as the gasification agent. In other words, the gasification agent sent to the underground gasifier at this time is only water vapor oxygen. Thereby, the combustion of the coal seam in the underground gasification furnace can be promoted, and the total load of the underground gasification furnace can be increased. In addition, the water vapor in the gasification agent can increase the content of effective components in the crude gas, thereby improving the subsequent production efficiency of gases such as methane.

Of course, the above-mentioned oxygen-enriched air can also be replaced by water vapor and oxygen-enriched as a gasification agent in the remaining steps, the replacement time and whether to replace it, whether it is necessary to improve the content of effective components in the crude gas, or whether it is necessary to underground The temperature of the flame working surface of the gasifier is adjusted according to the requirements.

When the total load of the underground gasifier reaches the above-mentioned set load, the gas pretreatment device and the low-temperature methanol washing device are started, and the crude gas discharged from the underground gasifier is passed into the gas pretreatment device for purification, namely dust removal, tar removal, Part of the impurity gas is washed, such as phenolic components, and the crude gas purified by the above process is dehydrated and pressurized, and then sent to a low-temperature methanol washing device for further purification to remove acid gas hydrogen sulfide and carbon dioxide.

In this embodiment, a steam turbine compressor is used as a crude gas compressor in the gas pretreatment device to pressurize the crude gas. And, steam is supplied to the steam turbocompressor using the above-mentioned boiler. Therefore, before the start-up of the gas pretreatment device and the low-temperature methanol washing device, a step of adjusting the load of the boiler is also included to provide steam for the crude gas compressor.

In summary, referring to Fig. 10, after step (s3) is executed, the start-up method of the present invention forms the process flow shown in Fig. 10, that is, the boilers are respectively the air separation compressor and the gas pretreatment device in the air separation plant The crude gas compressor in the air separation unit provides steam to drive the turbine, and the oxygen produced by the rectification tower in the air separation unit and part of the steam produced by the boiler form water vapor enriched with oxygen and sent to the underground gasifier as a gasification agent. The crude gas produced by the gasifier is purified by the gas pretreatment device and the low-temperature methanol washing device and then discharged. The purified gas mainly contains hydrogen and carbon monoxide, and may contain a small amount of carbon dioxide.

Optionally, after step (s3) and before step (s4), by increasing the load of the air separation unit and adjusting the amount of gasification agent injected into the underground gasifier, the total load of the underground gasifier is maintained at 50%— 70% range. That is, by increasing the amount of oxygen provided by the air separation unit and adjusting the flow rate of the gasification agent injected into the underground gasifier, the combustion of the coal seam in the underground gasifier is promoted, thereby gradually increasing the load of the underground gasifier to 50%-70% %, and maintain it at no more than 70%.

Execution step (s4): When the total load of the underground gasifier is stable within the range of 50%-70%, the synthesis loop starts up, and the crude gas purified by the low-temperature methanol washing device is sent into the synthesis loop. Among them, if the volume change rate of gas components is less than or equal to 0.5% and the change rate of gas production is less than 15% within 24 hours, it means that the operation of the underground gasifier is stable.

In summary, continue to refer to Fig. 8, after step (s4) is executed, the boiler provides steam for the air separation compressor in the air separation unit and the crude gas compressor in the gas pretreatment unit to drive the turbine respectively, and the air separation unit The oxygen produced by the rectifying tower and the steam produced by the boiler are composed of water vapor enriched with oxygen and sent to the underground gasifier. The crude gas produced by the underground gasifier is purified by the gas pretreatment device and the low-temperature methanol washing device and then discharged. To the synthesis circle, the purified gas mainly contains hydrogen and carbon monoxide, and may contain a small amount of carbon dioxide. In the synthesis cycle, the production of methane, methanol, dimethyl ether or olefins can be done.

Step (s5): Adjust the full load operation of the air separation unit to adjust the full load operation of the underground gasifier, and adjust the full load operation of the coal gas pretreatment device, low temperature methanol washing device and synthesis ring. Among them, when the air separation unit is running at full load, its load is 70%-100%; when the underground gasifier is running at full load, its total load is 70%-100%; when the gas pretreatment device is running at full load, Its load is 70%-100%; when the low-temperature methanol washing device is running at full load, its load is 70%-100%; when the synthesis ring is running at full load, its load is 70%-100%.

To sum up, in this embodiment, during the process from step (s1) to step (s3), the total load of the underground gasifier is gradually increased to 50%, and after step (s4) is completed, the underground The total load of the gasifier is gradually increased to the range of 50%-70%, and it maintains a stable operation. In performing step (s5), the total load of the underground gasifier is increased to a range of 70%-100%. In the process of gradually increasing the total load of the underground gasifier, the load of the air separation unit is correspondingly increased gradually, and each unit is gradually started up.

The above descriptions 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 (14)

1. A method for starting up an underground gasifier and ground supporting system, comprising the following steps in sequence: (s1) inject gasification agent into the underground gasifier and ignite the coal seam; (s2) When the oxygen consumption of the underground gasifier is consistent with the amount of oxygen produced corresponding to the minimum start-up load of the air separation plant, the air separation plant is started, and the air separation plant is discharged Oxygen-enriched air mixed with oxygen and air is sent into the underground gasifier as a gasifying agent; (s3) After adjusting the total load of the underground gasifier to the set load, the gas pretreatment device and the low-temperature methanol washing device are started, and the crude gas discharged from the underground gasifier is purified by the gas pretreatment device After sending into described low-temperature methanol washing device; (s4) start the synthesis loop, and send the crude gas purified by the low-temperature methanol washing device into the synthesis loop; (s5) by adjusting the air separation unit to enter full-load operation, to adjust the full-load operation of the underground gasifier, and adjust the gas pretreatment device, the low-temperature methanol washing device and the synthesis ring to perform full-load operation run. 2. The driving method according to claim 1, characterized in that, in the step (s3), Mixing the carbon dioxide removed by the low-temperature methanol washing unit with the oxygen generated by the air separation unit to form carbon dioxide enriched oxygen; The carbon dioxide enriched with oxygen is sent into the underground gasifier as a gasifying agent. 3. The driving method according to claim 2, characterized in that, The volume concentration of the oxygen in the carbon dioxide oxygen enrichment is 55%-80%. 4. The driving method according to claim 1, characterized in that, The minimum start-up load of the air separation unit is 30%. 5. The driving method according to claim 1, characterized in that, In said step (s2), Maintain the load of the air separation unit within the range of 30%-70%. 6. The driving method according to claim 1, characterized in that, In the step (s3): the set load is in the range of 30%-50%. 7. The driving method according to claim 6, characterized in that, Adjust the total load of the underground gasifier to the setting by adjusting the load of the air separation unit to the range of 30%-50% and adjusting the amount of gasification agent injected into the underground gasifier load. 8. The driving method according to claim 1, characterized in that, After said step (s3) and before performing said step (s4), by increasing the load of said air separation unit and adjusting the amount of gasification agent injected into said underground gasifier, the gasification capacity of said underground gasifier is maintained. The total load is in the range of 50%-70%. 9. The driving method according to claim 1, characterized in that, When the air separation unit is running at full load, its load is in the range of 70%-100%; When the underground gasifier is operating at full load, its total load is in the range of 70%-100%; When the coal gas pretreatment device, the low-temperature methanol washing device and the synthesis coil are in full-load operation, their loads are respectively in the range of 70%-100%. 10. The driving method according to claim 1, characterized in that, Before the start-up of the gas pretreatment device, part or all of the crude gas discharged from the underground gasifier is sent to the flare for combustion. 11. The driving method according to claim 1, characterized in that, The air separation compressor in the air separation plant is a steam turbine compressor; and/or The crude gas compressor in the gas pretreatment device is a steam turbine compressor; and/or The carbon dioxide compressor in the low-temperature methanol washing is a steam turbine compressor. 12. The driving method according to claim 11, characterized in that, The steam turbine compressor is driven by part or all of the steam generated by the boiler. 13. The driving method according to claim 12, characterized in that, The carbon dioxide removed by the low-temperature methanol washing unit, the oxygen generated by the air separation unit and part of the steam produced by the boiler are mixed as a gasification agent and sent to the underground gasifier. 14. The driving method according to claim 12, characterized in that, Before the start-up of the gas pretreatment device, part or all of the crude gas discharged from the underground gasification furnace is sent into the boiler as a co-combustion fuel.