A coal underground gasification injection-production linkage control system and method

Abstract

The present invention relates to the field of underground coalbed methane extraction, and discloses a coal underground gasification injection-production linkage control system and method, which includes a formation, an injection wellhead device, a winch, a production wellhead device, a main control station, an underground gasification and reaction control unit, a gasifying agent production unit, a heating unit, a first vent pipeline, a second vent pipeline, an underground coal gas production and state control unit, a raw coal gas treatment unit, and a flare system. The system adopts a distributed control system design to realize the integrated automation control of injection and production in coal underground gasification, improve the automation degree of underground coalbed methane extraction; and can change the control scheme according to different control processes, with high system flexibility; adopts a multi-channel cascade closed-loop control loop to realize the multi-variable coupling control of temperature, pressure, flow, etc., and reserves interfaces for intelligent algorithms and prediction models to solve the large lag problems brought by the analysis of raw coal gas components and the data transmission process.

Description

Technical Field

[0001] The present invention belongs to the technical field of underground coalbed methane extraction, and particularly relates to a coal underground gasification injection-production linkage control system and method. Background Art

[0002] Coal, as an important solid fuel in our life, occupies a very important position in the world's energy utilization. However, during the combustion and utilization process of coal, a large amount of harmful substances such as dust, sulfur dioxide, and nitrogen oxides are emitted, causing the deterioration of urban air quality, and meteorological disasters such as haze and acid rain, which endanger human health and the natural environment. Therefore, clean and efficient exploitation of coal resources will surely become the future development trend. Coal underground gasification is an important technology in the process of clean and efficient coal exploitation. In addition, large-scale development and utilization of coal underground gasification can form a strategic replacement for natural gas energy, solve the problem of excessive external dependence on natural gas in China, realize the comprehensive utilization of gasifiable resources, and accelerate the transformation of the energy structure.

[0003] China is the country with the largest number and types of coal gasification furnace technologies. Almost all mainstream gasification technologies are applied in China. Based on the accumulation of rich operation experience, a large number of gasification technologies with independent characteristics have been developed in China, and a good promotion and application situation has also been formed. However, the current domestic research mainly focuses on above-ground gasification technologies, and there is a lack of large-scale development and utilization of underground gasification. So far, the domestic self-operated underground gasification technology has not been successful and is still in the experimental stage. In the actual production process, the coal underground gasification injection-production linkage control system mainly needs to meet the following requirements:

[0004] First, the dynamic changes in the coal underground gasification process are integrated with the ground supporting process for control matching, realizing the automatic control of gasification agent production, gasification agent injection, underground gasification reaction, crude gas dust removal and desulfurization, and gas treatment.

[0005] Second, real-time monitoring of data such as the output, composition of the crude gas, temperature and pressure during the gasification chamber reaction process, and pressure, flow rate, and temperature at equipment such as the wellhead device, and realizing feedback control.

[0006] Third, providing an intelligent algorithm control interface to solve the large lag problem brought by the analysis of the crude gas composition and the data transmission process.

[0007] Fourth, the igniter can move back and forth to provide different control methods for different underground gasification processes. Summary of the Invention

[0008] To solve the above problems existing in the prior art, the object of the present invention is to provide a coal underground gasification injection-production linkage control system and method, which solve the problems of the mismatch between the dynamic changes in the coal underground gasification process and the integrated control of the ground supporting process, large fluctuations in the output and components of raw coal gas, and insufficient adaptability of the ground engineering, etc.

[0009] The technical solution adopted by the present invention is as follows:

[0010] A coal underground gasification injection-production linkage control system includes an injection wellhead device and a production wellhead device respectively connected to a reservoir of a formation through pipelines. The injection wellhead device is connected with a winch; it also includes a main control station, an injection well field, a production well field, and a flare system; the injection well field includes an underground gasification and reaction control unit, a gasifying agent production unit, a heat supply unit, and a first vent pipeline; the production well field includes: a second vent pipeline, an underground coal gas production and state control unit, and a raw coal gas treatment unit;

[0011] The injection wellhead device is provided with a nitrogen port and a gasifying agent injection water port, the production wellhead device is provided with a nitrogen port and a spray water port, and the winch is provided with an oxygen port and an ignition liquid port; it also includes an oxygen injection system connected to the oxygen port, a nitrogen injection system connected to the nitrogen port, a gasifying agent injection water system connected to the gasifying agent injection water port, an ignition liquid system connected to the ignition liquid port, and a spray water system connected to the spray water port; the main control station is respectively connected to the oxygen injection system, the nitrogen injection system, the gasifying agent injection water system, the ignition liquid system, and the spray water system;

[0012] The main control station includes an engineer station, a first operator station, a second operator station, a gasifying agent production controller, a gasifying agent injection controller, a heat supply controller, a spray water controller, a power generation controller, a flare combustion controller, a circulating water controller, and a data acquisition board;

[0013] The underground gasification and reaction control unit includes: an injection well nitrogen injection circuit, an injection well oxygen injection circuit, an injection water circuit, an ignition liquid injection circuit, a first circulating water circuit, and an injection well sensor unit;

[0014] The gasifying agent production unit includes a filter, a compressor, a heat exchanger, an air purifier, a booster, an expander, a liquid air separator, a tank truck, a pump set, and a storage tank;

[0015] The heat supply unit includes an electric hot water boiler, a gas steam boiler, a hot water circulating pump, a boiler feed water pump, a burner, and a steam pipeline network;

[0016] The underground coal gas production and state control unit includes: a spray water injection circuit, a production well nitrogen injection circuit, a second circulating water circuit, a nitrogen purging device, a gas chromatograph analyzer, a production well sensor unit, and a water replenishment circuit;

[0017] The raw coal gas treatment unit includes a scrubber, a water scrubbing tower, a separator, an electric heater, a shift reactor, a hydrolysis reactor, a water condenser, an oil removal tank, a gas-liquid separator, an absorption tower, a purification separator, and a power generation device;

[0018] The flare system includes a vent pipeline interface, a vent knockout drum, a flare, and a water seal tank;

[0019] Among them, the injection wellhead device and the production wellhead device are installed above the formation; the winch is connected to the downhole gasification and reaction control unit and the injection wellhead device through pipelines; the downhole gasification and reaction control unit is connected to the gasifying agent production unit through pipelines; the first vent pipeline and the second vent pipeline are connected to the flare system through pipelines; the downhole coal gas production and status control unit is connected to the raw coal gas treatment unit through pipelines; the main control station is electrically connected to the winch, the downhole gasification and reaction control unit, the gasifying agent production unit, the heat supply unit, the downhole coal gas production and status control unit, the raw coal gas treatment unit, and the flare system.

[0020] As a preferred solution of the present invention, the engineer station, the first operator station, the gasifying agent production controller, the gasifying agent injection controller, and the heat supply controller in the main control station are installed at the injection well site; the second operator station, the spray water controller, the power generation controller, the flare combustion controller, and the circulating water controller are installed at the production well site; the data acquisition board card collects the data returned from the injection well sensor unit, the production well sensor unit, and the gas chromatograph.

[0021] As a preferred solution of the present invention, the gasifying agent production controller controls the actions of the filter, compressor, heat exchanger, air purifier, booster, expander, and liquid air separator; the gasifying agent injection controller controls the nitrogen injection circuit of the injection well, the oxygen injection circuit of the injection well, the injection water circuit, the ignition liquid injection circuit, and the first circulating water circuit; the heat supply controller controls the actions of the electric hot water boiler, the gas steam boiler, the hot water circulation pump, the boiler feed pump, and the burner; the spray water controller controls the spray water injection circuit and the second circulating water circuit; the power generation controller controls the action of the power generation device; the flare combustion controller controls the actions of the vent knockout drum, the flare, and the water seal tank.

[0022] As a preferred solution of the present invention, the injection well sensor unit, the production well sensor unit, and the gas chromatograph transmit the temperature, pressure, flow rate, and raw coal gas component data to the engineer station, the first operator station, and the second operator station in real time through the data acquisition board card; the reaction process pressure is adjusted by controlling the nitrogen injection circuit of the injection well and the nitrogen injection circuit of the production well; the reaction process temperature is adjusted by controlling the oxygen injection circuit of the injection well and the ignition liquid injection circuit; the raw coal gas components are regulated by controlling the injection water circuit; the temperature of the production wellhead is adjusted by controlling the spray water injection circuit.

[0023] As a preferred embodiment of the present invention, the oxygen injection system includes a first diaphragm valve, an oxygen storage tank, a first booster, a first vaporizer, a first proportional valve, and a first sensor connected in sequence. A second diaphragm valve is connected in parallel with the first diaphragm valve, and a first transfer pump and an oxygen tank truck are connected in sequence to the end of the second diaphragm valve away from the oxygen storage tank.

[0024] As a preferred embodiment of the present invention, the nitrogen injection system includes a third diaphragm valve, a nitrogen storage tank, a second booster, a second vaporizer, a second proportional valve, and a second sensor connected in sequence. A fourth diaphragm valve is connected in parallel with the third diaphragm valve, and a second transfer pump and a nitrogen tank truck are connected in sequence to the end of the fourth diaphragm valve away from the nitrogen storage tank.

[0025] As a preferred embodiment of the present invention, the gasifying agent injection water system includes a gasifying agent water supply tank, a first feed water pump, a first filter, a first injection water pump, a first check valve, a third proportional valve, and a third sensor connected in sequence.

[0026] As a preferred embodiment of the present invention, the ignition liquid system includes an ignition liquid storage tank, a pressure pump, a fourth proportional valve, and a fourth sensor connected in sequence.

[0027] As a preferred embodiment of the present invention, the spray water system includes a spray water tank, a second feed water pump, a second filter, a second injection water pump, a second check valve, a fifth proportional valve, and a fifth sensor connected in sequence.

[0028] A method for controlling the injection and production linkage of underground coal gasification includes the following steps:

[0029] S1: Start the control of underground gasification reaction;

[0030] S2: In the preparation stage of underground gasification, install the injection wellhead device and the production wellhead device above the formation, and connect the winch, the main control station, the underground gasification and reaction control unit, the gasifying agent production unit, the heat supply unit, the first vent pipeline, the second vent pipeline, the underground gas output and state control unit, the raw gas treatment unit, and the flare system through pipelines, cables, and valves.

[0031] S3: In the control system debugging stage, it specifically includes the following steps:

[0032] S3-1: System communication test, test whether the communication between the engineer station, the first operator station, the second operator station, the gasifying agent production controller, the gasifying agent injection controller, the heat supply controller, the spray water controller, the power generation controller, the flare combustion controller, the circulating water controller, and the data acquisition board is good;

[0033] S3-2: System function test to check whether the functions of the winch, flare system, underground gasification and reaction control unit, gasifying agent production unit, heating unit, first vent pipeline, second vent pipeline, underground gas output and status control unit, and raw gas treatment unit are intact;

[0034] S4: Gasifying agent production stage. Air is passed through a filter, compressor, heat exchanger, air purifier, booster, expander, and liquid air separator in sequence, and then after being collected with the liquid at the tank truck, it is pumped to a storage tank for storage by a pump unit;

[0035] S5: Ignition stage. Control the rotation of the winch to adjust the ignition position, and then the ignition liquid injection circuit is connected to start ignition;

[0036] S6: Underground gasification and reaction control stage, mainly including the following steps:

[0037] S6-1: Underground gasification temperature control. Collect and calculate the reaction temperature of the gasification chamber through the injection well sensor unit and production well sensor unit, and adjust the valve openings at the oxygen injection circuit and ignition liquid injection circuit of the injection well to achieve the purpose of underground gasification temperature control;

[0038] S6-2: Underground gasification pressure control. Collect and calculate the reaction pressure of the gasification chamber through the injection well sensor unit and production well sensor unit, and adjust the valve openings at the nitrogen injection circuit of the injection well and the nitrogen injection circuit of the production well to achieve the purpose of underground gasification pressure control;

[0039] S7: Underground gas output and status control stage, mainly including the following steps:

[0040] S7-1: Spray cooling. Collect the temperature of the raw gas at the outlet of the production well through the production well sensor unit, and control the valve opening at the spray water injection circuit to achieve the purpose of controlling the temperature of the raw gas at the outlet;

[0041] S7-2: Raw gas component control. Analyze the components of the raw gas through a gas chromatograph analyzer, and adjust the valve opening at the injection water circuit to achieve the purpose of regulating the components of the raw gas;

[0042] S7-3: Raw gas output control. Collect the flow rate of the raw gas at the outlet of the production well through the production well sensor unit to calculate the output, and control the opening and closing of the oxygen injection circuit of the injection well to achieve the purpose of controlling the output of the raw gas;

[0043] S8: Dust removal and desulfurization stage. Connect the raw gas to the raw gas treatment unit, and pass it through a scrubber, water wash tower, separator, electric heater, shift reactor, hydrolysis reactor, water condenser, oil removal tank, gas-liquid separator, absorption tower, and purification separator in sequence to perform dust removal and desulfurization on the raw gas;

[0044] S9: Gas treatment stage, mainly including the following steps:

[0045] S9-1: Gas power generation, connecting the crude gas after dust removal and desulfurization to the power generation device;

[0046] S9-2: Torch combustion, connecting the gases at the first vent pipeline and the second vent pipeline to the torch system for combustion treatment;

[0047] S9-3: Gas gathering and transportation, conducting gathering and transportation treatment on the crude gas after dust removal and desulfurization;

[0048] S10: End of underground gasification.

[0049] The beneficial effects of the present invention are as follows:

[0050] 1. The present invention adopts a distributed control system design, and controllers are respectively set at the injection wellhead device, production wellhead device, crude gas output treatment, winch, and torch combustion, etc., to achieve integrated injection and production automation control of underground coal gasification and improve the automation degree of underground coalbed methane extraction.

[0051] 2. The present invention adopts a multi-channel cascade closed-loop control method for the injection of gasifying agent, spray water, injection water, and ignition liquid, to achieve multi-variable coupling control of temperature, pressure, flow rate, etc., so as to meet the intelligent controllability of underground gasification reaction and crude gas composition.

[0052] 3. The present invention can solve the large lag problem brought by crude gas composition analysis and data transmission process by reserving an interface for intelligent algorithms and prediction models and combining multi-channel closed-loop control loops. Description of the Drawings

[0053] Figure 1 is a schematic diagram of the control system structure of the present invention;

[0054] Figure 2 is a control flow chart of injection-production linkage of the present invention;

[0055] Figure 3 is a schematic diagram of the principle of the gasifying agent injection unit of the present invention;

[0056] Figure 4 is a control flow chart of temperature control of the present invention;

[0057] Figure 5 is a schematic diagram of the principle of temperature control of the present invention.

[0058] In the figure, 1 is the formation; 2 is the injection wellhead device; 3 is the winch; 4 is the production wellhead device; 5 is the main control station; 6 is the underground gasification and reaction control unit; 7 is the gasifying agent production unit; 8 is the heat supply unit; 9 is the first vent pipeline; 10 is the second vent pipeline; 11 is the underground coal gas production and state control unit; 12 is the raw coal gas treatment unit; 13 is the flare system;

[0059] 5-1 is the engineer station; 5-2 is the first operator station; 5-3 is the second operator station; 5-4 is the gasifying agent production controller; 5-5 is the gasifying agent injection controller; 5-6 is the heat supply controller; 5-7 is the spray water controller; 5-8 is the power generation controller; 5-9 is the flare combustion controller; 5-10 is the circulating water controller; 5-11 is the data acquisition board;

[0060] 6-1 is the nitrogen injection loop of the injection well; 6-2 is the oxygen injection loop of the injection well; 6-3 is the injection water loop; 6-4 is the ignition liquid injection loop; 6-5 is the first circulating water loop; 6-6 is the injection well sensor unit;

[0061] 7-1 is the filter; 7-2 is the compressor; 7-3 is the heat exchanger; 7-4 is the air purifier; 7-5 is the booster; 7-6 is the expander; 7-7 is the liquid air separator; 7-8 is the tank truck; 7-9 is the pump unit; 7-10 is the storage tank;

[0062] 8-1 is the electric hot water boiler; 8-2 is the gas steam boiler; 8-3 is the hot water circulation pump; 8-4 is the boiler feed water pump; 8-5 is the burner; 8-6 is the steam pipeline network;

[0063] 11-1 is the spray water injection loop; 11-2 is the nitrogen injection loop of the production well; 11-3 is the second circulating water loop; 11-4 is the nitrogen purging device; 11-5 is the gas chromatograph analyzer; 11-6 is the production well sensor unit; 11-7 is the make-up water loop;

[0064] 12-1 is the scrubber; 12-2 is the water scrubbing tower; 12-3 is the separator; 12-4 is the electric heater; 12-5 is the shift reactor; 12-6 is the hydrolysis reactor; 12-7 is the water condenser; 12-8 is the oil removal tank; 12-9 is the gas-liquid separator; 12-10 is the absorption tower; 12-11 is the purification separator; 12-12 is the power generation device;

[0065] 13-1 is the vent pipeline interface; 13-2 is the venting and liquid separating tank; 13-3 is the flare; 13-4 is the water seal tank;

[0066] 201 is an oxygen tank truck, and 202 is a nitrogen tank truck; 211 is a first transfer pump, 212 is a second transfer pump, 213 is a first feed water pump, 214 is a first injection water pump, 215 is a pressure pump, 216 is a second feed water pump, and 217 is a second injection water pump; 221 is a first diaphragm valve, 222 is a second diaphragm valve, 223 is a third diaphragm valve, and 224 is a fourth diaphragm valve; 231 is an oxygen storage tank, 232 is a nitrogen storage tank, 233 is a gasification agent water supply water tank, 234 is an ignition liquid storage tank, and 235 is a spray water tank; 241 is a first booster, and 242 is a second booster; 251 is a first vaporizer, and 252 is a second vaporizer; 261 is a first filter, and 262 is a second filter; 271 is a first check valve, and 272 is a second check valve; 281 is a first proportional valve, 282 is a second proportional valve, 283 is a third proportional valve, 284 is a fourth proportional valve, and 285 is a fifth proportional valve; 291 is a first sensor, 292 is a second sensor, 293 is a third sensor, 294 is a fourth sensor, and 295 is a fifth sensor;

[0067] A is an oxygen port; B is a nitrogen port; C is a gasification agent injection water port; D is an ignition liquid port; E is a spray water port. Specific embodiments

[0068] The embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

[0069] As Figure 1 As shown, the underground coal gasification injection-production linkage control system of this embodiment includes an injection wellhead device 2 and a production wellhead device 4 respectively connected to the reservoir of the formation 1 through pipelines. The injection wellhead device 2 is connected to a winch 3; it also includes a main control station 5, an injection well site, a production well site, and a flare system 13; the injection well site includes an underground gasification and reaction control unit 6, a gasification agent production unit 7, a heating unit 8, and a first vent pipeline 9; the production well site includes: a second vent pipeline 10, an underground coal gas production and state control unit 11, and a raw coal gas treatment unit 12.

[0070] The injection wellhead device 2 is provided with a nitrogen port B and a gasifying agent injection water port C, the production wellhead device 4 is provided with a nitrogen port B and a spray water port E, and the winch 3 is provided with an oxygen port A and an ignition liquid port D; it further includes an oxygen injection system connected to the oxygen port A, a nitrogen injection system connected to the nitrogen port B, a gasifying agent injection water system connected to the gasifying agent injection water port C, an ignition liquid system connected to the ignition liquid port D, and a spray water system connected to the spray water port E; the main control station 5 is respectively connected to the oxygen injection system, the nitrogen injection system, the gasifying agent injection water system, the ignition liquid system, and the spray water system.

[0071] The main control station 5 includes an engineer station 5-1, a first operator station 5-2, a second operator station 5-3, a gasifying agent production controller 5-4, a gasifying agent injection controller 5-5, a heat supply controller 5-6, a spray water controller 5-7, a power generation controller 5-8, a flare combustion controller 5-9, a circulating water controller 5-10, and a data acquisition board 5-11.

[0072] The underground gasification and reaction control unit 6 includes an injection well nitrogen injection circuit 6-1, an injection well oxygen injection circuit 6-2, an injection water circuit 6-3, an ignition liquid injection circuit 6-4, a first circulating water circuit 6-5, and an injection well sensor unit 6-6.

[0073] The gasifying agent production unit 7 includes: a filter 7-1, a compressor 7-2, a heat exchanger 7-3, an air purifier 7-4, a booster 7-5, an expander 7-6, a liquid air separator 7-7, a tank truck 7-8, a pump group 7-9, and a storage tank 7-10.

[0074] The heat supply unit 8 includes: an electric hot water boiler 8-1, a gas steam boiler 8-2, a hot water circulation pump 8-3, a boiler feed water pump 8-4, a burner 8-5, and a steam pipeline network 8-6.

[0075] The underground coal gas production and state control unit 11 includes: a spray water injection circuit 11-1, a production well nitrogen injection circuit 11-2, a second circulating water circuit 11-3, a nitrogen purging device 11-4, a gas chromatograph 11-5, a production well sensor unit 11-6, and a make-up water circuit 11-7.

[0076] The raw coal gas treatment unit 12 includes: a scrubber 12-1, a water wash tower 12-2, a separator 12-3, an electric heater 12-4, a shift reactor 12-5, a hydrolysis reactor 12-6, a water condenser 12-7, an oil removal tank 12-8, a gas-liquid separator 12-9, an absorption tower 12-10, a purification separator 12-11, and a power generation device 12-12.

[0077] The described flare system 13 includes: a vent pipeline interface 13-1, a vent knockout drum 13-2, a flare 13-3, and a water seal tank 13-4.

[0078] Among them, the injection wellhead device 2 and the production wellhead device 4 are installed above the formation 1; the winch 3 is connected to the downhole gasification and reaction control unit 6 and the injection wellhead device 2 through pipelines; the downhole gasification and reaction control unit 6 is connected to the gasifying agent production unit 7 through a pipeline; the first vent pipeline 9 and the second vent pipeline 10 are connected to the flare system 13 through pipelines; the downhole coal gas production and state control unit 11 is connected to the raw coal gas treatment unit 12 through a pipeline; the main control station 5 is electrically connected to the winch 3, the downhole gasification and reaction control unit 6, the gasifying agent production unit 7, the heat supply unit 8, the downhole coal gas production and state control unit 11, the raw coal gas treatment unit 12, and the flare system 13.

[0079] Among them, the engineer station 5-1, the first operator station 5-2, the gasifying agent production controller 5-4, the gasifying agent injection controller 5-5, and the heat supply controller 5-6 in the main control station 5 are installed at the injection well site; the second operator station 5-3, the spray water controller 5-7, the power generation controller 5-8, the flare combustion controller 5-9, and the circulating water controller 5-10 are installed at the production well site; the data acquisition board 5-11 collects the data returned from the injection well sensor unit 6-6, the production well sensor unit 11-6, and the gas chromatograph 11-5.

[0080] The gasifying agent injection controller 5-5 controls the injection well nitrogen injection circuit 6-1, the injection well oxygen injection circuit 6-2, the injection water circuit 6-3, the ignition liquid injection circuit 6-4, and the first circulating water circuit 6-5; the spray water controller 5-7 controls the spray water injection circuit 11-1 and the second circulating water circuit 11-3;

[0081] The injection well sensor unit 6-6, the production well sensor unit 11-6, and the gas chromatograph 11-5 transmit the temperature, pressure, flow rate, and raw coal gas component data to the engineer station 5-1, the first operator station 5-2, and the second operator station 5-3 in real time through the data acquisition board 5-11; the reaction process pressure is adjusted by controlling the injection well nitrogen injection circuit 6-1 and the production well nitrogen injection circuit 11-2; the reaction process temperature is adjusted by controlling the injection well oxygen injection circuit 6-2 and the ignition liquid injection circuit 6-4; the raw coal gas components are regulated by controlling the injection water circuit 6-3; the production well wellhead temperature is adjusted by controlling the spray water injection circuit 11-1.

[0082] The oxygen injection system includes a first diaphragm valve 221, an oxygen storage tank 231, a first booster 241, a first vaporizer 251, a first proportional valve 281, and a first sensor 291 that are connected in sequence. A second diaphragm valve 222 is connected in parallel with the first diaphragm valve 221. One end of the second diaphragm valve 222 away from the oxygen storage tank 231 is connected with a first transfer pump 211 and an oxygen tank truck 201 in sequence.

[0083] The nitrogen injection system includes a third diaphragm valve 223, a nitrogen storage tank 232, a second booster 242, a second vaporizer 252, a second proportional valve 282, and a second sensor 292 that are connected in sequence. A fourth diaphragm valve 224 is connected in parallel with the third diaphragm valve 223. One end of the fourth diaphragm valve 224 away from the nitrogen storage tank 232 is connected with a second transfer pump 212 and a nitrogen tank truck 202 in sequence.

[0084] The gasifying agent injection water system includes a gasifying agent water supply tank 233, a first feed water pump 213, a first filter 261, a first injection water pump 214, a first check valve 271, a third proportional valve 283, and a third sensor 293 that are connected in sequence.

[0085] The ignition liquid system includes an ignition liquid storage tank 234, a pressure pump 215, a fourth proportional valve 284, and a fourth sensor 294 that are connected in sequence.

[0086] The spray water system includes a spray water tank 235, a second feed water pump 216, a second filter 262, a second injection water pump 217, a second check valve 272, a fifth proportional valve 285, and a fifth sensor 295 that are connected in sequence.

[0087] As Figure 2 shown, the injection-production linkage control process of the present invention is as follows:

[0088] S1: The underground gasification reaction control starts;

[0089] S2: In the underground gasification preparation stage, the injection wellhead device 2 and the production wellhead device 4 are installed above the formation 1, and the winch 3, the main control station 5, the underground gasification and reaction control unit 6, the gasifying agent production unit 7, the heat supply unit 8, the first vent pipeline 9, the second vent pipeline 10, the underground coal gas output and state control unit 11, the raw coal gas treatment unit 12, and the flare system 13 are connected through pipelines, cables, and valves.

[0090] S3: In the control system debugging stage, it specifically includes the following steps:

[0091] S3-1: System communication test, testing whether the communication between the engineer station 5-1, the first operator station 5-2, the second operator station 5-3, the gasification agent production controller 5-4, the gasification agent injection controller 5-5, the heating controller 5-6, the spray water controller 5-7, the power generation controller 5-8, the torch combustion controller 5-9, the circulating water controller 5-10, and the data acquisition board 5-11 is good;

[0092] S3-2: System function test, testing whether the winch 3, flare system 13, underground gasification and reaction control unit 6, gasification agent production unit 7, heating unit 8, first venting pipeline 9, second venting pipeline 10, underground gas production and state control unit 11, and raw gas processing unit 12 are functioning properly;

[0093] S4: During the gasification agent production stage, the air passes through the filter 7-1, the compressor 7-2, the heat exchanger 7-3, the air purifier 7-4, the booster 7-5, the expander 7-6, the liquid-air separator 7-7, and then is collected with the liquid at the tank truck 7-8, and then pumped to the storage tank 7-10 for storage through the pump group 7-9;

[0094] S5: Ignition stage, the winch 3 is controlled to rotate to adjust the ignition position, and then the ignition liquid is injected into the circuit 6-4 to start ignition;

[0095] S6: Downhole gasification and reaction control stage, mainly including the following steps:

[0096] S6-1: Downhole gasification temperature control, through the injection well sensor unit 6-6 and the production well sensor unit 11-6 to collect and calculate the reaction temperature of the gasification chamber, adjust the valve opening size at the injection well oxygen injection loop 6-2 and the ignition liquid injection loop 6-4 to achieve the purpose of downhole gasification temperature control;

[0097] S6-2: Downhole gasification pressure control, through the injection well sensor unit 6-6 and the production well sensor unit 11-6 to collect and calculate the reaction pressure of the gasification chamber, adjust the valve opening size at the injection well nitrogen injection loop 6-1 and the production well nitrogen injection loop 11-2 to achieve the purpose of downhole gasification pressure control;

[0098] S7: underground gas production and state control stage, mainly including the following steps:

[0099] S7-1: Spray cooling, collect the raw gas outlet temperature through the production well sensor unit 11-6, control the valve opening size at the spray water injection loop 11-1, and achieve the purpose of controlling the raw gas outlet temperature;

[0100] S7-2: Control of raw gas composition. Analyze the raw gas composition through the gas chromatograph analyzer 11-5, and adjust the valve opening size at the injection water circuit 6-3 to achieve the purpose of regulating the raw gas composition;

[0101] S7-3: Control of raw gas production. Collect the raw gas flow rate at the production well outlet through the production well sensor unit 11-6 to calculate the production, and control the opening and closing of the oxygen injection circuit 6-2 of the injection well to achieve the purpose of controlling the raw gas production;

[0102] S8: Dust removal and desulfurization stage. Connect the raw gas to the raw gas treatment unit 12, and pass through the scrubber 12-1, water wash tower 12-2, separator 12-3, electric heater 12-4, shift reactor 12-5, hydrolysis reactor 12-6, water condenser 12-7, oil removal tank 12-8, gas-liquid separator 12-9, absorption tower 12-10, and purification separator 12-11 in sequence to perform dust removal and desulfurization on the raw gas;

[0103] S9: Gas treatment stage, mainly including the following steps:

[0104] S9-1: Gas power generation. Connect the raw gas after dust removal and desulfurization to the power generation device 12-12;

[0105] S9-2: Torch combustion. Connect the gases at the first vent pipeline 9 and the second vent pipeline 10 to the torch system 13 for combustion treatment;

[0106] S9-3: Gas gathering and transportation. Carry out gathering and transportation treatment on the raw gas after dust removal and desulfurization;

[0107] S10: End of underground gasification.

[0108] Reaction temperature control of the gasification cavity:

[0109] During the process of underground coal gasification reaction, when it is detected that the reaction temperature of the gasification cavity is too low, on the one hand, increase the oxygen-nitrogen ratio, increase the valve opening of the proportional valve and the rotation speed of the pump in the oxygen injection circuit to increase the oxygen content, and on the other hand, increase the flow rate of the ignition liquid in the ignition liquid injection circuit. Through the above methods, complete combustion can be promoted and more heat can be released. In addition, when the hydrogen element content in the raw gas composition at the production well is too high, the reaction temperature of the gasification cavity can also be slightly increased by appropriately reducing the injection water content. When it is detected that the reaction temperature of the gasification cavity is too high, it is the opposite of the above control method.

[0110] Production wellhead temperature control:

[0111] During the process of underground coal gasification reaction, when it is detected that the production wellhead temperature is too high, cooling can be achieved by increasing the spray water flow rate and spray time. When it is detected that the production wellhead temperature is too low, reduce the valve opening of the spray water proportional valve.

[0112] Gasification chamber reaction pressure control:

[0113] During the process of underground coal gasification reaction, when it is detected that the reaction pressure of the gasification chamber is too low, the opening degree of the proportional valve and the rotation speed of the pump in the nitrogen injection circuit are increased to increase the nitrogen content. When it is detected that the reaction pressure of the gasification chamber is too high, the control method is opposite to the above.

[0114] Raw gas composition control:

[0115] During the process of underground coal gasification reaction, the composition of the raw gas is detected and analyzed. When the hydrogen element content in the raw gas is too low, the opening degree of the proportional valve and the rotation speed of the pump in the water injection circuit are increased to increase the hydrogen element content. When it is detected that the hydrogen element content in the raw gas is too high, the control method is opposite to the above.

[0116] Production well output control:

[0117] During the process of underground coal gasification reaction, the output per unit measurement time is accumulated. When the raw gas output is close to or exceeds the set output value, the opening degree of the proportional valve and the rotation speed of the pump in the oxygen injection circuit are decreased to reduce the oxygen content. At the same time, the ignition liquid flow rate and the water injection content are decreased. When the raw gas output is much less than the set output value, the control method is opposite to the above.

[0118] During the process of underground coal gasification reaction, there is a monitoring and warning function for the temperature, pressure and flow rate during the operation of the equipment.

[0119] The present invention is not limited to the above optional embodiments. Anyone can obtain other various forms of products under the inspiration of the present invention. However, no matter what changes are made in its shape or structure, as long as the technical solutions fall within the scope defined by the claims of the present invention, they are all within the protection scope of the present invention.

Claims

1. A combined injection and production control system for underground coal gasification, characterized in that It includes an injection wellhead device (2) and a production wellhead device (4) respectively connected to the reservoir of the formation (1) through pipelines, and a winch (3) is connected to the injection wellhead device (2); it also includes a main control station (5), an injection well site, a production well site, and a flare system (13); the injection well site includes an underground gasification and reaction control unit (6), a gasifying agent production unit (7), a heat supply unit (8), and a first vent pipeline (9); the production well site includes: a second vent pipeline (10), an underground coal gas production and state control unit (11), and a raw coal gas treatment unit (12). The injection wellhead device (2) is provided with a nitrogen port (B) and a gasifying agent injection water port (C), the production wellhead device (4) is provided with a nitrogen port (B) and a spray water port (E), and the winch (3) is provided with an oxygen port (A) and an ignition liquid port (D); it also includes an oxygen injection system connected to the oxygen port (A), a nitrogen injection system connected to the nitrogen port (B), a gasifying agent injection water system connected to the gasifying agent injection water port (C), an ignition liquid system connected to the ignition liquid port (D), and a spray water system connected to the spray water port (E); the main control station (5) is respectively connected to the oxygen injection system, the nitrogen injection system, the gasifying agent injection water system, the ignition liquid system, and the spray water system. The main control station (5) includes an engineer station (5-1), a first operator station (5-2), a second operator station (5-3), a gasifying agent production controller (5-4), a gasifying agent injection controller (5-5), a heat supply controller (5-6), a spray water controller (5-7), a power generation controller (5-8), a flare combustion controller (5-9), a circulating water controller (5-10), and a data acquisition board (5-11). The underground gasification and reaction control unit (6) includes an injection well nitrogen injection circuit (6-1), an injection well oxygen injection circuit (6-2), an injection water circuit (6-3), an ignition liquid injection circuit (6-4), a first circulating water circuit (6-5), and an injection well sensor unit (6-6); the underground coal gas production and state control unit (11) includes: a spray water injection circuit (11-1), a production well nitrogen injection circuit (11-2), a second circulating water circuit (11-3), a nitrogen purging device (11-4), a gas chromatograph (11-5), a production well sensor unit (11-6), and a water replenishment circuit (11-7). Among them, the injection wellhead device (2) and the production wellhead device (4) are installed above the formation (1); the winch (3) is connected to the downhole gasification and reaction control unit (6) and the injection wellhead device (2) through pipelines; the downhole gasification and reaction control unit (6) is connected to the gasifying agent production unit (7) through pipelines; the first vent pipeline (9) and the second vent pipeline (10) are connected to the flare system (13) through pipelines; the downhole coal gas production and state control unit (11) is connected to the raw coal gas treatment unit (12) through pipelines; the main control station (5) is electrically connected to the winch (3), the downhole gasification and reaction control unit (6), the gasifying agent production unit (7), the heat supply unit (8), the downhole coal gas production and state control unit (11), the raw coal gas treatment unit (12), and the flare system (13).

2. The coal underground gasification injection-production linkage control system according to claim 1, characterized in that In the main control station (5), the engineer station (5-1), the first operator station (5-2), the gasifying agent production controller (5-4), the gasifying agent injection controller (5-5), and the heat supply controller (5-6) are installed at the injection well site; the second operator station (5-3), the spray water controller (5-7), the power generation controller (5-8), the flare combustion controller (5-9), and the circulating water controller (5-10) are installed at the production well site; the data acquisition board (5-11) collects the data returned from the injection well sensor unit (6-6), the production well sensor unit (11-6), and the gas chromatograph (11-5).

3. The coal underground gasification injection-production linkage control system according to claim 1, characterized in that, The gasifying agent injection controller (5-5) controls the nitrogen injection loop (6-1) of the injection well, the oxygen injection loop (6-2) of the injection well, the injection water loop (6-3), the ignition liquid injection loop (6-4), and the first circulating water loop (6-5); the spray water controller (5-7) controls the spray water injection loop (11-1) and the second circulating water loop (11-3).

4. The co-injection and production linkage control system for underground coal gasification according to claim 1, wherein, The injection well sensor unit (6-6), the production well sensor unit (11-6), and the gas chromatograph (11-5) transmit the temperature, pressure, flow rate, and raw coal gas component data to the engineer station (5-1), the first operator station (5-2), and the second operator station (5-3) in real time through the data acquisition board (5-11); the reaction process pressure is adjusted by controlling the nitrogen injection loop (6-1) of the injection well and the nitrogen injection loop (11-2) of the production well; the reaction process temperature is adjusted by controlling the oxygen injection loop (6-2) of the injection well and the ignition liquid injection loop (6-4); the raw coal gas components are regulated by controlling the injection water loop (6-3); the temperature of the production wellhead is adjusted by controlling the spray water injection loop (11-1).

5. The coal underground gasification injection-production linkage control system according to claim 1, wherein The oxygen injection system includes a first diaphragm valve (221), an oxygen storage tank (231), a first booster (241), a first vaporizer (251), a first proportional valve (281), and a first sensor (291) connected in sequence. A second diaphragm valve (222) is connected in parallel with the first diaphragm valve (221). One end of the second diaphragm valve (222) away from the oxygen storage tank (231) is connected with a first transfer pump (211) and an oxygen tank truck (201) in sequence.

6. The co-injection and production linkage control system for underground coal gasification according to claim 1, wherein, The nitrogen injection system includes a third diaphragm valve (223), a nitrogen storage tank (232), a second booster (242), a second vaporizer (252), a second proportional valve (282), and a second sensor (292) connected in sequence. A fourth diaphragm valve (224) is connected in parallel with the third diaphragm valve (223). One end of the fourth diaphragm valve (224) away from the nitrogen storage tank (232) is connected with a second transfer pump (212) and a nitrogen tank truck (202) in sequence.

7. The coal underground gasification injection-production linkage control system according to claim 1, wherein The gasifying agent injection water system includes a gasifying agent water supply tank (233), a first feed water pump (213), a first filter (261), a first injection water pump (214), a first check valve (271), a third proportional valve (283), and a third sensor (293) connected in sequence.

8. The co-injection and production linkage control system for underground coal gasification according to claim 1, wherein The ignition liquid system includes an ignition liquid storage tank (234), a pressure pump (215), a fourth proportional valve (284), and a fourth sensor (294) connected in sequence.

9. The co - mining linkage control system for underground coal gasification according to claim 1, wherein, The spray water system includes a spray water tank (235), a second feed water pump (216), a second filter (262), a second injection water pump (217), a second check valve (272), a fifth proportional valve (285), and a fifth sensor (295) connected in sequence.

10. A method for controlling the coordinated injection and production in underground coal gasification using the system according to claim 1, characterized in that, It includes the following steps: S1: The underground gasification reaction control starts. S2: In the underground gasification preparation stage, the injection wellhead device (2) and the production wellhead device (4) are installed above the formation (1), and the winch (3), the main control station (5), the underground gasification and reaction control unit (6), the gasifying agent production unit (7), the heat supply unit (8), the first vent pipeline (9), the second vent pipeline (10), the underground coal gas output and state control unit (11), the raw coal gas treatment unit (12), and the flare system (13) are connected through pipelines, cables, and valves. S3: In the control system commissioning stage, it specifically includes the following steps: S3-1: System communication test, to test whether the communication is good among the test engineer station (5-1), the first operator station (5-2), the second operator station (5-3), the gasifying agent production controller (5-4), the gasifying agent injection controller (5-5), the heat supply controller (5-6), the spray water controller (5-7), the power generation controller (5-8), the flare combustion controller (5-9), the circulating water controller (5-10), and the data acquisition board (5-11). S3-2: System function test, to test whether the functions of the winch (3), the flare system (13), the underground gasification and reaction control unit (6), the gasifying agent production unit (7), the heat supply unit (8), the first vent pipeline (9), the second vent pipeline (10), the underground coal gas output and state control unit (11), and the raw coal gas treatment unit (12) are in good condition. S4: The gasifying agent production stage. S5: In the ignition stage, control the winch (3) to rotate to adjust the ignition position, then the ignition liquid injection circuit (6-4) is connected, and ignition starts. S6: In the underground gasification and reaction control stage, it mainly includes the following steps: S6-1: Downhole gasification temperature control. The reaction temperature of the gasification cavity is collected and calculated through the injection well sensor unit (6-6) and the production well sensor unit (11-6), and the opening sizes of the valves at the oxygen injection circuit (6-2) and the ignition liquid injection circuit (6-4) of the injection well are adjusted to achieve the purpose of downhole gasification temperature control; S6-2: Downhole gasification pressure control. The reaction pressure of the gasification cavity is collected and calculated through the injection well sensor unit (6-6) and the production well sensor unit (11-6), and the opening sizes of the valves at the nitrogen injection circuit (6-1) of the injection well and the nitrogen injection circuit (11-2) of the production well are adjusted to achieve the purpose of downhole gasification pressure control; S7: The stage of downhole coal gas production and state control mainly includes the following steps: S7-1: Spray cooling. The temperature of the raw coal gas outlet is collected through the production well sensor unit (11-6), and the opening size of the valve at the spray water injection circuit (11-1) is controlled to achieve the purpose of controlling the temperature of the raw coal gas outlet; S7-2: Raw coal gas component control. The components of the raw coal gas are analyzed by a gas chromatograph (11-5), and the opening size of the valve at the injection water circuit (6-3) is adjusted to achieve the purpose of regulating the components of the raw coal gas; S7-3: Raw coal gas production control. The flow rate of the raw coal gas at the outlet of the production well is collected through the production well sensor unit (11-6) to calculate the production, and the opening and closing of the oxygen injection circuit (6-2) of the injection well are controlled to achieve the purpose of controlling the production of the raw coal gas; S8: The dust removal and desulfurization stage; S9: The coal gas treatment stage; S10: The end of underground gasification.

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