A V-shaped tunnel underground in-situ gasification coupling power generation system

Abstract

The application discloses a V-shaped tunnel underground in-situ gasification coupled power generation system, and relates to the technical field of coal underground gasification, in-situ combustion and clean energy power generation. The system is composed of an oxygen-enriched air separation unit, a vertical injection unit, a capillary pore network and a V-shaped tunnel gasification power generation unit, adopts a V-shaped shield tunnel with a concrete tile and an S32001 stainless steel composite lining to build an underground gasification area; high-pressure water and oxygen-enriched air are deeply injected into the capillary pores at a spacing of 50-200 meters through a branch pipe for multi-point injection, and synthesis gas is generated by underground high-temperature self-gasification; the synthesis gas drives a steam turbine to generate power, the gasification waste heat is recycled to increase efficiency, and slag is pumped under negative pressure to prevent blockage. The application realizes the integration of underground gasification and power generation, is stable and efficient, does not need large ground equipment, has a high coal utilization rate, is suitable for large-scale clean power generation of low-rank coal, and has industrial popularization value.

Description

Technical Field

[0001] This invention belongs to the field of underground coal gasification, in-situ combustion, and clean energy power generation technology. Specifically, it relates to a zero-power power generation system and method suitable for multi-layered coal and rock alternating geological structures, adopting a V-shaped slope configuration, relying on a triple anti-collapse mechanism to achieve long-term stable operation, utilizing the natural rise of hot gas to achieve double-end non-powered flow guidance, seamlessly connecting with a gas turbine through an adaptive sealing section, and utilizing the natural chimney effect to achieve self-pressurization. Background Technology

[0002] Traditional coal-fired power generation involves complex processes such as coal mining, transportation, pulverization, boiler combustion, heat exchange for steam generation, and steam turbine power generation. It has drawbacks such as high investment, high energy consumption, high pollution, high carbon emissions, and low coal resource recovery rate (only 50-60%). Existing underground gasification power generation technologies require intermediate steps such as fan extraction, compressor pressurization, pipeline transportation, gas purification, and heat exchange conversion. These technologies are complex, have high failure rates, significant heat loss, and high maintenance costs. Furthermore, they cannot utilize the thermodynamic properties of naturally rising hot gas to achieve zero-power transportation. For multi-layered coal and rock alternating geological conditions, traditional horizontal tunnels are prone to collapse and blockage at temperatures above 1000℃ due to rock softening and vertical gravity loads, resulting in short system lifespans and poor safety. Simultaneously, the high-temperature flue gas exceeding 1000℃ generated by underground combustion directly impacts the gas turbine, easily causing blade ablation. Existing technologies often use heat exchangers for cooling, resulting in substantial heat loss, and the gas turbine must rely on an external compressor to provide high pressure, further increasing energy consumption and costs. There is currently no complete technical solution that integrates continuous combustion on V-shaped slopes, high-temperature collapse prevention in multi-layered coal and rock, double-end zero-power diversion, adaptive sealing sections, self-pressurization via natural chimneys, and seamless direct connection to the gas turbine, making it impossible to achieve efficient, safe, and low-cost in-situ utilization of coal.

[0003] This invention addresses the aforementioned industry pain points by proposing a triple anti-collapse mechanism consisting of V-shaped slope gravity diversion, coal seam coking self-supporting arch, and high-temperature vitrification of interlayer rock. Combined with core technologies such as double-end natural diversion, outlet adaptive stainless steel sealing, seamless flange connection, and natural chimney self-pressurization, it constructs the world's only underground self-sustaining combustion zero-power power generation system that can operate stably for a long time in multi-layered coal and rock formations. Summary of the Invention

[0004] The purpose of this invention is to address the problems mentioned in the background section by providing a V-shaped tunnel underground in-situ gasification coupled power generation system, aiming to overcome the shortcomings of traditional underground coal gasification power generation technology. In multi-layered coal and rock alternating geological formations, long-term combustion at 1000℃ causes the rock layers to soften and collapse. Existing support methods are costly and have a short lifespan, and cannot guarantee the long-term stable operation of the system. High-temperature flue gas needs to go through intermediate steps such as fan extraction, compressor pressurization, pipeline transportation, heat exchange cooling, and gas purification. The equipment is complex, energy consumption is high, and thermal efficiency is low. There is currently no complete technical solution that integrates underground in-situ gasification, high-temperature self-stabilizing support, zero-power flue gas transportation, natural self-pressurization, and direct power generation into one, making it impossible to achieve efficient, safe, and low-cost clean power generation from coal in situ.

[0005] To achieve the above objectives, the present invention provides a V-shaped tunnel underground in-situ gasification coupled power generation system, as detailed below: The system consists of the following components: V-shaped symmetrical slope shield tunnel: The tunnel has a V-shaped symmetrical slope configuration, completely eliminating the bottom horizontal combustion section. The inner diameter is 6-12 meters, the inclination angle is 15-30°, and the total length is 3000-5000 meters. It obliquely penetrates 2-8 layers of alternating coal and rock interlayers. The tunnel is divided into a coal seam combustion section (accounting for about 90% of the total length) and an outlet sealing section (10-30 meters of adaptive length at each end). The whole is a natural high-temperature flue gas diversion channel. The hot gas rises naturally along the slope to the outlets at both ends without any pipeline assistance.

[0006] Ultra-long horizontal capillary oxygen supply system: φ300mm ultra-long horizontal capillary holes are continuously, symmetrically, and evenly spaced along both sides of the V-shaped slope, with a depth of 800-1200 meters on each side and a hole spacing of 50-200 meters. Oxygen and water mixing nozzles with a diameter of φ100mm are installed inside the holes. Injection holes with a diameter of φ5-10mm are provided every 200 meters along the pipe wall. The length of the mixing nozzle is half the length of the capillary hole. The combustion influence radius of a single hole is 90 meters, and the overlap rate of the combustion zone is <10%. Oxygen is supplied to the coal seam through a 3-5MPa high-pressure oxygen injection system, achieving low-oxygen self-sustaining combustion of the entire V-shaped slope coal seam, with the temperature stably controlled at 800-1000℃, ensuring stable combustion over a long period of 20-50 years.

[0007] Triple collapse-resistant self-stabilizing system: (1) V-shaped slope gravity diversion mechanism: The inclined structure of about 20° diverts the gravity of the upper rock layer along the slope, reducing the vertical load on the tunnel by 70% and preventing vertical collapse from the source. (2) Coal seam coking self-supporting arch mechanism: Incomplete combustion at the edge of coal seam combustion forms a high-temperature coking layer, which is sintered into a high-strength, high-temperature resistant (≥1400℃) self-supporting arch, which automatically supports the upper rock layer without external support; (3) High-temperature vitrification mechanism of interbedded rocks: Shale, mudstone and sandstone in coal and rock interbeds melt and vitrify at a high temperature of 1000℃ to form a hard ceramic glaze that does not crack, fall off or collapse.

[0008] Segmented Liner Protective System: (1) Coal seam combustion section: No concrete, refractory bricks or metal lining are installed. It relies entirely on the triple anti-collapse mechanism to achieve self-stability, with zero cost and no maintenance. (2) Outlet sealing section (adaptive length of 10-30 meters at each end): 6-14mm thick S32001 duplex stainless steel lining (resistant to 1300℃ high temperature, sulfur corrosion, thermal shock, and excellent sealing performance) is used to prevent the outlet rock layer from burning down at high temperature and to prevent flue gas leakage, thus ensuring the long-term sealed and stable operation of the system.

[0009] Seamless high-temperature resistant stainless steel flange connection system: A thickened stainless steel connecting flange is set at the end of the outlet sealing section. The gas turbine inlet is rigidly sealed to the flange through high-strength bolts, so that high-temperature and high-pressure flue gas can directly enter the gas turbine without heat dissipation, pressure drop and zero leakage, without the need for transition pipes, heat exchange and pretreatment.

[0010] Natural Chimney Self-Pressurization System: The V-shaped tunnel is 3-5km long and slopes upwards at 15-30° throughout. The high-temperature flue gas generated by underground combustion naturally rises to form a strong chimney effect, automatically forming a stable static pressure of 2-5 bar (0.2-0.5MPa) at the outlet sealing section, which fully meets the gas turbine intake pressure requirements, completely eliminating the need for traditional compressors, and achieving zero energy consumption, zero failures, and zero maintenance.

[0011] Dual-end gas turbine power generation system: Each of the sealed sections at the exits of the tunnel ends is connected to a 300MW-class gas turbine generator set, with a total installed capacity of 600MW. The gas turbine is directly driven by the seamlessly connected high-temperature and high-pressure flue gas to expand and generate electricity, forming a dual-end synchronous power generation and mutually redundant operation mode. Maintenance at one end does not affect the operation at the other end, achieving uninterrupted power generation throughout the year.

[0012] Negative pressure slag suction auxiliary system: Equipped with a wireless remote-controlled mini tunnel boring machine and a negative pressure slag suction device, it regularly cleans coal powder residue in the capillaries to prevent oxygen supply blockage and eliminates the need for manual underground operations.

[0013] The overall implementation process is as follows: 1. Coalfield exploration and geological assessment → Excavation of V-shaped symmetrical slope shield tunnel (6-12 meters inner diameter, 15-40° inclination angle, no horizontal section); 2. Drill 300mm capillary holes continuously along both sides of the V-shaped slope (50-200m interval) → Start the high-pressure oxygen injection system → Achieve low-oxygen self-sustaining combustion of the coal seam on the entire V-shaped slope; 3. High-temperature flue gas (800-1000℃) rises naturally due to density difference and is guided non-powered along the V-shaped slope to the two end outlets. The triple anti-collapse mechanism ensures the stability of the tunnel. 4. The flue gas enters the outlet adaptive sealing section (10-30 meters of stainless steel lining), forming a natural high pressure of 2-5 bar; 5. High-pressure, high-temperature flue gas directly enters the gas turbine through a seamless flange → dual-end synchronous power generation → grid connection and transmission; 6. Intelligent oxygen control regulates combustion intensity → periodic negative pressure slag suction ensures unobstructed capillaries → system operates stably for 20-50 years.

[0014] Compared with the prior art, the technical effects and advantages of the present invention are as follows: 1. V-shaped slope configuration without horizontal sections: Gravity diversion and load reduction, solving the problem of high-temperature collapse of multi-layer coal and rock from the root cause; 2. Triple anti-collapse self-stabilizing mechanism: coking self-support + rock vitrification + slope diversion, multi-layer coal and rock will never collapse at 1000℃; 3. Zero-lining design for coal seam sections: naturally self-stabilizing, saving 80% of lining costs, and requiring no maintenance; 4. Dual-end natural zero-power flow diversion: No fans, no compressors, no pipes, zero-energy transport of flue gas; 5. Adaptive outlet sealing section: Its length can be flexibly adjusted according to the burial depth, making it highly versatile; 6. S32001 stainless steel seal + seamless flange direct connection: temperature and corrosion resistant, reliable sealing, zero leakage; 7. Natural chimney self-pressurization: Automatically generates 2-5 bar high pressure on a 3-5 km slope, replacing the compressor and increasing efficiency by 30%; 8. Dual-end redundant power generation: maintenance at one end does not affect operation, and the system has high reliability. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of a multi-layered coal and rock cross-section of a V-shaped tunnel; Figure 2 This is a top view of the overall system of this invention patent; Figure 3 This is a schematic diagram of gravity diversion on a V-shaped ramp; Figure 4 This is a schematic diagram of the inner wall of a V-shaped tunnel - the self-supporting arch section of coal seam coking - the vitrified glaze surface of interlayered rock; Figure 5 This is a schematic diagram of the connection between the outlet seal and the stainless steel flange to the gas turbine.

[0016] Explanation of reference numerals in the attached figures: 1-Rock, 2-Coal seam, 3-Workshop, 4-V-shaped tunnel, 5-Gas turbine, 6-Stainless steel flange, 7-Outlet sealing section, 8-Capillary, 9-High-pressure oxygen injection device, 10-Oxygen-enriched air separation unit, 11-Gravity direction, 12-V-shaped slope gravity backflow direction, 13-Coal seam coking self-supporting arch section, 14-Intercalated rock vitrified glaze section, 15-S32001 duplex stainless steel lining tile. Detailed Implementation

[0017] The present invention will be further described in detail below with reference to specific embodiments, so as to more clearly illustrate the technical solution and beneficial effects of the present invention.

[0018] As attached Figures 1 to 5 As shown, a V-shaped tunnel underground in-situ gasification coupled power generation system is disclosed, and its specific implementation details are as follows: V-shaped tunnel: inner diameter 6-12 meters, dip angle 15-30°, total length 3000-5000 meters, pure slope with no horizontal section, penetrating 5 layers of coal and rock interlayers; Capillary pores: 20 pores on each side, totaling 40 pores, φ300mm, depth 1000m, spacing 200m; Combustion parameters: Low oxygen self-sustaining, temperature 1100℃, triple anti-collapse mechanism to ensure stability; Lining configuration: No lining is used for the 4970-meter section of the coal seam, and 14mm S32001 stainless steel lining is used for 15 meters at each end of the outlet. Pressurization method: 5km slope natural chimney effect, outlet pressure 3 bar; Connection method: Direct connection to the gas turbine using a seamless stainless steel flange; Power generation system: 300MW gas turbines at each end, with a total installed capacity of 600MW; Total investment: RMB 1.95 billion (78% lower than a traditional 600MW thermal power plant); Cost per kilowatt-hour: 0.068 yuan (including carbon emission reduction benefits); Annual carbon emission reduction: 3.1 million tons of CO2, annual carbon revenue of 186 million yuan; Service life: 45 years, maintenance-free, no collapse, no leakage.

[0019] Finally, the following points should be noted: First, in the description of this application, it should be noted that, unless otherwise specified and limited, the terms "installation", "connection", and "linkage" should be interpreted broadly, and can be mechanical or electrical connections, or internal connections between two components, or direct connections. "Up", "down", "left", "right", etc. are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may change. Secondly: The accompanying drawings of the embodiments disclosed in this invention only involve the structures involved in the embodiments disclosed in this invention. Other structures can refer to the general design. In the absence of conflict, the same embodiment and different embodiments of this invention can be combined with each other. In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A V-shaped tunnel underground in-situ gasification coupled power generation system, characterized in that, include: V-shaped tunnel (4), double-sided ultra-long horizontal capillary holes (8), high-pressure oxygen injection device (9), triple anti-collapse self-stabilizing system, segmented lining tile protection system, seamless stainless steel flange (6) connection mechanism, double-end gas turbine (5) generator set; The V-shaped main tunnel (4) has no bottom horizontal section, an inner diameter of 6-12 meters, an inclination angle of 15°-30°, and obliquely penetrates multiple coal and rock interlayers, with a total length of 3000-5000 meters; The capillary pores (8) are continuously arranged along both sides of the V-shaped slope, with a diameter of 250-350 mm, a depth of 500-3000 m on one side, and a spacing of 50-200 m between pores. An oxygen and water mixing nozzle with a diameter of φ100 mm is installed inside the pore. Every 200 m along the pipe wall, there are two injection holes with a diameter of φ5-10 mm on the left and right sides. The length of the mixing nozzle is half the length of the capillary pore. The triple anti-collapse self-stabilizing system includes: a V-shaped slope gravity diversion mechanism, a coal seam combustion coking self-supporting arch mechanism, and a high-temperature vitrification mechanism for interlayer rocks. The segmented lining protection system is as follows: there are no linings in the coal seam combustion section, and a 10-30 meter adaptive length sealing section is set at both ends of the tunnel, using 6-14mm thick S32001 duplex stainless steel linings. The seamless stainless steel flange (6) connection mechanism realizes a rigid sealing connection between the outlet sealing section and the gas turbine inlet; The underground coal seam self-sustaining combustion generates high-temperature flue gas of 800-1000℃, which is naturally guided at both ends along a V-shaped slope. The tunnel chimney effect is used to form a static pressure of 2-5 bar, which directly drives the gas turbine to generate electricity. The system has no fans, compressors, pipes, heat exchangers, or purification devices. The thermal efficiency is 52-58%, the carbon emission reduction rate is ≥92%, and the service life is 40-60 years.

2. The V-shaped tunnel underground in-situ gasification coupled power generation system according to claim 1, characterized in that, The optimal inner diameter of the main tunnel is 6-12 meters, the inclination angle is 15°-30°, and the total length is 3000-5000 meters; the optimal diameter of the capillary pores (8) is 300 mm, the depth is 500-3000 meters, and the spacing is 50-200 meters; the optimal length of the outlet sealing section is 15 meters, and the thickness of the lining tile is 6-14 mm.

3. The V-shaped tunnel underground in-situ gasification coupled power generation system according to claim 1, characterized in that, The coke self-supporting arch is formed by high-temperature sintering due to incomplete combustion at the edge of the coal seam, with a strength ≥1400℃, and supports the upper rock strata.

4. The V-shaped tunnel underground in-situ gasification coupled power generation system according to claim 1, characterized in that, The interbedded rock is vitrified at a high temperature of 1000℃ to form a ceramic glaze, preventing it from cracking and falling off.

5. The V-shaped tunnel underground in-situ gasification coupled power generation system according to claim 1, characterized in that, The seamless stainless steel flange (6) is a rigid stainless steel sealing connection, which realizes a direct connection with zero leakage of high temperature and high pressure flue gas.

6. The V-shaped tunnel underground in-situ gasification coupled power generation system according to claim 1, characterized in that, The V-shaped tunnel (4) forms a static pressure of 2-5 bar at the outlet through the natural chimney effect, which meets the high-pressure intake requirements of the gas turbine (5).

7. The V-shaped tunnel underground in-situ gasification coupled power generation system according to claim 1, characterized in that, The dual-end gas turbine has a total installed capacity of 600MW, with synchronous power generation at both ends and mutual redundancy, enabling uninterrupted operation throughout the year.

8. A V-shaped tunnel underground in-situ gasification coupled power generation system, characterized in that, Includes the following steps: S1 is a V-shaped symmetrical inclined shield tunnel with an inner diameter of 6-12 meters and an inclination angle of 15°-30°. It has no bottom horizontal section and penetrates multiple layers of coal and rock at an angle. At the junction of the inner wall of the S2 and V-shaped tunnels (4) and multiple coal seams, capillary holes (8) with a diameter of 250-350mm are drilled in the direction parallel to the coal seams. Oxygen and water mixing nozzles with a diameter of φ100mm are installed in the holes. Spray holes with a diameter of φ5-10mm are provided every 200 meters on the pipe wall. The length of the mixing nozzle is half the length of the capillary hole. S3. Low-oxygen self-sustaining combustion of V-shaped inclined coal seam is achieved through high-pressure oxygen injection device (9), with a temperature of 800-1000℃. S4. The tunnel collapse is prevented by a triple mechanism of gravity diversion of V-shaped slope, self-supporting arch of coal seam coking, and glassification of rock. S5. The high-temperature flue gas naturally rises to both ends along the slope and forms a natural high pressure of 2-5 bar through the outlet adaptive stainless steel sealing section. S6. The high-pressure and high-temperature flue gas is directly sent into the gas turbine (5) through the seamless stainless steel flange (6) treated with high-temperature resistant coating, so as to realize synchronous power generation at both ends.

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