An integrated process for oil production, hydrogen production, underground carbon sequestration and underground gasification of full energy utilization

Abstract

The application discloses an integrated process for oil and hydrogen production and underground carbon sequestration by underground gasification, belonging to the field of clean coal utilization, zero carbon hydrogen energy and underground carbon sequestration. For a large system with 40 million tons of raw coal processed annually to produce 10 million tons of finished oil, a V-shaped shield cavity coupling system is constructed to realize a closed-loop process of underground oxygen-enriched gasification, high-temperature purification, supercritical two-stage power generation, low-temperature advection catalytic oil production, waste heat recycling, surplus electricity electrolysis for hydrogen production, and carbon sequestration in the whole process. An oil and hydrogen physical isolation system is formed, and synthesis gas is specially used for oil production to ensure stable finished oil production capacity. 500 billion degrees of electricity are generated annually, 150 billion degrees of electricity are used, and 350 billion degrees of surplus electricity are used for hydrogen production. The low-temperature waste heat in electrolysis is recycled in stages, and waste heat is used for secondary power generation. Carbon dioxide is supercritically stored underground in the whole process to achieve near-zero emission on the ground and obtain zero-carbon certification and multiple carbon benefits. The process solves the problems of raw material conflict, power consumption, waste heat waste, carbon emission and the like, and has significant large-scale advantages.

Description

Technical Field

[0001] This invention relates to the fields of underground in-situ coal gasification technology, supercritical two-stage power generation technology, horizontal catalytic oil synthesis technology, large-scale green electrolysis hydrogen production technology, multi-stage industrial waste heat utilization, and deep underground carbon sequestration clean energy technology. Specifically, it relates to a new integrated process for underground in-situ gasification with full energy closed-loop, dual oil and hydrogen production, and full underground carbon reduction. Background Technology

[0002] Large-scale underground in-situ coal gasification to oil projects generally face industry bottlenecks: there is a raw material conflict between oil production and hydrogen production, and the by-product hydrogen needs to be extracted from syngas, which disrupts the optimal hydrogen-to-carbon ratio in advection catalytic synthesis, leading to a decrease in oil yield and fluctuations in production capacity and quality; large energy bases generally suffer from insufficient grid absorption, inability to absorb surplus electricity, and serious energy curtailment; the existing process energy system is fragmented, with multi-stage waste heat being directly released into the atmosphere, resulting in low overall system energy efficiency; traditional hydrogen energy projects do not thoroughly reduce carbon emissions and have limited carbon benefits, lacking a complete underground carbon sequestration pathway; the industry lacks a large-scale integrated oil and hydrogen production process that ensures unaffected oil production capacity, full absorption of surplus electricity, full recovery of waste heat, and near-zero emissions throughout the entire process. Summary of the Invention

[0003] Purpose of the invention Addressing the bottlenecks of existing technologies, such as conflicts between oil and hydrogen production, difficulties in utilizing surplus electricity, multi-stage waste heat release, high carbon emissions, fragmented process systems, and single project revenue streams, this invention provides an integrated underground gasification process for full energy utilization in oil and hydrogen production with underground carbon sequestration. This process aims to achieve the technical goals of stable supply from the main oil production business, efficient utilization of surplus electricity, closed-loop recycling of multi-stage waste heat, carbon reduction throughout the entire site, and stable parallel operation of both oil and hydrogen production.

[0004] SI. The underground gasification syngas is dedicated to oil production, while hydrogen production relies entirely on the system's surplus secondary electricity. This process avoids extracting syngas, disrupting the hydrogen-to-carbon ratio, and reducing oil production capacity, achieving the symbiotic and parallel production of both oil and hydrogen without interference. S2. Establish an industrialized, precise energy quantification and allocation model: rigid hierarchical allocation of electrical energy to form a standardized process for energy allocation in underground gasification energy bases that can be scaled up, audited, and certified.

[0005] S3. Construct a multi-level heat source cascade closed-loop utilization system: integrate high-temperature waste heat power generation, medium-temperature waste heat oil production, low-temperature waste heat system reuse, and residual low-grade waste heat secondary power generation to achieve full energy closed-loop, zero venting, and zero waste.

[0006] S4. Achieve near-zero carbon emissions and maximize carbon benefits across the entire process: The entire process involves unified collection, pressurization, supercritical phase change, and permanent underground storage of carbon dioxide, which can obtain international zero-carbon green hydrogen certification, domestic CCER carbon emission reduction, CCUS subsidies, and export carbon tariff exemptions.

[0007] S5. Multifunctional and intensive reuse of shield tunnel cavities: V-shaped cavities undertake gasification, reaction, and carbon sequestration; vertical cavities undertake hydrogen storage, pressure stabilization, heat exchange, and buffering, significantly reducing ground investment and improving system safety, confidentiality, and compliance.

[0008] Technical solution S1. Large-scale underground in-situ oxygen enrichment gasification: Construct an underground V-shaped deep-ground gasification shield tunnel cavity coupled with a vertical multi-functional shield tunnel cavity system. Adopt oxygen-enriched continuous gasification to complete the in-situ gasification of coal seams in an underground closed, high-temperature, and high-pressure environment, and continuously produce high-temperature and high-pressure crude coal gas.

[0009] S2. Underground full-area high-temperature purification: The crude coal gas undergoes high-temperature dust removal, desulfurization, decarbonization, and impurity interception in an underground closed channel to obtain clean synthesis gas with a stable hydrogen-to-carbon ratio that is suitable for horizontal catalytic synthesis. All of this gas is then directionally transported to the underground horizontal catalytic oil production unit.

[0010] S3. Supercritical + Subcritical Two-Stage Coaxial Flue Gas Turbine Power Generation: Utilizing underground gasification high-temperature flue gas, coal seam reaction residual pressure, and underground thermal pressure double closed-loop residual heat, a two-stage coaxial flue gas turbine combined cycle power generation system is driven to stably produce electricity.

[0011] S4. Precise graded power allocation: The plant’s power is rigidly graded and allocated, with a portion used for self-sufficiency, covering all loads of in-situ gasification, oxygen-enriched air separation, high-temperature purification, tunnel boring machine operation and maintenance, horizontal catalytic synthesis, low-temperature distillation, and instrumentation control; surplus power is completely isolated, with zero diversion, and is used entirely for the electrolysis of water to produce green hydrogen; the oil production material system and the hydrogen production energy system are completely independent.

[0012] S5. Underground advection catalytic synthesis for oil production and low-temperature distillation waste heat recovery: Clean synthesis gas enters the advection catalytic synthesis system to produce oil products. The crude oil is refined by underground low-temperature distillation. The waste heat from distillation is uniformly recovered and incorporated into the plant's cascade heat energy circulation system.

[0013] S6. Large-scale surplus green electricity electrolysis for hydrogen production: Surplus and stable green electricity is fed into an electrolyzer array to electrolyze pure water to produce high-purity industrial green hydrogen, converting unusable surplus electricity into high-value-added hydrogen energy.

[0014] S7. Closed-loop cascaded reuse of low-temperature waste heat from electrolysis: Low-temperature waste heat generated by the electrolyzer is utilized in a priority cascaded manner - sequentially supplied to preheating of horizontal catalytic synthesis, constant temperature of water-gas shift reaction, regeneration of air separation molecular sieve, and constant temperature and pressure of underground shield tunnel cavity; residual low-grade waste heat is introduced into the low-temperature generator set for secondary power generation to supplement the plant's power supply.

[0015] S8. Underground supercritical carbon emission storage for the entire process: Carbon dioxide generated throughout the process is collected, pressurized in multiple stages, undergoes supercritical phase change, and then introduced into a sealed cavity in a deep underground shield tunnel for permanent storage, achieving near-zero carbon emissions above ground.

[0016] S9. Multifunctional reuse of vertical shield tunnel cavity for hydrogen storage and external transportation: Green hydrogen is introduced into the sealed cavity of the vertical shield tunnel to complete buffering, pressure stabilization, high-pressure hydrogen storage, and static purification. Underground pressurization, liquefaction, and external transportation are carried out as needed to achieve safe underground hydrogen storage and external transportation.

[0017] Beneficial effects Compared with the prior art, the present invention has the following advantages: S1. Completely resolve the conflict between oil and hydrogen production capacity, and ensure stable supply of the main oil production business; S2. Efficiently absorbs surplus power, freeing it from grid absorption constraints; S3. Multi-level energy cascade closed-loop utilization significantly improves system energy efficiency; S4. Near-zero carbon emissions throughout the entire process, with the potential to generate multiple carbon asset benefits; S5. Underground intensive layout, low investment, high safety level, and strong compliance; S6. The process parameters are standardized and replicable, and have global promotion and technology licensing value. Attached Figure Description

[0018] Figure 1 is a schematic cross-sectional view of the overall layout of the present invention; Figure 2 is a top view of the overall system of the present invention; Figure 3 is Figure 2 (12) Enlarged view of a concentrated work area; Figure 4 This is a process flow diagram of the present invention.

[0019] Explanation of reference numerals in the attached figures: 1-Mud and rock, 2-Coal seam, 3-Vertical main entrance, 4-V-shaped tunnel coal in-situ gasification system, 5-Inner gasification power generation purification halogenation advection catalytic reaction unit, 6-Outer separation distillation oil storage unit, 7-Slag collection tank, 8-Capillary deep hole, 9-Negative pressure ash and slag suction pipe, 10-Fly ash return pipe, 11-Ash and slag treatment station, 12-Centralized operation area, 13-Vertical support well, 14-Oil-water-slag separation system, 15-Physical distillation separation system, 16-Underground sealed oil storage system, 17-Supercritical flue gas turbine power generation system, 18-High temperature synthesis purification system, 19-Halogenation advection catalytic reaction system, 20-Oxygen-enriched air separation unit, 21-Deep earth shield tunnel sealed cavity, 22-Waste heat cascade reuse system, 23-Electrolysis water to produce green hydrogen plant, 24-Underground sealed hydrogen storage system, 25-Carbon emission sealing channel. Specific Implementation The 40 million-ton-level underground in-situ gasification demonstration project in Hulunbuir, Inner Mongolia, serves as a specific example: The project processes 40 million tons of raw coal annually, using underground oxygen-enriched continuous gasification. The syngas purified at high underground temperatures is entirely supplied to low-temperature Fischer-Tropsch synthesis, resulting in a stable annual production of 10 million tons of refined oil. Utilizing underground waste heat and pressure, it drives a supercritical two-stage power generation system, generating a total of 50 billion kWh annually. Of this, 15 billion kWh ensures the self-sustaining operation of all process equipment, while the remaining 35 billion kWh of surplus electricity is 100% used for water electrolysis to produce green hydrogen. The 65-75°C low-temperature waste heat from the electrolysis system is fully recycled in stages for oil preheating, air separation regeneration, underground constant temperature operation, and ORC secondary power generation. All carbon emissions from the entire process are permanently sealed underground via supercritical storage. The finished green hydrogen is stored, pressurized, and liquefied in an underground vertical shield tunnel before being sold and exported.

[0021] This embodiment features a stable process, no energy waste, no production capacity conflict, carbon reduction across the entire region, and high returns from both industries, fully meeting the national standards for zero-carbon energy demonstration projects.

Claims

1. An integrated underground gasification process for full energy utilization, oil and hydrogen production, and underground carbon sequestration, characterized in that... It includes the following steps: S1. Large-scale underground in-situ oxygen enrichment: Construct an underground V-shaped deep underground gasification shield cavity - V-shaped tunnel coal in-situ gasification system (4) and a horizontal section multi-functional shield cavity to form a coupling system to realize continuous and controllable in-situ gasification of coal seams; the oxygen-enriched air separation unit (20) supplies high-purity oxygen to complete coal seam gasification in an underground closed high temperature and high pressure environment, producing high pressure and high temperature crude coal gas; S2. Underground full-area high-temperature purification: The crude coal gas undergoes high-temperature dust removal, desulfurization, decarbonization and impurity interception in the underground closed channel through the high-temperature synthesis purification system (18) to obtain clean synthesis gas with stable hydrogen-carbon ratio and suitable for horizontal catalytic synthesis. All of it is transported to the underground halogenation horizontal catalytic reaction system (19) oil production unit. S3. Supercritical + Subcritical Two-Stage Coaxial Flue Gas Turbine Power Generation: Utilizing underground gasification high-temperature flue gas, coal seam reaction residual pressure, and underground thermal pressure double closed-loop residual heat to drive the supercritical flue gas turbine power generation system (17) in a combined cycle to generate electricity stably; S4. Precise graded power allocation: The power of the whole plant is rigidly graded and configured. A portion of the power is used for the whole plant’s self-sufficiency and covers the underground V-shaped tunnel coal in-situ gasification system (4), oxygen-enriched air separation unit (20), high-temperature synthesis and purification system (18), the vertical main entrance (3) and vertical support well (13) of shield tunnel operation and maintenance, halogenation advection catalytic reaction system (19), physical distillation separation system (15), and instrument automatic control load; the remaining surplus power is completely isolated and is used entirely for the electrolysis of water to prepare green hydrogen plant (23). The oil synthesis gas material system and the hydrogen production power system are completely independent. S5. Underground advection catalytic synthesis of oil and low temperature distillation waste heat recovery: Clean synthesis gas enters the halogenation advection catalytic reaction system (19), crude oil is refined by underground low temperature distillation through the physical distillation separation system (15), and the waste heat of distillation is recovered and incorporated into the whole plant waste heat cascade recovery system (22) for recycling. S6. Large-scale surplus green electricity is fully electrolyzed to produce hydrogen: surplus stable electricity is connected to the water electrolysis plant to produce green hydrogen (23) electrolyzer array, and high-purity industrial green hydrogen is produced by electrolyzing pure water; S7. Full closed-loop cascade reuse of low-temperature waste heat in electrolysis: Zero discharge of low-temperature waste heat in electrolytic cells, cascade supply to halogenation horizontal catalytic reaction system (19) for preheating, water-gas shift constant temperature, air separation molecular sieve regeneration, and underground shield tunnel cavity constant temperature and pressure maintenance, and residual heat is fed back to the plant power through low-temperature generator set for secondary power generation. S8. Underground supercritical carbon emission storage of the whole process: After the carbon dioxide is collected, pressurized and supercritically phase-changed throughout the whole process, it is introduced into the deep shield tunnel sealed cavity (21) through the carbon emission storage channel (25) for permanent storage, so as to achieve near-zero carbon emissions above ground. S9. Vertical shield tunnel cavity multifunctional reuse hydrogen storage and external transportation: Green hydrogen is introduced into the underground sealed hydrogen storage system (24) to complete buffering, pressure stabilization, high-pressure hydrogen storage and purification, and underground pressurization, liquefaction and external transportation as needed.

2. The process according to claim 1, characterized in that: The oil feedstock system and the hydrogen energy system are completely physically isolated. Advection catalytic oil production relies on the chemical energy of underground gasification syngas, while hydrogen production relies on the system's surplus secondary electrical energy. It does not extract syngas, does not disrupt the hydrogen-carbon ratio, and does not reduce oil production capacity.

3. The process according to claim 1, characterized in that: The entire plant forms a four-level cascade energy utilization system: high-temperature waste heat power generation, medium-temperature waste heat oil production reaction, low-temperature waste heat system regeneration and insulation, and residual low-temperature waste heat secondary power generation, achieving a closed-loop utilization of thermal energy, electrical energy, and pressure energy.

4. The process according to claim 1, characterized in that: The system's electrical energy is rigidly distributed in a hierarchical manner, forming an oil-hydrogen symbiosis and quantitative energy distribution model for the underground gasification base.

5. The process according to claim 1, characterized in that: The low-temperature waste heat from electrolysis is precisely matched to the temperature range of oil production and air separation regeneration, and the system is self-heating balanced, requiring no external heating.

6. The process according to claim 1, characterized in that: The entire process involves underground, sealed storage of carbon emissions, forming a certifiable zero-carbon process system that is compatible with international green hydrogen certification, carbon tariff exemptions, and domestic carbon reduction and CCUS subsidy policies.

7. The process according to claim 1, characterized in that: The vertical shield tunnel cavity is integrated and reused as a hydrogen storage and pressure stabilization cavity, a waste heat exchange cavity, a process buffer cavity, and an auxiliary carbon sequestration cavity, realizing the intensive utilization of underground equipment.

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