Green coal crude methanol fuel gas-steam combined power generation system coupled with green circuit line
The gas-steam combined cycle power generation system, which produces green hydrogen from green electricity, solves the problems of high carbon emissions and high energy consumption in traditional coal-to-methanol systems. It achieves near-zero carbon emissions, high-efficiency energy conversion, and system flexibility, thereby enhancing economic competitiveness and the utilization rate of renewable energy.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NORTH CHINA ELECTRIC POWER UNIV
- Filing Date
- 2025-12-24
- Publication Date
- 2026-06-12
AI Technical Summary
Traditional coal-to-methanol systems suffer from high carbon emissions, heavy carbon tax burdens, high energy consumption, and high investment costs, making it difficult to meet the requirements of sustainable development.
Green hydrogen is produced using green circuitry and generated through a gas-steam combined cycle power generation system. Fuel is produced by cracking and reforming crude methanol to drive gas turbines and steam turbines for power generation, forming a highly efficient gas-steam combined cycle. The distillation and purification unit is eliminated, achieving multi-energy complementarity and system flexibility.
Achieve near-zero carbon emissions, improve energy conversion efficiency, reduce overall energy consumption, enhance system flexibility and economic competitiveness, simplify process flow, and reduce equipment investment and operating costs.
Smart Images
Figure CN122190859A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of green energy storage and efficient utilization technology, specifically a coal-to-crude methanol system that couples green circuit lines and uses crude methanol, after cracking and reforming, as fuel to drive a gas-steam combined cycle power generation. Background Technology
[0002] Methanol, as an important basic chemical raw material and a potential clean fuel, occupies a key position in the global chemical industry and energy sector. my country's energy structure, characterized by "abundant coal, scarce oil, and limited gas," dictates that the coal-based methanol production process will remain a crucial strategic choice for ensuring national energy security and the stability of the chemical industry chain for a considerable period in the past and for the foreseeable future.
[0003] The core process of traditional coal-to-methanol technology is as follows: First, the raw coal is gasified, reacting with a gasifying agent under high temperature to convert it into crude syngas, which is mainly composed of carbon monoxide (CO) and hydrogen (H2). The crude syngas is then washed and purified to remove impurities such as nitrogen oxides and sulfides. Subsequently, the syngas enters a water-gas shift process, converting some carbon monoxide into carbon dioxide, separating and discharging excess carbon dioxide, and increasing the hydrogen content to adjust the overall hydrogen-carbon ratio. Under specific pressure and temperature conditions, the syngas undergoes a synthesis reaction to produce methanol under the action of a catalyst. After cooling and condensation, crude methanol is obtained. The traditional process finally removes impurities and moisture from the crude methanol through distillation to obtain high-purity refined methanol.
[0004] However, traditional coal-to-methanol systems have significant drawbacks: First, the process is inherently a high-carbon emission system—coal gasification and water-gas shift reactions produce large amounts of high-concentration CO2. To meet the hydrogen-to-carbon ratio required for methanol synthesis, this CO2 is usually directly separated and released into the atmosphere. Furthermore, the heat required for coal gasification and methanol synthesis is largely provided by burning coal, which also produces a large amount of CO2. Second, the process has high energy consumption, which does not meet the requirements of sustainable development and faces significant carbon tax pressure and high investment costs, contradicting the strategic goal of "carbon peaking and carbon neutrality." Summary of the Invention
[0005] To address the issues of high carbon emissions, heavy carbon tax burden, and high investment costs associated with traditional coal-to-methanol systems, this invention provides a coal-to-crude methanol and gas-steam combined cycle power generation system coupled with green power lines. This scheme utilizes renewable energy sources such as wind and solar power to generate green hydrogen, completely eliminating the water-gas conversion step. The produced crude methanol is not purified by distillation but undergoes cracking and reforming to convert it into hydrogen-rich cracked gas, which is directly injected into the gas turbine as fuel. Simultaneously, the high-temperature flue gas from the gas turbine drives a waste heat recovery boiler to generate steam, which in turn drives a steam turbine to generate electricity, forming a highly efficient gas-steam combined cycle power generation system. The generated electricity can feed back into the green hydrogen production and methanol synthesis processes and participate in grid peak shaving. This deeply coupled, multi-energy complementary scheme achieves near-zero carbon emissions, high energy conversion efficiency, and system flexibility in the coal-to-methanol process.
[0006] To achieve the above technical objectives, the technical solution adopted by the present invention is as follows:
[0007] A coal-to-crude methanol gas-steam combined power generation system coupled with green circuit lines includes the following core components: an electrolytic cell, a gasifier, a methanol reactor, a crude methanol cracking and reforming unit, a gas turbine, a waste heat recovery boiler (HRSG), a steam turbine, a generator, a scrubbing tower, and a conveying pipeline.
[0008] The core operating conditions and connection methods of the system are as follows:
[0009] 1. Green Hydrogen Preparation and Injection: The electrolyzer is powered by electricity generated from wind and solar power, producing green hydrogen and oxygen through water electrolysis. The generated green hydrogen is precisely injected into the methanol reactor via a hydrogen pipeline, where it is mixed with crude syngas. The hydrogen-to-carbon ratio (H / C) is adjusted to the required 2.0–2.2 for methanol synthesis, thus completely avoiding carbon emissions from the traditional water-gas shift reaction (WGSR) process. The oxygen produced by the electrolyzer is sent to the gasifier via an oxygen pipeline as a supplement or replacement for the gasifying agent, further optimizing the gasification process and reducing energy consumption.
[0010] 2. Crude Methanol Preparation: Powdered coal, after being crushed, ground, and sieved, is added to the gasifier and reacts with a gasifying agent (such as oxygen and steam) under high temperature conditions to generate crude syngas. The crude syngas is then scrubbed to remove impurities such as nitrogen oxides and sulfides. The purified syngas (with its hydrogen-to-carbon ratio adjusted by green hydrogen) enters the methanol reactor, where it undergoes a synthesis reaction under the action of a CuO-ZnO-Al2O3 catalyst at a temperature of 210-280℃ and a pressure of 5-10 MPa to produce crude methanol.
[0011] 3. Crude Methanol Cracking and Reforming: Crude methanol, as a liquid intermediate product, is directly transported to the crude methanol cracking and reforming unit via pipeline. In this unit, crude methanol undergoes cracking and reforming reactions under specific catalyst and operating conditions (e.g., temperature approximately 200-300°C, pressure 1.0-5.0 MPa; specific conditions can be optimized based on catalyst and reactor design), generating cracked gas (or syngas gas) rich in hydrogen, CO, and a small amount of CO2. This cracking and reforming process effectively converts methanol into the clean fuel required for efficient combustion in gas turbines.
[0012] 4. Gas Turbine Power Generation: The pyrolysis gas, used as fuel, is directly transported to the gas turbine for combustion via pipelines. The gas turbine burns the pyrolysis gas under high temperature and pressure to produce high-speed gas, which drives the turbine section of the gas turbine to perform work, thereby driving the generator to produce electricity. This process efficiently converts the chemical energy of crude methanol pyrolysis gas into electrical energy, achieving cascaded energy utilization and flexible system operation. The start-up and operation of the gas turbine can be flexibly controlled according to grid demand. Using methanol as a liquid energy storage medium, it endows the grid with peak-shaving capabilities, and the response rate can be improved from ±2% / min to ±10% / min.
[0013] 5. Waste Heat Recovery and Steam Turbine Power Generation: The high-temperature flue gas (e.g., approximately 400-600°C) generated after the gas turbine burns pyrolysis gas is introduced into a waste heat recovery boiler. The waste heat recovery boiler utilizes the heat from the flue gas to generate high-temperature, high-pressure steam. This steam then drives a steam turbine to perform work, which in turn drives a generator to produce electricity. The gas turbine and steam turbine work together to form a highly efficient gas-steam combined cycle power generation mode, effectively improving overall power generation efficiency.
[0014] 6. Energy Cycle and Optimization: The electricity generated by the generator jointly driven by the gas turbine and steam turbine is used to power the compressors and pumping equipment in the electrolysis cell for green hydrogen production and methanol synthesis, achieving internal energy self-sufficiency. The remaining electricity can be sold to the grid during peak hours according to grid demand, realizing green electricity arbitrage (e.g., off-peak electricity for hydrogen production at 0.15 yuan / kWh, peak electricity sales at 0.6 yuan / kWh), thereby significantly reducing overall operating costs and improving economic efficiency.
[0015] Compared with the prior art, the system of the present invention has the following beneficial effects:
[0016] 1. Significant carbon emission reduction benefits: By replacing WGSR with green electricity to produce hydrogen, the carbon emission intensity is reduced from the traditional 1.93 t-CO2 / t-MeOH to below 0.05 t-CO2 / t-MeOH, achieving near-zero carbon emissions and a reduction of up to 97.4%. This completely solves the structural carbon emission dilemma of the traditional coal-to-methanol process.
[0017] 2. High energy conversion efficiency and reduced overall energy consumption: Integrating crude methanol cracking and reforming with gas-steam combined cycle power generation technology, the system achieves tiered utilization of energy quality, increasing energy conversion efficiency from 38% in traditional processes to over 61%, and reducing overall energy consumption by 16.6% (from 38.5 GJ / t to 32.1 GJ / t). The gas-steam combined cycle power generation efficiency can reach over 55%, with optimized efficiency exceeding 60%, significantly improving overall power generation efficiency.
[0018] 3. System flexibility and grid support capability: Crude methanol, as a liquid energy storage medium, achieves the decoupling of "gasification-power generation" through its cracking and reforming and combined cycle power generation system, giving the system strong peak-shaving capability (response rate ±10% / min) and operational flexibility (annual utilization hours increased from 1000h to 4000h), effectively absorbing wind and solar power curtailment and improving the utilization rate of renewable energy.
[0019] 4. Superior economic competitiveness: When the price of green electricity is ≤0.15 yuan / kWh, the levelized cost of crude methanol (LCOM) of the system of this invention is on par with, or even lower than, the traditional coal-to-methanol + carbon tax scheme. Combined with green electricity arbitrage and carbon trading revenue (a reduction of 1.88 tons of CO2 / ton of methanol can yield a revenue of 188 yuan / ton), the investment payback period can be shortened to 7.4 years.
[0020] 5. Simplified process flow: The distillation and purification unit is completely eliminated, which simplifies the downstream process and reduces equipment investment and operating energy consumption. Attached Figure Description
[0021] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.
[0022] Figure 1 A schematic diagram of the overall integrated energy system provided by this invention;
[0023] Figure 2 A schematic diagram of the methanol production process provided by this invention;
[0024] Figure 3 A schematic diagram of the process flow for the power generation stage of the system provided by the present invention. Detailed Implementation
[0025] Example 1: A coal-to-crude methanol gas-steam combined power generation system coupled with green circuit lines
[0026] Methanol production stage (see) Figure 2 )
[0027] 1. Raw material pretreatment and coal slurry preparation:
[0028] The raw coal and water first enter the mixer (B10) for preliminary mixing. The circulating liquid in stream 3 is also introduced into B10.
[0029] The mixed material stream (stream 1) enters the crusher / grinder / mixer (B11) for further crushing, grinding and uniform mixing to form a coal slurry that meets the requirements for gasification.
[0030] The processed material stream (stream 2) enters the separator / storage tank (B13) for coal slurry storage or further solid-liquid separation, while stream 3 may be recycled back to B10 as water or other light components.
[0031] The material processed by B13 (stream 4) is used as coal slurry and is ready to enter the gasifier.
[0032] 2. Green hydrogen preparation and oxygen compression:
[0033] The renewable energy-powered electrolyzer (B9) produces high-purity green hydrogen through the electrolysis of water.
[0034] The generated green hydrogen is compressed by a compressor (B5) to form a high-pressure hydrogen gas stream (S3), which is then processed by a heat exchanger (H3) (S4) before being sent to the subsequent syngas mixing unit.
[0035] Meanwhile, the oxygen produced by the electrolytic cell (B9) is compressed into high-pressure oxygen by the compressor (B2) and sent to the gasifier (B14) as a gasifying agent.
[0036] 3. Coal gasification unit:
[0037] In the gasifier (B14), the coal slurry (stream 4) from B13 reacts with the gasifying agent under high temperature and high pressure conditions to generate crude syngas.
[0038] A gasifier (B16) is connected to the bottom of the gasifier to separate and discharge the ash (ASH) produced during gasification. Stream 6 may be flushing water or steam returning from B16 to B17.
[0039] 4. Syngas purification and conditioning:
[0040] The high-temperature crude syngas discharged from the gasifier (B14) enters the heat exchanger / waste heat boiler (B17) for cooling and waste heat recovery, producing cooled syngas.
[0041] The crude syngas further enters the cooler (B18) for cooling, forming stream 8.
[0042] Stream 8 then enters the separator (B12), where condensable components and impurities (IM) are separated to obtain purified syngas (SYN-IN).
[0043] The purified syngas (SYN-IN) is compressed by the compressor (B1) to form a high-pressure syngas flow (S1), and then processed by the heat exchanger (H1) (S2).
[0044] In the mixer (B6), the syngas (S2) from H1 and the green hydrogen (S4) from H3 are thoroughly mixed to adjust the H / C ratio of the syngas to the optimal range (2.0-2.2) required for methanol synthesis, forming a mixed syngas (SYN-H2), which completely replaces the traditional water-gas shift reaction (WGSR).
[0045] 5. Crude methanol synthesis unit:
[0046] The mixed syngas (SYN-H2) enters the methanol reactor (B4). The reactor is loaded with a CuO-ZnO-Al2O3 catalyst. Under the conditions of 210-280℃ and 5-10MPa, the syngas reacts in the presence of the catalyst to produce a product containing crude methanol (S5).
[0047] The product stream (S5) is cooled by the cooler (B8) (S6) and then enters the separator (B7) for gas-liquid separation.
[0048] The liquid product flowing out from the bottom of B7 is crude methanol. The gas phase (S7) flowing out from the top of B7 consists of unreacted synthesis gas, inert gas, etc., which can be compressed and recycled back to the inlet of the mixer (B6) to improve the utilization rate of raw materials.
[0049] Methanol-gas combined heat and steam power generation stage (see Figure 3 )
[0050] The gas turbine intake compressor 1 draws in air and fuel vapor, compresses them, and sends them into the combustion chamber 2.
[0051] In combustion chamber 2, fuel vapor mixes with air and burns to produce high-temperature, high-pressure gas.
[0052] High-temperature and high-pressure gas enters gas turbines 3 and 4 to do work, and the gas turbine drives the generator to generate and output electrical energy.
[0053] The high-temperature exhaust gas from the gas turbine enters the waste heat recovery unit 5, which uses the waste heat to heat water and generate steam.
[0054] These steam and the by-product steam from the methanol production system enter the high-pressure turbine 6 to perform work. Part of the steam discharged from the high-pressure turbine 6 undergoes heat exchange in the heat exchanger 8, and the resulting waste heat is introduced into the waste heat recovery unit 5.
[0055] The steam discharged from high-pressure turbine 6 further enters low-pressure turbine 7 to perform work. High-pressure turbine 6 and low-pressure turbine 7 drive generators to produce and output electricity. The generated electricity is transmitted to a renewable energy storage device, achieving efficient energy utilization. In the above system, a strategy of producing hydrogen from off-peak electricity (electricity price 0.15 yuan / kWh) and selling electricity during peak hours (electricity price 0.6 yuan / kWh) is adopted to reduce costs.
[0056] Summary of Operation Process
[0057] This system first uses wind and solar power to drive an electrolyzer to produce green hydrogen and oxygen. The oxygen is then sent to a gasifier to react with pulverized coal to generate crude syngas. After purification, the crude syngas is mixed with green hydrogen to adjust the hydrogen-to-carbon ratio, and then fed into a methanol reactor to synthesize crude methanol. When power generation is needed, the crude methanol is sent to a crude methanol cracking and reforming unit to be converted into cracked gas. The cracked gas is then sent to a gas turbine for combustion and power generation. The exhaust gas from the gas turbine is heated by a waste heat recovery boiler to generate steam, which drives a steam turbine to further generate electricity. All the generated electricity can be used for green hydrogen production, methanol synthesis, and power supply to the grid, achieving energy recycling and high-efficiency conversion.
[0058] This invention utilizes crude methanol as a liquid energy storage fuel, combined with efficient gas-steam combined cycle technology, which not only improves the overall system efficiency and sustainability, but also helps to achieve more efficient energy storage and grid peak shaving, and is of great significance to promoting the development of sustainable energy solutions.
Claims
1. A coal-to-crude methanol gas-steam combined power generation system optimized for green electricity, characterized in that, It includes the following equipment: electrolytic cell, gasifier, methanol reactor, crude methanol storage tank, crude methanol cracking and reforming unit, gas turbine, waste heat recovery boiler, steam turbine, generator, scrubbing tower, and conveying pipeline.
2. The coal-to-crude methanol gas-steam combined power generation system based on green electricity optimization according to claim 1, characterized in that, The green energy optimization scheme described above can control the carbon emission intensity of each ton of crude methanol to below 0.1 t-CO2 / t-MeOH, with an optimal level of below 0.05 t-CO2 / t-MeOH.
3. The coal-to-crude methanol and gas-steam combined power generation system based on green electricity optimization according to claim 1 or 2, characterized in that, In the process of preparing green hydrogen by electrolysis of water, the power consumption is in the range of 45 kWh / kg H2 to 55 kWh / kg H2, and the preferred power consumption parameter is 48 kWh / kg H2.
4. The coal-to-crude methanol gas-steam combined power generation system based on green electricity optimization according to any one of claims 1 to 3, characterized in that, After replacing the water-gas shift reaction (WGSR) with green hydrogen, the process indicators have been significantly optimized: the raw coal consumption per ton of crude methanol has been reduced from the traditional 1.5 tons to 1.1 tons, while the carbon atom utilization rate has been greatly increased from 35% to over 95%.
5. The coal-to-crude methanol gas-steam combined power generation system based on green electricity optimization according to any one of claims 1 to 4, characterized in that, The crude methanol is cracked and reformed to produce cracked gas, which is then used as fuel in a gas turbine to burn and drive a generator to generate electricity.
6. The coal-to-crude methanol gas-steam combined power generation system based on green electricity optimization according to claim 5, characterized in that, The high-temperature flue gas discharged from the gas turbine is introduced into a waste heat recovery boiler (HRSG) to generate high-temperature and high-pressure steam. The steam drives the steam turbine to do work and drives the generator to generate electricity, forming a gas-steam combined cycle.
7. The coal-to-crude methanol gas-steam combined power generation system based on green electricity optimization according to any one of claims 1 to 6, characterized in that, The system also uses the crude methanol produced as a liquid energy storage medium for grid peak shaving operations or to absorb excess electricity generated by wind and solar power curtailment, thereby improving the overall efficiency of energy utilization.
8. The coal-to-crude methanol gas-steam combined power generation system based on green electricity optimization according to any one of claims 1 to 7, characterized in that, The system's overall energy consumption is below 35 GJ / t-MeOH, and under optimal conditions, it can be below 32.1 GJ / t-MeOH; meanwhile, its energy conversion efficiency is above 50%, with a preferred efficiency exceeding 61%. Furthermore, when the electricity price does not exceed 0.15 yuan / kWh, the levelized cost of crude methanol (LCOM) using the aforementioned green electricity optimization system is economically competitive compared to traditional coal-to-methanol systems; and the green hydrogen production process can utilize off-peak electricity, further reducing green hydrogen production costs.
9. A coal-to-crude methanol gas-steam combined power generation system optimized for green electricity, characterized in that, It mainly consists of the following units: a. Water electrolysis hydrogen production unit: Green hydrogen is produced by electrolyzing water using renewable energy electricity. This unit includes an alkaline electrolyzer or a proton exchange membrane electrolyzer. The produced green hydrogen is mixed with syngas to adjust the hydrogen-to-carbon ratio, thereby replacing the water-gas shift reaction (WGSR) unit in the traditional system. b. Coal gasification unit: responsible for producing crude syngas through coal gasification process; c. Methanol synthesis unit: converts the synthesis gas, after adjusting the hydrogen-to-carbon ratio, into crude methanol; d. Crude methanol cracking and reforming unit: Crude methanol is cracked and reformed to obtain cracked gas.
10. The coal-to-crude methanol gas-steam combined power generation system based on green electricity optimization according to claim 9, characterized in that, The system can also be equipped with auxiliary modules: one is a gas-steam combined cycle power generation module, which includes a crude methanol cracking and reforming unit, a gas turbine, a waste heat recovery boiler and a steam turbine, used to burn crude methanol cracked gas to generate electricity and recover waste heat for further power generation; the other is a crude methanol energy storage and application module, which includes a crude methanol storage tank, which can use crude methanol products as a liquid energy storage medium to provide auxiliary services such as peak shaving for the power grid.