Low-rank coal zero-carbon emission methanol system

Abstract

The utility model discloses a kind of low-rank coal zero carbon emission system for preparing methanol, including coal grading quality conversion unit for using low-rank coal to generate waste coal gas, high-quality carbon and CO2, waste coal gas processing unit for converting waste coal gas into coke coal oil, hydrogen and LNG, electrolytic water device for accommodating green electricity to generate hydrogen and oxygen, gasification device for converting high-quality carbon and steam with oxygen generated by electrolytic water device into water gas, methanol synthesis device for methanol synthesis treatment of hydrogen generated by electrolytic water device and water gas and generating methanol and release gas and CO2 capture and reuse unit, CO2 capture and reuse unit includes at least two capture modules, respectively for capturing carbon dioxide in carbon dioxide and release gas discharged by coal grading quality conversion unit, and carbon dioxide captured is all transported to the gasification device for reuse, low-rank coal quality utilization maximization, whole-process zero carbon emission, deeply fit "double carbon" target.

Description

Technical Field

[0001] This utility model belongs to the field of methanol production and manufacturing technology, specifically relating to a methanol production system using low-rank coal with zero carbon emissions. Background Technology

[0002] Guided by my country's strategic goal of "peak carbon and carbon neutrality," the clean and efficient conversion and low-carbon utilization of low-rank coal (such as lignite and long-flame coal), as a coal resource with abundant reserves, has become an important issue in the energy sector. Among them, the process of producing methanol from low-rank coal has attracted much attention from the industry because it can realize the high-value utilization of coal resources.

[0003] If low-rank coal is burned directly as fuel, its energy utilization rate is less than 30%, and it releases large amounts of pollutants such as CO2 and SO2, which does not meet the requirements for low carbon emissions. If used in traditional methanol production processes, it requires pretreatment stages such as drying and gasification, which not only consumes a large amount of external energy (such as natural gas and electricity), but also wastes organic matter in the coal (such as coal tar and light hydrocarbons) due to the extensive process, resulting in low comprehensive resource utilization. In addition, in traditional methanol production processes, after low-rank coal is gasified to produce water gas, the H2 / CO ratio needs to be adjusted through a "water-gas shift reaction" to meet the needs of methanol synthesis. This process generates a large amount of CO2 (approximately 2.5-3 tons of CO2 are emitted per ton of methanol); and most processes only perform end-of-pipe CO2 capture (such as geological sequestration) without recycling it in the production process, resulting in the inability to recycle CO2 and failing to achieve the "zero carbon emission" target, thus deviating from the "dual carbon" requirement. Utility Model Content

[0004] To address the technical problems existing in the prior art, this utility model provides a methanol production system with zero carbon emissions from low-rank coal.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A zero-carbon-emission methanol production system using low-rank coal includes: The coal grading and quality conversion unit is used to generate raw coal gas, high-quality char and CO2 from low-rank coal; Raw coal gas processing unit is used to convert raw coal gas into coal tar, hydrogen and LNG; An electrolysis water device is used to utilize green electricity to generate hydrogen and oxygen. Gasification unit, used to convert high-quality charcoal and steam into water gas with oxygen generated by water electrolysis unit; The methanol synthesis unit is used to process hydrogen generated by the water electrolysis unit with water gas to synthesize methanol and release gas. The CO2 capture and reuse unit includes at least two capture modules, which are used to capture carbon dioxide emitted from the coal grading and quality conversion unit and carbon dioxide released from the methanol synthesis unit, respectively, and to transport the captured carbon dioxide to the gasification unit for reuse.

[0006] Furthermore, the coal grading and quality conversion unit includes a fuel-rich grading and quality conversion device for graded pyrolysis treatment of low-rank coal raw materials under a fuel-rich environment. The fuel-rich grading and quality conversion device can convert the organic matter in low-rank coal into raw coal gas, high-quality char and CO2.

[0007] Furthermore, the raw coal gas treatment unit includes a condensing blower system, a coal gas purification device, and a deep cryogenic adsorption separation device. The condensing blower system is used to cool and condense the raw coal gas, perform electrostatic oil removal, and separate the gas and liquid to generate crude purified coal gas and coal tar. The coal gas purification device is used to deeply purify the coal gas to remove impurities and generate hydrogen-rich coal gas. The deep cryogenic adsorption separation device is used to cool and adsorb the hydrogen-rich coal gas at low temperature, converting the hydrocarbon components into LNG.

[0008] Furthermore, the hydrogen-rich gas remaining after the cryogenic adsorption separation of the coal gas can be transported to the combustion unit of the fuel-rich grading and pyrolysis device. The excess oxygen generated by the water electrolysis device in the process of absorbing green electricity to generate hydrogen and oxygen can also be transported to the combustion unit. By mixing and burning the hydrogen-rich gas and excess oxygen in the combustion unit, heat energy is generated, providing the required heat source for the fuel-rich grading and pyrolysis device to perform graded pyrolysis treatment of low-rank coal in a fuel-rich environment, realizing the resource recycling and self-use within the fuel-rich grading and pyrolysis device.

[0009] Furthermore, the gasification device is a pulverized coal slag gasification device.

[0010] Furthermore, the steam originates from the heat recovery of the gasification reaction in the pulverized coal slag gasification unit itself, the waste heat recovery of the pyrolysis in the fuel-rich staged and graded unit, the heat recovery of the reaction in the methanol synthesis unit, and an external supplementary steam unit connected to the pulverized coal slag gasification unit.

[0011] Furthermore, the pulverized coal slag gasification device introduces steam and high-quality char generated by the coal grading and quality conversion unit, along with oxygen prepared by the water electrolysis device, into the device. Under high-temperature gasification conditions, water gas is generated, and the ash slag produced during the gasification reaction is discharged and collected through a liquid slag discharge method.

[0012] Furthermore, the two capture modules are a first CO2 capture device and a second CO2 capture device. The first CO2 capture device is used to capture CO2 in the coal grading and quality conversion unit and transport the captured CO2 to the pulverized coal slag gasification device. The second CO2 capture device is used to capture CO2 in the released gas and transport the captured CO2 to the pulverized coal slag gasification device.

[0013] In summary, the beneficial effects of this utility model are as follows: First, it realizes the full-chain, high-value-added conversion of low-rank coal, eliminating resource waste. On the one hand, it maximizes the fractional utilization of low-rank coal: the system accurately separates the organic matter in low-rank coal into raw coal gas, high-quality char, and CO2 through a fuel-rich grading and fractionation device, avoiding the extensive mode of "either direct combustion or only conversion into a single syngas" in traditional processes; then, through the "condensation and blowing-deep purification-deep cryogenic separation" series process of the raw coal gas treatment unit, coal tar (industrial fuel / chemical raw material), LNG (which can be directly sold), and high-purity hydrogen-rich gas are further extracted from the raw coal gas, realizing "full component recovery and utilization without dead ends" of various organic matter in low-rank coal. On the other hand, the gasification ash residue is recycled: the pulverized coal slag gasification unit adopts liquid slag discharge technology, collecting the ash residue generated during the gasification process in liquid form, avoiding carbon residue in traditional solid slag discharge; and the liquid ash residue can be further processed into high-performance inorganic materials such as carbon-free fibers, microcrystalline stone, and rock wool, completely changing the current situation of "ash residue stockpiling pollution", forming a full resource recycling chain of "low-rank coal → methanol + by-products → ash residue → high value-added materials", and realizing the efficient utilization of coal resources. Second, the whole process has zero carbon emissions, which is in line with the "dual carbon" goal. On the one hand, closed-loop CO2 control from source to end: Source carbon reduction: The "water-gas shift reaction" in traditional methanol synthesis is eliminated. High-purity hydrogen is generated through water electrolysis to directly adjust the raw material ratio, thus avoiding CO2 generation at the source of the process; Process recovery: The CO2 capture and reuse unit uses two dedicated capture devices to capture CO2 emitted from the fuel-rich staged combustion unit and CO2 released from methanol synthesis, respectively. The captured CO2 is then returned to the gasification unit as a regulator to participate in the reaction, achieving "system-internal circulation and zero external emission" of CO2; Energy carbon reduction: The surplus hydrogen-rich gas and surplus oxygen in the system are mixed and burned in the combustion unit of the fuel-rich staged combustion unit to provide energy, replacing the traditional external fossil energy heating, reducing the additional CO2 emissions generated by burning fossil energy, and ultimately achieving near-zero carbon emissions throughout the entire methanol production process. On the other hand, the water electrolysis unit uses green electricity from western wind and solar power as its energy source, absorbing a large amount of green electricity annually. This is equivalent to reducing standard coal consumption and CO2 emissions, effectively solving the problems of difficult grid connection and high curtailment rates for green electricity in western China. It promotes the large-scale application of renewable energy and helps the energy structure shift from "fossil-dominated" to "green electricity priority." Third, the system achieves energy self-sufficiency, reducing external input. Thermal energy cycle: Waste heat from pyrolysis in the fuel-rich staged and graded unit, reaction heat from the gasification unit, and reaction heat from the methanol synthesis unit are all recovered and converted into steam through a waste heat boiler, providing core raw materials for the gasification unit. Fuel self-use: The hydrogen-rich gas remaining after the deep cryogenic separation of raw coal gas is mixed and burned with excess oxygen produced by the water electrolysis unit, providing a heat source for the pyrolysis of the fuel-rich staged and graded unit, replacing traditional natural gas and purchased electricity. This increases the system's energy self-sufficiency rate and significantly reduces dependence on external energy and procurement costs. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of a low-rank coal zero-carbon emission methanol production system provided by this utility model.

[0015] In the diagram, 100 is a fuel-rich grading and separation device, 200 is a raw coal gas treatment unit, 210 is a condensing blower system, 220 is a coal gas purification device, 230 is a coal gas cryogenic adsorption and separation device, 300 is a water electrolysis device, 400 is a crushed coal slag gasification device, 500 is a methanol synthesis device, 600 is a CO2 capture and reuse unit, 610 is a first CO2 capture device, and 620 is a second CO2 capture device. Detailed Implementation

[0016] The present invention will be further illustrated below with reference to specific figures.

[0017] Please see Figure 1 This utility model provides a zero-carbon-emission methanol production system using low-rank coal, comprising: Coal grading and quality conversion unit: The coal grading and quality conversion unit includes a fuel-rich grading and quality conversion device 100. As the core starting point for the system's raw material conversion, the coal grading and quality conversion unit is used to grade low-rank coal (such as lignite, long-flame coal, etc.) under a fuel-rich environment. By precisely controlling process parameters such as pyrolysis temperature and time, the organic matter in low-rank coal is efficiently separated, and raw coal gas (containing components such as methane and hydrogen), high-quality carbon (high fixed carbon content, low impurity content, which can be used as gasification feedstock) and CO2 are generated simultaneously, realizing the "graded utilization and cascade conversion" of low-rank coal resources. Raw coal gas treatment unit 200: It receives raw coal gas produced by the coal grading and quality conversion unit and converts the raw coal gas into three high-value products: coal tar (which can be used as industrial fuel or chemical raw material), hydrogen (used for methanol synthesis) and LNG (which can be sold separately or used by the unit itself), thus avoiding the waste of resources and pollution caused by the direct emission of raw coal gas. Electrolysis water unit 300: It uses green electricity generated by renewable energy sources (such as wind power, photovoltaic, hydropower, etc.) as an energy source. Through the electrolysis water reaction, it directionally generates high-purity hydrogen (to meet the raw material requirements of methanol synthesis) and oxygen. Moreover, it can flexibly adjust the electrolysis efficiency according to the real-time demand of hydrogen and oxygen in the system to ensure that the product supply is precisely matched with the requirements of subsequent processes. Gasification unit: As a key unit for water gas generation, it introduces high-quality carbon and steam produced by the coal grading and quality conversion unit and oxygen generated by the water electrolysis unit 300 into the unit in a preset ratio. Under the high temperature and high pressure gasification environment, an incomplete oxidation reaction occurs, which efficiently converts the gas into water gas (mainly composed of CO and H2, which meets the raw material ratio requirements for methanol synthesis). Methanol Synthesis Unit 500: Employs a low-pressure methanol synthesis process, mixing hydrogen generated by water electrolysis unit 300 with water gas produced by gasification unit in a specific ratio, and then processing the mixture through a catalytic reaction to obtain qualified methanol products; at the same time, a small amount of release gas will be generated during the reaction process; The CO2 capture and reuse unit 600 adopts the design concept of "separate source capture and centralized reuse", including at least two independent capture modules. One module is used to capture CO2 directly emitted during the pyrolysis of low-rank coal in the coal grading and quality conversion unit, and the other capture module is used to capture CO2 released from the methanol synthesis unit 500. The capture process adopts efficient decarbonization technologies such as amine absorption or pressure swing adsorption. The captured CO2 is transported to the gasification unit as a gasification regulator to participate in the gasification reaction of high-quality carbon, realizing "system internal circulation and zero emission" of CO2.

[0018] The methanol production system described above involves: Firstly, the coal grading and conversion unit (rich-fuel grading and conversion device 100) performs "graded utilization and tiered conversion" of low-rank coal, precisely separating it into raw coal gas, high-quality char, and CO2. Then, the raw coal gas treatment unit 200 further converts the raw coal gas into three products: tar oil, hydrogen, and LNG. This achieves the full recovery of organic matter in low-rank coal, completely changing the traditional process's "extensive utilization and resource loss" and significantly improving the comprehensive utilization rate of resources. Secondly, the traditional water-gas shift reaction is eliminated. High-purity hydrogen is generated through the water electrolysis unit 300 and directly mixed with the water-gas produced by the gasification unit to the required ratio for methanol synthesis, reducing CO2 generation at the source. Secondly, relying on the CO2 capture and reuse unit 600, CO2 emitted from the coal graded and graded conversion unit and CO2 released from methanol synthesis are captured from different sources and fed back to the gasification unit as a gasification regulator to participate in the reaction, achieving "internal circulation and zero emission" of CO2 and achieving the goal of "zero-carbon emission methanol production," meeting the dual-carbon requirements. Thirdly, the water electrolysis unit 300 utilizes green electricity from western wind and solar power, converting it into hydrogen and oxygen to participate in the process, reducing dependence on external fossil fuels.

[0019] The rich-fuel grading and quality-separating device 100 is equipped with multiple pyrolysis chambers and a temperature control module. It can perform grading treatment on low-rank coal raw materials through "low-temperature drying - medium-temperature pyrolysis - high-temperature upgrading". The organic matter is initially pyrolyzed to generate light volatiles (forming raw coal gas precursors). Finally, it is further cracked and reorganized at 800-900℃ to convert heavy organic matter into raw coal gas, while leaving high-quality carbon with high fixed carbon content. During the entire pyrolysis process, the oxygen supply is precisely controlled to ensure that some organic matter is completely burned to generate CO2. All products (raw coal gas, high-quality carbon, and CO2) are discharged separately through dedicated channels to avoid mutual mixing and contamination.

[0020] The raw coal gas treatment unit 200 includes a condensing blower system 210, a coal gas purification device 220, and a coal gas cryogenic adsorption separation device 230, which form a series process chain: The condensing blower system 210 includes a horizontal tube primary cooler, an electrostatic precipitator for coal tar, and a mechanized ammonia clarifier. Raw coal gas first enters the horizontal tube primary cooler, where it undergoes indirect heat exchange with circulating cooling water, reducing its temperature from 600-800℃ to 25-35℃, causing the coal tar vapor to condense into liquid oil droplets. The oil-containing gas then enters the electrostatic precipitator for coal tar. Under the influence of a high-voltage electrostatic field, the tiny oil droplets become charged and aggregate, further removing residual tar. Finally, the oil-water-dust mixture enters the mechanized ammonia clarifier, where gravity sedimentation separates the crude purified coal gas (sent to subsequent purification), coal tar (collected as a product), and ammonia (recirculated back to the primary cooler).

[0021] The gas purification unit 220 adopts a three-stage purification process of "naphthalene removal-desulfurization-ammonia removal". First, the naphthalene component in the gas is absorbed by washing oil in the naphthalene washing tower. Then, the acidic gas is removed by desulfurizing agent in the desulfurization tower. Finally, the ammonia in the gas is absorbed by sulfuric acid in the ammonia removal tower, and hydrogen-rich gas is obtained.

[0022] Cryogenic Adsorption Separation Unit 230: In a low-temperature environment of -160 to -165℃, hydrogen-rich coal gas undergoes cryogenic treatment, causing hydrocarbon components such as methane to condense into LNG. Simultaneously, trace impurities (such as CO2 and moisture) are removed through an adsorption tower. Finally, LNG (as a product) and the remaining high-purity hydrogen-rich gas are separated (sent to the fuel-rich grading and separation unit 100). The LNG, as a product, can be directly sold.

[0023] The hydrogen-rich gas remaining after LNG separation in the cryogenic adsorption separation unit 230 is directionally transported through a dedicated pipeline to the combustion unit of the fuel-rich staged pyrolysis unit 100, serving as the core fuel for the combustion unit. Simultaneously, the excess oxygen produced by the water electrolysis unit 300 after meeting the hydrogen and oxygen requirements for methanol synthesis is also transported to this combustion unit through an independent pipeline. Controlled combustion occurs in the combustion chamber, efficiently generating stable heat energy. This heat energy is transferred to the pyrolysis chamber of the fuel-rich staged pyrolysis unit 100 via a heat exchanger, providing the necessary heat source for the staged pyrolysis of low-rank coal (meeting the temperature requirements of 500-900℃ during the pyrolysis process). This achieves a self-sustaining cycle of "excess gas → heat energy → process heat," avoiding the waste of venting hydrogen-rich gas and excess oxygen, reducing external energy input, and further lowering system carbon emissions.

[0024] The gasification unit selected is the 400 pulverized coal slag gasification unit. This unit employs a "pulverized coal feeding - slag discharge" design, suitable for producing high-quality granular carbon from coal grading and quality conversion units. It eliminates the need for additional pulverization of the carbon raw material, reducing pretreatment costs. Simultaneously, the slag discharge method allows the ash produced by the gasification reaction to be discharged in liquid form, avoiding carbon residue found in traditional solid slag discharge, significantly improving carbon resource utilization. Furthermore, the liquid ash facilitates subsequent resource utilization. The high-temperature liquid slag discharged from the 400 pulverized coal slag gasification unit can be used to produce products such as carbon-free fiber, microcrystalline stone, and rock wool, achieving full resource utilization of coal.

[0025] The steam required by the 400-unit pulverized coal slag gasification unit adopts a "multi-source recovery + on-demand replenishment" supply mode, with sources including four parts: The 400 pulverized coal slag gasification unit recovers its own exothermic gasification reaction: the gasification reaction is an exothermic reaction, and the heat released by the reaction is transferred to soft water through the waste heat boiler in the unit to generate saturated steam; Pyrolysis waste heat recovery of the rich-fuel staged and graded separation device 100: The high-temperature flue gas discharged from the pyrolysis chamber enters the waste heat boiler to heat soft water and generate steam. Methanol Synthesis Unit 500: The methanol synthesis reaction is an exothermic reaction. The heat of the reaction is converted into steam through the water or waste heat boiler in the jacket of the synthesis tower. External steam supply device: The external steam supply device is connected to the pulverized coal slag gasification device 400. When the amount of steam generated by the waste heat recovery in the system is insufficient, steam can be generated by natural gas heating or electric heating to supplement the gasification device, ensuring a stable steam supply and avoiding a decrease in efficiency of the gasification reaction due to insufficient steam.

[0026] The operation of the pulverized coal slag gasification unit 400 adopts the process logic of "precise temperature control and efficient conversion": First, the high-quality char generated by the coal grading and quality conversion unit is evenly fed into the gasifier through the feeding device. At the same time, steam (from the multi-source recovery and replenishment system) and oxygen prepared by the water electrolysis unit 300 are introduced according to process requirements. Under the high-pressure environment in the gasifier, the high-quality char reacts with steam and oxygen to generate water gas, which is mainly composed of CO and H2. The water gas is discharged through the top outlet of the furnace and sent to the methanol synthesis unit 500. Meanwhile, the ash produced by the gasification reaction melts into liquid at high temperature and is continuously discharged through the slag discharge port at the bottom of the pulverized coal slag gasification unit 400. It is then collected in the slag pool after being cooled to room temperature, laying the foundation for subsequent ash resource utilization (such as the preparation of inorganic materials).

[0027] The CO2 capture and reuse unit 600 has two capture modules, namely a first CO2 capture device and a second CO2 capture device. Both use the same amine absorption process, but are optimized for capture based on different CO2 sources. The first CO2 capture device is connected to the CO2 emission port of the fuel-rich grading and quality-separating device 100. The CO2 generated by the fuel-rich grading and quality-separating device 100 during the pyrolysis of low-rank coal is finally captured. After the moisture is removed by the dryer, the CO2 is pressurized by the compressor and transported to the crushed coal slag gasification device 400 to participate in the gasification reaction of high-quality carbon as a gasification regulator. The second CO2 capture device is connected to the release gas outlet of the methanol synthesis unit 500. The release gas is removed by an adsorbent to remove impurities such as methanol vapor and trace hydrocarbons, resulting in high-purity CO2, which is also sent to the pulverized coal slag gasification unit 400 for reuse. Through the synergistic effect of the two capture devices, the full capture and recycling of CO2 in the system is achieved, ensuring that the overall carbon emissions of the system approach zero.

[0028] The above methanol production system achieves the following: First, it realizes the full-chain, high-value-added conversion of low-rank coal, eliminating resource waste. On the one hand, it maximizes the fractional utilization of low-rank coal: The system uses a fuel-rich fractional separation device 100 to precisely separate the organic matter in low-rank coal into raw coal gas, high-quality char, and CO2, avoiding the extensive mode of "either direct combustion or only conversion into a single syngas" in traditional processes; then, through the "condensation-blowing-deep purification-deep cryogenic separation" series process of the raw coal gas treatment unit 200, coal tar (industrial fuel / chemical raw material), LNG (which can be directly sold), and high-purity hydrogen-rich gas are further extracted from the raw coal gas, realizing "full component recovery and utilization without dead ends" of various organic matter in low-rank coal. On the other hand, the gasification ash residue is recycled: the 400 pulverized coal slag gasification unit adopts liquid slag discharge technology to collect the ash residue generated during the gasification process in liquid form, avoiding carbon residue in traditional solid slag discharge; and the liquid ash residue can be further processed into high-performance inorganic materials such as carbon-free fiber, microcrystalline stone, and rock wool, completely changing the status quo of "ash residue stockpiling pollution", forming a full resource recycling chain of "low-rank coal → methanol + by-products → ash residue → high value-added materials", and realizing the efficient utilization of coal resources.

[0029] Second, the entire process achieves zero carbon emissions, deeply aligning with the "dual carbon" goals. On the one hand, closed-loop CO2 control from source to end: Source carbon reduction: the "water-gas shift reaction" in traditional methanol synthesis is eliminated, and high-purity hydrogen is generated through a 300-volt water electrolysis unit to directly adjust the raw material ratio, thus avoiding CO2 generation from the source of the process; Process recovery: The CO2 capture and reuse unit 600 uses two dedicated capture devices to capture CO2 emitted from the fuel-rich staged and graded gas separation unit 100 and CO2 released from methanol synthesis, respectively. The captured CO2 is then sent back to the gasification unit as a regulator to participate in the reaction, realizing "system internal circulation and zero external emission" of CO2. Energy carbon reduction: The system mixes and combusts surplus hydrogen-rich gas and surplus oxygen in the 100 combustion unit of the fuel-rich staged and graded combustion device to provide energy, replacing the traditional external fossil energy heating, reducing the additional CO2 emissions generated by burning fossil energy, and ultimately achieving near-zero carbon emissions in the entire methanol production process.

[0030] On the other hand, the 300 water electrolysis device uses green electricity such as wind and solar power in western China as its energy source. It can consume a large amount of green electricity every year, which is equivalent to reducing standard coal consumption and CO2 emissions. It effectively solves the problems of difficult grid connection and high curtailment rate of green electricity in western China, promotes the large-scale application of renewable energy, and helps the energy structure to transform from "fossil-dominated" to "green electricity priority".

[0031] III. The system achieves energy self-sufficiency, reducing external input. Thermal energy cycle: Waste heat from the pyrolysis of the fuel-rich staged and fractionated gasifier 100, the reaction heat from the gasification unit, and the reaction heat from the methanol synthesis unit 500 are all recovered and converted into steam through a waste heat boiler, providing core raw materials for the gasification unit. Fuel self-use: The hydrogen-rich gas remaining after the cryogenic separation of raw coal gas is mixed and burned with excess oxygen produced by the water electrolysis unit 300, providing a heat source for the pyrolysis of the fuel-rich staged and fractionated gasifier 100. This replaces traditional natural gas, purchased electricity, and other external energy sources, increasing the system's energy self-sufficiency rate and significantly reducing dependence on external energy and procurement costs.

[0032] The above are merely embodiments of this utility model and do not limit the patent scope of this utility model. Any equivalent structure made using the contents of this utility model specification and drawings, whether directly or indirectly applied to other related technical fields, shall also be within the patent protection scope of this utility model.

Claims

1. A zero-carbon-emission methanol production system using low-rank coal, characterized in that, include: The coal grading and quality conversion unit is used to generate raw coal gas, high-quality char and CO2 from low-rank coal; Raw coal gas processing unit is used to convert raw coal gas into coal tar, hydrogen and LNG; An electrolysis water device is used to utilize green electricity to generate hydrogen and oxygen. Gasification unit, used to convert high-quality charcoal and steam into water gas with oxygen generated by water electrolysis unit; The methanol synthesis unit is used to process hydrogen generated by the water electrolysis unit with water gas to synthesize methanol and release gas. The CO2 capture and reuse unit includes at least two capture modules, which are used to capture carbon dioxide emitted from the coal grading and quality conversion unit and carbon dioxide released from the methanol synthesis unit, respectively, and to transport the captured carbon dioxide to the gasification unit for reuse.

2. The low-rank coal zero-carbon emission methanol production system according to claim 1, characterized in that: The coal grading and quality conversion unit includes a fuel-rich grading and quality conversion device that performs graded pyrolysis treatment on low-rank coal raw materials under a fuel-rich environment. The fuel-rich grading and quality conversion device can convert the organic matter in low-rank coal into raw coal gas, high-quality char and CO2.

3. The low-rank coal zero-carbon emission methanol production system according to claim 2, characterized in that: The raw coal gas treatment unit includes a condensing and blowing system, a coal gas purification device, and a deep cryogenic adsorption and separation device. The condensing and blowing system is used to cool and condense the raw coal gas, perform electrostatic oil removal, and gas-liquid separation to generate crude purified coal gas and coal tar. The coal gas purification device is used to deeply purify the coal gas to remove impurities and generate hydrogen-rich coal gas. The deep cryogenic adsorption and separation device is used to cool and adsorb the hydrogen-rich coal gas at low temperature to convert the hydrocarbon components into LNG.

4. The low-rank coal zero-carbon emission methanol production system according to claim 3, characterized in that: The cryogenic adsorption separation device for coal gas can transport the remaining hydrogen-rich gas after cryogenic adsorption separation to the combustion unit of the fuel-rich grading and pyrolysis device. The excess oxygen generated by the water electrolysis device during the process of absorbing green electricity to generate hydrogen and oxygen can also be transported to the combustion unit. By mixing and burning the hydrogen-rich gas and excess oxygen in the combustion unit, heat energy is generated, providing the required heat source for the fuel-rich grading and pyrolysis device to perform graded pyrolysis treatment of low-rank coal in a fuel-rich environment, realizing the resource recycling and self-use within the fuel-rich grading and pyrolysis device.

5. The low-rank coal zero-carbon emission methanol production system according to claim 1, characterized in that: The gasification device is a pulverized coal slag gasification device.

6. The low-rank coal zero-carbon emission methanol production system according to claim 5, characterized in that: The steam comes from the heat recovery of the gasification reaction of the pulverized coal slag gasification unit itself, the heat recovery of the pyrolysis waste heat of the fuel-rich grading and quality-separating unit, the heat recovery of the reaction of the methanol synthesis unit, and the external supplementary steam unit connected to the pulverized coal slag gasification unit.

7. The low-rank coal zero-carbon emission methanol production system according to claim 5, characterized in that: The pulverized coal slag gasification device introduces steam and high-quality char generated by the coal grading and quality conversion unit, along with oxygen prepared by the water electrolysis device, into the device. Under high-temperature gasification conditions, water gas is generated, and the ash slag produced during the gasification reaction is discharged and collected through liquid slag discharge.

8. The low-rank coal zero-carbon emission methanol production system according to claim 7, characterized in that: The two capture modules are a first CO2 capture device and a second CO2 capture device. The first CO2 capture device is used to capture CO2 in the coal grading and quality conversion unit and transport the captured CO2 to the pulverized coal slag gasification device. The second CO2 capture device is used to capture CO2 in the released gas and transport the captured CO2 to the pulverized coal slag gasification device.

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