System for preparing green methanol by coupling biomass gasification with green hydrogen

Abstract

The utility model discloses a system for preparing green methanol by biomass gasification coupling green hydrogen. The system comprises a gasification unit (A), a purification unit (B), a hydrogen and oxygen unit (C) and a synthesis unit (D), synthesis gas (104) generated by the gasification unit (A) is synthesized into raw material gas (107) after passing through the purification unit (B); oxygen (109) produced by the oxyhydrogen unit (C) is used as oxygen of the gasification unit, and hydrogen (113) produced by the oxyhydrogen unit (C) is used as a hydrogen source for adjusting the hydrogen-carbon ratio of raw material gas of the synthesis unit (D); part of purge gas (121) of the synthesis unit (D) is returned to the gasification unit for recycling. The system is stable and reliable in operation, high in renewable carbon source utilization rate and low in methanol preparation cost.

Description

Technical Field

[0001] The utility model relates to a system for coupling biomass gasification with green hydrogen production to produce green methanol, belonging to the technical field of green methanol preparation. Background Art

[0002] Coupling biomass gasification with green hydrogen production to produce chemical products such as methanol and green aviation kerosene is an important way for the clean development of chemical fuels. As a renewable resource, biomass has the characteristics of rich resource output, wide geographical distribution, and stable energy storage. The syngas produced by biomass gasification can be used as the raw material gas for methanol synthesis alone after adjusting the hydrogen-carbon ratio through conversion, but the conversion system requires additional steam consumption and discharges part of the CO2, resulting in a reduction in the utilization rate of renewable carbon sources. With the increase in the installed capacity of renewable energy power generation in China, due to the disadvantage of unstable output of renewable energy, there has been a relatively serious problem of "abandoning wind and light". The problem of abandoning electricity from new energy power generation has become increasingly prominent, hindering the development and utilization of new energy. Using renewable energy power generation (such as wind power and photovoltaic) to electrolyze water to produce hydrogen, and synthesizing methanol from the CO2 captured by the CO2 capture technology and the electrolyzed hydrogen is one of the effective ways to solve the problem of abandoning electricity from new energy power generation, but the cost of this technical route is too high and the technical economy is poor.

[0003] In summary, there is an urgent need for a system for coupling biomass gasification with green hydrogen production to produce green methanol to solve the problems of low utilization rate of renewable carbon sources in biomass gasification to produce methanol and high cost of synthesizing methanol from CO2 and electrolyzed hydrogen. Summary of the Utility Model

[0004] The technical problem to be solved by the utility model is the problems of low utilization rate of renewable carbon sources in biomass gasification to produce methanol and high cost of synthesizing methanol from CO2 and electrolyzed hydrogen.

[0005] To solve the above technical problems, the technical solution of the utility model is to provide a system for coupling biomass gasification with green hydrogen production to produce green methanol, and the technical solution is as follows:

[0006] The system includes: a gasification unit, a purification unit, a hydrogen-oxygen unit, and a synthesis unit; the syngas generated by the gasification unit is used as the raw material gas after passing through the purification unit; the oxygen produced by the hydrogen-oxygen unit is used as the oxygen for the gasification unit, and the hydrogen produced by the hydrogen-oxygen unit is used as the hydrogen source for adjusting the hydrogen-carbon ratio of the raw material gas for the synthesis unit; part of the purge gas from the synthesis unit is returned to the gasification unit for recycling.

[0007] Preferably, the gasification unit mainly includes a gasifier, a reformer, and a waste heat boiler.

[0008] Preferably, the purification unit mainly includes a first compressor, an oil removal tower, and a desulfurization and decarbonization tower; the oil removal tower is a spray absorption tower; the desulfurization and decarbonization tower is a multi-layer spray absorption tower; the desulfurization and decarbonization tower has the function of adjustable CO2 removal rate.

[0009] Preferably, the hydrogen-oxygen unit mainly includes an electrolytic cell, a hydrogen storage tank, and an oxygen storage tank; the electrolytic cell is an alkaline electrolytic cell or a PEM electrolytic cell or a combination of the two; the hydrogen and oxygen storage tanks are one of spherical tanks, vertical storage tanks, and horizontal storage tanks.

[0010] Preferably, the synthesis unit mainly includes a second compressor, a methanol synthesis tower, a heat exchanger, a gas-liquid separator, and a hydrogen recovery device; the purge gas generated by the hydrogen recovery device is divided into two paths, one of which returns to the reformer of the biomass gasification unit, and the other is discharged out of the system.

[0011] Preferably, the gasifier is a fluidized bed, a circulating fluidized bed, a fixed bed gasifier or a circulating fluidized bed gasifier; the oxygen required for the gasifier and the reformer comes from the oxygen produced by electrolyzing water in the electrolytic cell for hydrogen production or the oxygen from an air separation facility.

[0012] Preferably, the fuel used in the reformer is synthesis purge gas, or waste gas with calorific value, or methane, or diesel fuel.

[0013] A system for coupling biomass gasification with green hydrogen production to produce green methanol provided by the present utility model realizes the coupling of biomass gasification with green hydrogen production to produce green methanol. The system of the present utility model operates stably and reliably, has a high utilization rate of renewable carbon sources, and a low methanol preparation cost. Compared with the prior art, the present utility model has the following beneficial effects:

[0014] (1) The present utility model uses new energy power generation to produce hydrogen to adjust the hydrogen-carbon ratio in the methanol synthesis raw material gas, and eliminates the instability of new energy power generation to produce hydrogen by setting up a hydrogen storage tank and an oxygen storage tank, realizing the stable operation of biomass gasification and methanol synthesis;

[0015] (2) The present utility model uses a reformer in the biomass gasification unit to further increase the temperature of the syngas generated by the gasifier to improve the quality of the syngas. The required energy comes from the purge gas of the methanol synthesis unit without additional energy consumption. Combined with the methanol synthesis unit for rich CO2 syngas, the renewable carbon source and hydrogen source are efficiently utilized, and the methanol preparation cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of a system for coupling biomass gasification with green hydrogen production to produce green methanol provided by the present utility model;

[0017] Figure 2 It is another embodiment of a system for coupling biomass gasification with green hydrogen production to produce green methanol provided by the present utility model.

[0018] Explanation of the reference numerals in the drawings:

[0019] A - Gasification unit, B - Purification unit, C - Hydrogen - oxygen unit, D - Synthesis unit;

[0020] 1 - Biomass gasifier; 2 - Converter; 3 - Waste heat boiler; 4 - First compressor; 5 - De - oiling tower; 6 - Desulfurization and decarbonization tower; 7 - Electrolyzer; 8 - Oxygen storage tank; 9 - Hydrogen storage tank; 10 - Second compressor; 11 - Methanol synthesis tower; 12 - Heat exchanger; 13 - Gas - liquid separator; 14 - Hydrogen recovery device; 100 - Biomass raw material; 101 / 109 / 110 / 111 - Oxygen; 102 / 103 / 104 / 105 / 106 - Syngas; 107 / 114 / 115 - Methanol synthesis feed gas; 108 - Water; 112 / 113 - Hydrogen; 116 / 117 - Methanol, recycle gas; 118 - Crude methanol; 119 - Recycle gas; 120 - Recycle gas; 121 - Recycle purge gas; 122 - Off - gas purge gas. Detailed implementation manners

[0021] The following further elaborates on the present utility model in conjunction with specific embodiments.

[0022] Embodiment 1: Figure 1 This is a schematic diagram of an embodiment of a system for biomass gasification coupled with green hydrogen production of green methanol provided by the present utility model. As Figure 1 shown, a system for biomass gasification coupled with green hydrogen production of green methanol mainly includes a biomass gasification to syngas unit; a syngas purification unit; an electrolytic water hydrogen production and hydrogen and oxygen storage unit; and a CO₂ - rich syngas methanol synthesis unit.

[0023] The biomass gasification to syngas unit, abbreviated as the gasification unit, mainly includes a gasifier 1, a converter 2, and a waste heat boiler 3.

[0024] The syngas purification unit, abbreviated as the purification unit, mainly includes a first compressor 4, a de - oiling tower 5, and a desulfurization and decarbonization tower 6.

[0025] The electrolytic water hydrogen production and hydrogen and oxygen storage unit, abbreviated as the hydrogen - oxygen unit, mainly includes an electrolyzer 7, a hydrogen storage tank 9, and an oxygen storage tank 8.

[0026] The CO₂ - rich syngas methanol synthesis unit, abbreviated as the synthesis unit, mainly includes a second compressor 10, a methanol synthesis tower 11, a heat exchanger 12, a gas - liquid separator 13, and a hydrogen recovery device 14.

[0027] The syngas 104 generated by the gasification unit is used as the feed gas 107 of the synthesis unit after passing through the purification unit; the oxygen 109 of the hydrogen - oxygen unit is used as the oxygen of the gasification unit, and the hydrogen 113 is used as the hydrogen source for adjusting the hydrogen - carbon ratio of the feed gas of the synthesis unit; a part of the purge gas 121 of the synthesis unit is returned to the gasification unit for recycling.

[0028] The desulfurization and decarbonization tower 6 has the function of adjustable CO2 removal rate.

[0029] The purge gas generated by the hydrogen recovery device 14 is divided into two paths. One path returns to the reformer 2 of the gasification unit, and the other path is discharged out of the system.

[0030] The gasifier 1 can be a fluidized bed, circulating fluidized bed, or fixed bed gasifier; the oxygen required by the gasifier 1 and the reformer 2 comes from the oxygen 109 of the electrolytic water hydrogen production unit or the oxygen 101 of the air separation facility.

[0031] The fuel used in the reformer 2 is synthetic purge gas 121, waste gas with calorific value, methane, diesel, and other fuels.

[0032] The biomass raw material 100 enters the biomass gasifier 1 to produce syngas. The gasifier 1 mainly includes a fluidized bed gasifier body, a cyclone separator, a slag discharge pipe, a gasifying agent preheater, and other equipment. The gasifying agent is usually a mixture of pure oxygen / vapor, and CO2 gas can also be added. After preheating, it enters the gasifier. The optimal gasification temperature of the gasifier is 750°C to 850°C. The syngas generated is sent to the reformer 2 after being dust-removed by the cyclone separator. The particles captured by the cyclone separator for dust removal are returned to the gasifier for reaction.

[0033] After the syngas generated by the gasifier enters the reformer 2, the temperature is raised to 1000°C to 1100°C. The tar and methane in the syngas are converted at high temperature, and their contents are greatly reduced. The fuel for raising the temperature of the reformer 2 comes from the recycle purge gas 121 of the methanol synthesis unit. The purge gas of a conventional methanol synthesis device is usually vented or used as fuel gas. The purge gas contains a large amount of renewable carbon sources (CO / CO2 / CH4) and renewable H2. In this utility model, the methanol purge gas is used as the fuel for the reformer to improve the utilization efficiency of renewable hydrogen and renewable carbon in the system.

[0034] The high-temperature syngas 103 coming out of the reformer 2 has a relatively high temperature and enters the waste heat recovery boiler 3. The waste heat boiler usually includes equipment such as a syngas dust collector, a steam generator, an economizer, and a syngas cooler. After the syngas is dust-removed and cooled, the dust content is less than 1 mg / Nm3, and the temperature is reduced to 40°C and sent to the inlet of the first compressor 4 of the syngas purification unit. The steam generated by the waste heat boiler is partially used as the gasifying agent of the gasifier and partially supplied externally.

[0035] The syngas purification unit adopts an improved Rectisol process, mainly including equipment such as an oil removal tower, a desulfurization and decarbonization tower, a desorption tower, a methanol recovery tower, and a refrigeration system. The Rectisol process utilizes the excellent characteristics of methanol having a great solubility for acid gases under low temperature and high pressure to remove acid gases and light oil from the raw gas. This process has a high gas purification degree and good selectivity, and the gas oil removal, desulfurization, and decarbonization can be selectively carried out separately in the same process. After passing through the purification unit, the total sulfur content of the syngas is less than 0.1 ppm, and the CO2 content can be adjusted in the range of 5 - 35%, serving as the raw gas for the CO2-rich synthesis unit. The hydrogen-carbon ratio of the methanol synthesis raw gas after passing through the purification unit cannot meet the requirements of methanol synthesis for the hydrogen-carbon ratio, and hydrogen needs to be supplemented.

[0036] An electrolytic water hydrogen production unit is set up to produce hydrogen for adjusting the hydrogen-carbon ratio of the methanol synthesis raw gas. The electrolytic water hydrogen production unit mainly includes an electrolytic cell, a purification system, a pure water preparation system, etc. An alkaline electrolytic cell is selected for the electrolytic cell. Considering the disadvantage of unstable output of renewable energy, a hydrogen storage tank and an oxygen storage tank are set up to ensure the stable supply of hydrogen and oxygen. In the present utility model, the hydrogen storage tank 9 is a gaseous spherical tank, and the oxygen storage tank is a gaseous spherical tank. The storage capacity of the spherical tank is selected according to the characteristics of new energy power generation, and the storage capacity usually needs to meet the gas consumption for 24 - 72 hours.

[0037] In order to make the best use of the renewable carbon in biomass as much as possible, the methanol synthesis unit of the present utility model is a CO2-rich synthesis unit, and the methanol reactor and catalyst can adapt to the range of 5 - 35% of the CO2 content in the raw gas. When the CO2 content in the raw gas is relatively high, the required amount of hydrogen increases accordingly. Therefore, when new energy power generation (wind power, photovoltaic) is at full load, the electrolytic water hydrogen production operates at a high load to provide a large amount of hydrogen for the methanol synthesis unit, and the methanol synthesis unit can accept the raw gas with a high CO2 concentration, thereby efficiently utilizing the renewable carbon source.

[0038] Embodiment 2: Figure 2 This is another implementation manner of a biomass gasification coupled green hydrogen production to produce green methanol system provided by the present utility model. The difference between Embodiment 2 and Embodiment 1 lies in whether the syngas at the outlet of the reformer 2 is subjected to waste heat recovery. In Embodiment 1, a waste heat boiler is used to recover the heat of the syngas. In Embodiment 2, the heat of the syngas is not recovered, and the syngas is quenched with quench water. The temperature of the quenched syngas is about 70 - 150 °C. This implementation manner is beneficial for reducing the investment cost, but the comprehensive energy consumption is higher than that of Embodiment 1.

[0039] As can be seen from the above embodiments, through innovative system design and reasonable process parameter setting, the present utility model uses new energy power generation to produce hydrogen to adjust the hydrogen-carbon ratio in the methanol synthesis raw material gas, and eliminates the instability of power generation for hydrogen production by setting up a hydrogen storage tank and an oxygen storage tank, realizing the stable operation of biomass gasification and methanol synthesis; the biomass gasification unit uses a reformer to further increase the temperature of the syngas generated by the gasifier to improve the quality of the syngas, and the required energy comes from the purge gas of the methanol synthesis unit without additional energy consumption. Combining with the methanol synthesis unit using syngas rich in CO2, the renewable carbon source and hydrogen source are efficiently utilized, and the methanol preparation cost is low.

[0040] The above embodiments are only a part of the embodiments of the present utility model, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model.

Claims

1. A system for producing green methanol by coupling biomass gasification with green hydrogen, characterized in that: include: Gasification unit (A), purification unit (B), hydrogen and oxygen unit (C), synthesis unit (D); The synthesis gas (104) generated by the gasification unit (A) passes through the purification unit (B) to synthesize the raw gas (107); The oxygen (109) produced by the hydrogen-oxygen unit (C) is used as oxygen for the gasification unit, and the hydrogen (113) produced by the hydrogen-oxygen unit (C) is used as a hydrogen source for adjusting the hydrogen-carbon ratio of the raw gas of the synthesis unit (D); Part of the purge gas (121) of the synthesis unit (D) is returned to the gasification unit for recycling.

2. A system for producing green methanol by coupling biomass gasification with green hydrogen as claimed in claim 1, characterized in that: The gasification unit (A) mainly comprises a gasification furnace (1), a reforming furnace (2), and a waste heat boiler (3).

3. A system for producing green methanol by coupling biomass gasification with green hydrogen as claimed in claim 1, characterized in that: The purification unit (B) mainly comprises a first compressor (4), a deoiling tower (5), and a desulfurization and decarbonization tower (6); The de-oiling tower (5) is a spray absorption tower; The desulfurization and decarbonization tower (6) is a multi-layer spray absorption tower; The desulfurization and decarbonization tower (6) has the function of adjusting the CO2 removal rate.

4. A system for producing green methanol by coupling biomass gasification with green hydrogen as claimed in claim 1, characterized in that: The hydrogen-oxygen unit (C) mainly comprises an electrolyzer (7), a hydrogen storage tank (9), and an oxygen storage tank (8); The electrolytic cell (7) is an alkaline electrolytic cell or a PEM electrolytic cell or a combination of the two; The hydrogen storage tank (9) and the oxygen storage tank (8) are one of a spherical tank, a vertical storage tank, and a horizontal storage tank.

5. The system for producing green methanol by coupling biomass gasification with green hydrogen as claimed in claim 1, characterized in that: The synthesis unit (D) mainly includes a second compressor (10), a methanol synthesis tower (11), a heat exchanger (12), a gas-liquid separator (13), and a hydrogen recovery device (14); The purge gas generated by the hydrogen recovery device (14) is divided into two paths, one of which is returned to the reformer (2) of the biomass gasification unit, and the other is discharged outside the system.

6. A system for producing green methanol by coupling biomass gasification with green hydrogen as claimed in claim 2, characterized in that: The gasifier (1) is a fluidized bed, a circulating fluidized bed, a fixed bed gasifier or a circulating fluidized bed gasifier; the oxygen required by the gasifier (1) and the reformer (2) comes from the oxygen (109) of the electrolytic cell (7) water electrolysis hydrogen production unit or the oxygen (101) of the air separation facility.

7. A system for producing green methanol by coupling biomass gasification with green hydrogen as claimed in claim 2, characterized in that: The fuel used by the reformer (2) is synthetic purge gas (121), or waste gas containing calorific value, or methane, or diesel fuel.

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