Hydrogen-coupled green methanol production system and method

Abstract

The invention discloses a hydrogen-coupled green methanol production system and method, and a green methanol product is obtained through the procedures of gasification, purification, methanol synthesis, methanol rectification and the like. The hydrogen-coupled green methanol production system comprises a gas making unit, a purification unit, a methanol synthesis unit and a methanol rectification unit, the gas making unit is a biomass gasification unit, the biomass gasification unit comprises a normal-pressure circulating fluidized bed, the normal-pressure circulating fluidized bed gasifies a biomass raw material to generate crude synthesis gas, the purification unit is used for purifying the crude synthesis gas, and the methanol rectification unit is used for rectifying the crude synthesis gas. The hydrogen compression unit is connected in front of the methanol synthesis unit, the hydrogen compression unit is used for providing hydrogen, the methanol synthesis unit is used for synthesizing synthesis gas and hydrogen into crude methanol, and the methanol rectification unit is used for rectifying the crude methanol into refined methanol. The method can promote the resource utilization of biomass materials, achieves the purposes of energy conservation, emission reduction and environmental protection, meets the current requirements of environmental protection, energy conservation and low-carbon economy, and is beneficial to green and sustainable development.

Description

Technical Field

[0001] The present invention relates to a coupled hydrogen green methanol production system and method, belonging to the technical field of methanol production. Background Art

[0002] In the prior art, most methanol production uses coal, petroleum, and natural gas as raw materials, and through gasification, purification, synthesis, and rectification, refined methanol products are obtained. This methanol production technology consumes a large amount of non-renewable energy. Currently, the industry is actively moving towards green and low-carbon transformation, controlling fossil energy consumption, especially strictly restricting coal consumption. Therefore, the methanol industry needs to actively explore new raw material sources and production technologies, such as green methanol, to achieve more sustainable and environmentally friendly development in the future. Summary of the Invention

[0003] The purpose of the present invention is to provide a coupled hydrogen green methanol production system, which uses hydrogen and biomass raw materials to replace petrochemical raw materials for methanol production and synthesis, achieving energy conservation, emission reduction, and sustainable development. At the same time, the present invention also provides a coupled hydrogen green methanol production method.

[0004] The coupled hydrogen green methanol production system of the present invention adopts the following technical solutions: A coupled hydrogen green methanol production system includes a gasification unit, a purification unit, a methanol synthesis unit, and a methanol rectification unit. The gasification unit is a biomass gasification unit, and the biomass gasification unit includes an atmospheric pressure circulating fluidized bed, which gasifies biomass raw materials to produce crude synthesis gas. The purification unit is used to purify the crude synthesis gas. A hydrogen compression unit is connected before the methanol synthesis unit, and the hydrogen compression unit is used to provide hydrogen. The methanol synthesis unit is used to synthesize synthesis gas and hydrogen into crude methanol. The methanol rectification unit is used to rectify the crude methanol into refined methanol.

[0005] The purification unit includes a washing unit, an electric precipitator unit, a first-stage compression unit, a desulfurization unit, a temperature swing adsorption unit, a second-stage compression unit, a fine desulfurization unit, a CO conversion unit, and a decarbonization unit, which are arranged in sequence.

[0006] An air separation unit is connected before the biomass gasification unit. The air separation unit is used to separate oxygen and nitrogen in the air. The separated oxygen is introduced into the biomass gasification unit, and the separated nitrogen is introduced into the temperature swing adsorption unit.

[0007] The coupled hydrogen green methanol production system further includes a sewage treatment unit. The washing wastewater generated by the washing unit and the waste liquid generated by the electric precipitator unit are introduced into the sewage treatment unit. The decarbonization unit is provided with a CO2 emission port connected to the biomass gasification unit.

[0008] The methanol synthesis unit is connected to a hydrogen recovery unit. The hydrogen recovered by the hydrogen recovery unit is fed into the methanol synthesis unit. The purge gas outlet of the hydrogen recovery unit is connected to a power island unit, and the power island unit includes a once-through boiler for power generation.

[0009] The coupled hydrogen green methanol production method of the present invention adopts the following technical solution: A coupled hydrogen green methanol production method, which includes the following steps: (1) Feeding the biomass raw material into the biomass gasification unit, and gasifying the biomass raw material by using an atmospheric pressure circulating fluidized bed to generate raw syngas; (2) Feeding the raw syngas into the purification unit, and the raw syngas undergoes dust removal, tar removal, desulfurization, decarbonization, naphthalene removal, shift conversion, and decarbonization processes to obtain the syngas required for methanol synthesis; (3) Mixing the syngas with hydrogen and feeding it into the methanol synthesis unit, and the syngas undergoes a methanol synthesis reaction under the action of a catalyst to obtain crude methanol; (4) Feeding the crude methanol into the methanol rectification unit, and the crude methanol is rectified to obtain the refined methanol product.

[0010] In step (2), first, the raw syngas is washed and dedusted by the washing unit, and the raw syngas is defouled by the electric precipitator for tar. The washing wastewater and the tar capture waste liquid are sent to the sewage treatment unit for purification, and the tar and ammonia nitrogen content in the wastewater are reduced by flocculation, air flotation, steam stripping, and hydrolysis acidification; then it enters the gas holder unit for buffering, and the raw syngas then enters the first-stage compression unit for pressurization, and then the raw syngas is desulfurized by the raw desulfurization unit to remove H2S, and enters the temperature swing adsorption unit. The temperature swing adsorption unit adsorbs benzene, naphthalene, and tar in the raw syngas. The raw syngas leaving the temperature swing adsorption unit enters the second-stage compression unit, and after being compressed by the second stage, it is sent to the fine desulfurization unit for desulfurization and impurity removal, and then sent to the CO shift unit. After adjusting the hydrogen-carbon ratio required for methanol synthesis, it enters the downstream decarbonization unit, and CO2 is removed by amine liquid absorption. The purified gas leaving the decarbonization unit is sent to the methanol synthesis device; the CO2 desorbed from the regeneration tower of the decarbonization unit is cooled and divided into two streams. One stream goes to the biomass gasification unit as the back blowing gas and the sealing gas, and the other stream is directly discharged into the atmosphere.

[0011] The flash gas generated by the raw desulfurization unit, the nitrogen regeneration gas generated by the temperature swing adsorption unit, the flash gas generated by the decarbonization unit, the expansion gas generated by the methanol rectification unit, and the nitrogen-containing tail gas generated by the sewage pretreatment unit are jointly sent to the TO furnace, and are discharged after incineration and post-treatment.

[0012] Before step (1), the oxygen and nitrogen in the air are separated by the air separation unit. The separated oxygen is fed into the biomass gasification unit, and the oxygen in the biomass gasification unit and the steam by-produced by the gasification itself undergo a gasification reaction in the atmospheric pressure circulating fluidized bed; the nitrogen separated by the air separation unit is fed into the temperature swing adsorption unit.

[0013] The purge gas in the methanol synthesis unit recovers hydrogen through the hydrogen recovery unit and returns it to the compressor inlet of the methanol synthesis unit. The non-permeate gas rich in methane is sent as purge gas to the once-through boiler of the power island unit for power generation.

[0014] The beneficial effects of the present invention are as follows: In the present invention, biomass raw materials from outside the plant are fed into the biomass gasification unit, where gasification reactions occur with oxygen from the air separation unit and steam by-produced by the gasification itself in an atmospheric pressure circulating fluidized bed to produce raw syngas. The raw syngas undergoes a series of processes such as dust removal, tar removal, desulfurization, debenzolization, denaphthalization, conversion, and decarbonization to obtain the syngas required for methanol synthesis. The syngas undergoes methanol synthesis reactions under the action of a catalyst to obtain crude methanol, which is refined to obtain refined methanol products.

[0015] The present invention uses biomass raw materials to prepare syngas and can also be combined with a green hydrogen production system, which is a green methanol production system. Compared with alternative energy sources such as coal and coal chemical industry, the development and utilization of biomass energy, as a new energy source, has significant competitive advantages such as low cost, environmental protection, and economy, and has become the primary way of new energy utilization. The present invention can promote the resource utilization of biomass materials, achieve energy conservation, emission reduction, and environmental protection purposes, meet the current requirements of environmental protection, energy conservation, and low-carbon economy, and is conducive to achieving green sustainable development. Description of the Drawings

[0016] Figure 1 It is the process flow diagram of a coupled hydrogen green methanol production system according to an embodiment of the present invention.

[0017] In the figure: 1 - Biomass gasification unit, 2 - Washing unit, 3 - Electrostatic tar precipitator unit, 4 - Gas holder unit, 5 - First-stage compression unit, 6 - Coarse desulfurization unit, 7 - Temperature swing adsorption unit, 8 - Second-stage compression unit, 9 - Fine desulfurization unit, 10 - CO conversion unit, 11 - Decarbonization unit, 12 - Methanol synthesis unit, 13 - Methanol rectification unit, 14 - Hydrogen recovery unit, 15 - Hydrogen compression unit, 16 - Air separation unit, 17 - Power island unit, 18 - Sewage pretreatment unit. Detailed Embodiments

[0018] The present invention will be described in detail below in conjunction with the drawings and specific embodiments.

[0019] As Figure 1As shown in the figure, a coupling hydrogen green methanol production system according to an embodiment of the present invention includes a gasification unit, a purification unit, a methanol synthesis unit 12 and a methanol rectification unit 13. The gasification unit is a biomass gasification unit 1, and the biomass gasification unit 1 includes an atmospheric circulating fluidized bed. The atmospheric circulating fluidized bed gasifies biomass raw materials to generate crude syngas. The purification unit is used to purify the crude syngas. A hydrogen compression unit 15 is connected before the methanol synthesis unit 12. The hydrogen compression unit 15 is used to provide hydrogen, which comes from hydrogen produced by a green hydrogen production system (such as electrolytic hydrogen production). The methanol synthesis unit 12 is used to synthesize syngas and hydrogen into crude methanol, and the methanol rectification unit 13 is used to rectify the crude methanol into refined methanol.

[0020] The purification unit includes a washing unit 2, an electric precipitator unit 3, a first-stage compression unit 5, a desulfurization unit 6, a temperature swing adsorption unit 7, a second-stage compression unit 8, a fine desulfurization unit 9, a CO conversion unit 10, and a decarbonization unit 11 arranged in sequence. A gas holder unit 4 is provided between the electric precipitator unit 3 and the first-stage compression unit 5. The washing unit 2 is used to wash and dust the crude syngas. The electric precipitator unit 3 is used to remove coke from the crude syngas. The gas holder unit 4 buffers the incoming gas. The first-stage compression unit is used to pressurize the crude syngas. The crude desulfurization unit is used to remove H2S from the crude syngas. The temperature swing adsorption unit is used to adsorb benzene, naphthalene, and tar in the crude syngas. The second-stage compression unit compresses the crude syngas after temperature swing adsorption. The fine desulfurization unit is used to desulfurize and remove impurities from the compressed crude syngas. The CO conversion unit is used to adjust the hydrogen-carbon ratio required for methanol synthesis. The decarbonization unit is used to remove CO2.

[0021] An air separation unit 16 is connected before the biomass gasification unit 1. The air separation unit 16 is used to separate oxygen and nitrogen in the air. The separated oxygen is introduced into the biomass gasification unit 1, and the separated nitrogen is introduced into the temperature swing adsorption unit 7.

[0022] The coupling hydrogen green methanol production system further includes a sewage treatment unit 18. The washing wastewater generated by the washing unit 2 and the waste liquid generated by the electric precipitator unit 3 are introduced into the sewage treatment unit 18. The decarbonization unit 11 is provided with a CO2 discharge port connected to the biomass gasification unit 1. The sewage treatment unit purifies and treats the washing wastewater and the coking waste liquid, and reduces the tar and ammonia nitrogen content in the wastewater through flocculation, air flotation, steam stripping, and hydrolysis acidification.

[0023] The methanol synthesis unit 12 is connected to a hydrogen recovery unit 14. The hydrogen recovered by the hydrogen recovery unit 14 is introduced into the methanol synthesis unit 12. The flue gas outlet of the hydrogen recovery unit 14 is connected to a power island unit 17. The power island unit 17 includes a direct-fired boiler for power generation. The fuel of the direct-fired boiler can be biomass and gasification fly ash from the biomass gasification unit.

[0024] An embodiment of the method for producing coupled hydrogen green methanol according to the present invention includes the following steps: (1) Feed the biomass raw material into the biomass gasification unit, and gasify the biomass raw material using an atmospheric circulating fluidized bed to produce raw syngas; before this step, separate oxygen and nitrogen in the air using an air separation unit, and feed the separated oxygen into the biomass gasification unit. The oxygen in the biomass gasification unit and the steam by-produced during gasification itself undergo a gasification reaction in the atmospheric circulating fluidized bed; the nitrogen separated by the air separation unit is fed into the temperature swing adsorption unit of the purification unit.

[0025] (2) Feed the raw syngas into the purification unit, and obtain the syngas required for methanol synthesis through processes such as dust removal, tar removal, desulfurization, debenzolization, denaphthalization, conversion, and decarbonization; in this step, first wash and dust the raw syngas through the washing unit, remove tar from the raw syngas through the electric tar catcher unit, and send the washing wastewater and tar-catching waste liquid to the sewage treatment unit for purification, and reduce the tar and ammonia nitrogen content in the wastewater through flocculation, air flotation, steam stripping, and hydrolysis acidification; then enter the gas holder unit for buffering, and the raw syngas enters the first-stage compression unit for pressurization, and then use the raw desulfurization unit to remove H2S in the raw syngas, enter the temperature swing adsorption unit, and the temperature swing adsorption unit adsorbs benzene, naphthalene, and tar in the raw syngas. The raw syngas leaving the temperature swing adsorption unit enters the second-stage compression unit, and after being compressed in the second stage, it is sent to the fine desulfurization unit for desulfurization and impurity removal, and then sent to the CO conversion unit. After adjusting the hydrogen-carbon ratio required for methanol synthesis, it enters the downstream decarbonization unit, and CO2 is removed through amine solution absorption. The purified gas leaving the decarbonization unit is sent to the methanol synthesis device; the CO2 desorbed from the regeneration tower of the decarbonization unit is cooled and divided into two streams, one goes to the biomass gasification unit as the back blowing gas and sealing gas, and the other is directly discharged into the atmosphere. Send the flash gas generated by the raw desulfurization unit, the nitrogen regeneration gas generated by the temperature swing adsorption unit, the flash gas generated by the decarbonization unit, the expansion gas generated by the methanol rectification unit, and the nitrogen-containing tail gas generated by the sewage pretreatment unit to the TO furnace, and discharge them after incineration and post-treatment.

[0026] (3) Mix the syngas with hydrogen and feed it into the methanol synthesis unit. The syngas undergoes a methanol synthesis reaction under the action of a catalyst to obtain crude methanol; the purge gas in the methanol synthesis unit is recycled through the hydrogen recovery unit to return hydrogen to the compressor inlet of the methanol synthesis unit, and the methane-rich non-permeate gas is sent as the purge gas to the once-through boiler of the power island unit for power generation.

[0027] (4) Feed the crude methanol into the methanol rectification unit, and obtain the refined methanol product after rectification.

[0028] The following is illustrated with a specific application example: Taking a 230,000-ton / year coupled green hydrogen green methanol project of a certain factory as an example, 59 t / h of biomass raw materials from outside the plant enter the gasification unit through a conveying machine, together with 10,637 Nm3 Oxygen and the steam by-produced during the gasification process itself undergo a gasification reaction in an atmospheric pressure circulating fluidized bed to produce raw syngas. The raw syngas undergoes a series of processes such as dust removal, tar removal, desulfurization, debenzolization, denaphthalization, conversion, and decarbonization to obtain the syngas required for methanol synthesis. The syngas undergoes a methanol synthesis reaction under the action of a catalyst to obtain crude methanol, which is refined to obtain refined methanol products after distillation.

[0029] First, the 92982 Nm 3 / h of raw syngas leaving the gasification unit after being treated by bag filter dust removal successively enters the washing and electrocoking units to control the ash content in the raw syngas at 1 mg / Nm 3 and the tar content at ≤20 mg / Nm 3 . After entering the light oil gas holder unit for buffering, it is pressurized to 0.59 MPaG by the first-stage compressor of the raw syngas and then enters the raw desulfurization unit. After the H2S content in the raw syngas is removed to below 20 ppm, it is sent to the temperature swing adsorption unit (TSA). The benzene content in the raw syngas is controlled within 10 mg / Nm 3 and the naphthalene content within 5 mg / Nm 3 , and the tar content within 1 mg / Nm 3 . The raw syngas leaving the TSA is pressurized to 2.35 MPaG by the second-stage compression and then sent to the fine desulfurization unit for desulfurization and impurity removal. Organic sulfur such as mercaptan, thioether, thiophene, and carbonyl sulfide in the raw syngas is converted into inorganic sulfur H2S, which is then removed by zinc oxide. After that, the total sulfur in the raw syngas is controlled within 0.1 ppm, phosphorus within 10 ppb, and chlorine within 10 ppb, and then it is sent to the conversion unit. After adjusting the hydrogen-carbon ratio required for methanol synthesis, it enters the downstream decarbonization unit. Most of the CO2 is removed by amine liquid absorption. The purified gas leaving the decarbonization unit is sent to the methanol synthesis unit to maintain the hydrogen-carbon ratio of the purified gas close to 2.0. The CO2 desorbed from the regeneration tower is cooled and divided into two streams. One stream goes to the gasification plant as back blowing gas and sealing gas, and the other stream is directly discharged into the atmosphere.

[0030] 1.2 MPaG, 29000 Nm 3 / h of green hydrogen from outside the plant enters the hydrogen compressor and is pressurized to 2.0 MPaG. The purified gas from the purification plant is mixed with hydrogen and then enters the syngas compressor of the methanol synthesis plant. After being pressurized to 5.1 - 5.4 MPaG, it is sent to the methanol synthesis unit to participate in the reaction. The synthesis pressure is controlled at 5.1 - 5.4 MPaG, and the recycle ratio is controlled at 3 - 5.5. The off-gas is sent through a hydrogen recovery process (membrane separation or PSA) to recover hydrogen and return it to the inlet of the synthesis compressor. The non-permeate gas rich in methane is sent as off-gas to the power island direct-fired boiler for power generation. The crude methanol from the methanol synthesis unit is refined by the methanol distillation unit to obtain 230,000 tons / year of industrial-grade methanol products.

[0031] The washing water from the battery limit is sent to the gasification washing and decoking unit as part of the makeup water for the raw syngas washing. It washes the raw syngas together with the makeup fresh water. The sewage discharged from the washing, together with the condensate generated by the syngas cooling, is discharged as gasification wastewater into the sewage pretreatment unit. Through processes such as flocculation, air flotation, steam stripping, and hydrolysis acidification, the contents of impurities such as tar and ammonia nitrogen in the wastewater are reduced. After meeting the requirements, it is sent to the whole-plant sewage treatment device.

[0032] The waste gases such as the raw syngas rough desulfurization flash gas, decarbonization flash gas, expansion gas of the rectification unit, and pre-rectification tail gas, and the stripping tail gas of the sewage pretreatment unit are jointly sent to the TO furnace, and after incineration and post-treatment, they are discharged up to the standard.

Claims

1. A hydrogen-coupled green methanol production system, comprising a gasification unit, a purification unit, a methanol synthesis unit and a methanol rectification unit, characterized in that: The gasification unit is a biomass gasification unit, which includes an atmospheric pressure circulating fluidized bed. The atmospheric pressure circulating fluidized bed gasifies biomass raw materials to produce raw syngas. The purification unit is used to purify the raw syngas. A hydrogen compression unit is connected before the methanol synthesis unit, and the hydrogen compression unit is used to provide hydrogen. The methanol synthesis unit is used to synthesize syngas and hydrogen into crude methanol. The methanol rectification unit is used to rectify crude methanol into refined methanol.

2. The coupled hydrogen green methanol production system according to claim 1, wherein: The purification unit includes a washing unit, an electric precipitator unit, a first-stage compression unit, a desulfurization unit, a temperature swing adsorption unit, a second-stage compression unit, a fine desulfurization unit, a CO conversion unit, and a decarbonization unit, which are arranged in sequence.

3. The coupled hydrogen green methanol production system according to claim 2, wherein: An air separation unit is connected before the biomass gasification unit. The air separation unit is used to separate oxygen and nitrogen in the air. The separated oxygen is introduced into the biomass gasification unit, and the separated nitrogen is introduced into the temperature swing adsorption unit.

4. The coupled hydrogen green methanol production system according to claim 2, characterized in that: The coupled hydrogen green methanol production system also includes a sewage treatment unit. The washing wastewater generated by the washing unit and the waste liquid generated by the electric precipitator unit are introduced into the sewage treatment unit. The decarbonization unit is provided with a CO2 discharge port connected to the biomass gasification unit.

5. The coupled hydrogen green methanol production system according to claim 2, wherein: The methanol synthesis unit is connected with a hydrogen recovery unit. The hydrogen recovered by the hydrogen recovery unit is introduced into the methanol synthesis unit. The purge gas outlet of the hydrogen recovery unit is connected with a power island unit, and the power island unit includes a once-through boiler for power generation.

6. A method for coupling hydrogen production with green methanol production, characterized in that, It includes the following steps: (1) Feed the biomass raw materials into the biomass gasification unit, and use the atmospheric pressure circulating fluidized bed to gasify the biomass raw materials to produce raw syngas; (2) Feed the raw syngas into the purification unit. The raw syngas undergoes dust removal, tar removal, desulfurization, decoking, naphthalene removal, conversion, and decarbonization processes to obtain syngas required for methanol synthesis; (3) Mix the syngas and hydrogen and introduce them into the methanol synthesis unit. The syngas undergoes a methanol synthesis reaction under the action of a catalyst to obtain crude methanol; (4) Feed the crude methanol into the methanol rectification unit. The crude methanol is rectified to obtain refined methanol products.

7. The method for producing coupled hydrogen green methanol according to claim 6, characterized in that: In step (2), first, the raw syngas is washed and dedusted by the washing unit, and defocused by the electric precipitator unit. The washing wastewater and the defocusing waste liquid are sent to the sewage treatment unit for purification. The tar and ammonia nitrogen content in the wastewater are reduced by flocculation, air flotation, steam stripping, and hydrolysis acidification; then it enters the gas holder unit for buffering. The raw syngas then enters the first-stage compression unit for pressurization, and the H2S in the raw syngas is removed by the crude desulfurization unit. It enters the temperature swing adsorption unit, and the temperature swing adsorption unit adsorbs benzene, naphthalene, and tar in the raw syngas. The raw syngas leaving the temperature swing adsorption unit enters the second-stage compression unit, and after being compressed in the second stage, it is sent to the fine desulfurization unit for desulfurization and impurity removal, and then sent to the CO conversion unit. After adjusting the hydrogen-carbon ratio required for methanol synthesis, it enters the downstream decarbonization unit, and CO2 is removed by amine liquid absorption. The purified gas leaving the decarbonization unit is sent to the methanol synthesis device; the CO2 desorbed from the regeneration tower of the decarbonization unit is cooled and divided into two streams. One stream goes to the biomass gasification unit as back blowing gas and sealing gas, and the other stream is directly discharged into the atmosphere.

8. The method for coupling hydrogen production and green methanol production according to claim 7, wherein: The flash gas generated by the rough desulfurization unit, the nitrogen regeneration gas generated by the temperature swing adsorption unit, the flash gas generated by the decarbonization unit, the expansion gas generated by the methanol rectification unit, and the nitrogen-containing tail gas generated by the sewage pretreatment unit are jointly sent to the TO furnace and discharged after incineration and post-treatment.

9. The method for coupling hydrogen production of green methanol according to claim 7, characterized in that: Before step (1), the oxygen and nitrogen in the air are separated by the air separation unit. The separated oxygen is introduced into the biomass gasification unit, and the oxygen in the biomass gasification unit and the steam by-produced by the gasification itself undergo a gasification reaction in an atmospheric pressure circulating fluidized bed; the nitrogen separated by the air separation unit is introduced into the temperature swing adsorption unit.

10. The method for producing coupled hydrogen green methanol according to claim 6, wherein: The purge gas in the methanol synthesis unit is sent to the compressor inlet of the methanol synthesis unit after the hydrogen is recovered by the hydrogen recovery unit, and the non-permeate gas rich in methane is sent as the purge gas to the once-through boiler of the power island unit for power generation.

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