Method for preparing low-carbon methanol based on oxygen-enriched combustion

Abstract

The invention discloses a method for preparing low-carbon methanol based on oxygen-enriched combustion, which comprises the following steps: pyrolyzing biomass to obtain biochar, pyrolysis gas and lysis buffer, and ball-milling the obtained biochar to obtain biochar powder with the particle size of less than 100 mu m; the solid waste is pretreated and then subjected to oxygen-enriched combustion, pyrolysis gas and pyrolysis liquid supply energy to the oxygen-enriched combustion, and a solid phase and a gas phase are obtained; the solid phase is used as a raw material for cement production after being recycled; carrying out cooling purification treatment on the gas phase, then carrying out CO2 capture, desorption and compression treatment in sequence, and carrying out gasification reaction on the gas phase, charcoal powder and oxygen to generate crude synthesis gas; and cooling, purifying and deacidifying the crude synthesis gas, supplementing green hydrogen to meet the hydrogen-carbon ratio, and carrying out synthesis reaction and rectification treatment to obtain the low-carbon methanol. The low-carbon methanol prepared by coupling the carbon source of the solid waste and the biochar has obvious low-carbon emission reduction effect on CO2 emission, and the sustainable development concept is promoted.

Description

Technical Field

[0001] The present invention relates to the technical field of low-carbon methanol synthesis, and more specifically, to a method for preparing low-carbon methanol based on oxygen-enriched combustion. Background Art

[0002] Energy shortage is a major issue facing the world. The reasons include the limited reserves of traditional fossil energy, the rate of extraction exceeding the rate of regeneration, and environmental pollution. Energy shortage not only restricts economic development, but also poses a threat to the sustainable development of society. For example, the consumption rate of fossil fuels such as coal, oil and natural gas far exceeds their regeneration rate, resulting in insufficient energy supply. At the same time, the large amount of greenhouse gases produced during their use exacerbates global warming. In addition, energy shortage will push up energy prices, increase production and transportation costs, and even trigger economic recession. In order to cope with the problem of energy shortage, it is of great significance to develop new energy sources.

[0003] In summary, there is an urgent need for a system that couples carbon sources from municipal sludge, domestic waste and livestock and poultry manure with biochar to produce low-carbon methanol using green hydrogen to solve the problem of carbon emissions. Summary of the invention

[0004] The purpose of the present invention is to overcome the above-mentioned defects of the prior art and provide a method for preparing low-carbon methanol based on oxygen-enriched combustion, wherein the methanol prepared by coupling the carbon source of municipal sludge, domestic garbage and livestock and poultry manure with biochar is used to react with CO 2 It has a significant low-carbon emission reduction effect, effectively reduces environmental pollution and greenhouse gas emissions, and promotes the concept of sustainable development.

[0005] To achieve the above object, the technical solution of the present invention is as follows:

[0006] A method for preparing low-carbon methanol based on oxygen-enriched combustion comprises the following steps:

[0007] (1) pyrolyzing biomass to obtain biochar, pyrolysis gas and pyrolysis liquid, and ball-milling the obtained biochar to obtain biochar powder with a particle size of less than 100 μm;

[0008] (2) subjecting the pretreated solid waste to oxygen-enriched combustion, using the cracking gas and cracking liquid in step (1) to provide energy, to obtain a solid phase and a gas phase; the solid phase is recycled and used as a raw material for cement production;

[0009] (3) cooling and purifying the gas phase, and then CO 2 Capture and convert the captured CO 2 After desorption and compression, the biochar powder obtained in step (1) and oxygen are gasified to generate a crude synthesis gas;

[0010] (4) The crude synthesis gas is sequentially cooled and purified and deacidified to obtain purified synthesis gas, and green hydrogen is added to meet the hydrogen-to-carbon ratio, followed by synthesis reaction and distillation to obtain low-carbon methanol.

[0011] Optionally, in step (2), the water content of the solid waste is reduced to below 20% by the pretreatment.

[0012] Optionally, in step (2), the temperature of the oxygen-enriched combustion is 800-1100° C., and the pressure of the oxygen-enriched combustion is normal pressure.

[0013] Optionally, in step (1), the biomass includes at least one of agricultural waste and forestry waste.

[0014] Optionally, the particle size of the biomass is 3 to 5 mm.

[0015] Optionally, the moisture content of the biomass is 10-20%.

[0016] Optionally, in step (1), pyrolysis is carried out under oxygen-deficient conditions at a temperature of 350 to 800° C. and a heating rate of 10 to 100° C. / min.

[0017] Optionally, in step (3), the pressure of the gasification reaction is 1.0 to 9.0 MPa, and the temperature of the gasification reaction is 800 to 1600°C.

[0018] Optionally, in step (3), the CO 2 Capture of CO 2 The collector includes at least one of ethanolamine MEA, phase change solvent PCS, dimethyl carbonate DMC, gas membrane separation GMS, CaO and MgO.

[0019] Optionally, in step (1), the rotation speed of the ball mill is 200 to 500 r / min, and the grinding time is 5 to 40 min.

[0020] Optionally, in step (4), the deacidification treatment is to remove CO by low-temperature methanol washing technology. 2 and sulfides to obtain purified synthesis gas, and the removed CO 2 Through CO 2 After being captured, it is used as a carrier gas to transport the biomass carbon powder to achieve self-circulation.

[0021] Optionally, the synthesis reaction pressure is 2.5 MPa to 5 MPa, the temperature is 200° C. to 300° C., the space velocity is maintained at 3000 ml / (g cat·h) to 10000 ml / (g cat·h), and the methanol selectivity is >80%.

[0022] Optionally, the method uses green electricity and green hydrogen.

[0023] Implementing the embodiments of the present invention will have the following beneficial effects:

[0024] The present invention discloses a method for preparing low-carbon methanol based on oxygen-enriched combustion, wherein at least one of municipal sludge, domestic garbage or livestock and poultry excrement is subjected to oxygen-enriched combustion, the generated ash residue can be recycled as a raw material for cement production, and the generated flue gas is cooled and purified before CO 2 Capture and convert the captured CO 2 After being released and compressed, it is used as biochar powder delivery gas. The pyrolysis gas and pyrolysis liquid produced by biomass pyrolysis provide energy for oxygen-enriched combustion, and the captured CO 2 After desorption and compression treatment, the gasification reaction is carried out with biochar powder and oxygen produced by biomass cracking to generate crude synthesis gas, followed by cooling purification and deacidification treatment to remove acidic compounds, and then the carbon-hydrogen ratio is adjusted through a green hydrogen supplement unit, followed by synthesis reaction and distillation treatment to obtain low-carbon methanol; the present invention uses green electricity and green hydrogen without increasing coal consumption, and the CO generated 2 Recycling can effectively improve carbon utilization, reduce carbon dioxide emissions, and achieve sustainable development of ecological environment protection and corporate economy. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a flow chart of a method for preparing low-carbon methanol based on oxygen-enriched combustion according to an embodiment of the present invention. DETAILED DESCRIPTION

[0026] The present invention is further described below in conjunction with specific embodiments, but the present invention is not limited in any way.

[0027] The present invention discloses a method for preparing low-carbon methanol based on oxygen-enriched combustion, comprising the following steps:

[0028] (1) Pyrolyzing biomass to obtain biochar, pyrolysis gas and pyrolysis liquid, and ball-milling the obtained biochar to obtain biochar powder with a particle size of less than 100 μm.

[0029] In a specific embodiment, the biomass includes at least one of agricultural waste and forestry waste.

[0030] In a specific embodiment, the particle size of the biomass is 3-5 mm.

[0031] In a specific embodiment, the moisture content of the biomass is 10-20%.

[0032] In a specific embodiment, the pyrolysis is carried out under oxygen-deficient conditions, the temperature is 350-800° C., and the heating rate is 10-100° C. / min.

[0033] In a specific embodiment, the rotation speed of the ball mill is 200-500 r / min, and the grinding time is 5-40 min.

[0034] (2) The solid waste is pretreated and then subjected to oxygen-enriched combustion, and the pyrolysis gas and pyrolysis liquid in step (1) are used for energy supply to obtain a solid phase and a gas phase; the solid phase is recovered and used as a raw material for cement production.

[0035] In a specific embodiment, the water content of the solid waste is reduced to below 20% by pretreatment.

[0036] In a specific embodiment, the temperature of the oxygen-enriched combustion is 800-1100° C., and the pressure of the oxygen-enriched combustion is normal pressure.

[0037] (3) Cooling and purifying the gas phase, and then CO 2 Capture and convert the captured CO 2 After desorption and compression, the biochar powder obtained in step (1) and oxygen are gasified to generate crude synthesis gas.

[0038] In a specific embodiment, the pressure of the gasification reaction is 1.0-9.0 MPa, and the temperature of the gasification reaction is 800-1600°C.

[0039] In one embodiment, CO 2 Capture of CO 2 The collector includes at least one of ethanolamine MEA, phase change solvent PCS, dimethyl carbonate DMC, gas membrane separation GMS, CaO and MgO.

[0040] (4) The crude synthesis gas is sequentially cooled and purified and deacidified to obtain purified synthesis gas, and green hydrogen is added to meet the hydrogen-to-carbon ratio, followed by synthesis reaction and distillation to obtain low-carbon methanol.

[0041] In a specific embodiment, the deacidification treatment is to remove CO by low temperature methanol washing technology. 2 and sulfides to obtain purified synthesis gas, and the removed CO 2 By CO 2 After being captured, it is used as a carrier gas to transport biomass carbon powder to achieve self-circulation.

[0042] In a specific embodiment, the synthesis reaction pressure is 2.5 MPa-5 MPa, the temperature is 200° C.-300° C., the space velocity is maintained at 3000 ml / (g cat·h)-10000 ml / (g cat·h), and the methanol selectivity is >80%.

[0043] In a specific embodiment, the method uses green electricity and green hydrogen.

[0044] The present invention also discloses a production system for preparing low-carbon methanol based on oxygen-enriched combustion, which is used to implement the production method of any embodiment of the present invention. The production system includes a solid waste pretreatment unit, an oxygen-enriched combustion unit, a cooling and purification unit, a by-product recovery unit, a CO 2 Capture unit, CO 2 Release unit, CO 2 Compression unit, biomass pyrolysis unit, biochar pretreatment unit, air separation unit, biochar powder gasification unit, cooling and purification unit, acid gas removal unit, green hydrogen supplement unit, synthesis gas to methanol unit and methanol distillation unit. Specifically:

[0045] The solid waste pretreatment unit is used to reduce the water content of solid waste to below 20%.

[0046] The biomass pyrolysis unit is used to pyrolyze biomass to obtain biochar, pyrolysis gas and pyrolysis liquid. The outlet of the biomass pyrolysis unit is divided into two branches, one of which is used to transport the obtained biochar to the biochar pretreatment unit for ball milling to obtain biochar powder with a particle size of less than 100 μm, and the other is used to transport the obtained pyrolysis gas and pyrolysis liquid to the oxygen-enriched combustion unit for energy supply.

[0047] The inlet of the oxygen-enriched combustion unit is also connected to the outlet of the solid waste pretreatment unit for oxygen-enriched combustion. The outlet of the oxygen-enriched combustion unit is provided with two branches, one of which is used to treat the obtained solid phase in the by-product recovery unit as a raw material for cement production, and the other is used to transport the obtained gas phase to the cooling and purification unit for treatment, and then enter the CO 2 Capture unit, CO 2 Desorption unit, CO 2 The compression unit is mixed with the biochar powder in the form of carrier gas and enters the biochar powder gasification unit, and oxygen is added at the same time for gasification reaction to generate raw synthesis gas.

[0048] The purification cooling unit is communicated with the outlet of the gasification unit and is used for cooling and purifying the raw synthesis gas to remove fly ash and carbon black in the raw synthesis gas.

[0049] The acid gas removal unit is connected to the outlet of the purification cooling unit and is used to separate the raw synthesis gas to separate the acid compounds and obtain the purified synthesis gas.

[0050] The green hydrogen replenishment unit is connected to the acid gas removal unit and is used to adjust the hydrogen-carbon ratio to meet the subsequent low-carbon methanol synthesis needs of 2.05 to 2.10.

[0051] The methanol synthesis unit is connected to the outlet of the green hydrogen supplement unit to obtain crude methanol. The outlet of the methanol synthesis unit is connected to the gas inlet of the methanol distillation unit to purify the crude methanol to obtain low-carbon methanol.

[0052] In a specific embodiment, the production system further comprises an air separation device, and an oxygen outlet of the air separation device is connected to the biochar pretreatment unit to provide oxygen to the biochar pretreatment unit.

[0053] The following are specific embodiments

[0054] Example 1

[0055] (1) The corn stalks were crushed into particles of 3 to 5 mm, heated and dried to make the moisture content reach 10 to 20%, and pyrolyzed in an air-tight state at a heating rate of 25°C / min and 500°C to obtain biochar, pyrolysis gas and pyrolysis oil. The obtained biochar was then ground in a ball mill at a speed of 300 r / min and a grinding time of 25 min, and sieved to obtain biochar powder with a particle size of less than 100 μm.

[0056] (2) The pretreated municipal sludge is heated and dried to make the moisture content reach 10-20%, and oxygen-enriched combustion is carried out under normal pressure and 900° C. The cracking gas and cracking oil obtained in step (1) are used to provide energy for the sludge, and the combustion generates flue gas and ash, which is recycled and used as a raw material for cement production.

[0057] (3) The flue gas generated in step (1) is cooled and purified to remove impurities such as fly ash in the flue gas, and then the cooled and purified gas phase is subjected to CO2 removal using ethanolamine at normal pressure and 25°C. 2 Capture and convert the captured CO 2 After desorption treatment at normal pressure and 90°C, the mixture is compressed and mixed with the biochar powder obtained in step (1), oxygen and water vapor to undergo a gasification reaction. The gasification reaction conditions are as follows: the gasification pressure is 4.2 MPa and the gasification temperature is 1500°C to obtain a crude synthesis gas. The crude synthesis gas includes CO, CO 2 , H 2 and CH 4 Two or more of the above.

[0058] (4) Cooling the crude synthesis gas to remove fly ash and carbon black impurities, and then using methanol as a removal agent to remove sulfides and CO from the crude synthesis gas using low-temperature methanol washing technology. 2 , to obtain purified synthesis gas; and the removed CO 2 Through CO 2 After being captured, it is used as a carrier gas to transport biomass carbon powder to achieve self-circulation.

[0059] (6) Purifying the synthesis gas by adding green hydrogen to adjust the hydrogen-carbon ratio to 2.05-2.10, and then performing synthesis reaction and rectification treatment to obtain low-carbon methanol; wherein the synthesis reaction conditions are: reaction pressure of 2.5 MPa, temperature of 240°C, space velocity of 8000 ml / (g cat·h), and the catalyst used is a Cu-Zn-Al-based catalyst; CO and H 2 The reaction formula for preparing low-carbon biomass methanol as raw material is shown in (Ⅰ):

[0060] CO+2H 2 →CH 3 OH (Ⅰ)

[0061] The method of this embodiment uses green electricity and green hydrogen.

[0062] Example 2

[0063] (1) The corn stalks are crushed into particles of 3 to 5 mm, heated and dried to make the moisture content reach 10 to 20%, and thermally cracked at a heating rate of 30°C / min and 500°C in an air-tight state to obtain biochar, pyrolysis gas and pyrolysis oil. The obtained biochar is ground by a ball mill at a speed of 350 r / min and a grinding time of 20 min, and sieved to obtain biochar powder with a particle size of less than 100 μm.

[0064] (2) The pretreated domestic waste is heated and dried to make the moisture content reach 10-20%, and oxygen-enriched combustion is carried out at 950° C. The cracking gas and cracking oil obtained in step (1) are used as energy for the combustion, and smoke and ash are generated. The generated ash is recycled and used as a raw material for cement production.

[0065] (3) The flue gas generated in step (1) is cooled and purified to remove impurities such as fly ash in the flue gas, and then the cooled and purified gas phase is subjected to CO2 removal by ethanolamine at normal pressure and 25°C. 2 Capture, the captured CO 2 After desorption treatment at normal pressure and 80°C, the mixture is compressed and mixed with the biochar powder obtained in step (1), oxygen and water vapor to undergo a gasification reaction. The gasification reaction conditions are as follows: the gasification pressure is 4.7 MPa and the gasification temperature is 1450°C to obtain a crude synthesis gas. The crude synthesis gas includes CO, CO 2 , H 2 and CH 4 Two or more of the above.

[0066] (4) Cooling the crude synthesis gas to remove fly ash and carbon black impurities, and then using methanol as a removal agent to remove sulfides and CO from the crude synthesis gas using low-temperature methanol washing technology. 2 , to obtain purified synthesis gas; and the removed CO2 Through CO 2 After being captured, it is used as a carrier gas to transport biomass carbon powder to achieve self-circulation.

[0067] (6) Purifying the synthesis gas by adding green hydrogen to adjust the hydrogen-carbon ratio to 2.05-2.10, and then performing synthesis reaction and distillation treatment to obtain low-carbon methanol; wherein the synthesis reaction conditions are: reaction pressure of 2.7 MPa, temperature of 260°C, space velocity of 8500 ml / (g cat·h), and the catalyst used is a Cu-Zn-Al-based catalyst.

[0068] The method of this embodiment uses green electricity and green hydrogen.

[0069] Example 3

[0070] (1) The corn stalks are crushed into particles of 3 to 5 mm, heated and dried to a moisture content of 10 to 20%, and thermally cracked in an airtight state at a heating rate of 40°C / min and 500°C to obtain biochar, pyrolysis gas and pyrolysis oil. The obtained biochar is ground by a ball mill at a rotation speed of 400 r / min and a grinding time of 15 min, and sieved to obtain biochar powder with a particle size of less than 100 μm.

[0071] (2) The pre-treated livestock and poultry manure is heated and dried to make the moisture content reach 10-20%, and oxygen-enriched combustion is carried out at 1000° C. The cracking gas and cracking oil obtained in step (1) are used to provide energy for the combustion, and smoke and ash are generated. The generated ash enters a recovery unit, and the generated ash is recycled and treated as a raw material for cement production.

[0072] (3) The flue gas generated in step (1) is cooled and purified to remove impurities such as fly ash in the flue gas, and then the gas phase after cooling and purification is captured by ethanolamine under normal pressure and 25°C to capture the captured CO 2 CO was carried out under normal pressure and 90°C 2 After desorption, CO 2 The raw syngas is compressed and mixed with the biochar powder obtained in step (1), oxygen and water vapor to undergo a gasification reaction. The gasification reaction conditions are as follows: a gasification pressure of 5.1 MPa and a gasification temperature of 1400°C to obtain a crude syngas. The crude syngas includes CO, CO 2 , H 2 and CH 4 Two or more of the above.

[0073] (4) Cooling the crude synthesis gas to remove fly ash and carbon black impurities, and then using methanol as a removal agent to remove sulfides and CO from the crude synthesis gas using low-temperature methanol washing technology. 2 , to obtain purified synthesis gas; and the removed CO 2By CO 2 After being captured, it is used as a carrier gas to transport biomass carbon powder to achieve self-circulation.

[0074] (6) Purifying the synthesis gas by adding green hydrogen to adjust the hydrogen-carbon ratio to 2.05-2.10, and then performing synthesis reaction and distillation treatment to obtain low-carbon methanol; wherein the synthesis reaction conditions are: reaction pressure of 2.9 MPa, temperature of 280°C, space velocity of 9000 ml / (g cat·h), and the catalyst used is a Cu-Zn-Al based catalyst.

[0075] The method of this embodiment uses green electricity and green hydrogen.

[0076] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing low-carbon methanol based on oxygen-enriched combustion, characterized in that: The following steps are involved: (1) pyrolyzing biomass to obtain biochar, pyrolysis gas and pyrolysis liquid, and ball-milling the obtained biochar to obtain biochar powder with a particle size of less than 100 μm; (2) subjecting the pretreated solid waste to oxygen-enriched combustion, using the pyrolysis gas and pyrolysis liquid in step (1) to provide energy, to obtain a solid phase and a gas phase; the solid phase is recycled and used as a raw material for cement production; (3) cooling and purifying the gas phase, then capturing CO2 from the cooled and purified gas phase, and gasifying the captured CO2 with the biochar powder and oxygen obtained in step (1) after desorption and compression to generate a crude synthesis gas; (4) The crude synthesis gas is sequentially cooled and purified and deacidified to obtain purified synthesis gas, and green hydrogen is added to meet the hydrogen-to-carbon ratio, followed by synthesis reaction and distillation to obtain low-carbon methanol.

2. The method for preparing low-carbon methanol based on oxygen-enriched combustion according to claim 1, characterized in that: In step (2), the water content of the solid waste is reduced to below 20% by the pretreatment.

3. The method for preparing low-carbon methanol based on oxygen-enriched combustion according to claim 1, characterized in that: In step (2), the temperature of oxygen-enriched combustion is 800-1100° C., and the pressure of oxygen-enriched combustion is normal pressure.

4. The method for preparing low-carbon methanol based on oxygen-enriched combustion according to claim 1, characterized in that: In step (1), the biomass includes at least one of agricultural waste and forestry waste; The particle size of the biomass is 3 to 5 mm; The moisture content of the biomass is 10-20%.

5. The method for preparing low-carbon methanol based on oxygen-enriched combustion according to claim 1, characterized in that: In step (1), pyrolysis is carried out under oxygen-deficient conditions at a temperature of 350 to 800° C. and a heating rate of 10 to 100° C. / min.

6. The method for preparing low-carbon methanol based on oxygen-enriched combustion according to claim 1, characterized in that: In step (3), the pressure of the gasification reaction is 1.0 to 9.0 MPa, and the temperature of the gasification reaction is 800 to 1600°C.

7. The method for preparing low-carbon methanol based on oxygen-enriched combustion according to claim 1, characterized in that: In step (3), the CO2 capture agent used for CO2 capture includes at least one of ethanolamine MEA, phase change solvent PCS, dimethyl carbonate DMC, gas membrane separation GMS, CaO and MgO.

8. The method for preparing low-carbon methanol based on oxygen-enriched combustion according to claim 1, characterized in that: In step (1), the rotation speed of the ball mill is 200 to 500 r / min, and the grinding time is 5 to 40 min.

9. The method for preparing low-carbon methanol based on oxygen-enriched combustion according to claim 1, characterized in that: In step (4), the deacidification treatment is to remove CO2 and sulfide by low-temperature methanol washing technology to obtain purified synthesis gas, and the removed CO2 is captured by CO2 and used as the carrier gas for transporting the biomass carbon powder to achieve self-circulation; The synthesis reaction is carried out under a pressure of 2.5 MPa to 5 MPa, a temperature of 200° C. to 300° C., a space velocity of 3000 ml / (gcat·h) to 10000 ml / (g cat·h), and a methanol selectivity of more than 80%.

10. The method for preparing low-carbon methanol based on oxygen-enriched combustion according to claim 1, characterized in that: The method uses green electricity and green hydrogen.

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