Method for preparing low-carbon methanol by utilizing biomass carbon source obtained by slow cracking way

Abstract

The invention discloses a method for preparing low-carbon methanol by utilizing a biomass carbon source obtained by a slow cracking way, which comprises the following steps: mixing municipal rural wastes with biomass, pyrolyzing the obtained mixture, and then separating to obtain a solid-phase product, a liquid-phase product and a gas-phase product; the liquid-phase and gas-phase products are subjected to oxygen-enriched combustion, gas generated in the combustion process is subjected to gas adsorption through a CO2 adsorbent, then captured CO2 is subjected to release and compression treatment and then subjected to a gasification reaction with biochar and oxygen, and crude synthesis gas is generated; cooling and purifying the crude synthesis gas, supplementing green hydrogen to meet the hydrogen-carbon ratio, and deacidifying to obtain purified synthesis gas; the purified synthesis gas is subjected to a synthesis reaction to obtain crude methanol, and then the crude methanol is rectified to obtain low-carbon methanol. Municipal rural waste and biomass are coupled to prepare methanol, a slow thermal cracking technology is fully utilized, and green hydrogen and a carbon capture technology are coupled to prepare low-carbon methanol.

Description

Technical Field

[0001] The present invention relates to the technical field of low-carbon methanol synthesis technology, and more specifically, to a method for preparing low-carbon methanol by obtaining biomass carbon sources through a slow cracking pathway. Background Art

[0002] With the continuous advancement of urbanization and the breeding industry, the amount of municipal and rural waste is gradually increasing. Municipal and rural waste mainly includes municipal sludge, livestock and poultry manure, domestic garbage, etc. Municipal and rural waste is rich in a large amount of organic matter, nitrogen, phosphorus and other components. If not properly disposed of, it will cause serious pollution to the soil, water and atmospheric environment, becoming an ecological hazard. In addition, in the context of global energy transformation, it is urgent to seek sustainable low-carbon energy. Summary of the invention

[0003] The purpose of the present invention is to overcome the above-mentioned defects of the prior art and provide a method for producing low-carbon methanol by obtaining biomass carbon source through a slow cracking pathway, which has an obvious carbon emission reduction effect and is low-carbon methanol.

[0004] To achieve the above object, the technical solution of the present invention is as follows:

[0005] A method for preparing low-carbon methanol by obtaining biomass carbon source through a slow cracking pathway comprises the following steps:

[0006] Pre-processing municipal and rural waste and mixing it with biomass, pyrolyzing the obtained mixture, and then separating to obtain solid phase products, liquid phase products and gas phase products;

[0007] The liquid phase product and the gas phase product are subjected to oxygen-enriched combustion, and the gas generated during the combustion is passed through a CO 2 The adsorbent absorbs the gas and then captures the CO 2 After release and compression, the gasification reaction is carried out with biochar and oxygen to generate a crude synthesis gas;

[0008] The crude synthesis gas is cooled and purified, green hydrogen is added to the crude synthesis gas after the cooling and purification process to meet the hydrogen-carbon ratio, and then deacidification is performed to separate acidic compounds to obtain purified synthesis gas;

[0009] The purified synthesis gas is subjected to a synthesis reaction to obtain crude methanol, and then the crude methanol is distilled to obtain low-carbon methanol.

[0010] Optionally, in the mixture, the mass of the municipal and rural waste accounts for 0% to 100% of the total mass of the mixture.

[0011] Optionally, the moisture content of the pretreated municipal and rural waste is less than 40%.

[0012] Optionally, the moisture content of the mixture is less than 15%.

[0013] Optionally, the municipal and rural waste includes one or more of municipal sludge, livestock and poultry manure and domestic garbage.

[0014] Optionally, the source of the biomass includes one or more of rice husks, wood chips, straws and other agricultural and forestry wastes.

[0015] Optionally, the pyrolysis temperature is 300° C. to 800° C., and the pyrolysis pressure is normal pressure.

[0016] Optionally, the pressure of the gasification reaction is 1.0 MPa to 9.0 MPa, and the temperature of the gasification reaction is 800°C to 1600°C.

[0017] 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%.

[0018] Optionally, the solid product is recovered and used as fertilizer.

[0019] Optionally, the CO 2 The adsorbent includes at least one of CaO, MgO, ethanolamine MEA, phase change solvent PCS, dimethyl carbonate DMC and gas membrane separation GMS.

[0020] Optionally, the removal agent used in the deacidification treatment is methanol.

[0021] Optionally, when the CO 2 When the adsorbent is CaO, the adsorption temperature is 500-800°C and the adsorption pressure is normal pressure.

[0022] Optionally, when the CO 2 When the adsorbent is MgO, the adsorption temperature is 50-200°C and the adsorption pressure is normal pressure.

[0023] Optionally, when the CO 2 When the adsorbent is ethanolamine MEA, the adsorption temperature is 50°C or below, and the adsorption pressure is normal pressure.

[0024] Optionally, the release process includes at least one of microwave-assisted desorption, high-pressure separation and high-temperature desorption.

[0025] Optionally, the method includes coupling green hydrogen and green electricity.

[0026] Implementing the embodiments of the present invention will have the following beneficial effects:

[0027] The embodiment of the present invention provides a method for producing low-carbon methanol by obtaining biomass carbon source through a slow pyrolysis pathway, introducing municipal and rural waste into the field of low-carbon methanol synthesis, coupling it with biomass to produce methanol, opening up a new path for the recycling of waste, making full use of the pyrolysis gas and pyrolysis liquid produced by the slow pyrolysis technology, and combining gasification and methanol synthesis processes to produce low-carbon methanol; by coupling green hydrogen and carbon capture technology, biomass CO 2 Self-circulation occurs within the reaction system, achieving self-sufficiency and efficient utilization of system energy. This can effectively alleviate the contradiction of insufficient biomass resources faced in preparing methanol from biochar, and can also help transform municipal and rural waste into harmless ones, which is of great significance to promoting environmental improvement and energy development. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a flow chart of a method for producing low-carbon methanol by obtaining biomass carbon sources through a slow cracking pathway according to an embodiment of the present invention. DETAILED DESCRIPTION

[0029] The present invention is further described below in conjunction with specific embodiments, but the present invention is not limited in any way.

[0030] The present invention discloses a method for preparing low-carbon methanol by using a slow cracking pathway to obtain a biomass carbon source. Figure 1 As shown, the following steps are included:

[0031] (1) Pre-treating municipal and rural waste and mixing it with biomass, pyrolyzing the resulting mixture, and then separating to obtain solid phase products, liquid phase products, and gas phase products.

[0032] In a specific embodiment, in the mixture, the mass of municipal and rural waste accounts for 0% to 100% of the total mass of the mixture.

[0033] In a specific embodiment, the pretreatment specifically includes the following steps: pretreating the sludge of municipal and rural waste by physical, chemical or biological methods, performing multiple pretreatments, and then performing high-pressure or ultra-high-pressure secondary mechanical filtration. The moisture content of the pretreated municipal and rural waste is less than 40%.

[0034] In a specific embodiment, biochar can act as a moisture carrier to absorb part of the moisture, so the biochar can be used to further dehydrate the water to achieve the goal of reducing the moisture content to below 15%.

[0035] In a specific embodiment, the municipal rural waste includes one or more of municipal sludge, livestock and poultry manure and domestic garbage.

[0036] In a specific embodiment, the source of biomass includes one or more of rice husks, wood chips, straws and other agricultural and forestry wastes.

[0037] In a specific embodiment, the pyrolysis temperature is 300° C. to 800° C., and the pyrolysis pressure is normal pressure.

[0038] (2) The liquid and gas products are burned in oxygen-enriched combustion, and the gases generated during the combustion are passed through CO 2 The adsorbent absorbs the gas and then captures the CO 2 After release and compression, it undergoes gasification reaction with biochar and oxygen to generate raw synthesis gas.

[0039] In a specific embodiment, the pressure of the gasification reaction is 1.0 MPa to 9.0 MPa, and the temperature of the gasification reaction is 800° C. to 1600° C.

[0040] In one embodiment, CO 2 The adsorbent includes at least one of CaO, MgO, ethanolamine MEA, phase change solvent PCS, dimethyl carbonate DMC and gas membrane separation GMS.

[0041] In one embodiment, when CO 2 When the adsorbent is CaO, the adsorption temperature is 500-800°C and the adsorption pressure is normal pressure; then it is released in the form of carrier gas at a temperature of 800-1000°C and a pressure of normal pressure.

[0042] In one embodiment, when CO 2 When the adsorbent is MgO, the adsorption temperature is 50-200°C and the adsorption pressure is normal pressure.

[0043] In one embodiment, when CO 2 When the adsorbent is ethanolamine MEA, the adsorption temperature is 50°C or below, and the adsorption pressure is normal pressure; it is then released in the form of carrier gas at a temperature of 50-150°C and a normal pressure.

[0044] In a specific embodiment, the release process includes at least one of microwave assisted desorption, high pressure separation and high temperature desorption.

[0045] (3) Cooling and purifying the crude synthesis gas, adding green hydrogen to the crude synthesis gas after cooling and purification to meet the hydrogen-to-carbon ratio, and then performing a deacidification treatment to separate the acidic compounds to obtain a purified synthesis gas.

[0046] In a specific embodiment, the removal agent used in the deacidification treatment is methanol.

[0047] (4) subjecting the purified synthesis gas to a synthesis reaction to obtain crude methanol, and then distilling the crude methanol to obtain low-carbon methanol.

[0048] 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%.

[0049] In a specific embodiment, the solid phase product includes organic carbon, alkali metals, alkaline earth metals and phosphates, and the solid phase product is recovered and used as a fertilizer.

[0050] In a specific embodiment, the method includes coupling green hydrogen and green electricity.

[0051] In one embodiment, the carrier gas of the biochar includes CO 2 and / or N 2 .

[0052] The present invention also discloses a production system for producing low-carbon methanol by obtaining biomass carbon sources through a slow cracking pathway, which is used to implement the production method of any embodiment of the present invention.

[0053] The production system includes a pretreatment unit, a pyrolysis unit, a separation and recovery unit, an oxygen-enriched combustion unit, a CO 2 Capture unit, CO 2 Release unit, CO 2 Compression unit, gasification unit, cooling and purification unit, green hydrogen supplement unit, acid gas separation unit, methanol synthesis unit and methanol refining unit.

[0054] Furthermore, the production system is specifically:

[0055] The municipal and rural waste is placed in a pretreatment unit for pretreatment; the pretreated municipal and rural waste is mixed with biomass and placed in a pyrolysis unit for pyrolysis; the pyrolysis products are placed in a separation and recovery unit for separation to obtain solid phase products, liquid phase products and gas phase products; the liquid phase products and gas phase products are placed in an oxygen-enriched combustion unit for oxygen-enriched combustion to obtain CO 2 and H 2 O mixed raw gas; CO generated during combustion 2 and H 2 O mixed raw gas into CO 2 Capture unit for CO 2 Adsorption, and then the captured CO 2 Through CO 2 Release unit, CO 2The compression unit mixes with the biochar in the form of carrier gas and enters the gasification unit, and oxygen is added for gasification to obtain raw synthesis gas. 2 The cracking gas and cracking liquid produced from the slow thermal cracking of biomass undergo oxygen-enriched combustion as the biomass carbon source, and self-circulate in the reaction system; the crude synthesis gas enters the cooling and purification unit for purification of the crude synthesis gas, and then enters the green hydrogen replenishment unit to make the crude synthesis gas meet the hydrogen-carbon ratio and the hydrogen-carbon ratio reach the ratio requirement for methanol synthesis; the acid gas separation unit is connected to the water-gas shift unit, and is used to separate the converted crude synthesis gas to separate the acidic compounds to obtain purified synthesis gas; the purified synthesis gas enters the acid gas separation unit to separate the acidic compounds to obtain purified synthesis gas; the purified synthesis gas is passed into the methanol synthesis unit for synthesis treatment to obtain crude methanol; the crude methanol is passed into the methanol refining unit for purification of the crude methanol to obtain low-carbon methanol.

[0056] The production system also includes a product recycling unit, which recycles the solid phase product separated by the separation and recovery unit and uses it as a fertilizer.

[0057] The system also includes an air separation unit, and an oxygen outlet of the air separation unit is communicated with the gasification unit to provide oxygen to the gasification device.

[0058] The following are specific embodiments

[0059] Example 1

[0060] The method of this embodiment of using a slow cracking pathway to obtain a biomass carbon source to produce low-carbon methanol comprises the following steps:

[0061] (1) The corn stalks are crushed into particles of 2 to 6 mm and mixed with municipal sewage sludge in a ratio of 1:1, and heated and dried to reduce the moisture content to less than 15%. The heating rate is 25°C / min, and the corn stalks are thermally cracked in an airtight environment at 500°C. The solid phase product, the liquid phase product and the gas phase product are then separated. The solid phase product is recovered and used as a fertilizer.

[0062] (2) The liquid phase product and the gas phase product in step (1) are subjected to oxygen-enriched combustion, and the gas generated during the combustion process is subjected to gas adsorption by CaO at 500°C and normal pressure, and then the captured CO 2 At 800℃, it is released to the compression device for compression, and used as a carrier gas to react with biochar and oxygen for gasification. The gasification reaction conditions are: gasification pressure of 4.2MPa, gasification temperature of 1500℃, and crude synthesis gas is generated. The crude synthesis gas includes CO, CO 2 , H 2 and CH 4 Two or more of the above.

[0063] (3) Cooling and purifying the crude synthesis gas to remove ash and carbon black impurities, adding green hydrogen to the crude synthesis gas after cooling and purification to meet the hydrogen-carbon ratio of 2.05 to 2.10, and then using methanol to remove sulfides and CO from the crude synthesis gas using low-temperature methanol washing technology. 2 , and obtain purified synthesis gas.

[0064] (4) The purified synthesis gas is subjected to a synthesis reaction to obtain crude methanol. The reaction pressure is 2.6 MPa, the temperature is 270°C, the space velocity is maintained at 7500 ml / (g cat·h), and the catalyst used is a Cu-Zn-Al-based catalyst with CO and H 2 The reaction formula for preparing low-carbon biomass methanol as raw material is shown below, and then the crude methanol is distilled to obtain low-carbon methanol.

[0065] CO+2H 2 →CH 3 OH

[0066] The method of this embodiment is to couple green hydrogen and green electricity.

[0067] Example 2

[0068] The method of this embodiment of using a slow cracking pathway to obtain a biomass carbon source to produce low-carbon methanol comprises the following steps:

[0069] (1) The corn stalks are crushed into particles of 2 to 6 mm and mixed with livestock and poultry manure in a ratio of 1:1, and heated and dried to reduce the moisture content to less than 15%, with a heating rate of 40°C / min, and thermally cracked in an air-tight environment at 500°C, and then separated to obtain solid phase products, liquid phase products and gas phase products; wherein the solid phase products are recovered and used as fertilizer.

[0070] (2) The liquid product and the gas product in step (1) are subjected to oxygen-enriched combustion, and the gas generated during the combustion process is subjected to gas adsorption by CaO at 600°C and normal pressure, and then the captured CO 2 At 900℃, it is released to the compression device for compression, and used as a carrier gas to react with biochar and oxygen for gasification. The gasification reaction conditions are: gasification pressure of 4.6MPa, gasification temperature of 1450℃, and crude synthesis gas is generated. The crude synthesis gas includes CO, CO 2 , H 2 and CH 4 Two or more of the above.

[0071] (3) Cooling and purifying the crude synthesis gas to remove ash and carbon black impurities, adding green hydrogen to the crude synthesis gas after cooling and purification to meet the hydrogen-carbon ratio of 2.05 to 2.10, and then using methanol to remove sulfides and CO from the crude synthesis gas using low-temperature methanol washing technology. 2 , and obtain purified synthesis gas.

[0072] (4) The purified synthesis gas is subjected to a synthesis reaction to obtain crude methanol. The reaction pressure is 2.7 MPa, the temperature is 240°C, the space velocity is maintained at 8000 ml / (g cat h), and the catalyst used is a Cu-Zn-Al-based catalyst with CO and H 2 The reaction formula for preparing low-carbon biomass methanol as raw material is shown below, and then the crude methanol is distilled to obtain low-carbon methanol.

[0073] CO+2H 2 →CH 3 OH

[0074] The method of this embodiment is to couple green hydrogen and green electricity.

[0075] Example 3

[0076] The method of this embodiment of using a slow cracking pathway to obtain a biomass carbon source to produce low-carbon methanol comprises the following steps:

[0077] (1) The corn stalks are crushed into particles of 2 to 6 mm and mixed with domestic waste in a ratio of 1:1, and heated and dried to reduce the moisture content to less than 15% at a heating rate of 25°C / min. The corn stalks are thermally cracked in an airtight environment at 500°C, and then separated to obtain solid phase products, liquid phase products, and gas phase products; wherein the solid phase products are recovered and used as fertilizer.

[0078] (2) The liquid phase product and the gas phase product in step (1) are subjected to oxygen-enriched combustion, and the gas generated during the combustion process is subjected to gas adsorption by CaO at 700°C and normal pressure, and then the captured CO 2 At 950℃, it is released to the compression device for compression, and used as a carrier gas to react with biochar and oxygen for gasification. The gasification reaction conditions are: gasification pressure of 4.9MPa, gasification temperature of 1400℃, and crude synthesis gas is generated. The crude synthesis gas includes CO, CO 2 , H 2 and CH 4 Two or more of the above.

[0079] (3) Cooling and purifying the crude synthesis gas to remove ash and carbon black impurities, adding green hydrogen to the crude synthesis gas after cooling and purification to meet the hydrogen-carbon ratio of 2.05 to 2.10, and then using methanol to remove sulfides and CO from the crude synthesis gas using low-temperature methanol washing technology.2 , and obtain purified synthesis gas.

[0080] (4) The purified synthesis gas is subjected to a synthesis reaction to obtain crude methanol. The reaction pressure is 3.2 MPa, the temperature is 280°C, the space velocity is maintained at 9000 ml / (g cat·h), and the catalyst used is a Cu-Zn-Al-based catalyst with CO and H 2 The reaction formula for preparing low-carbon biomass methanol as raw material is shown below, and then the crude methanol is distilled to obtain low-carbon methanol.

[0081] CO+2H 2 →CH 3 OH

[0082] The method of this embodiment is to couple green hydrogen and green electricity.

[0083] 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 by using a slow cracking pathway to obtain a biomass carbon source, characterized in that: The following steps are involved: Pre-processing municipal and rural waste and mixing it with biomass, pyrolyzing the obtained mixture, and then separating to obtain solid phase products, liquid phase products and gas phase products; The liquid phase product and the gas phase product are subjected to oxygen-enriched combustion, and the gas generated during the combustion is adsorbed by a CO2 adsorbent, and then the captured CO2 is subjected to a release treatment and a compression treatment, and then subjected to a gasification reaction with biochar and oxygen to generate a crude synthesis gas; The crude synthesis gas is cooled and purified, green hydrogen is added to the crude synthesis gas after cooling and purification to meet the hydrogen-carbon ratio, and then deacidification is performed to separate acidic compounds to obtain purified synthesis gas; The purified synthesis gas is subjected to a synthesis reaction to obtain crude methanol, and then the crude methanol is distilled to obtain low-carbon methanol.

2. The method for preparing low-carbon methanol by using a slow cracking pathway to obtain biomass carbon sources according to claim 1, characterized in that: In the mixture, the mass of the municipal and rural waste accounts for 0% to 100% of the total mass of the mixture.

3. The method for preparing low-carbon methanol by using a slow cracking pathway to obtain biomass carbon sources according to claim 1, characterized in that: The moisture content of the pretreated municipal and rural waste is less than 40%; The moisture content of the mixture is less than 15%.

4. The method for preparing low-carbon methanol by using a slow cracking pathway to obtain biomass carbon sources according to claim 1, characterized in that: The municipal and rural waste includes one or more of municipal sludge, livestock and poultry manure and domestic garbage; The sources of the biomass include one or more of rice husks, wood chips, straws and other agricultural and forestry wastes.

5. The method for preparing low-carbon methanol by using a slow cracking pathway to obtain biomass carbon sources according to claim 1, characterized in that: The pyrolysis temperature is 300°C to 800°C, and the pyrolysis pressure is normal pressure; The pressure of the gasification reaction is 1.0MPa to 9.0MPa, and the temperature of the gasification reaction is 800°C to 1600°C; 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%.

6. The method for preparing low-carbon methanol by using a slow cracking pathway to obtain biomass carbon sources according to claim 1, characterized in that: The solid phase product is recovered and used as fertilizer.

7. The method for preparing low-carbon methanol by using a slow cracking pathway to obtain biomass carbon sources according to claim 1, characterized in that: The CO2 adsorbent includes at least one of CaO, MgO, ethanolamine MEA, phase change solvent PCS, dimethyl carbonate DMC and gas membrane separation GMS; The removal agent used in the deacidification treatment is methanol.

8. The method for preparing low-carbon methanol by using a slow cracking pathway to obtain biomass carbon sources according to claim 7, characterized in that: When the CO2 adsorbent is CaO, the adsorption temperature is 500-800°C and the adsorption pressure is normal pressure; When the CO2 adsorbent is MgO, the adsorption temperature is 50-200°C and the adsorption pressure is normal pressure; When the CO2 adsorbent is ethanolamine MEA, the adsorption temperature is 50°C or below, and the adsorption pressure is normal pressure.

9. The method for preparing low-carbon methanol by using a slow cracking pathway to obtain biomass carbon sources according to claim 1, characterized in that: The release process includes at least one of microwave assisted desorption, high pressure separation and high temperature desorption.

10. The method for preparing low-carbon methanol by using a slow cracking pathway to obtain biomass carbon sources according to claim 1, characterized in that: The method includes coupling green hydrogen and green electricity.

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