Whole-cycle green methanol production process and production system

Abstract

The invention relates to a whole-cycle green methanol production process and a production system, and the production process comprises the following steps: S1, crushing biomass, carrying out enzymolysis, and drying to obtain a solid; in addition, the crushed biomass is used for biogas fermentation to prepare biogas, and biogas residues are separated out; s2, pyrolysis: pyrolyzing the biomass and the solids and biogas residues in the S1 by using the biogas in the S1 as a heat source to obtain primary wood gas and bio-based carbon powder; s3, gasification and purification: gasifying the bio-based carbon powder in the S2 by using the biogas in the S1 as a heat source to obtain secondary wood gas; the first-stage wood gas and the second-stage wood gas are combined, impurity gas is removed, and hydrogen and carbon monoxide mixed gas is prepared; hydrogen is prepared from waste electricity electrolyzed water generated by renewable energy power generation, hydrogen in the mixed gas is supplemented, and green methanol is further synthesized. The method has the beneficial effects that the whole process is high in economical efficiency, environment-friendly, high in gasification yield of biomass raw materials and suitable for popularization and application.

Description

Technical Field

[0001] The present invention relates to the technical field of methanol preparation, and in particular to a full-cycle green methanol production process and a production system. Background Art

[0002] As a low-carbon or zero-carbon emission alternative fuel, the production and use of green methanol is of great significance to reducing greenhouse gas emissions. At present, my country's domestic biomass gasification methanol production process and technology have made certain progress, such as Fujian methanol in Fujian Province and Jiaodong methanol in Shandong Province. In order to reduce production costs, many have adopted the co-production of electricity, heat, gas and chemical products.

[0003] However, there are still some problems in the production of methanol from biomass gasification in my country, such as low biomass gasification efficiency; impurities in biomass gasification products may be toxic or corrosive to methanol synthesis catalysts, resulting in a short catalyst life, requiring frequent replacement, and increasing production costs; the wood gas produced by biomass gasification has a complex composition and is usually returned as a heat source for biomass thermal reactions, reducing the output of synthetic methanol at the back end; the above problems restrict the development of the green industry of biomass gasification for methanol. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a full-cycle green methanol production process and production system, which solves the technical problems of low gasification efficiency, high cost and process flow to be optimized in the existing biomass gasification to prepare green methanol.

[0006] (II) Technical solution

[0007] In order to achieve the above object, the main technical solutions adopted by the present invention include:

[0008] In a first aspect, an embodiment of the present invention provides a full-cycle green methanol production process, comprising the following steps: S1, pulverizing, enzymolyzing and drying the biomass in sequence to obtain a solid; further using the pulverized biomass for biogas fermentation to obtain biogas, and separating out biogas residue; S2, pyrolysis: using the biogas in S1 as a heat source to pyrolyze the biomass and the solids and biogas residue produced in S1 to obtain primary wood fuel gas and bio-based charcoal powder; S3, gasification and purification: using the biogas in S1 as a heat source to gasify the bio-based charcoal powder in S2 to obtain secondary wood fuel gas; combining the primary wood fuel gas and the secondary wood fuel gas, removing impurity gases, and obtaining a mixed gas of hydrogen and carbon monoxide; S4, using abandoned electricity generated by renewable energy to electrolyze water to obtain hydrogen, supplementing the mixed gas in S3 with hydrogen to adjust the molar ratio of hydrogen to carbon monoxide to 2:1, and further synthesizing green methanol.

[0009] Among them, in the pyrolysis step, among the proportions of biomass, solid matter after enzymatic hydrolysis and sludge, the greater the amount of solid matter after biomass enzymatic hydrolysis, the higher the proportion of wood fuel gas in the final pyrolysis gasification product.

[0010] As a preferred embodiment of the present invention, in the process, in S4, oxygen produced by electrolyzing water using abandoned electricity generated by renewable energy is used to assist the combustion of biogas in S2 and S3.

[0011] Among them, the oxygen produced by electrolyzing water with abandoned electricity from renewable energy power generation can be used to assist the combustion of biogas in the pyrolysis and gasification of biomass, which can improve the combustion efficiency and combustion temperature of biogas and provide a high-temperature environment for the pyrolysis and gasification of biomass.

[0012] As a preferred embodiment of the present invention, in the process, in S1, the enzymatic hydrolysis process is to add water to the crushed biomass raw material and the lignin degrading enzyme to mix evenly, and stir to remove the lignin in the biomass raw material by enzymatic hydrolysis to obtain a first mixed mixture; then add cellulose degrading enzyme and hemicellulose degrading enzyme to the first mixed mixture, and stir to remove the cellulose and hemicellulose in the biomass raw material by enzymatic hydrolysis to obtain a second mixed mixture.

[0013] Among them, in the process of crushing and enzymatic hydrolysis of biomass raw materials, lignin, cellulose and hemicellulose are removed in turn. By removing lignin, more cellulose and hemicellulose can be exposed, making them easier to be enzymatically hydrolyzed. This not only improves the efficiency of enzymatic hydrolysis, but also reduces the amount and cost of enzymes. At the same time, the monosaccharides or polysaccharides produced by the hydrolysis of cellulose, hemicellulose and lignin can be converted into wood gas more quickly in the subsequent pyrolysis process, thereby increasing the yield of wood gas during the pyrolysis process.

[0014] As a preferred embodiment of the present invention, in the process, the lignin degrading enzyme is selected from one or a combination of laccase, manganese peroxidase and lignin peroxidase; the cellulose degrading enzyme is selected from endoglucanase and / or exoglucanase; the hemicellulose degrading enzyme is selected from a combination of xylanase, arabinanase and mannanase; wherein the enzyme substrate ratio of the lignin degrading enzyme, the cellulose degrading enzyme and the hemicellulose degrading enzyme is 0.01-0.03IU / mg; the biomass crushing particle size is 0.5-2mm, and the mass concentration of the crushed biomass during the enzymatic hydrolysis process is 1%-5%. The above reaction conditions can maximize the enzyme reaction efficiency and save the amount of enzyme.

[0015] As a preferred embodiment of the present invention, in the process, when enzymatic hydrolysis is used to remove lignin, the reaction temperature is 30-50°C and the pH value is 4.0-6.0; when enzymatic hydrolysis is used to remove cellulose and hemicellulose, the reaction temperature is 45-65°C and the pH value is 4.0-5.5; the stirring speed of the enzymatic hydrolysis process is 150-200rpm; and the enzymatic hydrolysis heat source comes from the combustion of biogas in S1.

[0016] Among them, lignin degrading enzymes and cellulose degrading enzymes are used to specifically degrade lignin and cellulose, reducing the generation of volatile impurity gases in the subsequent pyrolysis and gasification steps. Lignin degrading enzymes and cellulose degrading enzymes use different reaction conditions to increase the activity of the enzymes, and stirring will also increase the efficiency of the enzyme reaction.

[0017] As a preferred embodiment of the present invention, in the process, in S2, the pyrolysis temperature is 190-320°C and the pyrolysis time is 2-3h.

[0018] Among them, low-temperature pyrolysis is first used, and the bio-based charcoal powder prepared at a lower temperature contains more carbon, hydrogen and oxygen elements, which is beneficial to improve the yield of wood gas in the gasification step. At this time, the volatile organic matter in the wood gas produced by low-temperature pyrolysis becomes wood vinegar and tar, which are first separated, which is beneficial to reduce the impurity gas in the wood gas in the subsequent gasification step (gas other than the wood gas in the gasification step). The polysaccharide substances produced by the enzymatic hydrolysis of the biomass can shorten the pyrolysis time, while reducing the pyrolysis temperature, reducing the pyrolysis energy consumption, and improving the pyrolysis efficiency.

[0019] As a preferred embodiment of the present invention, in the process, in S3, the gasification temperature is 700-900°C, and the gasification reaction time is 20-60s.

[0020] Among them, a higher temperature is selected in the gasification stage to increase the gasification rate, shorten the reaction time, and increase the yield of synthesis gas (mainly H2 and CO). At the same time, high temperature can promote the cracking and conversion of tar, reduce the generation of tar, and improve the cleanliness of synthesis gas. In addition, because the heat source in the biomass pyrolysis and gasification steps comes from biomass fermentation product biogas, it is a low-cost green energy and can meet the high temperature reaction conditions.

[0021] As a preferred embodiment of the present invention, in the process, in S1, after the biomass is enzymatically hydrolyzed, the solid matter and the enzymatic hydrolyzate in the second mixture are separated, the pH value of the enzymatic hydrolyzate is adjusted to 6.8-7.2, and used in biogas fermentation together with the crushed biomass.

[0022] Among them, the sugars and other substances released from the biomass in the enzymatic hydrolysis solution participate in the biogas fermentation and can increase the substrate concentration of the fermenting microorganisms; the hydrolytic enzymes remaining in the enzymatic hydrolysis solution can also promote the hydrolysis of the biomass directly involved in the biogas fermentation under suitable conditions. The biomass after enzymatic hydrolysis usually has better fermentation characteristics and can provide a more suitable environment for microorganisms, ultimately improving the fermentation conditions and increasing the efficiency and quality of biogas generation. In addition, the solid matter after the enzymatic hydrolysis of biomass can also directly participate in the biogas fermentation.

[0023] In a second aspect, an embodiment of the present invention provides a full-cycle green methanol production system, which is used to run the full-cycle green methanol production process described in the first aspect, and the production system includes a pretreatment module, a pyrolysis module, a gasification purification module and a methanol synthesis module; wherein the pretreatment module is used for enzymatic hydrolysis of biomass raw materials and biogas fermentation of biomass raw materials; the pyrolysis module uses the biogas generated by the pretreatment module to simultaneously pyrolyze the biomass raw materials and the solid enzymatic hydrolysate and biogas residue generated by the pretreatment module to prepare a primary wood gas and bio-based charcoal powder; the gasification purification module is used to gasify the bio-based charcoal powder to prepare a second wood gas; the gasification purification module further combines the primary wood gas and the secondary wood gas, removes impurity gases, and produces a mixed gas of hydrogen and carbon monoxide; the methanol synthesis module is used to synthesize green methanol from the hydrogen and carbon monoxide mixed gas prepared by the gasification purification module and the hydrogen produced by electrolyzing water using abandoned electricity generated by renewable energy.

[0024] (III) Beneficial effects

[0025] The beneficial effects of the present invention are as follows: a full-cycle green methanol production process and production system of the present invention is aimed at the technical problems of low gasification efficiency and high cost in the existing process of preparing green methanol by gasification of biomass; wherein, in the full-cycle green methanol production process, biogas prepared from biomass is used in the heating process of preparing wood gas from biomass. Hydrogen is then produced by electrolyzing water with abandoned electricity from renewable energy power generation to adjust the molar ratio of hydrogen and carbon monoxide, and green methanol is synthesized with green hydrogen. The entire production cycle of green methanol provides a new green and environmentally friendly energy conversion method, realizes the integrated utilization of biomass resources, improves the comprehensive utilization efficiency of renewable resources, and promotes environmental sustainability.

[0026] In addition, since a part of the biomass raw materials are pretreated by enzymatic hydrolysis, the proportion of volatile substances produced during the pyrolysis and gasification of the biomass raw materials can be reduced, the formation of coke can be reduced, and the proportion of wood gas in the biomass pyrolysis and gasification products can be increased; at the same time, the H2 / CO ratio in the wood gas is increased, and the quality of the wood gas is improved; enzymatic hydrolysis pretreatment can make the biomass raw materials more uniform and easy to handle, thereby simplifying the operating conditions in the pyrolysis and gasification process, reducing energy consumption, and improving production efficiency. Before the gasification step, adding pyrolysis treatment helps to improve the reaction rate and efficiency in the biomass pyrolysis and gasification process and reduce the generation of tar as a byproduct of pyrolysis. Compared with the existing technology, the overall process is highly economical, environmentally friendly, and has a high gasification yield of biomass raw materials, which is suitable for promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a full-cycle green methanol production process and production system.

[0028] [Description of Reference Numerals]

[0029] 1: Pretreatment module; 2: Pyrolysis module; 3: Gasification purification module; 4: Methanol synthesis module 4. DETAILED DESCRIPTION

[0030] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below through specific implementation modes in conjunction with the accompanying drawings.

[0031] The embodiments of the present invention propose a full-cycle green methanol production process and production system, which are aimed at the technical problems of low gasification efficiency, high cost and process flow to be optimized in the existing biomass gasification to prepare green methanol; wherein, the full-cycle green methanol production process uses biogas prepared from biomass in the heating process of preparing wood gas from biomass. Then, the abandoned electricity from renewable energy power generation is electrolyzed to produce hydrogen for adjusting the molar ratio of hydrogen and carbon monoxide, and green methanol is synthesized from green hydrogen. The entire production cycle of green methanol provides a new green and environmentally friendly energy conversion method, realizes the integrated utilization of biomass resources, improves the comprehensive utilization efficiency of renewable resources, and promotes environmental sustainability.

[0032] In addition, since a part of the biomass raw materials are pretreated by enzymatic hydrolysis, the proportion of volatile substances produced during the pyrolysis and gasification of the biomass raw materials can be reduced, the formation of coke can be reduced, and the proportion of wood gas in the biomass pyrolysis and gasification products can be increased; at the same time, the H2 / CO ratio in the wood gas is increased, and the quality of the wood gas is improved; enzymatic hydrolysis pretreatment can make the biomass raw materials more uniform and easy to handle, thereby simplifying the operating conditions in the pyrolysis and gasification process, reducing energy consumption, and improving production efficiency. Before the gasification step, adding pyrolysis treatment helps to improve the reaction rate and efficiency in the biomass pyrolysis and gasification process and reduce the generation of tar as a byproduct of pyrolysis. Compared with the existing technology, the overall process is highly economical, environmentally friendly, and has a high gasification yield of biomass raw materials, which is suitable for promotion and application.

[0033] In order to better understand the above technical solution, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a clearer and more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0034] Example 1

[0035] Reference Figure 1 This embodiment provides a full-cycle green methanol production process, which specifically includes the following steps:

[0036] (1) crushing the biomass raw material to a particle size of 0.5-2 mm; enzymatic hydrolysis and drying to obtain a solid;

[0037] (2) using part of the pulverized biomass raw materials for biogas fermentation, wherein the biogas fermentation can be carried out by mixing the biomass raw materials with feces in a mass ratio of 1-3:1 to produce biogas and separate biogas residue;

[0038] (3) At the same time, another part of the above-mentioned crushed biomass raw material is subjected to enzymatic hydrolysis: the crushed biomass raw material and laccase are mixed with water, wherein the mass concentration of the biomass raw material is 1%, and the corresponding enzyme substrate ratio of laccase is 0.01 IU / mg, and more than 90% of the lignin in the biomass raw material is removed by stirring and enzymatic hydrolysis, the stirring speed is 150-200 rpm, the enzymatic hydrolysis reaction temperature is 30-50° C., the pH value is 4.0-6.0, and the enzymatic hydrolysis is carried out for 3-4 days to obtain a first mixed mixture;

[0039] (4) The pH value of the first co-mixture in (3) is adjusted to 4.0-5.5, and then endoglucanase and xylanase are added, the enzyme substrate ratio of the two enzymes is 0.03 IU / mg, the temperature is 45-65°C, and the reaction is stirred at 150-200 rpm for 4 days to remove more than 90% of the cellulose and hemicellulose in the first co-mixture by enzymatic hydrolysis to obtain a second co-mixture, and the solid-liquid separation is carried out, wherein the solid is dried for use, and the liquid enzymatic hydrolyzate is adjusted to pH 6.8-7.2 and then used in the biogas fermentation in (2).

[0040] (5) Pyrolysis: The oxygen produced by electrolyzing water from abandoned electricity generated by renewable energy is used as a combustion aid. The biogas in (2) is used as a heat source to pyrolyze the crushed biomass raw materials in (1), the solid matter separated and dried in (4), and the biogas residue separated in (2). The pyrolysis temperature is 320°C and the pyrolysis time is 2 hours to obtain first-grade wood fuel gas and bio-based charcoal powder.

[0041] (6) Gasification and purification: using oxygen produced by electrolyzing water from abandoned electricity generated by renewable energy to assist combustion, and using the biogas in (2) as a heat source, the bio-based charcoal powder in (5) is gasified at a gasification temperature of 700°C and a gasification reaction time of 60 seconds to obtain secondary wood fuel gas;

[0042] The primary wood fuel gas and the secondary wood fuel gas are combined, and impurity gases are removed (refer to the prior art for details), to produce a mixed gas of hydrogen and carbon monoxide.

[0043] (7) Using the abandoned electricity generated by renewable energy to electrolyze water to produce hydrogen, the molar ratio of hydrogen and carbon monoxide in S3 is adjusted to 2:1 to synthesize green methanol (the specific synthesis steps refer to the existing technology).

[0044] Example 2

[0045] This embodiment provides a full-cycle green methanol production process, which differs from Embodiment 1 in that:

[0046] In step (5), the pyrolysis temperature is 190° C. and the pyrolysis time is 3 h;

[0047] The ratio of the biomass raw material in the pyrolysis raw material, the dried solid matter after enzymatic hydrolysis separated in (4), and the sludge separated in (2) can be adjusted as needed. It can be determined that increasing the usage ratio of the dried solid matter after enzymatic hydrolysis in (4) can increase the H2 / CO ratio in the wood gas.

[0048] The rest of the steps are the same.

[0049] Example 3

[0050] This embodiment provides a full-cycle green methanol production process, which differs from Embodiment 1 in that:

[0051] In step (6), the gasification temperature is 900° C. and the gasification reaction time is 20 s; the remaining steps are the same.

[0052] Example 4

[0053] Reference Figure 1 , this embodiment provides a full-cycle green methanol production system, the production system is used to operate the full-cycle green methanol production process described in Example 1, the production system includes a pretreatment module 1, a pyrolysis module 2, a gasification purification module 3 and a methanol synthesis module 4;

[0054] Among them, the pretreatment module is used for enzymatic hydrolysis of biomass raw materials and biogas fermentation of biomass raw materials; the pyrolysis module uses the biogas generated by the pretreatment module to simultaneously pyrolyze the biomass raw materials and the solid enzymatic hydrolysate and biogas residue generated by the pretreatment module to prepare primary wood gas and bio-based charcoal powder; the gasification and purification module is used to gasify the bio-based charcoal powder to prepare a second wood gas; the gasification and purification module further combines the primary wood gas and the secondary wood gas, removes impurity gases, and produces a mixed gas of hydrogen and carbon monoxide; the methanol synthesis module is used to synthesize green methanol from the mixed gas of hydrogen and carbon monoxide prepared by the gasification and purification module and the hydrogen produced by electrolyzing water with abandoned electricity generated by renewable energy.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A full-cycle green methanol production process, characterized in that: The following steps are involved: S1, crushing, enzymolysis and drying the biomass in sequence to obtain a solid; In addition, the crushed biomass is used for biogas fermentation to produce biogas, and biogas residue is separated; S2, pyrolysis: using the biogas in S1 as a heat source to pyrolyze the biomass and the solid matter and biogas residue produced in S1 to obtain primary wood gas and bio-based charcoal powder; S3, gasification and purification: using the biogas in S1 as a heat source, the bio-based carbon powder in S2 is gasified to obtain secondary wood gas; The primary wood gas and the secondary wood gas are combined, and impurity gases are removed to produce a mixed gas of hydrogen and carbon monoxide; S4: Using the abandoned electricity generated by renewable energy to electrolyze water to produce hydrogen, add hydrogen to the mixed gas in S3 to adjust the molar ratio of hydrogen to carbon monoxide to 2:1, and further synthesize green methanol.

2. The process according to claim 1, characterized in that In S4, oxygen produced by electrolyzing water using abandoned electricity generated by renewable energy is used to assist the combustion of biogas in S2 and S3.

3. The process according to claim 1, characterized in that In S1, the enzymatic hydrolysis process is to mix the crushed biomass and the lignin degrading enzyme with water, and stir and enzymatically hydrolyze to remove lignin in the biomass to obtain a first mixed mixture; Then, cellulose degrading enzyme and hemicellulose degrading enzyme are added to the first mixed mixture, and the cellulose and hemicellulose in the biomass are removed by enzymolysis through stirring to obtain a second mixed mixture.

4. The process according to claim 3, characterized in that The lignin degrading enzyme is selected from one or a combination of laccase, manganese peroxidase and lignin peroxidase; The cellulose degrading enzyme is selected from endoglucanases and / or exoglucanases; The hemicellulose degrading enzyme is selected from the group consisting of xylanase, arabinanase and mannanase; Among them, the enzyme-substrate ratios of lignin-degrading enzymes, cellulose-degrading enzymes, and hemicellulose-degrading enzymes were all 0.01-0.03 IU / mg; The biomass is crushed into particles with a diameter of 0.5-2 mm, and the mass concentration of the crushed biomass during the enzymatic hydrolysis process is 1%-5%.

5. The process according to claim 4, characterized in that When enzymatic hydrolysis is used to remove lignin, the reaction temperature is 30-50°C and the pH value is 4.0-6.0; when enzymatic hydrolysis is used to remove cellulose and hemicellulose, the reaction temperature is 45-65°C and the pH value is 4.0-5.5; The stirring speed during the enzymatic hydrolysis process was 150-200 rpm; The heat source for enzymatic hydrolysis comes from the combustion of biogas in S1.

6. The process according to claim 1, characterized in that In S2, the pyrolysis temperature is 190-320°C and the pyrolysis time is 2-3h.

7. The process according to claim 1, characterized in that In S3, the gasification temperature is 700-900°C, and the gasification reaction time is 20-60s.

8. The process according to claim 3, characterized in that In S1, after the biomass is enzymatically hydrolyzed, the solid matter and the enzymatic hydrolyzate in the second mixture are separated, and the pH value of the enzymatic hydrolyzate is adjusted to 6.8-7.2, and used in biogas fermentation together with the crushed biomass.

9. A full-cycle green methanol production system, characterized in that: The production system is used to operate the full-cycle green methanol production process described in any one of claims 1 to 8, and the production system comprises a pretreatment module, a pyrolysis module, a gasification purification module and a methanol synthesis module; Among them, the pretreatment module is used for biomass enzymatic hydrolysis and biomass biogas fermentation; The pyrolysis module utilizes the biogas generated by the pretreatment module to simultaneously pyrolyze the biomass and the solid enzymatic hydrolysate and biogas residue generated by the pretreatment module to prepare primary wood gas and bio-based charcoal powder; The gasification purification module is used to gasify the bio-based carbon powder to produce a second wood gas; the gasification purification module further combines the first wood gas and the second wood gas, removes impurity gases, and produces a mixed gas of hydrogen and carbon monoxide; The methanol synthesis module is used to synthesize green methanol from the hydrogen and carbon monoxide mixed gas prepared by the gasification purification module and the hydrogen produced by electrolyzing water using abandoned electricity generated by renewable energy.

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