Method for preparing green methanol by pressure gasification of multi-carbon-based raw material

Abstract

The invention belongs to the technical field of energy and chemical industry, and particularly relates to a method for preparing green methanol by pressure gasification of a multi-carbon-based raw material. According to the method, multi-element carbon-based raw materials such as biomass and urban solid waste are utilized, the energy conversion efficiency of the multi-element carbon-based raw materials is improved through the pressurized gasification technology, the multi-element carbon-based raw materials are converted into green methanol, meanwhile, waste gas is effectively treated, and cyclic utilization of energy is achieved. The method has the innovation points that different methanol preparation routes can be selected according to regional resource characteristics, so that maximum utilization of resources and effective cost control are realized; the links of microalgae culture, CO2 capture and reutilization and the like are integrated, and the separated CO2 is converted into high value-added chemicals or biomass fuel, so that a flexible green methanol production system is formed, and waste resource utilization is realized. Compared with a traditional coal-to-methanol technology, the method has the advantages that pollutant emission can be effectively reduced, the equipment maintenance cost is reduced, clean and green methanol is generated, and economic benefits and ecological benefits are both achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy and chemical engineering, specifically the cross-field of carbon-based raw material gasification technology and green methanol production technology, and relates to a pressurized gasification technology for multi-component carbon-based raw materials and a synthesis method of green methanol. Technical Background

[0002] In the context of the current global energy transition, it is crucial to find low-carbon and efficient energy solutions. Multi-component carbon-based raw materials, including but not limited to natural gas, biomass, municipal solid waste, etc., have become ideal candidates due to their abundant reserves and wide distribution. Through appropriate processing technologies such as gasification, pyrolysis, and catalytic conversion, these raw materials can be transformed into various useful products. Compared with relying solely on fossil fuels, the application of multi-component carbon-based raw materials can enhance energy security and contribute to the diversification of the energy structure. In particular, biomass, as a carbon-neutral raw material, absorbs the same amount of CO2 during its growth as it releases during combustion, and its utilization can effectively reduce greenhouse gas emissions, conforming to the development trend of green and low-carbon. By means of innovative technologies to convert it into higher-value-added products such as green methanol, the maximization of resource utilization and the sustainable development of the economy can be achieved.

[0003] The gasification of multi-component carbon-based raw materials is usually carried out under atmospheric or low-pressure conditions. Common gasification technologies include fixed-bed gasification, fluidized-bed gasification, and entrained-flow gasification, etc. Although these methods have been mature and widely used in industry, they also have some significant drawbacks: the energy conversion efficiency is relatively low, especially more obvious in small-scale devices; a certain amount of pollutants such as SOx, NOx, and particulate matter are generated during the gasification process, which requires additional purification steps, increasing the cost; due to the harsh gasification conditions, the equipment is vulnerable to corrosion and wear, and the maintenance cost is high; some gasification technologies have relatively strict requirements for raw materials, restricting the range of raw material selection.

[0004] Methanol (CH3OH) is both a clean energy and an important chemical raw material, and is the core of the "methanol economy" concept. As a versatile chemical raw material, methanol is widely used in the production of products such as formaldehyde, acetic acid, MTBE (methyl tert-butyl ether), dimethyl ether, methanol fuel, and methanol-to-olefins (MTO). In addition, methanol is regarded as a clean fuel due to its high octane number and good combustion characteristics, and has broad application prospects in the fields of transportation, power generation, etc. The advantage of methanol as a fuel is that it can reduce harmful gas emissions, such as sulfur oxides (SOx) and nitrogen oxides (NOx), and it has a relatively high energy density, suitable for replacing diesel and gasoline.

[0005] Green methanol refers to methanol produced through non-fossil fuel routes. Traditional synthesis methods mainly include two main methods: biomass gasification and biological fermentation. The gasification method heats biomass under anoxic conditions to produce syngas, which is then catalytically synthesized into methanol. However, biomass resources are dispersed and the collection cost is high, and by-products such as tar may be produced during the biomass gasification process, which requires additional treatment. The fermentation method converts sugars or other organic substances into methanol through microbial metabolism. Although this method is more environmentally friendly, the production efficiency is low, and a large amount of biomass raw materials are required, which poses a certain competitive pressure on agricultural land.

[0006] In view of the problems in the traditional methods, there is an urgent need to provide a new gasification technology for multi-component carbon-based raw materials and a green methanol synthesis method, which can not only overcome the problems of low atmospheric pressure gasification pressure affecting the device scale and efficiency, but also effectively improve the production efficiency of green methanol, reduce the generation of tar, and form a safe, reliable and economical green methanol synthesis route. Summary of the Invention

[0007] Aiming at the deficiencies of the existing technology, the present invention proposes a method for preparing green methanol by pressurized gasification of multi-component carbon-based raw materials. The aim is to gasify the multi-component carbon-based raw materials under pressurized conditions to improve the energy conversion efficiency of the raw materials, and combine with multi-route green methanol synthesis methods to achieve the efficient conversion of multi-component carbon-based raw materials and the efficient production of green methanol, meeting the urgent needs of the chemical production industry for green and low-carbon technologies. At the same time, fully utilize the CO2 separated from the syngas. Part of it is captured by the CO2 capture device and can be used to prepare ethylene glycol and co-produce ethylene oxide through a series of processes such as electrocatalysis. The other part is used for microalgae photosynthesis fixation and converted into biomass fuel to realize the circular utilization of carbon resources.

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0009] A method for preparing green methanol by pressurized gasification of multi-component carbon-based raw materials, which selects a suitable methanol production route according to the wind energy, light energy and multi-component carbon-based raw material reserves in the region. The specific steps are as follows:

[0010] S1, Screen and pre-treat the multi-component carbon-based raw materials. After being crushed by a crusher, they are transported to a pressurized circulating fluidized bed gasifier;

[0011] S2, Under high temperature and pressurized conditions, react the raw materials with a gasifying agent to generate syngas, the main components of which are CO, CO2, and H2;

[0012] S3. In regions where polycarbonaceous raw materials are abundant and prices are low, an air separation unit is configured to provide pure oxygen for gasification. After the pyrolysis system, a water gas shift (WGS) unit is configured to adjust the carbon-hydrogen ratio in the syngas, separate the excess CO2, and introduce the separated syngas into a methanol synthesis tower to produce methanol. Or, in regions where both polycarbonaceous raw materials and wind-solar resources are abundant, the electric energy generated by wind energy or photovoltaic power generation is used to electrolyze water. The O2 generated from the electrolysis of water is introduced into the gasifier, and a small-scale air separation unit is configured as an emergency backup for the electrolytic water equipment. A small amount of CO2 in the syngas is separated, and the H2 generated from the electrolysis of water reacts with the syngas after separating CO2 to produce methanol.

[0013] S4. Reuse the separated CO2.

[0014] Furthermore, the CO2 separated in S4 is transported to a microalgae cultivation system. Using the photosynthesis of microalgae, the CO2 is converted into biomass fuel, which is used as auxiliary fuel in the pressurized gasification process.

[0015] Furthermore, in S4, a part of the separated CO2 is transported to a microalgae cultivation system. Using the photosynthesis of microalgae, the CO2 is converted into biomass fuel, which is used as auxiliary fuel in the pressurized gasification process. Another part of the separated CO2 is captured by a carbon dioxide capture device and undergoes an electrocatalytic process to generate chemicals such as ethylene oxide, ethylene glycol, and ethylene carbonate.

[0016] Furthermore, in S3, in regions where both polycarbonaceous raw materials and wind-solar resources are abundant, using the characteristics of wind-solar complementarity and the characteristics of electrolytic water hydrogen production equipment, wind-solar coupled electrolytic water hydrogen production is carried out, integrating the alcohol production process with water electrolysis organically. The O2 generated from the electrolysis of water is introduced into the gasifier as an oxidant to improve the gasification efficiency. A part of the generated H2 is introduced into the syngas to balance the C / H ratio in the syngas, and another part is used in the CO2 capture and utilization link to catalytically synthesize ethylene glycol and methanol from ethylene carbonate.

[0017] Furthermore, in S1, select appropriate carbonaceous raw materials, crush the raw materials to 0.2 mm, and ensure uniform particle size through screening for subsequent processing. Mix the crushed raw materials with a liquid medium, add necessary additives, and make a slurry with a certain fluidity. Transport the slurry to the gasifier.

[0018] Furthermore, the high-temperature pressurization in S2 is carried out at 900 - 1250 °C. Using a high-pressure variable-frequency air compressor, the pressure in the furnace is increased to 1.6 MPa, enabling the slurry to contact O2 and undergo an oxidation reaction to generate syngas containing CO, CO2, and H2.

[0019] Further, in S3, the syngas is introduced into a shift reactor, mixed with steam, and undergoes a water-gas shift reaction under the action of a cobalt-molybdenum-based wide-temperature sulfur-tolerant shift catalyst. The ratio of H2 / CO is adjusted through the shift reaction to be close to the optimal ratio required for methanol synthesis, i.e., the molar ratio of H2 to CO is 2:1. The gas after the shift reaction is purified to remove impurities that interfere with methanol synthesis.

[0020] Further, in S3, the syngas is introduced into a cooling system to condense and separate out part of the CO2 as a liquid, and the purified syngas containing only CO and H2 is discharged.

[0021] Further, in S3, the purified syngas containing only CO and H2 is introduced into a methanol synthesis tower. Under the action of a catalyst, the syngas undergoes a methanol synthesis reaction at 200 - 300 °C and 50 - 100 atmospheres. The methanol synthesis tower uses a fluidized bed reactor, which can effectively manage heat. The catalyst uses a copper-based catalyst, such as Cu / Zn / Al oxide.

[0022] Further, the mixed gas obtained in the methanol synthesis tower is passed through a condenser to liquefy the methanol, separating the liquid methanol and the unreacted syngas. The unreacted gas is recycled back to the synthesis tower to continue participating in the reaction. The crude methanol is rectified through a distillation tower to remove water and other impurities, obtaining high-purity methanol.

[0023] Based on the above technical solutions, compared with the prior art, the technical achievements obtained by the present invention are as follows:

[0024] (1) According to the regional resource characteristics (such as the abundance, price of polycarbon-based raw materials, and the adequacy of wind energy and solar energy), different methanol production routes can be flexibly selected, with high flexibility and scalability, achieving the maximization of resource utilization and effective control of costs;

[0025] (2) Integrating multiple links such as pretreatment, gasification, syngas adjustment, methanol synthesis, and CO2 capture and reuse to form a flexible green methanol production system, improving production efficiency and solving the energy consumption and emission problems in traditional processes.

[0026] (3) Converting the separated CO2 into high-value-added chemicals or biomass fuels, reducing greenhouse gas emissions, realizing the resource utilization of waste, enhancing the added value and competitiveness of the entire industrial chain, and achieving a win-win situation of economic and ecological benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a process flow diagram of the method for preparing green methanol by pressurized gasification of polycarbon-based raw materials of the present invention.

[0028] Figure 2It is a comparison chart of fixed carbon content, ash content, volatile content, and moisture content of four types of multi-carbon-based raw materials.

[0029] Figure 3 It is a comparison chart of the unit cost of producing methanol from multi-carbon-based raw materials.

[0030] Figure 4 It is a process flow chart (Route 1) for preparing green methanol by pressurized gasification of multi-carbon-based raw materials in Example 1.

[0031] Figure 5 It is a process flow chart for preparing green methanol by pressurized gasification of multi-carbon-based raw materials in Example 2.

[0032] Figure 6 It is a process flow chart (Route 2) for preparing green methanol by pressurized gasification of multi-carbon-based raw materials in Example 3. Detailed implementation manners

[0033] The following further describes the detailed implementation manners of the present invention. It should be noted here that the description of these implementation manners is used to help understand the present invention, but does not constitute a limitation to the present invention. In addition, the technical features involved in the various implementation manners of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0034] The experimental methods in the following examples are all conventional methods unless otherwise specified, and the test materials used in the following examples are all available through conventional commercial channels unless otherwise specified.

[0035] Selection of multi-carbon-based raw materials:

[0036] In the present invention, non-fossil fuels are preferably selected for pressurized gasification to promote the recycling of resources and reduce the dependence on fossil fuels.

[0037] As shown in Table 1 and Figure 2 as shown, four types of multi-carbon-based raw materials, namely agricultural waste, forestry waste, waste plastics, and municipal solid waste (MSW), are selected to analyze their characteristics and judge their suitability and effects for pressurized gasification.

[0038] Table 1 Comparison table of the characteristics (thermal stability, adhesiveness, oxygen content) of four types of multi-carbon-based raw materials

[0039]

[0040] As can be seen from Table 1, the gasification effect of agricultural waste is the worst. Municipal solid waste has complex components, with large variations in thermal stability and adhesiveness. Waste plastics are raw materials with the best thermal stability and the lowest oxygen content, but their strong adhesiveness may cause blockage of the gasifier. In contrast, forestry waste has good thermal stability, low oxygen content, and moderate adhesiveness, making it an ideal raw material.

[0041] As Figure 2 can be seen, waste plastics have a high fixed carbon content, low ash content, moderate volatile matter, and low moisture content, making them an ideal raw material, followed by forestry waste.

[0042] Table 2 Market price list of different raw materials (taking Henan as an example)

[0043]

[0044] In the cost of preparing green methanol from multi-carbon-based raw materials, the raw material cost accounts for as high as 70%. Considering only the price changes of raw materials, the unit cost ranking of preparing green methanol from multi-carbon-based raw materials is shown in Figure 3 , and the cost ranking from low to high is forestry waste (miscellaneous wood), refuse-derived fuel (RDF), agricultural waste (peanut shell fuel), agricultural waste (wheat straw fuel), forestry waste (pine), forestry waste (Scotch pine), standard coal, and waste plastics.

[0045] Preferably, considering comprehensively the characteristics, cost, and environmental impact of the raw materials, it is most economical to use forestry waste (miscellaneous wood) as the multi-carbon-based raw material for pressurized gasification.

[0046] Example 1

[0047] As Figure 4 ( Figure 1 Route 1) shows that in areas where multi-carbon-based raw materials are abundant and the price is low, the method for preparing green methanol by pressurized gasification of multi-carbon-based raw materials is as follows:

[0048] (1) Use forestry waste (miscellaneous wood) as the multi-carbon-based raw material for pressurized gasification. Screen and pre-treat the multi-carbon-based raw material, and after crushing by a crusher, transport it to a pressurized circulating fluidized bed gasifier;

[0049] (2) Under high-temperature and high-pressure conditions, react the multi-carbon-based raw material with pure oxygen to generate syngas, the main components of which are CO, CO2, and H2;

[0050] The specific operation is as follows: crush the multi-carbon-based raw materials to 0.2mm, and ensure uniform particle size through screening for subsequent processing; mix the crushed raw materials with an appropriate amount of pure water to make a slurry slurry, on this basis, add the necessary additives in sequence to optimize the slurry performance: first add lignin sulfonate dispersant (0.2% to 1.5% per kilogram of dry raw materials), and then add PAM stabilizer (0.05% to 2% per kilogram of dry raw materials) to make a slurry with certain fluidity and stability to ensure that it will not precipitate or agglomerate during transportation. The slurry is smoothly transported to the pressurized circulating fluidized bed gasifier, and under high temperature conditions (900 to 1250°C), the furnace is pressurized to 1.6MPa using a high-pressure variable frequency air compressor, so that the slurry contacts with O2 and undergoes oxidation reaction to generate synthesis gas containing CO, CO2, and H2.

[0051] The main chemical reaction formula of this process is:

[0052]

[0053] (3) In areas where multi-carbon-based raw materials are abundant and relatively cheap, an air separation device is used to provide pure oxygen for gasification. A water-gas shift (WGS) unit is configured after the pyrolysis system, i.e., the gasifier, to adjust the carbon-hydrogen ratio in the synthesis gas and separate the excess CO2. The separated synthesis gas is then introduced into a methanol synthesis tower to prepare methanol. The specific operation is as follows:

[0054] The synthesis gas containing CO, CO2 and H2 is introduced into a shift reactor, mixed with water vapor, and subjected to a water-gas shift reaction under the action of a cobalt-molybdenum wide-temperature and sulfur-resistant shift catalyst. The ratio of H2 / CO is adjusted through the shift reaction to be close to the optimal ratio required for synthesizing methanol, that is, the molar ratio of H2 to CO is 2:1, and the gas after the shift reaction is purified to remove impurities that interfere with methanol synthesis; the synthesis gas after the H2 / CO ratio is adjusted is introduced into a cooling system to condense CO2 into liquid and separate it, and the purified synthesis gas containing only CO and H2 is discharged;

[0055] The purified synthesis gas containing only CO and H2 is introduced into a methanol synthesis tower. Under the action of a copper-based catalyst, the synthesis gas undergoes a methanol synthesis reaction at 200-300°C and 50-100 atmospheres. The methanol synthesis tower uses a fluidized bed reactor, which can effectively manage heat.

[0056] Furthermore, the mixed gas obtained in the methanol synthesis tower is passed through a condenser to liquefy the methanol, and the liquid methanol and unreacted synthesis gas are separated. The unreacted gas is circulated back to the synthesis tower to continue to participate in the reaction. The crude methanol is distilled through a distillation tower to remove water and other impurities to obtain high-purity methanol.

[0057] (4) The CO2 separated in step (3) is transported to the microalgae cultivation system. Through the photosynthesis of microalgae, the CO2 is converted into biomass fuel, which is used as auxiliary fuel in the pressurized gasification process. Specifically, the captured CO2 is transported through a pipeline to the microalgae cultivation system. Under light conditions, microalgae absorb CO2 through photosynthesis and simultaneously utilize nutrients in water to grow and reproduce. The microalgae accumulate a large amount of organic substances such as oils, proteins, and polysaccharides, which serve as precursors for biofuels. When the microalgae reach a certain concentration or the growth cycle ends, the microalgae are harvested by centrifugation and filtration methods. The oils are converted into biodiesel through pyrolysis and are put back into gasification as biomass fuel again.

[0058] The main chemical reaction formula for this process is:

[0059]

[0060] Example 2

[0061] As Figure 5 shown, Example 2 is an area rich in both multi-carbon-based raw materials and wind and solar resources. A method for preparing green methanol by pressurized gasification using forestry waste (miscellaneous wood) as the multi-carbon-based raw material for pressurized gasification. The difference from Example 1 is only in step (3). In an area rich in both multi-carbon-based raw materials and wind and solar resources, the electric energy generated by wind energy or photovoltaic power generation is used to electrolyze water. The O2 generated by electrolyzing water is introduced into the gasification furnace (equipped with a small-scale air separation device as an emergency backup for the electrolysis equipment), and a small amount of CO2 in the syngas is separated. The H2 generated by electrolyzing water reacts with the syngas after separating CO2 to prepare methanol; specifically as follows: The syngas containing CO, CO2, and H2 generated in step (2) is introduced into a cooling system, so that part of the CO2 condenses into a liquid and is separated out, and the purified syngas containing only CO and H2 is discharged; the separated CO2 is collected by a CO2 capture device; the H2 generated by electrolyzing water reacts with the syngas containing only CO and H2 after separating CO2 to prepare methanol; other operations are the same as in Example 1.

[0062] Example 3

[0063] As Figure 6 ( Figure 1 (Route 2) shown, in an area rich in multi-carbon-based raw materials with low prices and rich wind and solar resources, a method for preparing green methanol by pressurized gasification using forestry waste (miscellaneous wood) as the multi-carbon-based raw material for pressurized gasification is as follows:

[0064] (1) Use forestry waste (miscellaneous wood) as the multi-carbon-based raw material for pressurized gasification. Screen and pre-treat the multi-carbon-based raw material. After being crushed by a crusher, it is transported to a pressurized circulating fluidized bed gasification furnace;

[0065] (2) Under high temperature and pressure conditions, react the raw materials with pure oxygen to produce syngas, the main components of which are CO, CO2, and H2;

[0066] The specific operation is as follows: Crush the raw materials to 0.2 mm and ensure uniform particle size through screening for subsequent processing; Mix the crushed raw materials with an appropriate amount of pure water to make a slurry. On this basis, add necessary additives in sequence to optimize the slurry performance: First, add lignosulfonate dispersant (the addition amount per kilogram of dry-based raw materials is 0.2% - 1.5%), and then add PAM stabilizer (the addition amount per kilogram of dry-based raw materials is 0.05% - 2%) to make a slurry with certain fluidity and stability, ensuring that there is no precipitation or agglomeration during transportation. Transport the slurry to a pressurized circulating fluidized bed gasifier. Under high temperature conditions (900 - 1250 °C), use a high-pressure variable-frequency air compressor to pressurize the furnace to 1.6 MPa, so that the slurry contacts with O2 and undergoes an oxidation reaction to generate syngas containing CO, CO2, and H2.

[0067] The main chemical reaction equations for this process are:

[0068]

[0069] (3) Utilize the characteristics of wind-solar complementary and the features of electrolytic water hydrogen production equipment to carry out the coupling of wind power and photovoltaic power generation for electrolytic water hydrogen production. Combine the alcohol production process with water electrolysis organically. The O2 generated by water electrolysis is introduced into the gasifier as an oxidant to improve the gasification efficiency. The syngas containing CO, CO2, and H2 generated in step (2) is introduced into a cooling system to condense CO2 into a liquid and separate it out. Discharge the purified syngas containing only CO and H2, and collect the separated CO2 using a CO2 capture device; Part of the H2 generated by water electrolysis is introduced into the syngas to balance the C / H ratio in the syngas, and the other part is used in the CO2 capture and utilization link to catalytically synthesize ethylene carbonate into ethylene glycol and methanol.

[0070] The main chemical reaction equations for this process are:

[0071]

[0072] After introducing the H2 generated by water electrolysis to balance the C / H ratio in the syngas containing only CO and H2, purify the balanced gas, remove the impurities interfering with methanol synthesis, and then introduce it into a methanol synthesis tower to prepare methanol; The specific operation is as follows:

[0073] Introduce the purified syngas containing only CO and H2 into a methanol synthesis tower. Under the action of a copper-based catalyst, carry out the methanol synthesis reaction at 200 - 300 °C and 50 - 100 atmospheres. The methanol synthesis tower uses a fluidized bed reactor, which can effectively manage heat.

[0074] Further, the mixed gas obtained in the methanol synthesis tower is passed through a condenser to liquefy methanol, separating liquid methanol and unreacted syngas. The unreacted gas is recycled back to the synthesis tower to continue participating in the reaction. The crude methanol is rectified through a distillation tower to remove water and other impurities, obtaining high-purity methanol. The chemical reaction formula for methanol synthesis is as follows:

[0075]

[0076] The chemical reaction formula for methanol refining is as follows:

[0077]

[0078] (4) Part of the CO2 separated and collected in step (3) is transported to the microalgae cultivation system, where through the photosynthesis of microalgae, CO2 is converted into biomass fuel, which is used as an auxiliary fuel in the pressurized gasification process. Specifically, the captured CO2 is transported through a pipeline to the microalgae cultivation system. Under light conditions, microalgae absorb CO2 through photosynthesis and simultaneously grow and reproduce using nutrients in the water. Microalgae accumulate a large amount of organic substances such as oils, proteins, and polysaccharides, which are precursors of biofuels. When the microalgae reach a certain concentration or the growth cycle ends, the microalgae are harvested using centrifugation and filtration methods. The oils are converted into biodiesel through cracking and are put back into gasification as biomass fuel.

[0079] The main chemical reaction formula for this process is:

[0080]

[0081] Another part of the CO2 separated and collected in step (3) is used to prepare ethylene oxide through an electrocatalytic process, serving as a reactant for synthesizing ethylene carbonate, an intermediate for ethylene glycol and methanol. H2 generated by electrolyzing water is added to catalyze the preparation of ethylene glycol and co-produce methanol. Preferably, CO2 and O2 generated by the electrolytic water device are passed through a new redox-mediated electrocatalytic system. At the cathode of the electrolytic cell, using the captured and filtered CO2, C2H4 and H2O are electrolytically generated. At the anode of the electrolytic cell, O2 generated by electrolyzing water is introduced, and the product C2H4 at the cathode reacts with O2 at the anode to generate ethylene oxide. Further, the CO2 provided by the capture device is mixed with ethylene oxide and reacts to form ethylene carbonate under the action of a catalyst. Further, H2 prepared by electrolyzing water is added to ethylene carbonate and, after catalysis, a mixture of ethylene glycol and methanol is generated. Further, through gas-liquid separation, crude ethylene glycol and a mixed gas of methanol and H2 are obtained. Further, the mixed gas is cooled to separate liquid methanol and H2 to obtain green methanol, and the separated H2 can be introduced into the ethylene carbonate catalysis link for recycling.

[0082] II. Overall Energy Consumption Analysis (taking Figure 1 as the benchmark)

[0083] The comprehensive energy consumption for preparing methanol is equal to the various energies input during the methanol production process minus the various energies output. The calculation formula is Equation (9-1):

[0084]

[0085] Among them, E represents the comprehensive energy consumption of methanol, E i represents the i-th type of input energy, E j represents the j-th type of output energy, and the unit is kilogram standard coal (kgce). K i represents the conversion coefficient of the i-th type of input energy, and K j represents the conversion coefficient of the j-th type of output energy.

[0086] The comprehensive energy consumption per unit product is equal to the comprehensive energy consumption of methanol during the reporting period divided by the methanol output during the reporting period. The calculation formula is Equation (9-2):

[0087]

[0088] Among them, e represents the comprehensive energy consumption per unit product of methanol, with the unit of kilogram standard coal per ton (kgce / t), E represents the comprehensive energy consumption of methanol during the reporting period, with the unit of kilogram standard coal (kgce), and P represents the methanol output during the reporting period, with the unit of ton (t).

[0089] The energy consumption of coal-to-methanol mainly consists of coal gasification, air separation, coal gas purification, methanol synthesis, and methanol rectification. According to the calculations of Equation (9-1) and Equation (9-1), the energy consumption required for producing one unit of methanol from coal is approximately around 1150 kgce / t.

[0090] The energy consumption of methanol production from multi-carbon-based raw materials mainly consists of pressurized gasification, conversion and decarbonization, methanol synthesis, and distillation. The volatile components of different raw materials are different, and raw materials with high volatile components can show higher reaction activity and efficiency during the pressurized gasification process.

[0091] In this method, a CO2 capture and reuse system and a microalgae cultivation system are introduced to effectively reduce CO2 emissions and lower the energy consumption for preparing methanol.

[0092] According to the calculations of Equation (9-1) and Equation (9-1), the energy consumption required for producing one unit of methanol from multi-carbon-based raw materials (municipal solid waste) is approximately around 1300 kgce / t.

[0093] According to the calculations of Equation (9-1) and Equation (9-1), the energy consumption required for producing one unit of methanol from multi-carbon-based raw materials (forestry waste) is approximately around 1070 kgce / t.

[0094] Calculated according to Formula (9-1) and Formula (9-1), the energy consumption required for producing unit methanol from multi-component carbon-based raw materials (agricultural waste) is approximately about 1180 kgce / t.

[0095] Calculated according to Formula (9-1) and Formula (9-1), the energy consumption required for producing unit methanol from multi-component carbon-based raw materials (waste plastics) is approximately about 1130 kgce / t.

[0096] Based on the comprehensive cost analysis and energy consumption analysis, the economic efficiency of producing methanol by pressurized gasification of multi-component carbon-based raw materials (forestry waste) is the best.

[0097] Those not described in detail in the present invention are all conventional technical means of those skilled in the art.

[0098] The above has made a detailed description of the embodiments of the present invention, but the present invention is not limited to the described embodiments. For those skilled in the art, without departing from the principle and spirit of the present invention, various changes, modifications, substitutions and variations made to these embodiments still fall within the protection scope of the present invention.

Claims

1. A method for preparing green methanol by pressurized gasification of a multi-component carbon-based raw material. According to the wind energy, solar energy, and reserves of the multi-component carbon-based raw material in the region, a suitable methanol production route is selected. The specific steps are as follows: S1. Screen and pre-treat the multi-component carbon-based raw material. After being crushed by a crusher, it is transported to a pressurized circulating fluidized bed gasifier. S2. Under high-temperature and high-pressure conditions, react the raw material with a gasifying agent to generate syngas, the main components of which are CO, CO2, and H2. S3. In regions where multi-component carbon-based raw materials are abundant and the price is low, a air separation unit is equipped to provide pure oxygen for gasification. After the pyrolysis system, a water gas shift (WGS) unit is configured to adjust the carbon-hydrogen ratio in the syngas, separate the excess CO2, and introduce the separated syngas into a methanol synthesis tower to prepare methanol. Or, in regions where both multi-component carbon-based raw materials and wind-solar resources are abundant, use the electric energy generated by wind energy or photovoltaic power generation to electrolyze water. Introduce the O2 generated by electrolyzing water into the gasifier, and equip a small-scale air separation unit as an emergency backup for the electrolytic water equipment. Separate a small amount of CO2 in the syngas, and use the H2 generated by electrolyzing water to react with the syngas after separating CO2 to prepare methanol. S4. Reuse the separated CO2.

2. The method for preparing green methanol by pressurized gasification of a multi-component carbon-based raw material according to claim 1, characterized in that, The CO2 separated in S4 is transported to a microalgae cultivation system. Using the photosynthesis of microalgae, the CO2 is converted into biomass fuel, which is used as an auxiliary fuel in the pressurized gasification process.

3. The method for preparing green methanol by pressurized gasification of a multi-component carbon-based raw material according to claim 1, characterized in that, In S4, a part of the separated CO2 is transported to a microalgae cultivation system. Using the photosynthesis of microalgae, the CO2 is converted into biomass fuel, which is used as an auxiliary fuel in the pressurized gasification process. Another part of the separated CO2 is captured by a carbon dioxide capture device and undergoes an electrocatalytic process to generate chemicals such as ethylene oxide, ethylene glycol, and ethylene carbonate.

4. The method for preparing green methanol by pressurized gasification of a multi-component carbon-based raw material according to claim 1, characterized in that, In S3, in regions where both multi-component carbon-based raw materials and wind-solar resources are abundant, utilize the characteristics of wind-solar complementarity and the characteristics of the electrolytic water hydrogen production equipment to carry out wind-solar coupled electrolytic water hydrogen production, organically combine the alcohol production process with water electrolysis. Introduce the O2 generated by electrolyzing water into the gasifier as an oxidant to improve the gasification efficiency. A part of the generated H2 is introduced into the syngas to balance the C / H ratio in the syngas, and the other part is used in the CO2 capture and utilization link to catalytically synthesize ethylene glycol and methanol from ethylene carbonate.

5. The method for preparing green methanol by pressurized gasification of a multi-component carbon-based raw material according to claim 1, characterized in that, In S1, select a suitable carbon-based raw material, crush the raw material to 0.2 mm, and ensure uniform particle size through screening for subsequent treatment. Mix the crushed raw material with a liquid medium, add necessary additives to make a slurry with certain fluidity, and transport the slurry to the gasifier.

6. The method for preparing green methanol by pressurized gasification of a multi-component carbon-based raw material according to claim 1, characterized in that, The high temperature and high pressure in S2 are under the conditions of 900~1250 °C. Use a high-pressure variable-frequency air compressor to pressurize the furnace to 1.6 MPa, so that the slurry contacts with O2 and undergoes an oxidation reaction to generate syngas containing CO, CO2, and H2.

7. The method for preparing green methanol by pressurized gasification of a multi-component carbon-based raw material according to claim 1, characterized in that, In S3, the syngas is introduced into a shift reactor, mixed with steam, and undergoes a water-gas shift reaction under the action of a cobalt-molybdenum-based wide-temperature sulfur-tolerant shift catalyst. The ratio of H2 / CO is adjusted through the shift reaction to be close to the optimal ratio required for methanol synthesis, that is, the molar ratio of H2 to CO is 2:

1. The gas after the shift reaction is purified to remove impurities that interfere with methanol synthesis.

8. The method for preparing green methanol by pressurized gasification of a multi-component carbon-based raw material according to claim 1, characterized in that, In S3, the syngas is introduced into a cooling system to condense CO2 into a liquid and separate it out, and the purified syngas containing only CO and H2 is discharged.

9. The method for preparing green methanol by pressurized gasification of a multi-component carbon-based raw material according to claim 1, wherein, In S3, the purified syngas containing only CO and H2 is introduced into a methanol synthesis tower. Under the action of a catalyst, the syngas undergoes a methanol synthesis reaction at 200 - 300 °C and 50 - 100 atmospheres. The methanol synthesis tower uses a fluidized bed reactor, which can effectively manage heat. The catalyst uses a copper-based catalyst, such as Cu / Zn / Al oxide.

10. The method for preparing green methanol by pressurized gasification of a multi-component carbon-based raw material according to claim 9, characterized in that, The mixed gas obtained in the methanol synthesis tower is passed through a condenser to liquefy methanol, separating liquid methanol and unreacted syngas. The unreacted gas is recycled back to the synthesis tower to continue participating in the reaction. The crude methanol is rectified through a distillation column to remove water and other impurities, obtaining high-purity methanol.

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