Novel device and method for preparing green methanol from biogas
By employing a two-stage conversion reaction and catalyst design, the problem of carbon deposition in biogas-to-methanol production was solved, improving reaction efficiency and reducing costs, thus achieving efficient and green methanol production.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- SHANGHAI HANXING ENERGY TECH
- Filing Date
- 2025-10-27
- Publication Date
- 2026-05-15
AI Technical Summary
In traditional biogas-to-methanol processes, the high-temperature conversion reaction leads to frequent carbon buildup in equipment, necessitates frequent catalyst replacement, and results in low efficiency and high cost.
The process employs a two-stage conversion reaction, with a lower initial conversion temperature and a higher secondary conversion temperature. It utilizes a nickel-based catalyst and a specific catalyst design to reduce carbon buildup, and combines an adsorption tower and a distillation tower for gas separation and purification.
It reduces catalyst carbon buildup, improves reaction efficiency, lowers production costs, and enhances energy utilization and product purity.
Smart Images
Figure CN2025130110_15052026_PF_FP_ABST
Abstract
Description
A novel biogas-to-green methanol production device and method Technical Field
[0001] This application relates to the field of clean energy technology, such as a novel biogas-to-green methanol device and method. Background Technology
[0002] Biogas is a mixture containing various gases, its main components including methane, carbon dioxide, nitrogen, hydrogen, oxygen, and hydrogen sulfide. Methane (CH4) is the main component of biogas, accounting for 50% to 80%. It is a colorless and odorless gas with a high calorific value and is the primary source of energy for biogas utilization. Carbon dioxide (CO2) accounts for approximately 20% to 40% of biogas. Carbon dioxide is one of the byproducts of biogas fermentation and has a certain impact on the calorific value and combustion performance of biogas. Nitrogen (N2) accounts for 0% to 5%, mainly from residual air in the raw materials or from microbial metabolism. Hydrogen (H2) content is less than 1%. Hydrogen is produced during biogas fermentation, but its content is relatively low. Oxygen (O2) content is less than 0.4%. Hydrogen sulfide (H2S) content is between 0.1% and 3%. Hydrogen sulfide is a harmful gas during biogas fermentation, with an irritating odor and toxicity, posing certain hazards to the environment and human health.
[0003] Traditional methanol production methods rely primarily on fossil fuels such as coal. The combustion of these fuels produces large amounts of carbon dioxide and other greenhouse gases, negatively impacting the environment. In contrast, biogas-based methanol production utilizes carbon from biomass resources, converting it into methanol through a biochemical process, thereby reducing dependence on fossil fuels and carbon emissions. A biogas-to-methanol process, as described in Chinese patent CN113527052A, relies on an electrically heated converter. The process involves returning the syngas separated from the crude methanol separator in two streams to the inlet of the syngas compressor and the inlet of the feedstock heat exchanger, recovering effective gases from the syngas. The methane utilization rate in the biogas can reach over 95%. An electric heater is used to preheat the feedstock gas at the converter inlet, allowing for flexible temperature adjustment. The high-temperature converter gas at the outlet is used to produce medium-pressure steam and superheated medium-pressure steam. All the medium-pressure superheated steam produced by the unit is used for steam distribution, adjusting the steam-water ratio at the converter inlet. This eliminates the need for external steam, reducing energy consumption and improving energy efficiency. The converter in this technology uses electric heating to provide the heat required for the reaction. Compared to traditional open-flame furnaces, it eliminates the need for fuel gas consumption and flue gas emissions, saving the complex combustion control system and waste heat recovery control system of traditional converters, thus simplifying the process flow.
[0004] In this related technology, although high temperatures can accelerate the rate of methane reforming reactions, higher temperatures also lead to carbon buildup inside the equipment after the reaction, requiring frequent cleaning and catalyst replacement, resulting in low efficiency and high production costs. Therefore, a novel biogas-to-green methanol production device and method are proposed. Summary of the Invention
[0005] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of the claims.
[0006] This application provides a novel biogas-to-green methanol production device and method.
[0007] The objective of this application can be achieved through the following technical solutions:
[0008] A novel method for producing green methanol from biogas includes the following steps:
[0009] S1: The raw material gas is input into the raw material gas compressor and pressurized to 1.3 MPaG, and then preheated to 330℃ through the primary convection section of the converter;
[0010] S2: Enters the hydrogenation reactor to remove olefins and oxygen by olefin saturation, and then enters the zinc oxide desulfurization reactor to remove excess hydrogen sulfide gas.
[0011] S3: The refined raw material gas is mixed with the steam output from the boiler, and then preheated to 600℃ in the secondary convection section of the converter for the first conversion reaction.
[0012] S4: The preheated gas is transported to the radiant section of the converter for a secondary conversion reaction at 910°C.
[0013] S5: Methanol synthesis is carried out in an isothermal methanol synthesis tower.
[0014] As an optional technical solution of this application, a nickel-based catalyst is provided in the primary convection section of the converter, and a converted nickel-based catalyst is provided in the secondary convection section of the converter.
[0015] As an optional technical solution of this application, between S4 and S5, S401 is also included: the synthesis gas passes through the conversion gas steam generator and the boiler feedwater preheater in sequence, and then the synthesis gas is cooled to 40°C in the water cooler, and then the liquid water is separated by the water separator.
[0016] As an optional technical solution of this application, it also includes S402: the syngas output from the water separator is passed through an adsorption tower to remove a portion of the carbon dioxide, and then pressurized to 6MPaG by a syngas compressor, mixed with the purge gas circulated by the purge gas compressor, and preheated to 215°C in the tower preheater.
[0017] As an optional technical solution of this application, it also includes S403: entering the methanol separation and washing tower, allowing the top gas phase to be released and circulated, and the methanol at the bottom of the tower to enter the methanol distillation tower for distillation after being buffered by the expansion tank. The distillation tower consists of a pre-distillation tower, a pressurized distillation tower and an atmospheric distillation tower.
[0018] A novel biogas-to-green methanol device is disclosed, applicable to a novel biogas-to-green methanol method. The converter includes a shell, an inner liner, a burner, a convection pipe, and a radiant pipe. The inner liner is disposed within the shell, the burner is disposed within the inner liner, the convection pipe is arranged around the outside of the inner liner, and the radiant pipe connects to the convection pipe, penetrates the inner liner, and is disposed within the inner liner. A convection hole is provided at the bottom of the inner liner, connecting to the outside of the inner liner. An exhaust port is provided on the shell for discharging the high-temperature gas generated by the burner combustion. A primary catalyst and a secondary catalyst are respectively disposed within the convection pipe and the radiant pipe.
[0019] As an optional technical solution of this application, the convection tube includes a primary convection tube and a secondary convection tube. The primary convection tube is separately disposed from the inner liner sidewall, and the secondary convection tube is attached to the inner liner. The primary catalyst is disposed in the secondary convection tube. The output end of the primary convection tube is connected to the hydrogenation reactor, and the input end of the secondary convection tube is connected to the zinc oxide desulfurization reactor. The output end of the secondary convection tube is connected to the radiation tube.
[0020] As an optional technical solution of this application, the primary catalyst is rotatably disposed in the secondary convection tube, and the primary catalyst is provided with a plurality of inclined air passages extending from the center to the rim surface, the plurality of inclined air passages being used to drive the primary catalyst to rotate.
[0021] As an optional technical solution of this application, the secondary convection pipe is provided with a plurality of reverse thrust ports at positions corresponding to the plurality of inclined gas channels of the primary catalyst, and the plurality of reverse thrust ports are used for the gas flow passing through the inclined gas channels of the reactor.
[0022] As an optional technical solution of this application, a plurality of ball bearings are provided at the downstream end of the primary catalyst, which are rotatably arranged with the secondary convection tube.
[0023] The beneficial effects of this application are as follows:
[0024] (1) In the process of preparing carbon monoxide and hydrogen from methane, the conversion is carried out through two conversion reactions. The reaction temperature of the two conversion reactions increases sequentially. In the first conversion reaction with a lower temperature, when the concentration of methane in the raw gas is high, only part of the methane in the raw gas is converted into hydrogen, carbon monoxide and carbon dioxide. The unreacted methane is further converted through the subsequent secondary conversion reaction. While the reaction rate is reduced, carbon deposition can be reduced. Since the temperature of the secondary conversion reaction is higher, the reaction rate is faster. Some of the carbon deposits attached to the catalyst of the first conversion reaction will also be blown away with the flow of the raw gas and move to the radiation section of the secondary conversion reaction. In this process, the temperature of the radiation section reaches 910℃, which reaches the ignition point of carbon. Therefore, the carbon blown off reacts again in the radiation section to generate carbon monoxide or carbon dioxide, thus avoiding carbon adsorption on the catalyst of the secondary conversion reaction.
[0025] (2) After the raw gas enters the primary catalyst, part of it passes through the cavity and reacts with the catalyst in the cavity. The other part passes through the inclined gas channel, which causes the raw gas entering the inclined gas channel to hit the inner wall of the secondary convection tube and rotate the primary catalyst, causing the catalyst inside to tumble. The raw gas passing through reacts with the catalyst on the one hand, and blows off some of the carbon deposits adhering to the surface of the catalyst on the other hand. Under the action of the raw gas flow, it moves towards the secondary catalyst in the radiant tube. The convection tube is wrapped around the outside of the inner liner from bottom to top and is connected to the top of the radiant tube. After entering the radiant tube, the raw gas moves from top to bottom. The secondary catalyst is set in the lower part of the radiant tube, so that the upper part of the radiant tube is used to burn carbon to make it carbon monoxide or carbon dioxide.
[0026] After reading and understanding the accompanying diagrams and detailed descriptions, other aspects can be understood. Attached Figure Description
[0027] To facilitate understanding by those skilled in the art, the present application will be further described below with reference to the accompanying drawings.
[0028] Figure 1 is a flowchart of the preparation of syngas according to an embodiment of this application;
[0029] Figure 2 is a flowchart of methanol preparation according to an embodiment of this application;
[0030] Figure 3 is a schematic diagram of the internal structure of an activation furnace according to an embodiment of this application;
[0031] Figure 4 is a schematic diagram of the internal structure of the activation furnace liner according to an embodiment of this application;
[0032] Figure 5 is a schematic diagram of the structure of the primary catalyst in the secondary convection tube according to an embodiment of this application.
[0033] Explanation of reference numerals in the attached drawings: 1. Shell; 2. Inner liner; 3. Primary convection pipe; 4. Secondary convection pipe; 41. Thrust reverser; 5. Radiation pipe; 6. Primary catalytic converter; 61. Inclined air passage; 7. Secondary catalytic converter; 8. Combustor; 9. Convection orifice; 10. Exhaust port. Detailed Implementation
[0034] To further illustrate the technical means and effects adopted in this application, the following detailed description of the specific implementation methods, structures, features and effects based on this application is provided in conjunction with the accompanying drawings and preferred embodiments.
[0035] As shown in Figures 1-5, a novel method for producing green methanol from biogas according to this application includes the following steps:
[0036] S1: The raw material gas is input into the raw material gas compressor and pressurized to 1.3 MPaG, and then preheated to 330℃ through the primary convection section of the converter;
[0037] S2: Enters the hydrogenation reactor to remove olefins and oxygen by olefin saturation, and then enters the zinc oxide desulfurization reactor to remove excess hydrogen sulfide gas.
[0038] S3: The refined raw material gas is mixed with the steam output from the boiler, and then preheated to 600℃ in the secondary convection section of the converter for the first conversion reaction.
[0039] S4: The preheated gas is transported to the radiant section of the converter for a secondary conversion reaction at 910°C.
[0040] S5: Methanol synthesis is carried out in an isothermal methanol synthesis tower.
[0041] In the process of preparing methanol, methane in biogas first needs to be converted into carbon monoxide and hydrogen through a conversion reaction, which is then used to synthesize methanol. However, in the process of conversion reaction, a primary conversion is usually carried out in a conversion furnace at a high temperature. Although high temperature can accelerate the rate of methane reforming reaction, the higher temperature will also cause carbon to accumulate inside the equipment after the reaction, thus requiring frequent cleaning of the equipment and replacement of the catalyst used in the reaction.
[0042] Therefore, in order to reduce carbon buildup in the reaction, the process of preparing carbon monoxide and hydrogen from methane involves two conversion reactions, and the two conversion reactions require different temperatures. The reaction temperature is increased sequentially according to the order of the two conversion reactions.
[0043] In step S1, preheating can raise the temperature of the feed gas to a suitable reaction temperature range of 330°C, which helps to accelerate the chemical reaction rate and cause the feed gas to collide and react more frequently on the catalyst surface in subsequent steps, thereby improving the reaction efficiency.
[0044] In step S2, the hydrogenation reactor is a key piece of equipment in the biogas treatment process. It provides a high-temperature, high-pressure environment filled with catalyst, enabling the hydrogenation reaction to proceed efficiently. Inside the reactor, biogas, as the feed gas, is thoroughly mixed with hydrogen and comes into contact with the catalyst, resulting in olefin saturation and oxygen removal reactions. In the hydrogenation reactor, biogas (mainly composed of methane, carbon dioxide, etc., and containing small amounts of olefins and oxygen) reacts with hydrogen under the action of the catalyst. The carbon-carbon double bonds (C=C) in the olefin molecules undergo an addition reaction with hydrogen (H2) to generate saturated hydrocarbon compounds, thereby removing olefins from the feed gas.
[0045] Meanwhile, if the biogas contains oxygen, hydrogen can react with the oxygen to produce water (H2O) and release heat, further removing the oxygen. The zinc oxide desulfurization reactor is used to remove excess hydrogen sulfide gas. By combining the hydrogenation reactor and the zinc oxide desulfurization reactor, substances that do not need to participate in the reaction can be removed, improving the purity of the raw gas.
[0046] During the conversion reaction, although steam is introduced to mix with the feed gas, some of the methane (CH4) in the feed gas will decompose into carbon (C) and hydrogen (H2) under high temperature and the action of the catalyst. The carbon produced will be adsorbed on the catalyst surface, resulting in a decrease in catalyst activity. In the initial conversion reaction at a lower temperature, the reaction rate is reduced due to the lower temperature. That is, when the secondary preheating is carried out to about 600°C, 30% to 40% of the methane in the feed gas can be consumed by the reaction.
[0047] When the concentration of methane in the feed gas is high, only a portion of the methane in the feed gas is converted into hydrogen, carbon monoxide, and carbon dioxide, while the remaining 60% to 70% of the unreacted methane is further converted through subsequent secondary conversion reactions. This reduces carbon buildup while lowering the reaction rate.
[0048] Meanwhile, because the secondary conversion reaction occurs at a higher temperature, the reaction rate is faster. Some of the carbon deposits attached to the catalyst in the primary conversion reaction are also blown away by the flow of the feed gas and move towards the radiation section of the secondary conversion reaction. During this process, the temperature in the radiation section reaches 910℃, which is the ignition point of carbon. Therefore, the carbon blown off reacts again in the radiation section to generate carbon monoxide or carbon dioxide, thus preventing carbon from adsorbing onto the catalyst in the secondary conversion reaction. At the same time, because the catalyst in the primary conversion reaction reacts at a slower rate, carbon deposits are also reduced, and the concentration of methane in the feed gas is also reduced. With a lower methane concentration, methane can be mixed more fully with water vapor in the secondary conversion reaction to generate carbon monoxide and hydrogen. Therefore, the carbon deposits produced by the secondary conversion reaction can be ignored.
[0049] Specifically, because the reaction temperatures of the primary and secondary conversion reactions differ, and the catalyst activity varies under different temperature conditions, a nickel-based catalyst is used in the primary convection section of the reformer to achieve the best reaction results, while a modified nickel-based catalyst is used in the secondary convection section. The nickel-based catalyst exhibits good catalytic activity and selectivity at 600℃, effectively promoting the reforming reaction of methane and carbon dioxide in biogas to produce syngas. Furthermore, nickel-based catalysts are relatively inexpensive and easy to prepare and regenerate; however, at high temperatures such as 910℃, catalysts with high-temperature stability and high activity are typically required. High temperatures favor shifting the chemical equilibrium towards syngas production, increasing the reaction conversion rate. Therefore, high-temperature resistant nickel-based catalysts, such as Ni / SBA-15 catalyst or its modified versions, are used. These catalysts maintain good catalytic performance at high temperatures, promoting the biogas conversion reaction.
[0050] After the two conversion reactions are completed, the temperature of the syngas converted from the raw gas reaches about 910°C. It needs to be cooled before entering the next step. In order to avoid energy waste, in one embodiment, between S4 and S5, S401 is also included: the syngas passes through the conversion gas steam generator and the boiler feed water preheater in sequence, and then the syngas is cooled to 40°C in the water cooler and the liquid water is separated by the water separator.
[0051] After the syngas enters the reformer steam generator, it comes into contact with the internal heat exchange tubes or heat exchange surfaces. Because the syngas has a high temperature, it can transfer heat to the water inside the heat exchange tubes. Similarly, the boiler feedwater preheater absorbs the high-temperature waste heat from the syngas, preheating the boiler feedwater to a certain temperature before sending it into the boiler. In this way, the amount of fuel required by the boiler to heat this preheated feedwater is reduced, thereby improving the boiler's thermal efficiency. The steam generated by the boiler can then be used to mix with the feed gas during the reforming reaction.
[0052] When syngas enters the water separator, the liquid water in the syngas condenses and settles at the bottom of the separator due to the relatively low temperature inside (relative to the syngas temperature). The dry syngas continues to flow upwards and enters subsequent processes through the separator's outlet. Therefore, the main purpose of syngas entering the water separator is to utilize the temperature difference to condense and separate the liquid water in the syngas, ensuring the stable operation of subsequent processes and product quality.
[0053] As an optional technical solution of this application, it also includes S402: removing part of the carbon dioxide from the syngas output from the water separator through the adsorption tower, then pressurizing it to 6MPaG through the syngas compressor, mixing it with the purge gas circulated through the purge gas compressor, and preheating it to 215°C in the tower preheater.
[0054] Adsorption towers capture carbon dioxide from gases using specific adsorption materials (such as activated carbon, molecular sieves, and alkali metal oxides). When syngas containing carbon dioxide passes through an adsorption tower, carbon dioxide molecules are captured by the micropores or active sites on the surface of the adsorption material, thereby achieving gas separation and purification.
[0055] As an optional technical solution of this application, it also includes S403: the methanol enters the methanol separation and washing tower, the top gas phase is released and circulated, and the methanol at the bottom of the tower is buffered by the expansion tank and then enters the methanol distillation tower for distillation. The distillation tower consists of a pre-distillation tower, a pressurized distillation tower and an atmospheric distillation tower.
[0056] The working principle of a methanol separation and scrubbing tower is based on the principles of solubility and affinity. In the scrubbing tower, polluted gas flows into the tower body through the inlet, while a certain amount of methanol solution is sprayed in from the bottom. When the polluted gas passes through the methanol solution, the methanol in the solution undergoes physical adsorption or chemical reaction with the pollutants in the gas, separating the pollutants. Scrubbing towers are typically equipped with trays or packing layers to increase the contact area between substances and improve the absorption efficiency of pollutants.
[0057] Specifically, solubility refers to the property that pollutants are soluble in methanol solution, and separation can be achieved by measuring the solubility of the substance; while affinity refers to the mutual attraction between pollutants and methanol molecules, and pollutants tend to be separated by adsorption or reaction with methanol molecules.
[0058] As a type of gas compression equipment, the main function of a gas compressor is to compress specific gases (such as gases generated during a reaction process that need to be discharged or reused) to increase gas pressure, facilitate storage, transportation, or further processing.
[0059] In order to avoid catalyst carbon buildup in the above embodiments, the feed gas needs to undergo two conversion reactions to form syngas. Therefore, the converter used for the conversion reaction needs to be modified accordingly. Thus, the converter includes a shell 1, an inner liner 2, a burner 8, a convection pipe and a radiation pipe 5. The inner liner 2 is located inside the shell 1, the burner 8 is located inside the inner liner 2, the convection pipe is arranged around the outside of the inner liner 2, and the radiation pipe 5 is connected to the convection pipe and passes through the inner liner 2 and is located inside the inner liner 2. The bottom of the inner liner 2 is provided with a convection hole 9 that connects to the outside of the inner liner 2. The shell 1 is provided with an exhaust port 10 for discharging the high-temperature gas generated by the combustion of the burner 8. The convection pipe and the radiation pipe 5 are respectively provided with a primary catalyst 6 and a secondary catalyst 7.
[0060] A cavity is formed between the shell 1 and the inner liner 2, and the burner 8 is located inside the inner liner 2. When the burner 8 is burning, a radiant section is formed inside the inner liner 2. The radiant tube 5 is heated mainly by the heat radiation generated by the combustion of the burner 8. The high-temperature gas generated by the combustion of the burner 8 flows through the convection hole 9 at the bottom of the inner liner 2 into the cavity between the inner liner 2 and the shell 1. This cavity is the convection section. The temperature is higher in the radiant section and lower in the convection section. Therefore, the temperature inside the radiant tube 5 is higher and the temperature inside the convection tube is lower, so that the high-temperature and low-temperature conversion reactions can be carried out respectively.
[0061] Specifically, the convection tube includes a primary convection tube 3 and a secondary convection tube 4. The primary convection tube 3 is separately set on the side wall of the inner liner 2, and the secondary convection tube 4 is attached to the inner liner 2. The primary catalyst 6 is set in the secondary convection tube 4. The output end of the primary convection tube 3 is connected to the hydrogenation reactor, the input end of the secondary convection tube 4 is connected to the zinc oxide desulfurization reactor, and the output end of the secondary convection tube 4 is connected to the radiation tube 5.
[0062] Since the raw gas needs to be heated twice in the convection tube, specifically to 330°C in S1 and 600°C in S3, in order to create different temperatures within the convection tube, the primary convection tube 3 is not attached to the side wall of the inner liner 2. The temperature of the raw gas in the primary convection tube 3 is only heated by the high-temperature gas output from the radiation section. The secondary convection tube 4, on the other hand, is attached to the side wall of the inner liner 2. In addition to absorbing the heat from the high-temperature gas, it can also be heated through heat transfer from the inner liner 2, resulting in a higher temperature for the secondary convection tube 4.
[0063] Because the conversion rate of the raw gas is low when it passes through the primary catalyst 6 in the secondary convection pipe 4, some carbon deposits will be left on the catalyst in the primary catalyst 6. In order to clean the small amount of carbon deposits, in one embodiment, the primary catalyst 6 is rotatably arranged in the secondary convection pipe 4. The primary catalyst 6 is provided with a number of inclined air passages 61 that extend from the center to the rim surface. The number of inclined air passages 61 are used to drive the primary catalyst 6 to rotate.
[0064] The catalyst is cylindrical, with a cavity inside for placing the catalyst. An inclined gas channel 61 is connected to the cavity, and a mesh cover at the outlet of the inclined gas channel 61 blocks the catalyst. After the raw gas enters the primary catalyst 6, part of it passes through the cavity and reacts with the catalyst inside. The other part passes through the inclined gas channel 61, causing the raw gas entering the inclined gas channel 61 to impact the inner wall of the secondary convection tube 4 and rotate the primary catalyst 6, causing the catalyst inside to tumble. The passing raw gas reacts with the catalyst on one hand, and on the other hand, it blows off some of the carbon deposits adhering to the surface of the catalyst and moves towards the secondary catalyst 7 in the radiant tube 5 under the action of the raw gas flow. The convection tube surrounds the outer side of the inner liner 2 from bottom to top and connects to the top of the radiant tube 5. After entering the radiant tube 5, the raw gas moves from top to bottom. The secondary catalyst 7 is located in the lower part of the radiant tube 5, so that the upper part of the radiant tube 5 is used for the combustion of carbon to turn it into carbon monoxide or carbon dioxide.
[0065] As an optional technical solution of this application, a plurality of thrust reversers 41 are provided in the secondary convection pipe 4 at positions corresponding to the plurality of inclined gas channels 61 of the primary catalyst 6. The plurality of thrust reversers 41 are perpendicular to the flow direction of the gas in the inclined gas channels 61 and are used to reverse the gas flow in the inclined gas channels 61. Since the inclined gas channels 61 are offset from the center of the primary catalyst 6 and are in an eccentric direction, the gas blown out of the inclined gas channels 61 will push the primary catalyst 6 to rotate after hitting the inner wall of the secondary convection pipe 4. In order to accelerate the rotation speed, thrust reversers 41 are provided in the secondary convection pipe 4. The raw material gas in the inclined gas channels 61 can provide greater thrust after hitting the thrust reversers 41 to make the catalyst rotate, thereby increasing the rotation speed of the primary catalyst 6.
[0066] As an optional technical solution of this application, a number of ball bearings are provided at the downstream end of the primary catalyst 6, which are rotatably arranged with the secondary convection tube 4. The ball bearings can reduce friction and increase the rotation speed of the primary catalyst 6.
[0067] Working principle:
[0068] (1) The main reaction principle of biogas to methanol synthesis:
[0069]
[0070] (2) The main components of biogas are methane (about 60% by volume) and carbon dioxide (about 40% by volume). The methane in biogas can react with water vapor to produce syngas containing hydrogen, carbon monoxide and carbon dioxide. The reaction principle is as follows:
[0071]
[0072] (3) The synthesized gas is then mixed with green hydrogen produced by wind or solar power, or excess carbon dioxide is removed, to achieve the following hydrogen-to-carbon ratio for methanol synthesis:
[0073]
[0074] The crude methanol obtained is subjected to methanol three-tower distillation to produce green refined methanol that meets the requirements.
[0075] The specific process scheme for this device is as follows:
[0076] After being pressurized, the biogas in this unit enters the biogas refining process, where oxygen and hydrogen sulfide are removed from the feedstock. The refined feedstock gas is then mixed with steam from the boiler and preheated to 600°C in the convection section of the converter for the initial conversion reaction. It then enters the radiant section of the converter for the secondary conversion reaction. Under the action of a catalyst, a balanced mixture of hydrogen, methane, carbon monoxide, carbon dioxide, and water is produced. The high-temperature syngas exiting the converter undergoes waste heat recovery via a heat exchanger for steam production. The cooled syngas is then pressurized and enters the methanol synthesis unit, where methanol synthesis takes place in an isothermal methanol synthesis reactor. After cooling, crude methanol and water are obtained and enter the methanol distillation unit. The crude methanol is then distilled in a pre-distillation column, a pressurized column, and an atmospheric column. The refined methanol obtained from the distillation is stored in a refined methanol storage tank for subsequent loading and transportation.
[0077] The above description is merely a preferred embodiment of this application and is not intended to limit this application in any way. Although this application has been disclosed above with reference to preferred embodiments, it is not intended to limit this application. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the technical solution of this application. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of this application without departing from the scope of the technical solution of this application shall still fall within the scope of the technical solution of this application.
Claims
1. A novel method for producing green methanol from biogas, comprising the following steps: S1: The raw material gas is pressurized to 1.3 MPaG by the raw material gas compressor and then preheated to 330℃ through the primary convection section of the converter; S2: Enters the hydrogenation reactor for olefin saturation to remove olefins and oxygen, and then enters the zinc oxide desulfurization reactor to remove excess hydrogen sulfide gas. S3: The refined raw material gas is mixed with the steam output from the boiler, and then preheated to 600℃ in the secondary convection section of the converter for the first conversion reaction. S4: The preheated gas is transported to the radiant section of the converter for a secondary conversion reaction at 910°C. S5: Methanol synthesis is carried out in an isothermal methanol synthesis tower.
2. The novel method for producing green methanol from biogas according to claim 1, wherein, The primary convection section of the converter is equipped with a nickel-based catalyst, and the secondary convection section of the converter is equipped with a modified nickel-based catalyst.
3. A novel method for producing green methanol from biogas according to claim 2, wherein, Between S4 and S5, S401 is also included: the synthesis gas passes through the conversion gas steam generator and the boiler feedwater preheater in sequence, and then the synthesis gas is cooled to 40°C in the water cooler, and then the liquid water is separated by the water separator.
4. A novel method for producing green methanol from biogas according to claim 3, wherein, Including S402: The syngas output from the water separator is passed through an adsorption tower to remove a portion of the carbon dioxide, and then pressurized to 6MPaG by a syngas compressor. It is then mixed with the purge gas circulated by the purge gas compressor and preheated to 215°C in the tower preheater.
5. A novel method for producing green methanol from biogas according to claim 4, wherein, It also includes S403: entering the methanol separation and washing tower, allowing the top gas phase to be released and circulated, and the methanol at the bottom of the tower to enter the methanol distillation tower for distillation after being buffered by the expansion tank. The distillation tower consists of a pre-distillation tower, a pressurized distillation tower and an atmospheric distillation tower.
6. A novel biogas-to-green methanol apparatus, applicable to the novel biogas-to-green methanol method described in claim 5, wherein, The converter includes a shell, an inner liner, a burner, a convection tube, and a radiant tube. The inner liner is disposed inside the shell, the burner is disposed inside the inner liner, the convection tube is arranged around the outside of the inner liner, and the radiant tube is connected to the convection tube, passes through the inner liner, and is disposed inside the inner liner. The bottom of the inner liner is provided with a convection hole that connects to the outside of the inner liner. The shell is provided with an exhaust port for discharging the high-temperature gas generated by the combustion of the burner. A primary catalyst and a secondary catalyst are respectively disposed inside the convection tube and the radiant tube.
7. A novel biogas-to-green methanol production device according to claim 6, wherein, The convection tube includes a primary convection tube and a secondary convection tube. The primary convection tube is separately disposed on the side wall of the inner liner, and the secondary convection tube is attached to the inner liner. The primary catalyst is disposed in the secondary convection tube. The output end of the primary convection tube is connected to the hydrogenation reactor, the input end of the secondary convection tube is connected to the zinc oxide desulfurization reactor, and the output end of the secondary convection tube is connected to the radiant tube.
8. A novel biogas-to-green methanol production device according to claim 7, wherein, The primary catalyst is rotatably mounted in the secondary convection tube. The primary catalyst is provided with several inclined air passages extending from the center to the rim surface. These inclined air passages are used to drive the primary catalyst to rotate.
9. A novel biogas-to-green methanol apparatus according to claim 8, wherein a plurality of reverse thrust ports are provided in the secondary convection pipe at positions corresponding to the plurality of inclined gas channels of the primary catalyst, the plurality of reverse thrust ports being perpendicular to the flow direction of the gas in the inclined gas channels, and the plurality of reverse thrust ports being used to reverse the gas flow passing through the inclined gas channels.
10. A novel biogas-to-green methanol production device according to claim 9, wherein, The downstream end of the primary catalyst is provided with several ball bearings that rotate with the secondary convection tube.