Methanol production system

Abstract

The invention provides a methanol production system comprising a reverse water gas reaction module having a first in-situ separation reactor configured to perform reverse water gas conversion of carbon dioxide and hydrogen, generate and in-situ separate carbon monoxide and water, a methanol synthesis module connected to the reverse water gas reaction module, and the second in-situ separation module is provided with a second in-situ separation reactor, and the second in-situ separation reactor is configured to generate and separate methanol in situ by utilizing the carbon monoxide generated by the reverse water gas reaction module to react with hydrogen. According to the scheme provided by the invention, a two-step methanol preparation process and the in-situ separation type reactor are organically coupled, so that the conversion of carbon dioxide can be completed under a relatively mild working condition; the problems of low one-way conversion rate, high recycling compression work and the like in methanol preparation through carbon dioxide hydrogenation are solved; the energy consumption for separating water and methanol is saved; the methanol production cost is further reduced, and the reliability and economy of the system are improved.

Description

Technical Field

[0001] The present invention relates to the production and preparation of organic compounds, and particularly to a methanol production system. Background Art

[0002] The development and utilization of fossil energy have strongly promoted the social and economic development. However, the combustion of fossil fuels has already caused unavoidable environmental pollution problems. In recent years, the extreme climate problems caused by global warming have reminded humanity that it is necessary to take actions to alleviate the crisis.

[0003] Energy storage is an unavoidable key issue in the utilization of renewable energy such as wind and solar energy. As a fuel that remains liquid at room temperature, methanol is convenient to store, has low transportation costs, and is highly compatible with the existing industrial system, making it an excellent chemical energy storage carrier. Using renewable electric energy to electrolyze water to produce hydrogen, and then using hydrogen and carbon dioxide as raw materials to produce green methanol. This process not only has the potential to achieve large-scale stable utilization of unstable renewable energy such as wind and photovoltaic power, but also can convert the captured carbon dioxide into high-value chemicals, achieving carbon dioxide emission reduction.

[0004] However, currently, the process for producing methanol by hydrogenating carbon dioxide still has the problem of high energy consumption, which makes green methanol lack sufficient competitiveness in the market. Due to the low equilibrium conversion rate of carbon dioxide, a relatively high recycle ratio needs to be set in traditional green methanol production to fully utilize the raw materials, and the recycle compressor will consume a large amount of high-grade energy. Currently, there is a lack of existing technologies to solve the above problems and achieve low-energy-consumption methanol production. Summary of the Invention

[0005] One object of the present invention is to provide a methanol production system that reduces production energy consumption.

[0006] A further object of the present invention is to increase the single-pass conversion rate of carbon dioxide.

[0007] Another further object of the present invention is to achieve the step-by-step production of water and methanol, reducing the methanol rectification section.

[0008] In particular, the present invention provides a methanol production system, which includes:

[0009] A reverse water-gas shift reaction module, which has a first in-situ separation reactor configured to perform the reverse water-gas shift of carbon dioxide and hydrogen to generate and in-situ separate carbon monoxide and water.

[0010] A methanol synthesis module, connected to the reverse water-gas shift reaction module, which has a second in-situ separation reactor configured to react carbon monoxide generated by the reverse water-gas shift reaction module with hydrogen to generate and in-situ separate methanol.

[0011] Optionally, the first in-situ separation reactor and the second in-situ separation reactor are respectively condensation-type in-situ separation reactors, and each includes:

[0012] A reaction section configured to carry out a reaction to obtain reaction product gas;

[0013] A separation section having a cooling medium pipe and a condensation section provided on the outer peripheral wall of the cooling medium pipe. A cooling medium is passed through the cooling medium pipe to condense and separate the reaction product gas on the condensation section by using the cooling medium;

[0014] A heat-insulating and gas-permeable layer provided between the reaction section and the separation section, allowing the reaction product gas to pass through and reducing the heat loss of the reaction section.

[0015] Optionally, the cooling medium is water, and

[0016] the inlet temperature range of the cooling medium of the first in-situ separation reactor is set to 40°C to 110°C;

[0017] the inlet temperature range of the cooling medium of the second in-situ separation reactor is set to 40°C to 100°C.

[0018] Optionally, the above methanol production system further includes a cooling medium circulation module, which includes:

[0019] A refrigerant connecting pipe connecting the cooling medium outlet of the second in-situ separation reactor to the cooling medium inlet of the first in-situ separation reactor to supply the cooling medium discharged from the second in-situ separation reactor into the first in-situ separation reactor;

[0020] A heat absorption device, whose inlet is connected to the cooling medium outlet of the first in-situ separation reactor, whose outlet is connected to the cooling medium inlet of the second in-situ separation reactor, and is configured to absorb the heat of the cooling medium discharged from the first in-situ separation reactor, thereby recycling the cooling medium.

[0021] Optionally, the heat absorption device is a desorption tower in the carbon capture system, and the desorption tower uses the heat of the cooling medium to desorb the absorbent of the carbon capture system.

[0022] Optionally, the reverse water gas shift reaction module includes:

[0023] A plurality of first compressors arranged in series in sequence, configured to pressurize carbon dioxide;

[0024] At least one cooler, each cooler being provided between adjacent first compressors and configured to cool the carbon dioxide compressed by the upstream first compressor;

[0025] A first mixer configured to mix hydrogen and the carbon dioxide compressed by the plurality of first compressors;

[0026] A heat exchanger is disposed between the first mixer and the first in-situ separation reactor, and is configured to preheat the mixed gas of carbon dioxide and hydrogen after being mixed by the first mixer and supply it to the first in-situ separation reactor;

[0027] The first storage tank is connected to the first in-situ separation reactor and is configured to receive the water separated by the first in-situ separation reactor.

[0028] Optionally, the molar ratio of carbon dioxide and hydrogen in the mixed gas at the raw material gas inlet of the first in-situ separation reactor is configured to be 1:1, the temperature range is configured to be 350 °C to 500 °C, the pressure range is configured to be 10 bar to 70 bar, and the first in-situ separation reactor is filled with an iron-based catalyst inside.

[0029] The carbon monoxide separated by the first in-situ separation reactor is sent to the heating channel of the heat exchanger, so as to preheat the mixed gas of carbon dioxide and hydrogen by using the heat of carbon monoxide.

[0030] Optionally, the methanol synthesis module includes:

[0031] A second compressor is configured to pressurize the carbon monoxide separated by the first in-situ separation reactor;

[0032] A second mixer is configured to mix hydrogen and the carbon monoxide compressed by the second compressor and supply it to the second in-situ separation reactor;

[0033] The second storage tank is connected to the second in-situ separation reactor and is configured to receive the methanol separated by the second in-situ separation reactor.

[0034] Optionally, the molar ratio of carbon monoxide and hydrogen in the mixed gas at the raw material gas inlet of the second in-situ separation reactor is configured to be 1:2, the temperature range is configured to be 220 °C to 280 °C, the pressure range is configured to be 50 bar to 80 bar, and the second in-situ separation reactor is filled with a copper-based catalyst inside.

[0035] The methanol production system of the present invention uses carbon dioxide and hydrogen as raw materials. First, the reverse water-gas shift reaction module converts carbon dioxide into carbon monoxide, and then the methanol synthesis module converts carbon monoxide into methanol, producing methanol through a two-step method. The reverse water-gas shift reaction module and the methanol synthesis module respectively use in-situ separation reactors to separate the reaction products synchronously during the reaction, and the conversion rate of the raw material gas will increase significantly. Under optimal conditions, it can even approach 100%. This follows Le Chatelier's principle. With the continuous separation of the reaction products, the reaction proceeds in the forward direction, thereby increasing the conversion rate. On the other hand, the separation of the reaction products also facilitates the operation of the reaction (especially the reverse water-gas shift reaction) under milder conditions. Therefore, the methanol production system of the present invention has the characteristics of mild reaction conditions and high conversion rate of the raw material gas, which significantly has remarkable technical effects compared with the existing two-step methanol preparation technology, and can greatly simplify the reaction system, improving reliability and economy.

[0036] Furthermore, the methanol production system of the present invention organically combines the in-situ separation reactor with the two-step methanol production process, enabling the reaction to proceed under milder conditions, making the selection of the catalyst more targeted, facilitating the development of the catalyst and the improvement of the system performance, and avoiding the easy deactivation of the copper-based catalyst used for methanol production when encountering water.

[0037] Furthermore, in the methanol production system of the present invention, the first in-situ separation reactor and the second in-situ separation reactor respectively use condensing in-situ separation reactors, which have a relatively simple structure and the cooling medium can be reused. The heat absorbed by the cooling medium in the first in-situ separation reactor and the second in-situ separation reactor can be further utilized, saving energy consumption.

[0038] Even further, in the methanol production system of the present invention, the gas in the reverse water-gas shift reaction module has been compressed to a relatively high pressure before entering the methanol synthesis module and is mixed with hydrogen that has also been pressurized. Compared with the one-step hydrogenation of carbon dioxide to produce methanol, the amount of hydrogen that needs to be pressurized in the whole system is reduced by 33%, thereby reducing the input energy required by the compressor and reducing the number and cost of the compressors.

[0039] Based on the following detailed description of the specific embodiments of the present invention in conjunction with the drawings, those skilled in the art will become more clear about the above and other purposes, advantages and features of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Some specific embodiments of the present invention will be described in detail hereinafter with reference to the drawings in an exemplary but not restrictive manner. The same reference numerals in the drawings denote the same or similar components or parts. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings:

[0041] Figure 1Schematic block diagram of a methanol production system according to an embodiment of the present invention;

[0042] Figure 2 Structural schematic diagram of a methanol production system according to an embodiment of the present invention;

[0043] Figure 3 Schematic block diagram of a methanol production system according to another embodiment of the present invention;

[0044] Figure 4 Structural schematic diagram of a methanol production system according to another embodiment of the present invention; and

[0045] Figure 5 Structural schematic diagram of an in-situ separation reactor used in a methanol production system according to an embodiment of the present invention. Detailed implementation manners

[0046] Figure 1 Schematic block diagram of a methanol production system according to an embodiment of the present invention, and Figure 2 Structural schematic diagram of a methanol production system according to an embodiment of the present invention. The methanol production system of this embodiment generally may include: a reverse water-gas shift reaction module 100 and a methanol synthesis module 200. The reverse water-gas shift reaction module 100 and the methanol synthesis module 200 are connected in series. Among them, the reverse water-gas shift reaction module 100 completes the reverse water-gas shift reaction of carbon dioxide and hydrogen to produce carbon monoxide; and the methanol synthesis module 200 uses the carbon monoxide produced by the reverse water-gas shift reaction module 100 to carry out a hydrogenation reaction with hydrogen to generate methanol. Thus, the methanol production system of this embodiment uses carbon dioxide and hydrogen as raw materials to produce methanol by a two-step method. Since the carbon monoxide leaving the reverse water-gas shift reaction module 100 has been compressed to a relatively high pressure before entering the methanol synthesis module 200 to be mixed with the equally pressurized hydrogen, overall, compared with the process of directly hydrogenating carbon dioxide to produce methanol by a one-step method, the amount of hydrogen that needs to be pressurized in the whole system is reduced by 33%, thereby reducing the input energy required by the compressor and reducing the number and cost of the compressors.

[0047] The reverse water-gas shift reaction module 100 and the methanol synthesis module 200 are respectively provided with an in-situ separation reactor. Among them, the reverse water-gas shift reaction module 100 has a first in-situ separation reactor 151, and the methanol synthesis module 200 has a second in-situ separation reactor 251. The first in-situ separation reactor 151 is configured to carry out the reverse water-gas shift of carbon dioxide and hydrogen to generate and in-situ separate carbon monoxide and water, and its reaction is mainly The second in-situ separation reactor 251 is configured to react the carbon monoxide produced by the reverse water-gas shift reaction module 100 with hydrogen to generate and in-situ separate methanol, and its reaction is mainly

[0048] Both the first in-situ separation reactor 151 and the second in-situ separation reactor 251 can use a condensing reactor. In the traditional preparation process, the product is separated and purified after the reaction is completed. While in the in-situ separation reactor, the product is separated during the reaction, thereby improving the reaction kinetics and maintaining a high yield. Through the test of the actual product applying this embodiment, the application of the in-situ separation reactor can significantly increase the conversion rate of the raw material gas, and can even approach 100% under the optimal working conditions. This follows Le Chatelier's principle. With the continuous separation of the reaction product, the reaction proceeds in the forward direction, thus increasing the conversion rate. In addition, the application of the in-situ separation reactor is also beneficial for the reaction, especially the reverse water-gas shift reaction, to operate under milder working conditions. The above characteristics can greatly simplify the reaction system and improve the reliability and economy of the reaction system.

[0049] As an alternative implementation, the first in-situ separation reactor 151 and the second in-situ separation reactor 251 can also use membrane separation reactors respectively, and use semi-permeable membranes to separate the reaction products.

[0050] The reverse water-gas shift reaction module 100 can also include: a plurality of first compressors 101, at least one cooler 111, a first mixer 121, a heat exchanger 131, a heater 141, a first in-situ separation reactor 151, and a first storage tank 161.

[0051] The plurality of first compressors 101 are arranged in series in sequence and are configured to pressurize carbon dioxide. Each cooler 111 is arranged between adjacent first compressors 101 and is configured to cool the carbon dioxide compressed by the upstream first compressor 101. The first compressor 101 and the cooler 111 together form a multi-stage compression intercooling structure. The use of a plurality of first compressors 101 can gradually increase the pressure of the raw material gas and pressurize the raw material gas to the pressure range required for the reaction of the first in-situ separation reactor 151. The compressed raw material gas may be overheated and is not conducive to further compression by the downstream compressor. Therefore, the cooler 111 is used to cool the compressed overheated gas.

[0052] Hydrogen can be prepared by renewable energy using green technology. For example, it can be prepared by electrolyzing renewable energy for power generation. The pressure of hydrogen is equivalent to the pressure of compressed carbon dioxide. In some embodiments, the self-pressure of hydrogen or the pressure after compression can be equivalent to the pressure of compressed carbon dioxide.

[0053] The first mixer 121 is configured to mix hydrogen and the carbon dioxide compressed by the plurality of first compressors 101, thereby obtaining a mixture of carbon dioxide and hydrogen as the raw material gas for the first in-situ separation reactor 151. The ratio of the raw material gas can be: the molar ratio of carbon dioxide to hydrogen is 1:1.

[0054] A heat exchanger 131 is disposed between the first mixer 121 and the first in-situ separation reactor 151, and is configured to preheat the carbon dioxide and hydrogen gas mixture mixed by the first mixer 121 and supply it to the first in-situ separation reactor 151. In some embodiments, the heat exchanger 131 may use the produced carbon monoxide separated by the first in-situ separation reactor 151 as a heat source, so as to make full use of heat and reduce energy consumption. That is to say, the carbon monoxide separated by the first in-situ separation reactor 151 is sent into the heating channel of the heat exchanger 131, and the heat of the carbon monoxide is used to preheat the carbon dioxide and hydrogen gas mixture. Thus, part of the heat source for heating the raw material gas comes from the outlet gas of the reverse water gas shift reaction module 100.

[0055] The heater 141 reheats the gas mixture preheated by the heat exchanger 131 to raise the temperature of the gas mixture to the reaction required temperature. In some embodiments, the temperature range is configured to be 350 °C to 500 °C.

[0056] The first storage tank 161 is connected to the first in-situ separation reactor 151 and is configured to receive the water separated by the first in-situ separation reactor 151. After testing, the separation rate of water in the first in-situ separation reactor 151 reaches more than 90%, and particularly preferably can reach more than 99%, achieving a relatively high carbon dioxide conversion rate.

[0057] The reaction conditions of the reverse water gas shift reaction module 100 are significantly milder. In some embodiments, the molar ratio of carbon dioxide and hydrogen in the gas mixture at the raw material gas inlet of the first in-situ separation reactor 151 is configured to be 1:1, the temperature range is configured to be 350 °C to 500 °C, the pressure range is configured to be 10 bar to 70 bar, and the first in-situ separation reactor 151 is filled with an iron-based catalyst inside. That is, the raw material gas is pressurized and heated by auxiliary equipment to the reaction conditions and then enters the first in-situ separation reactor 151, and the temperature is any value between 350 °C and 500 °C, for example, it can be set to: 350 °C, 400 °C, 450 °C, 500 °C, etc.; the pressure is any value between 10 bar and 70 bar, for example, it can be set to 10 bar, 20 bar, 30 bar, 40 bar, 50 bar, 60 bar, 70 bar. Preferably, the pressure can be set to 30 bar. Although the increase in pressure does not directly enhance the reverse water gas shift reaction degree, it is more conducive to the in-situ separation of products. The reason is that the partial pressure of the products increases, thereby increasing the gas separation rate. In addition, the reaction pressure matches the operating pressure of the electrolytic water hydrogen production process. On the one hand, there is no need for further pressurization, and on the other hand, there is no need for pressure relief, avoiding pressure loss.

[0058] The methanol synthesis module 200 may include: a second compressor 201, a second mixer 221, and a second storage tank 261. The second compressor 201 is configured to re-pressurize the carbon monoxide separated by the first in-situ separation reactor 151 so that the pressure of the carbon monoxide reaches the pressure range required for the reaction of the second in-situ separation reactor 251. The pressure required for the reaction of the second in-situ separation reactor 251 is greater than the pressure required for the reaction of the first in-situ separation reactor 151. The hydrogen gas introduced into the methanol synthesis module 200 can also be pressurized by a third compressor 202.

[0059] Before the gas from the reverse water-gas shift reaction module 100 enters the methanol synthesis module 200, it has been compressed to a relatively high pressure and mixed with the similarly pressurized hydrogen gas. Compared with the one-step hydrogenation of carbon dioxide to produce methanol, the amount of hydrogen gas that needs to be pressurized in the whole system is reduced by 33%, thereby reducing the compressor and its required input energy, and reducing the number and cost of compressors.

[0060] The second mixer 221 is configured to mix hydrogen gas and the carbon monoxide compressed by the second compressor 201 and supply it to the second in-situ separation reactor 251. The second mixer 221 mixes to obtain a mixed gas of carbon monoxide and hydrogen gas, which serves as the raw material gas for the second in-situ separation reactor 251. The ratio of the raw material gas can be: the molar ratio of carbon dioxide to hydrogen gas is 1:2. Thus, the volume content of hydrogen gas in the gas entering the methanol synthesis module 200 is 66%.

[0061] The second storage tank 261 is connected to the second in-situ separation reactor 251 and is configured to receive the methanol separated by the second in-situ separation reactor 251.

[0062] The reaction conditions of the second in-situ separation reactor 251 are also relatively mild. In some embodiments, the molar ratio of carbon monoxide and hydrogen gas in the mixed gas at the raw material gas inlet of the second in-situ separation reactor 251 is configured to be 1:2, the temperature range is configured to be 220°C to 280°C (the reaction temperature is lower than the reaction temperature of the first in-situ separation reactor 151), and the pressure range is configured to be 50 bar to 80 bar (the reaction pressure is higher than the reaction pressure of the first in-situ separation reactor 151). That is, the raw material gas of the second in-situ separation reactor 251 is secondarily pressurized to the corresponding reaction conditions, and the temperature is any value from 220°C to 280°C, for example, it can be set to: 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, etc.; the pressure is any value from 50 bar to 80 bar, for example, it can be set to 50 bar, 60 bar, 70 bar, 80 bar.

[0063] Since the water in the first in-situ separation reactor 151 has been separated, the problem that the copper-based catalyst for methanol production is easily deactivated by water is avoided. In this way, the first in-situ separation reactor 151 and the second in-situ separation reactor 251 can select appropriate catalysts according to the reaction requirements to improve the reaction efficiency. The second in-situ separation reactor 251 can achieve a methanol separation rate of more than 90%, and particularly preferably more than 99%. Therefore, a high carbon monoxide conversion rate and a high methanol selectivity are achieved.

[0064] The first in-situ separation reactor 151 and the second in-situ separation reactor 251 can be condensation-type in-situ separation reactors respectively. The cooling medium can be water, and the inlet temperature range of the cooling medium of the first in-situ separation reactor 151 is set to 40°C to 110°C; the inlet temperature range of the cooling medium of the second in-situ separation reactor 251 is set to 40°C to 100°C. Through experiments, the results show that the above cooling medium temperature can create a high separation ratio and a condensation separation rate, thereby achieving a high product conversion rate. In some embodiments, the inlet temperature of the cooling medium of the second in-situ separation reactor 251 can be set lower.

[0065] A specific reaction process of the methanol production system of the above embodiments may include:

[0066] The carbon dioxide feed gas is pressurized to 30 bar through multi-stage compression and intermediate cooling (30 bar is the preferred value, and the pressure for specific applications can be selected within the range of 10 bar to 70 bar). The first mixer 121 adiabatically mixes the compressed carbon dioxide with the hydrogen from the electrolyzed water system. The pressure of this hydrogen is the same as the compression pressure of the carbon dioxide, for example, both are 30 bar. The molar ratio of carbon dioxide to hydrogen in the mixed gas is 1:1. The mixed gas is preliminarily heated in the heat exchanger 131, and the heat source is the high-temperature gas from the outlet of the first in-situ separation reactor 151; the preheated mixer is heated to the reaction temperature of 400°C (400°C is the preferred value, and the temperature for specific applications can be selected within the range of 350°C to 500°C).

[0067] A mixed gas of carbon dioxide and hydrogen at 30 bar and 400 °C enters the first in-situ separation reactor 151 for the reverse water-gas shift reaction. The first in-situ separation reactor 151 is configured as a condensing in-situ separation reactor. The reaction section and the separation section of the first in-situ separation reactor 151 are separated by a total heat-insulating and gas-permeable layer. The reaction section is filled with an iron-based catalyst, and the reaction gas (reaction products and unreacted reactants) in the reaction section can diffuse through the porous heat-insulating and gas-permeable layer to the separation section. The separation section is in contact with a cooling medium and is provided with a condensation section, which can achieve the condensation separation of the reaction gas and the diversion of the liquid. The cooling medium can condense gaseous water, that is, realize the separation of product water from the reaction system, so as to achieve reaction and separation at the same time and improve the reaction conversion rate.

[0068] The cooling medium in the first in-situ separation reactor 151 is atmospheric pressure water or medium pressure water, and the inlet temperature is 70 °C (70 °C is the preferred value, and the specific application temperature can be selected within the range of 40 °C to 110 °C), and the flow direction is opposite to the flow direction of the reaction gas. When the cooling medium is atmospheric pressure water with an inlet temperature of 70 °C, the carbon dioxide conversion rate can reach a very high level. Since the reverse water-gas shift reaction is an endothermic reaction and there is heat conduction between the reaction section and the separation section, in order to maintain the relative stability of the reaction temperature, an additional heating device is arranged in the reaction section to heat the reaction gas. The heating device can use medium pressure water as the heating medium or an electric heater. The energy grade of the medium pressure water as the heating medium is lower than that of electricity, and using water as the heating medium is more conducive to heat integration at the system level. With the configuration of the heating medium, the reactor outlet temperature reaches 350 °C. The reaction area of the reactor needs to maintain a relatively high temperature because the reverse water-gas shift reaction is mainly limited by kinetic factors under low-temperature conditions.

[0069] There are two streams of materials at the outlet of the first in-situ separation reactor 151. One is the liquid component separated by condensation, mainly water, which flows out along the flow channel of the separation section and is collected by the first storage tank 161. The other is the gas component, mainly carbon monoxide, which flows out along the reaction section.

[0070] The carbon monoxide flowing out of the reaction section enters the heat exchanger 131 to preheat the carbon dioxide hydrogen mixed gas, realizing partial heat recovery and improving the energy utilization efficiency of the system. On the other hand, when the materials flowing out of the reverse water-gas shift reaction module 100 enter the methanol synthesis module 200, they need to be pressurized. The reduction of the gas temperature can not only save the energy consumed by compression, but also reduce the requirements for the materials and manufacturing of the gas compressor.

[0071] The gas discharged from the reverse water-gas shift reaction module 100 enters the methanol synthesis module 200. The gas discharged from the reverse water-gas shift reaction module 100 is compressed to 70 bar by the second compressor 201 (70 bar is the preferred value, and the pressure for specific applications can be selected within the range of 50 bar to 80 bar). Subsequently, it is adiabatically mixed with hydrogen from the electrolyzed water system in the second mixed gas. In this section, hydrogen also needs to go through an additional compression process and is compressed to 70 bar by the third compressor 202 in the compressor 15 (70 bar is the preferred value, and the specific application pressure is the same as the compression pressure of carbon monoxide). The molar ratio of carbon monoxide to hydrogen in the mixed gas is about 1:2, and the temperature can be any value between 230°C and 280°C. When the temperature is not within this range, a necessary heat exchanger needs to be added to cool / heat the mixed gas.

[0072] The mixed gas of carbon monoxide and hydrogen enters the second in-situ separation reactor 251 and is converted into methanol. The structure and principle of the second in-situ separation reactor 251 are the same as those of the first in-situ separation reactor 151.

[0073] In the methanol synthesis module 200, the cooling medium condenses the gaseous methanol, that is, the separation of the product methanol from the reaction system is achieved. The cooling medium in the second in-situ separation reactor 251 is atmospheric pressure water with an inlet temperature of 70°C, and the flow direction is opposite to that of the reaction gas. Setting the cooling medium as atmospheric pressure water with an inlet temperature of 70°C can improve the conversion rate of carbon monoxide. The reaction section of the second in-situ separation reactor 251 is filled with a copper-based catalyst. Since water has been separated in advance, the problem that the copper-based catalyst is easily deactivated when encountering water is solved.

[0074] There are two streams of materials at the outlet of the reactor in the methanol synthesis module 200. One is the liquid component separated by condensation, mainly methanol, which flows out along the flow channel of the separation section and is collected by the second storage tank 261. The other is the gas component, mainly a small amount of unreacted carbon monoxide and hydrogen, which is collected by the third storage tank 262. This part of the gas can be supplied to a gas turbine for power generation or directly burned to supply the energy-consuming equipment inside the system.

[0075] Figure 3 is a schematic block diagram of a methanol production system according to another embodiment of the present invention; Figure 4 is a schematic structural diagram of a methanol production system according to another embodiment of the present invention.

[0076] In this embodiment, the methanol production system is further provided with a cooling medium circulation module 300. The cooling medium circulation module 300 may include: a refrigerant connection pipe 310 and a heat absorption device 320.

[0077] The refrigerant connecting pipe 310 connects the cooling medium outlet of the second in-situ separation reactor 251 to the cooling medium inlet of the first in-situ separation reactor 151, so as to supply the cooling medium discharged from the second in-situ separation reactor 251 to the first in-situ separation reactor 151. That is, the cooling medium that has completed its application in the second in-situ separation reactor 251 is further supplied for use in the first in-situ separation reactor 151.

[0078] The inlet of the heat absorption device 320 is connected to the cooling medium outlet of the first in-situ separation reactor 151, and the outlet of the heat absorption device 320 is connected to the cooling medium inlet of the second in-situ separation reactor 251, and is configured to absorb the heat of the cooling medium discharged from the first in-situ separation reactor 151, so as to recycle the cooling medium. The heat absorption device 320 can be a desorption tower in the carbon capture system, and the desorption tower uses the heat of the cooling medium to desorb the absorbent of the carbon capture system. The carbon capture system can also capture carbon dioxide, and the obtained carbon dioxide is further used as the raw material gas of the reverse water gas shift reaction module 100, achieving the purpose of emission reduction.

[0079] The two-step carbon dioxide hydrogenation to methanol in the methanol production system is organically coupled with the carbon dioxide capture system. The cooling medium of the first in-situ separation reactor 151 can be supplied to the heat unit for carbon capture (such as a desorption tower) after being heated by the reaction gas in the reaction area. The desorption tower is desorbed under the action of heat energy to release the carbon dioxide absorbed by the absorbent, thereby realizing the cascade utilization of energy and improving the overall energy utilization efficiency of the system.

[0080] The 40°C medium-pressure cooling water is first preliminarily heated by passing through the second in-situ separation reactor 251 in the methanol synthesis module 200, and then enters the first in-situ separation reactor 151 in the reverse water gas shift reaction module 100 to be heated again. The outlet temperature of the first in-situ separation reactor 151 is 110 to 130°C, and finally enters the desorption tower 17 in the carbon capture system and is cooled and flows back to the second in-situ separation reactor 251 of the methanol synthesis module 200, thus forming a closed loop of the cooling medium. This not only facilitates the recovery of heat energy, but also saves the water consumption of the system and further reduces costs.

[0081] Figure 5 It is a schematic structural diagram of an in-situ separation reactor used in a methanol production system according to an embodiment of the present invention. The first in-situ separation reactor 151 and the second in-situ separation reactor 251 are respectively condensing in-situ separation reactors, and the condensing in-situ separation reactor may include: a reaction part 410, a separation part 420, and a heat insulation and air permeable layer 430.

[0082] The reaction section 410 is configured to carry out a reaction to obtain a reaction product gas; the separation section 420 has a cooling medium pipe 421 and a condensation section 422 provided on the outer peripheral wall of the cooling medium pipe 421. A cooling medium flows through the cooling medium pipe 421 to condense and separate the reaction product gas on the condensation section 422 by means of the cooling medium. The heat-insulating and gas-permeable layer 430 is provided between the reaction section 410 and the separation section 420, allowing the reaction product gas to pass through and reducing the heat loss of the reaction section 410.

[0083] The inlet of the reaction section 410 is for inputting a raw material gas (for example, a mixture of carbon dioxide and hydrogen, or a mixture of carbon monoxide and hydrogen), and is filled with a catalyst inside. The raw material gas reacts inside the reaction section 410. The separation section 420 is arranged in parallel with the reaction section 410 and receives the gas generated and diffused from the reaction section 410. The separation section 420 separates the reaction products by means of condensation and fractionation. A cooling medium (water) flows through the inside of the cooling medium pipe 421 of the separation section 420.

[0084] The heat-insulating and gas-permeable layer 430 is configured to allow the gas flow to diffuse through and condense on the surface of the separation section 420, and increase the convective and conductive thermal resistances of heat transfer from the reaction section 410 to the separation section, thereby reducing the heat loss of the reactants. That is, the heat-insulating and gas-permeable layer 430 is provided on the gas flow path from the reaction section 410 to the separation section 420. On the one hand, the heat-insulating and gas-permeable layer 430 can allow the gas flow to reach the separation section 420 smoothly for condensation and separation in the separation section 420; on the other hand, the heat-insulating and gas-permeable layer 430 also has certain heat-insulating properties, which can form a large thermal resistance between the reaction section 410 and the separation section 420, reducing the heat transfer efficiency from the reaction section 410 to the separation section 420 and preventing the system temperature from being too low. Since the raw material gas can only reach the separation section 420 in a diffusive form and cannot flow in a convective form due to the blockage of the heat-insulating and gas-permeable layer 430, the thermal conductivity of the gas is relatively low, so the raw material gas is little affected by heat dissipation and can continue to react while maintaining its temperature.

[0085] The reaction section 410 is a cylindrical reaction section, and a channel is provided in the middle of the cylindrical reaction section 410. The separation section 420 is located in this channel, and the heat-insulating and gas-permeable layer 430 is provided between the inner peripheral wall of the reaction section 410 and the separation section 420 to achieve heat insulation. The heat-insulating and gas-permeable layer 430 can be made of heat-insulating and gas-permeable materials such as wire mesh, rock wool, and glass wool, and is provided with micropores communicating in its thickness direction.

[0086] The condensation section 422 can be arranged as a spiral groove or other flow guiding structures wound around the cooling medium pipe 421 to improve the condensation efficiency and guide the condensed products to be better exported.

[0087] Through the above description, the methanol production system of this embodiment breaks through the thermodynamic equilibrium limit of carbon dioxide hydrogenation to methanol by adopting an in-situ separation reactor, improves the single-pass conversion rate of raw materials, and solves the problem of high energy consumption of high-pressure recycle gas in traditional processes; through the organic coupling of the two-step methanol production process and the in-situ separation reactor, the problems of high temperature and high energy consumption in the reverse water-gas shift reaction in traditional processes are effectively solved, enabling the reaction to achieve a relatively high carbon dioxide conversion rate under relatively mild operating conditions. Through the organic coupling of the two-step methanol production process and the in-situ separation reactor, the step-by-step separation of water and methanol is realized, that is, water is separated in the in-situ separation reactor in the reverse water-gas reaction module 100, and then methanol is separated in the methanol synthesis module 200, thereby reducing the methanol rectification section and saving the energy consumption of separating water and methanol. The reaction system based on the condensing in-situ separation reactor can be well integrated with the carbon capture system in terms of heat, thereby further reducing the cost of green methanol production.

[0088] At this point, those skilled in the art should recognize that although multiple exemplary embodiments of the present invention have been shown and described in detail herein, many other variations or modifications that conform to the principles of the present invention can still be directly determined or derived from the content disclosed in the present invention without departing from the spirit and scope of the present invention. Therefore, the scope of the present invention should be understood and determined to cover all these other variations or modifications.

Claims

1. A methanol production system, characterized in that Comprising: A reverse water gas shift reaction module having a first in-situ separation reactor configured to perform a reverse water gas shift of carbon dioxide and hydrogen to produce and in-situ separate carbon monoxide and water. A methanol synthesis module connected to the reverse water gas shift reaction module and having a second in-situ separation reactor configured to react carbon monoxide and hydrogen generated by the reverse water gas shift reaction module to produce and in-situ separate methanol.

2. The methanol production system according to claim 1, wherein, The first in-situ separation reactor and the second in-situ separation reactor are respectively condensing in-situ separation reactors and include: A reaction section configured to perform a reaction to obtain a reaction product gas. A separation section having a cooling medium pipe and a condensing section provided on the outer peripheral wall of the cooling medium pipe, wherein a cooling medium is passed through the cooling medium pipe to condense and separate the reaction product gas on the condensing section by using the cooling medium. A heat insulation and gas permeable layer provided between the reaction section and the separation section to allow the reaction product gas to pass through and reduce heat loss of the reaction section.

3. The methanol production system according to claim 2, wherein The cooling medium is water, and The inlet temperature range of the cooling medium of the first in-situ separation reactor is set to 40°C to 110°C; The inlet temperature range of the cooling medium of the second in-situ separation reactor is set to 40°C to 100°C.

4. The methanol production system according to claim 3, wherein It further includes a cooling medium circulation module, and the cooling medium circulation module includes: A refrigerant connection pipe connecting the cooling medium outlet of the second in-situ separation reactor to the cooling medium inlet of the first in-situ separation reactor to supply the cooling medium discharged from the second in-situ separation reactor to the first in-situ separation reactor. A heat absorption device having an inlet connected to the cooling medium outlet of the first in-situ separation reactor, an outlet connected to the cooling medium inlet of the second in-situ separation reactor, and configured to absorb the heat of the cooling medium discharged from the first in-situ separation reactor, thereby recycling the cooling medium.

5. The methanol production system according to claim 4, wherein The heat absorption device is a desorption tower in a carbon capture system, and the desorption tower uses the heat of the cooling medium to desorb the absorbent of the carbon capture system.

6. The methanol production system according to claim 1, characterized in that, The reverse water gas shift reaction module includes: A plurality of first compressors arranged in series in sequence and configured to pressurize carbon dioxide. At least one cooler, each cooler being provided between adjacent first compressors and configured to cool the carbon dioxide compressed by the upstream first compressor. A first mixer configured to mix hydrogen and carbon dioxide compressed by the plurality of first compressors. A heat exchanger provided between the first mixer and the first in-situ separation reactor and configured to preheat the carbon dioxide and hydrogen mixture gas mixed by the first mixer and supply it to the first in-situ separation reactor. A first storage tank connected to the first in-situ separation reactor and configured to receive the water separated by the first in-situ separation reactor.

7. The methanol production system according to claim 6, wherein The molar ratio of carbon dioxide to hydrogen in the mixed gas at the raw material gas inlet of the first in-situ separation reactor is configured to be 1:1, the temperature range is configured to be 350°C to 500°C, the pressure range is configured to be 10 bar to 70 bar, and the first in-situ separation reactor is filled with an iron-based catalyst inside.

8. The methanol production system according to claim 6, wherein The carbon monoxide separated by the first in-situ separation reactor is sent to the heating channel of the heat exchanger, so as to preheat the carbon dioxide and hydrogen mixed gas by using the heat of the carbon monoxide.

9. The methanol production system according to claim 1, characterized in that The methanol synthesis module includes: A second compressor configured to pressurize the carbon monoxide separated by the first in-situ separation reactor; A second mixer configured to mix hydrogen and the carbon monoxide compressed by the second compressor and supply it to the second in-situ separation reactor; A second storage tank connected to the second in-situ separation reactor and configured to receive the methanol separated by the second in-situ separation reactor.

10. The methanol production system according to claim 9, wherein The molar ratio of carbon monoxide to hydrogen in the mixed gas at the raw material gas inlet of the second in-situ separation reactor is configured to be 1:2, the temperature range is configured to be 220°C to 280°C, the pressure range is configured to be 50 bar to 80 bar, and the second in-situ separation reactor is filled with a copper-based catalyst inside.

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