Methanol synthesis reactor, system and method

Abstract

The invention provides a methanol synthesis reactor, system and method, and belongs to the technical field of chemical equipment. The methanol synthesis reactor comprises a shell, the upper part of the shell is provided with a raw material inlet for receiving raw material gas, and the lower part of the shell is provided with a product outlet for discharging mixed products including methanol; each section of reaction unit comprises an upper partition plate and a lower partition plate which are arranged in the shell at an interval; the plurality of reaction tube nests are connected between the upper partition plate and the lower partition plate, and a heat exchange shell pass is formed outside the reaction tube nests and in a cavity among the upper partition plate, the lower partition plate and the shell; the heat exchange medium inlet and the heat exchange medium outlet are formed in the shell, and the heat exchange shell side communicates with at least one temperature control device through the heat exchange medium inlet and the heat exchange medium outlet; and the heat exchange assembly is mounted around the reaction tube nest, and a flow guide channel is arranged between the heat exchange assembly and the reaction tube nest.

Description

Technical Field

[0001] This application relates to the field of chemical equipment technology, and more specifically, to a methanol synthesis reactor, system, and method. Background Technology

[0002] Traditional methanol synthesis processes typically involve gasifying coal or natural gas to obtain feed gas. This feed gas primarily consists of carbon monoxide, carbon dioxide, and hydrogen, with a hydrogen-to-carbon ratio of 2. The feed gas enters the methanol synthesis reaction system, where it reacts under the action of a catalyst to produce crude methanol. This crude methanol then proceeds to a downstream methanol refining unit to obtain high-purity methanol. In related technologies, the methanol synthesis reactor can be a tubular reactor. The reaction tubes can be filled with catalyst. As the feed gas passes through the catalyst bed within the reaction tubes, the methanol synthesis reaction occurs. The reaction temperature is controlled by heat exchange between the reaction tubes and the external heat exchange medium. The mixed products, including feed gas, byproduct gas, and methanol, are discharged from the bottom of the reactor.

[0003] The production process of green methanol is largely similar to that of traditional methanol production. The key difference lies in the fact that, to ensure the green properties of green methanol, the feedstock gas must originate from renewable energy sources or other resources. One source is biomass, such as agricultural and forestry waste straw and other carbon-containing raw materials. This carbon-containing material is gasified in a gasifier to produce syngas, primarily composed of carbon monoxide, carbon dioxide, and hydrogen. However, this syngas has a high carbon monoxide and carbon dioxide content and a low hydrogen content, failing to meet the hydrogen-to-carbon ratio requirement of 2 for methanol synthesis. Therefore, additional hydrogen needs to be added. To maintain the green properties of green methanol, the coupled hydrogen must originate from renewable energy sources. Currently, the main method for producing hydrogen from renewable energy sources is through water electrolysis generated from wind and solar power.

[0004] In the process of realizing this application, it was discovered that the synthesis of green methanol suffers from problems such as insufficient utilization of raw material gas and low methanol yield. Summary of the Invention

[0005] In view of this, in order to at least partially solve the aforementioned technical problems, this application provides a methanol synthesis reactor, system, and method.

[0006] According to an embodiment of the first aspect of this application, a methanol synthesis reactor is provided, comprising: a shell, wherein the upper part of the shell is provided with a feed inlet for receiving feed gas and the lower part is provided with a product outlet for discharging a mixture including methanol; and multiple reaction units connected sequentially from top to bottom, each reaction unit comprising: an upper partition and a lower partition spaced apart within the shell; a plurality of reaction tubes connected between the upper partition and the lower partition to receive feed gas from the feed inlet or intermediate products from the previous reaction unit, wherein a cavity outside the reaction tubes, between the upper partition, the lower partition, and the shell forms a heat exchange shell side; a heat exchange medium inlet and a heat exchange medium outlet disposed on the heat exchange shell side, wherein the heat exchange shell side is connected to at least one temperature control device through the heat exchange medium inlet and the heat exchange medium outlet; and a heat exchange assembly installed around the reaction tubes, wherein a flow guide channel is provided between the heat exchange assembly and the reaction tubes.

[0007] According to an embodiment of the second aspect of this application, a methanol synthesis system is provided, comprising: a methanol synthesis unit for reacting a feed gas including carbon monoxide, carbon dioxide, and hydrogen in a methanol synthesis reaction, and discharging a low-temperature mixed product including methanol and the feed gas; a first separation unit for separating the low-temperature mixed product to obtain methanol condensate, hydrogen-rich gas, and hydrogen-lean gas, wherein the hydrogen-rich gas is incorporated into the feed gas; a vortex tube for depressurizing the hydrogen-lean gas to obtain high-temperature purge gas and low-temperature carbon dioxide-rich gas, wherein the low-temperature carbon dioxide-rich gas is incorporated into the feed gas; and a second separation unit comprising a stripping tower for stripping the feed gas dissolved in the methanol condensate using at least a portion of the high-temperature purge gas to obtain a medium-temperature purge gas containing the feed gas and crude methanol.

[0008] According to an embodiment of the third aspect of this application, a methanol synthesis method is provided, comprising: reacting a feed gas including carbon monoxide, carbon dioxide, and hydrogen in a methanol synthesis reaction and discharging a low-temperature mixed product including methanol and the feed gas; separating the low-temperature mixed product to obtain methanol condensate, hydrogen-rich gas, and hydrogen-lean gas, wherein the hydrogen-rich gas is incorporated into the feed gas; depressurizing the hydrogen-lean gas to obtain high-temperature purge gas and low-temperature carbon dioxide-rich gas, wherein the low-temperature carbon dioxide-rich gas is incorporated into the feed gas; and stripping the feed gas dissolved in the methanol condensate using at least a portion of the high-temperature purge gas to obtain a medium-temperature purge gas containing the feed gas and crude methanol.

[0009] According to embodiments of this application, by controlling the temperature control devices connected to each reaction unit separately, the temperature of the heat exchange medium in each reaction unit can be controlled separately, thereby controlling the reaction temperature in the reaction tubes of each reaction unit separately. To more accurately and effectively control the reaction temperature in the reaction tubes of each reaction unit, heat exchange components are further provided to enhance the contact between the heat exchange medium and the reaction tubes, reduce heat transfer resistance, and increase the heat exchange rate. Therefore, the temperature in the reaction tubes of each reaction unit, i.e., the methanol synthesis temperature, can be quickly and accurately controlled, improving the utilization rate of the feed gas and thus increasing the methanol yield. Attached Figure Description

[0010] The above and other objects, features and advantages of this application will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0011] Figure 1 This is a cross-sectional schematic diagram of a methanol synthesis reactor according to an embodiment of this application;

[0012] Figure 2 This is a schematic diagram of a reaction unit according to an embodiment of this application;

[0013] Figure 3A This is a schematic diagram of a heat dissipation assembly according to one embodiment of this application;

[0014] Figure 3B This is a schematic diagram of a heat dissipation assembly and a reactor tube according to one embodiment of this application;

[0015] Figure 3C This is a partial cross-sectional schematic diagram of a reaction unit according to an embodiment of this application;

[0016] Figure 3D This is a top cross-sectional schematic diagram of a reaction unit according to an embodiment of this application;

[0017] Figure 3E This is a partial cross-sectional schematic diagram of a heat dissipation assembly according to another embodiment of this application;

[0018] Figure 4 This is a schematic diagram of a methanol synthesis system according to an embodiment of this application;

[0019] Figure 5 This is a schematic diagram of a methanol synthesis system according to another embodiment of this application;

[0020] Figure 6 A flowchart of a methanol synthesis method according to an embodiment of this application;

[0021] [Explanation of Labels in the Attached Image]

[0022] 100-Methanol Synthesis Unit;

[0023] 110-Methanol Synthesis Reactor;

[0024] 1-Shell; 2-Raw material inlet; 3-Product outlet; 4-Upper partition; 41-Upper partition through hole; 5-Lower partition; 51-Lower partition through hole; 6-Reaction tube; 7-Heat exchange assembly; 71-Fin; 72-Heat exchange tube; 73-Through hole; 8-Heat exchange medium inlet; 9-Heat exchange medium outlet;

[0025] 120 - First heat exchanger;

[0026] 130 - Cooler;

[0027] 140 - Raw material gas compressor;

[0028] 200 - First Separation Unit;

[0029] 210-Gas-Liquid Separator;

[0030] 220-Hydrogen Separator;

[0031] 300-vortex tube;

[0032] 400 - Second Separation Unit;

[0033] 410 - Stripping Tower;

[0034] 420-Water Washing Tower;

[0035] 430 - Second heat exchanger;

[0036] 440 - Exhaust gas compressor. Detailed Implementation

[0037] The embodiments of this application will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of this application. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of this application for ease of explanation. However, it will be apparent that one or more embodiments may be implemented without these specific details. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of this application.

[0038] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The term "comprising" as used herein indicates the presence of features, steps, or operations, but does not exclude the presence or addition of one or more other features.

[0039] When using expressions such as "at least one of A, B, and C," the expression should generally be interpreted in accordance with the meaning commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, and C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.). When using expressions such as "at least one of A, B, or C," the expression should generally be interpreted in accordance with the meaning commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, or C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.).

[0040] In this application, the main components of the raw gas include carbon monoxide, carbon dioxide, and hydrogen. The methanol synthesis reaction mainly includes the addition of hydrogen to carbon monoxide to produce methanol (see reaction formula (1), and the addition of hydrogen to carbon dioxide to produce methanol and water (see reaction formula (2). Both reactions are exothermic, but the exothermic amounts of the two reactions are different. In addition, the reverse water-gas shift reaction is also included (see reaction formula (3)).

[0041] (1)

[0042] (2)

[0043] (3)

[0044] In this application, the hydrogen-to-carbon ratio can refer to the molar ratio of hydrogen to carbon source (carbon monoxide and carbon dioxide) in the feed gas, which can be calculated using formula (4):

[0045] (4)

[0046] In the formula, H2, CO, and CO2 represent the percentage molar amounts of hydrogen, oxidant, and carbon dioxide in the gas, respectively. (Molecular part) This reflects the effective hydrogen content after deducting the hydrogen required to react with carbon dioxide to produce water. The denominator ( ) is the total carbon source.

[0047] In this application, the heat exchange shell side can refer to the channel formed by the space between the tube walls, baffles, and outer shell of the methanol synthesis reactor in the methanol synthesis reactor. During operation of the methanol synthesis reactor, a heat exchange medium can flow within the heat exchange shell side, such as water or other heat-conducting media. It is understood that in the case of a methanol synthesis reactor comprising multiple reaction units, the methanol synthesis reactor can include multiple independent heat exchange shell sides, with the heat exchange medium within each heat exchange shell side not interconnected.

[0048] In this application, "tube pass" can refer to the channel formed within the reaction tubes of a methanol synthesis reactor, between the lower partition of the current reaction unit and the upper partition of the next reaction unit. During operation of the methanol synthesis reactor, the flow within the tube pass can be either the feed gas for the methanol synthesis reaction or the intermediate product from the previous reaction unit. It is understood that a methanol synthesis reactor may include a tube pass, through which multiple reaction units are sequentially connected.

[0049] In the process of developing this application, it was discovered that wind and solar power generation is dependent on both wind and sunlight; without wind and sunlight, power generation is impossible. This results in a fluctuating flow rate of green hydrogen. Since the feedstock gas is formed by mixing green hydrogen with syngas obtained from biomass gasification, its composition and flow rate also fluctuate. Specifically, due to the fluctuation in the flow rate of the coupled green hydrogen, the content of carbon monoxide and carbon dioxide in the feedstock gas must also fluctuate to ensure a hydrogen-to-carbon ratio of 2. For example, if the carbon monoxide content is high, the carbon dioxide content will decrease to maintain a hydrogen-to-carbon ratio of 2, and vice versa. Since the heat release for the production of methanol from carbon monoxide and hydrogen, the production of methanol from carbon dioxide and hydrogen, and the production of water are different (see reaction formulas (1) and (2)), the temperature inside the reaction tube is constantly fluctuating. Moreover, there will be a large temperature difference between different reaction units in the reaction tube. Therefore, the methanol synthesis reactor needs to flexibly adjust the cooling power of the reaction tube to keep the temperature of the reaction tube within a suitable range, so as to avoid the temperature inside the reaction tube being too high, which would lead to catalyst ablation and deactivation, or the temperature inside the reaction tube being too low, which would lead to a decrease in catalyst activity and thus a low methanol yield.

[0050] However, in related technologies, methanol synthesis reactors cannot well adapt to the fluctuations in feed gas during the aforementioned green methanol production process, and cannot quickly and accurately control the cooling power of the reaction tubes, resulting in insufficient utilization of feed gas and low methanol yield.

[0051] This application utilizes heat exchange components installed around the reaction tubes and a flow channel between the heat exchange components and the reaction tubes. This facilitates the flow of the heat exchange medium along the flow channel, enhancing the contact between the heat exchange medium and the reaction tubes, reducing heat transfer resistance, and increasing the heat exchange rate. This allows for rapid and precise temperature control of the reaction tubes within each reaction unit, adapting to fluctuations in feed gas during methanol production, especially in green methanol production, thereby improving methanol yield.

[0052] Specifically, according to one embodiment of this application, a methanol synthesis reactor is provided. Figure 1 This is a cross-sectional schematic diagram of a methanol synthesis reactor according to one embodiment of this application. Figure 1 As shown, the methanol synthesis reactor includes a shell 1 and multiple reaction units connected vertically. The upper part of the shell 1 is provided with a raw material inlet 2 for receiving raw material gas, and the lower part is provided with a product outlet 3 for discharging a mixture including methanol. Each reaction unit includes an upper baffle 4 and a lower baffle 5 spaced apart within the shell, multiple reaction tubes 6, multiple heat exchange components 7, a heat exchange medium inlet 8, and a heat exchange medium outlet 9.

[0053] Multiple reaction tubes 6 are connected between the upper partition 4 and the lower partition 5 to receive feed gas from the feed inlet 2 or intermediate products from the previous reaction unit, causing the feed gas or intermediate products to react and ultimately generate a mixed product. A heat exchange medium inlet 8 and a heat exchange medium outlet 9 are located on the shell 1. The cavity between the reaction tubes 6, the upper partition 4, the lower partition 5, and the shell 1 forms the heat exchange shell side. The heat exchange shell side is connected to at least one temperature control device through the heat exchange medium inlet 8 and the heat exchange medium outlet 9; the temperature control device connected to each heat exchange shell side can be different. A heat exchange assembly 7 is installed around the reaction tubes 6, and a flow guide channel is provided between the heat exchange assembly 7 and the reaction tubes 6.

[0054] According to embodiments of this application, by controlling the temperature control devices connected to each reaction unit separately, the temperature of the heat exchange medium in each reaction unit can be controlled separately, thereby controlling the reaction temperature within the reaction tubes 6 of each reaction unit. To more accurately and effectively control the reaction temperature within the reaction tubes 6 of each reaction unit, a heat exchange component 7 is further provided, and a flow guide channel is provided between the heat exchange component 7 and the reaction tubes 6. This facilitates the flow of the heat exchange medium along the flow guide channel, thereby enhancing the contact between the heat exchange medium and the reaction tubes 6, reducing heat transfer resistance, and increasing the heat exchange rate. Thus, the temperature within the reaction tubes 6 of each reaction unit, i.e., the methanol synthesis temperature, can be quickly and accurately controlled, improving the utilization rate of the feed gas and thus increasing the methanol yield.

[0055] In this application, the shell 1 may include an upper head section, a straight section, and a lower head section. The raw material inlet 2 may be located in the upper head section, the product outlet 3 may be located in the lower head section, and multiple reaction units may be located in the straight section.

[0056] In the methanol synthesis reactor of this application, each reaction tube is filled with a catalyst. This application does not impose any particular restrictions on the morphology and filling method of the catalyst within the reaction tube 6, as long as the purpose of this application can be achieved. For example, the catalyst can be in granular form, such as cylindrical, spherical, or flake-shaped, uniformly filled inside the reaction tube 6 to form a fixed catalyst bed. When the feed gas flows through the catalyst bed from the tube side, a catalytic reaction occurs on the catalyst surface to produce methanol. Thus, the catalyst particles can be tightly packed but remain stationary, and the reaction tube 6 can exchange heat with the external heat exchange medium through its tube wall, achieving temperature control of the reaction and ensuring effective contact between the gas and solid phases and timely removal of reaction heat, which is beneficial for the efficient and stable synthesis reaction. This application does not impose any particular restrictions on the material of the catalyst, as long as the purpose of this application can be achieved. For example, the catalyst can be a copper-based catalyst, a zinc-chromium catalyst, or other novel catalysts. Among them, the copper-based catalyst can use copper oxide as the active component, with zinc oxide and aluminum oxide as the carrier and promoter, respectively, to stabilize the catalyst structure and improve its activity.

[0057] In this application, the heat exchange assembly 7 can be configured such that the heat exchange medium from the heat exchange medium inlet 8 flows relative to the guide channel on the heat exchange assembly 7. Specifically, the guide channel can be a plane, curved surface, groove, or pipe extending in a certain direction, guiding the heat exchange medium to flow in a certain direction to fully cool the reaction tube 6. The heat exchange medium can enter the heat exchange shell side through the heat exchange medium inlet 8 and flow relative to the guide channel on the heat exchange assembly 7. After being heated by the reaction tube 6, the heat exchange medium flows out through the heat exchange medium outlet 9 to achieve the purpose of cooling the reaction tube 6, so that the methanol reaction can continue under a controllable temperature.

[0058] This application does not impose any particular restrictions on the heat exchange medium, as long as it can achieve the purpose of this application. For example, the heat exchange medium can be water, oil, etc. This application does not impose any particular restrictions on the temperature control device, as long as it can achieve the purpose of this application. For example, the temperature control device can be a steam drum, heat exchanger, etc.

[0059] In some embodiments of this application, the heat exchange medium can be water, and the temperature control device can be a steam drum. The steam drum is connected to the heat exchange medium inlet 8 via a downcomer and to the heat exchange medium outlet 9 via a gas-liquid pipe. The water in the steam drum is saturated, and the temperature of the heat exchange medium can be controlled by adjusting the operating pressure within the steam drum, thereby controlling the temperature of the reaction tube 6. For example, if fluctuations in the composition of the feed gas cause an increase in carbon monoxide content and a decrease in carbon dioxide content, enhancing the reaction activity of the feed gas, then the feed gas entering the catalyst in the reaction tube 6 will rapidly release a large amount of heat, leading to excessively high catalyst temperature fluctuations within the reaction tube. This results in the catalyst being at a high temperature, posing a risk of ablation and deactivation. In this case, the operating pressure of the steam drum in this section of the reaction unit can be reduced, thereby reducing the water temperature within the steam drum, increasing the heat transfer temperature difference in the reaction tube 6 within this section of the reaction unit, and thus increasing heat transfer. This reduces the temperature of the reaction tube 6, thereby reducing the catalyst activity within the reaction tube 6, inhibiting the intensity of the methanol synthesis reaction, and ultimately lowering the catalyst temperature, thus protecting the catalyst.

[0060] In some embodiments of this application, the methanol synthesis reactor provided by this application can also be equipped with detection equipment to achieve process parameter monitoring, reaction control, and safety assurance. This application does not impose any particular limitations on the detection equipment; relevant personnel can select according to actual needs. For example, the detection equipment may include temperature detection equipment, pressure detection equipment, flow detection equipment, component analysis equipment, etc. Specifically, the temperature detection equipment can be located in the catalyst bed and heat exchange medium inside the reaction tube 6 to detect the temperature of the catalyst bed and the temperature of the heat exchange medium inside the reaction tube 6. The temperature detection equipment can also be set at the raw material inlet 2 and the product outlet 3 to detect the temperature of the raw material gas and the mixed product. The pressure detection equipment can be used to detect the raw material gas pressure at the raw material inlet 2, the pressure of the mixed product at the product outlet 3, and the pressure of the heat exchange medium, etc. The component analysis equipment can be used to detect the composition and content of each component of the raw material gas at the raw material inlet 2, and the composition and content of each component of the mixed product at the product outlet 3, etc. The temperature of the reaction tube 6 can be quickly and accurately controlled by adjusting the heat exchange medium in the reaction unit based on the temperature of the catalyst bed inside the reaction tube detected by the temperature detection equipment and the composition and content of each component of the raw gas analyzed by the component analysis equipment.

[0061] The following is for reference. Figure 2 , Figures 3A-3E In conjunction with specific embodiments, Figure 1 The methanol synthesis reactor shown will be further explained. Among other things, Figure 2 This is a schematic diagram of a reaction unit according to an embodiment of this application. Figure 3A This is a schematic diagram of a heat dissipation assembly according to one embodiment of this application; Figure 3B This is a schematic diagram of a heat dissipation assembly and a reactor tube according to one embodiment of this application; Figure 3CThis is a partial cross-sectional schematic diagram of a reaction unit according to an embodiment of this application; Figure 3D This is a top cross-sectional schematic diagram of a reaction unit according to an embodiment of this application; Figure 3E This is a partial cross-sectional schematic diagram of a heat dissipation assembly according to another embodiment of this application.

[0062] In some embodiments of this application, such as Figure 1 and Figure 2 As shown, the diameters of the upper partition 4 and the lower partition 5 can be equal to the inner diameter of the shell 1. The upper partition 4 can be provided with an upper partition through hole 41, and the lower partition 5 can be provided with a lower partition through hole 51. The apertures of the upper partition through hole 41 and the lower partition through hole 51 can be equal to the outer diameter of the reaction tube 6. The upper partition 4 and the lower partition 5 can be connected to the inner wall of the shell. The two ends of the reaction tube 6 can be connected to the upper partition through hole 41 and the lower partition through hole 51 respectively, so that the reaction tube 6 can receive the raw material gas from the raw material inlet 2 or the intermediate product from the previous reaction unit. Thus, when the methanol synthesis reactor is working, the raw material gas enters the shell 1 through the raw material inlet 2 and enters the reaction tube 6 through the upper partition through hole 41 on the upper partition 4, where it reacts with the catalyst. The mixed product flows out through the lower partition through hole 51 of the lower partition 5 and enters the next reaction unit, or flows out through the product outlet 3.

[0063] In some embodiments of this application, such as Figure 1 , Figures 3A-3D As shown, the heat exchange assembly may include multiple rows of fins 71 arranged along the outer periphery of the reaction tubes 6. Each row of fins is arranged sequentially along the height direction of the reaction tubes 6, and one end of each fin 71 is connected to one of the reaction tubes 6. The flow channel is formed by the multiple rows of fins. Specifically, the multiple rows of fins 71 arranged along the outer periphery of the reaction tubes can be either continuously wound around the outer periphery of the reaction tubes 6 or spaced apart along the outer periphery of the tubes, thereby ensuring that the heat exchange medium is adequately guided to the outer periphery of the reaction tubes 6. Because the fins 71 are arranged sequentially along the height direction, the multiple rows of fins can form a flow channel arranged periodically along the direction of the reaction tubes 6. Furthermore, the connection of one end of each fin 71 to the reaction tubes 6 facilitates the uniform distribution of the heat exchange medium around the reaction tubes, thereby enabling rapid and precise temperature control of the reaction tubes 6.

[0064] The fins 71 can have regular or irregular shapes, as long as they can form flow channels. For example, the shape of the fins 71 can be straight (such as rectangular, trapezoidal, triangular, etc.), corrugated, sawtooth, louvered, perforated, or irregular (such as circular, elliptical, spiral, biomimetic, etc.).

[0065] In the process of developing this application, it was also discovered that during the operation of the methanol synthesis reactor, the heat exchange medium vaporizes upon heating on the outer surface of the reaction tube 6, forming bubbles. This results in a large number of bubbles adhering to the outer surface of the reaction tube 6, causing insufficient contact between the reaction tube 6 and the heat exchange medium, thus hindering heat dissipation from the reaction tube 6. To reduce bubble adhesion on the outer surface of the reaction tube 6, this application includes, for example... Figure 1 , Figures 3A-3D As shown, the heat exchange assembly 7 may also include multiple heat exchange tubes 72. These multiple heat exchange tubes 72 can be arranged along the outer periphery of one of the reaction tubes 6, and the other end of each fin 71 is connected to one of the heat exchange tubes 72, such that each row of fins 71 is arranged sequentially along the height direction of the heat exchange tubes 72. Thus, bubbles adhering to the outer surface of the reaction tubes 6, during their ascent, encounter the fins 71 and can flow through the guide channel, and after further guidance by the heat exchange tubes 72, finally rise along the heat exchange tubes 72 to the upper end of the heat exchange tubes 72, and are discharged from the methanol synthesis reactor through the heat exchange medium outlet 9. This effectively reduces the adhesion of bubbles to the outer surface of the reaction tubes 6, facilitating rapid and precise control of the temperature of the reaction tubes 6, i.e., the temperature of methanol synthesis. Furthermore, each heat exchange tube 72 may be provided with multiple through holes 73, each through hole being located between two adjacent fins and close to the upper fin, thereby allowing the bubbles attached to the outer surface of the reaction tube 6 to converge and quickly penetrate into the heat exchange tube 72 and mix with the heat exchange medium inside the heat exchange tube, and then be discharged from the methanol synthesis reactor through the heat exchange medium outlet 9.

[0066] In some embodiments of this application, each fin 71 may form a downward-opening groove. Thus, the fin 71 can further form a groove-shaped flow channel from the reaction tube 6 to the heat exchange tube 72, which is more conducive to the flow of the heat exchange medium, especially bubbles.

[0067] In some embodiments of this application, the end of each fin 71 connected to the heat exchange tube 72 is located above the end of the fin connected to the reaction tube, which is beneficial for the bubbles outside the reaction tube 6 to accumulate, grow larger, and leave the reaction tube.

[0068] In some embodiments of this application, such as Figure 1 , Figure 3B , Figure 3C As shown, the heat exchange tube 72 can be spaced apart from the upper baffle 4 and the lower baffle 5, so that the heat exchange medium can enter through the lower end of the heat exchange tube 72 and flow out from the upper end of the heat exchange tube 72. For example, the upper end of the heat exchange tube 72 can be 5-100 mm lower than the lower end of the upper baffle 4, and the lower end of the heat exchange tube 72 can be 5-10 mm higher than the upper end of the lower baffle 5.

[0069] In some embodiments of this application, the methanol synthesis reactor may include two or more reaction units. For example, the methanol synthesis reactor may include two or three reaction units. Each reaction unit may have an independent temperature control device, such as a steam drum. Each steam drum may have a different operating pressure. Since the water in the steam drum is saturated, different operating pressures will correspond to different temperatures. If the composition of the feed gas fluctuates, causing the carbon monoxide content to increase and the carbon dioxide content to decrease, the reactivity of the feed gas will increase. This will result in a rapid and significant release of heat as the feed gas enters the catalyst in the reaction tube 6, causing excessively high catalyst temperature fluctuations in the first reaction unit. This will place the catalyst at a high temperature, posing a risk of ablation and deactivation. At this point, the operating pressure of the steam drum corresponding to the first reaction unit can be reduced, thereby lowering the water temperature inside the steam drum. This increases the heat transfer temperature difference in the reaction tubes 6 within the first reaction unit, increasing heat transfer and lowering the temperature of the reaction tubes 6. Consequently, the catalyst temperature decreases, reducing catalyst activity and inhibiting the intensity of the methanol synthesis reaction. This lowers the catalyst temperature, protecting the catalyst. Unreacted feed gas can then enter the next reaction unit to continue reacting with the catalyst in the reaction tubes 6. Adjustments are made gradually based on the reaction intensity to maintain the catalyst bed in each reaction unit at a suitable operating temperature, controlling the intensity of the methanol synthesis reaction and ensuring the rationality of the overall operating temperature of the methanol synthesis reactor. This guarantees both the synthesis efficiency and the safety of the catalyst. If the carbon dioxide content in the feed gas increases, the opposite operation should be performed: increasing the steam drum pressure corresponding to the first catalyst bed increases the water temperature inside the steam drum, reducing the cooling effect on the catalyst in the first reaction unit. This allows the catalyst to maintain a higher temperature to sustain the energy for the carbon dioxide hydrogenation reaction to produce methanol.

[0070] For example, such as Figure 1 As shown, the methanol synthesis reactor can include three reaction units: a first reaction unit, a second reaction unit, and a third reaction unit. The surfaces of the upper baffle 4 and the lower baffle 5 are perpendicular to the axis of the shell 1, and the reaction tubes 6 are parallel to the axis of the shell 1. Thus, within the methanol synthesis reactor, the upper end cap connects to the interior of the reaction tubes 6 of the first reaction unit, continues to connect to the space enclosed by the lower baffle 5, the upper baffle 4 of the second reaction unit, and the shell 1, and continues to connect to the interior of the reaction tubes 6 of the second reaction unit; and so on, connecting to the interior of the reaction tubes 6 of the third reaction unit, finally connecting to the lower end cap. This pathway constitutes the tube side of the methanol synthesis reactor. The space formed between the outside of the reaction tubes 6 and the upper baffle 4 and lower baffle 5 at both ends of the reaction tubes 6 is called the shell side, meaning the methanol synthesis reactor has three non-connected shell sides.

[0071] It should be noted that two adjacent reaction units can also be separated by a single partition to create two independent heat exchange shell sides. In this case, the lower partition of the current reaction unit is the same as the upper partition of the next reaction unit.

[0072] During operation of the methanol synthesis reactor, each reaction unit corresponds to a separate steam drum. Makeup water from the outside can enter each steam drum individually. Liquid water in the steam drum enters the shell side of the corresponding reaction unit via a downcomer. In the shell side, after absorbing heat from the reaction tubes, some of the water vaporizes, forming a gas-liquid mixture. This mixture returns to the steam drum via a gas-liquid pipe. Gas-liquid separation occurs within the steam drum; the liquid phase can re-enter the downcomer, while the gas phase is discharged after passing through the gas phase outlet valve at the top of the steam drum. The gas phases discharged from multiple steam drums merge to form steam. The opening of the gas phase outlet valve controls the pressure within the steam drum; decreasing the valve opening increases the gas phase discharge pressure drop, thus increasing the steam drum pressure; conversely, increasing the valve opening decreases the gas phase discharge pressure drop, thus decreasing the steam drum pressure. The control of the gas phase outlet valve opening can be based on the temperature inside the corresponding reaction tube 6 of the steam drum. If the temperature inside the reaction tube 6 is too high due to fluctuations in the composition of the raw gas, the corresponding steam drum valve can be opened to reduce the pressure inside the steam drum, thereby lowering the boiling point of water inside the steam drum. Since the steam drum is connected to the shell side and the pressure is equal, the boiling point of water inside the shell side will decrease synchronously. The water on the outer surface of the reaction tube 6 will rapidly vaporize in large quantities. At the same time, the fins 71 and heat exchange tubes 72 will quickly remove water vapor bubbles. Liquid water will continuously and rapidly contact the outer surface of the reaction tube 6. The rapid vaporization of water can quickly reduce the temperature of the reaction tube 6, thereby quickly and effectively controlling the temperature of the reaction tube 6. Conversely, if the temperature of the reaction tube 6 drops rapidly due to fluctuations in the raw material composition, the corresponding steam drum valve can be reduced in opening based on the temperature of the reaction tube 6, increasing the pressure inside the steam drum and thus increasing the boiling point of water inside the steam drum. Since the steam drum is connected to the shell side and the pressure is equal, the boiling point of water inside the shell side will increase synchronously. Water on the outer surface of the reaction tube 6 will not be able to vaporize or will vaporize less. Reduced water vaporization reduces the heat absorption effect on the reaction tube 6, allowing the temperature of the reaction tube 6 to be maintained or increased to maintain the methanol synthesis reaction. If the tube temperature is too low, the methanol synthesis reaction will stop, thus quickly and effectively controlling the temperature of the reaction zone.

[0073] According to an embodiment of the second aspect of this application, a methanol synthesis system is provided. In some embodiments, feed gas from upstream is pressurized by a feed gas compressor and mixed with gas-liquid separated gas from a circulating compressor before entering an inlet / outlet heat exchanger to be preheated to the required temperature. The mixture then enters the methanol synthesis reactor from the top, and the reaction products are discharged from the bottom of the reactor as a mixed product. The mixture mainly contains methanol, water, by-products (such as methane and other hydrocarbons) generated from the reaction, and unreacted feed gas. After being cooled by the feed heat exchanger, the mixture enters the cooler for further cooling, condensing the high-boiling-point substances such as methanol and water in the mixture into a liquid state. Then, it enters the gas-liquid separator for gas-liquid separation. The liquid phase mainly contains water, methanol, and some feed gas dissolved in the liquid phase, which is sent as crude methanol to the downstream refining unit. The unreacted feed gas and some methanol vapor are discharged from the top of the gas-liquid separator and then split into two streams. One stream is pressurized by the circulating gas compressor and mixed with the feed gas outlet of the feed gas compressor, and continues to enter the feed heat exchanger. The other stream is separated by a hydrogen recovery device (such as a membrane separator) into a hydrogen-rich feed gas and a purge gas containing by-products such as methane and ethane generated from the side reaction and some feed gas. The purge gas is discharged outside the boundary, and the hydrogen-rich feed gas is mixed with fresh feed gas and enters the feed gas compressor.

[0074] In the process of realizing this application, it was discovered that the crude methanol product carries away some of the raw material gas, resulting in a waste of raw material gas; and the direct discharge of the off-gas also results in a waste of raw material gas.

[0075] In view of this, this application provides a methanol synthesis system. Figure 4 This is a schematic diagram of a methanol synthesis system according to an embodiment of this application, as shown below. Figure 4 As shown, the methanol synthesis system includes a methanol synthesis unit 100, a first separation unit 200, a vortex tube 300, and a second separation unit 400. The methanol synthesis unit 100 is used to perform a methanol synthesis reaction on a feed gas containing carbon monoxide, carbon dioxide, and hydrogen, and discharges a low-temperature mixed product containing methanol and the feed gas. The first separation unit 200 is used to separate the low-temperature mixed product to obtain methanol condensate, hydrogen-rich gas, and hydrogen-lean gas, wherein the hydrogen-rich gas is incorporated into the feed gas. The vortex tube 300 is used to depressurize the hydrogen-lean gas to obtain high-temperature purge gas and low-temperature carbon dioxide-rich gas, which is incorporated into the feed gas. The second separation unit 400 includes a stripping tower, which is used to strip the feed gas dissolved in the methanol condensate using at least a portion of the high-temperature purge gas to obtain a medium-temperature purge gas containing the feed gas and crude methanol. The methanol synthesis system provided in this application can incorporate hydrogen-rich gas and low-temperature carbon dioxide-rich gas into the feed gas, and use at least part of the high-temperature purge gas to strip the feed gas dissolved in the methanol condensate, thereby improving the utilization rate of the feed gas.

[0076] The following is for reference. Figure 5 In conjunction with specific embodiments Figure 4 The methanol synthesis system shown will be further explained. Specifically, Figure 5 This is a schematic diagram of a methanol synthesis system according to another embodiment of this application.

[0077] In some embodiments of this application, such as Figure 5 As shown, the methanol synthesis unit 100 may include a methanol synthesis reactor 110, a first heat exchanger 120, a cooler 130, and may also include a compressor 140.

[0078] like Figure 5 As shown, during the operation of the methanol synthesis system, the feed gas, including carbon monoxide, carbon dioxide, and hydrogen, first enters the feed gas compressor 140, is pressurized, and then enters the first heat exchanger 120. After further temperature increase, it enters the methanol synthesis reactor 110. The compression of the feed gas by the feed gas compressor 140 facilitates its transport in the pipeline and ensures thorough mixing of its components. Furthermore, it increases the molecular collision frequency of the feed gas, accelerates the reaction rate, and shifts the reaction towards methanol production. Preheating the feed gas before entering the methanol synthesis reactor 110 allows the methanol synthesis reaction to proceed under suitable temperature conditions, further accelerating the reaction rate.

[0079] The raw material gas compressor 140 can be a mechanical device used to compress gas and increase gas pressure. This application does not impose any particular limitation on the raw material gas compressor 140, as long as it can achieve the purpose of this application. For example, the raw material gas compressor 140 can compress gas through mechanical motion, such as the reciprocating motion of a piston or the high-speed rotation of an impeller. Structurally, the raw material gas compressor 140 may include a power system, compression components, a cooling system, etc.

[0080] The first heat exchanger 120 can be a device for achieving heat transfer between two or more fluids at different temperatures. This application does not impose any particular limitation on the first heat exchanger 120, as long as it can achieve the purpose of this application. For example, the first heat exchanger 120 can be a tubular heat exchanger, a plate heat exchanger, a spiral plate heat exchanger, etc.

[0081] The methanol synthesis reactor 110 can perform a methanol synthesis reaction on the feed gas and discharge a high-temperature mixed product including methanol and the feed gas. The high-temperature mixed product may also include by-product gases such as methane and ethane generated from side reactions. The methanol synthesis reactor 110 can be the methanol synthesis reactor provided in any of the above embodiments, or any methanol synthesis reactor available in related technologies.

[0082] The first heat exchanger 120 can exchange heat between the high-temperature mixed product and the raw material gas to obtain a medium-temperature mixed product. The first heat exchanger 120 can also cool the high-temperature mixed product to a medium-temperature mixed product and preheat the raw material gas, thereby achieving efficient energy utilization.

[0083] Cooler 130 can be a heat exchange device used to lower the temperature of a fluid. It lowers the temperature of the hot fluid by transferring heat from the hot fluid to a cooling medium (such as air, water, etc.). This application does not impose any particular limitation on cooler 130, as long as it achieves the purpose of this application. For example, cooler 130 can be an air cooler, a water cooler, an evaporative cooler, etc. Cooler 130 can cool a medium-temperature mixture into a low-temperature mixture for further processing.

[0084] In some embodiments of this application, such as Figure 5 As shown, the first separation unit 200 may include a gas-liquid separator 210 and a hydrogen separator 220.

[0085] The gas-liquid separator 210 can be a device for separating gas and liquid mixtures. It utilizes the differences in physical properties between the gas and liquid, such as density and velocity, and through a specific structure and working principle, separates and collects the gas and liquid components in the mixture, thereby achieving effective separation of the two phases. This application does not impose any particular limitation on the gas-liquid separator 210, as long as it achieves the purpose of this application. For example, the gas-liquid separator 210 can be a gravity-type gas-liquid separator, a centrifugal-type gas-liquid separator, a filtration-type gas-liquid separator, etc.

[0086] During methanol synthesis system operation, gas-liquid separator 210 can separate the low-temperature mixed products into methanol condensate and recycle gas. The methanol condensate may include methanol and feed gas adsorbed and dissolved in the methanol. This feed gas may include one or more of carbon monoxide and carbon dioxide. The recycle gas may include unreacted feed gas, by-product gas, and methanol. The recycle gas can be divided into two streams. At least a portion of the recycle gas can be incorporated into the feed gas. Further, this portion of the recycle gas can be pressurized by a compressor and then incorporated into the feed gas.

[0087] The hydrogen separator 220 can be a device for separating hydrogen from a mixed gas or gas-liquid mixture containing hydrogen. It can utilize the differences in physical or chemical properties between hydrogen and other components, and extract hydrogen from the mixture through specific separation techniques and apparatus. This application does not impose any particular limitation on the hydrogen separator 220, as long as it achieves the purpose of this application. For example, the hydrogen separator 220 can be a pressure swing adsorption hydrogen separator, a membrane separation hydrogen separator, a cryogenic condensation hydrogen separator, etc.

[0088] At least a portion of the recycle gas can enter the hydrogen separator 220, where it is separated into hydrogen-rich gas and hydrogen-lean gas, with the hydrogen content in the hydrogen-lean gas being less than that in the hydrogen-rich gas. The hydrogen-lean gas may include by-product gas and feed gas. The hydrogen-rich gas can be incorporated into the feed gas, while the hydrogen-lean gas enters the vortex tube 300.

[0089] Because carbon dioxide has a high boiling point, depressurizing the lean hydrogen gas within the vortex tube 300 yields high-temperature purge gas and low-temperature carbon dioxide-rich gas. The high-temperature purge gas may include by-product gas and a small amount of feed gas. The low-temperature carbon dioxide-rich gas can enter the second heat exchanger 430 to exchange heat with water from outside, lowering the water temperature. After heating, the low-temperature carbon dioxide-rich gas can become carbon dioxide-rich gas and be incorporated into the feed gas. The water from outside, after cooling, can enter the water scrubbing tower 420.

[0090] According to embodiments of this application, the vortex tube 300 can be a device that utilizes the vortex effect to achieve energy separation. This application does not impose any particular limitation on the vortex tube 300, as long as it achieves the purpose of this application. For example, the vortex tube 300 may include a nozzle, a vortex chamber, a separation orifice plate, a hot-end tube, and a cold-end tube. When gas with a certain pressure enters the vortex chamber through the nozzle, a high-speed rotating vortex is formed. The pressure energy of the gas is converted into kinetic energy, and the gas pressure decreases. Due to the different motion characteristics of the gas molecules, temperature separation occurs in the axial direction of the gas within the vortex tube, producing high-temperature gas at one end and low-temperature gas at the other. For example, when the aforementioned hydrogen-deficient gas enters the vortex chamber through the nozzle, due to the different motion characteristics of the gas molecules, high-temperature purge gas and low-temperature carbon dioxide-rich gas can be obtained.

[0091] In some embodiments of this application, such as Figure 5 As shown, the second separation unit may include a stripping tower 410 and a water washing tower 420.

[0092] The stripping tower 410 can be a chemical device used to separate volatile components from a liquid mixture. This application does not impose any particular limitation on the stripping tower 410, as long as it achieves the purpose of this application. For example, the stripping tower 410 can be a cylindrical tower with multiple layers of trays or packing inside. By introducing steam or other gases as the stripping medium, the volatile components in the liquid mixture are extracted during gas-liquid mass transfer, thereby achieving the separation of the mixture. Exemplarily, the stripping tower 410 can be a plate stripping tower, a packed stripping tower, a spray stripping tower, etc.

[0093] During the operation of the methanol synthesis system, the methanol condensate separated by the gas-liquid separator 210 can enter the stripping tower 410 and come into countercurrent contact with the high-temperature purge gas from the vortex tube 300. The high-temperature purge gas in the stripping tower 410 can strip the raw material gas that has been adsorbed and dissolved in the methanol condensate. Then, the adsorbed and dissolved raw material gas and the high-temperature purge gas are discharged together through the top of the stripping tower 410 as medium-temperature purge gas. The medium-temperature purge gas will inevitably carry some methanol vapor and raw material gas.

[0094] The water scrubbing tower 420 can be a device for gas purification and separation. This application does not impose any particular limitation on the water scrubbing tower 420, as long as it achieves the purpose of this application. For example, the water scrubbing tower 420 can be a cylindrical tower that uses water as an absorbent, dissolving impurities or specific components in the gas into the water through gas-liquid contact, thereby achieving the purpose of gas purification, cooling, or separation. The water scrubbing tower 420 may also be equipped with packing, trays, or nozzles to increase the gas-liquid contact area and contact time, thereby improving mass transfer efficiency. Exemplarily, the water scrubbing tower 420 can be a packed water scrubbing tower, a plate water scrubbing tower, a spray water scrubbing tower, etc.

[0095] The intermediate-temperature purge gas can enter the water washing tower 420 and come into countercurrent contact with the low-temperature water from the second heat exchanger 430. The low-temperature water helps to wash away the methanol in the intermediate-temperature purge gas. The bottom of the water washing tower 420 discharges a separation liquid, which is a mixture of methanol and water. The separation liquid flows into the crude methanol and goes to the downstream process. The intermediate-temperature purge gas at the top of the water washing tower 420, after methanol removal, becomes the separation tail gas. The separation tail gas can include by-product gas and feed gas. The separation tail gas can be compressed by the tail gas compressor 440 and then incorporated into the lean hydrogen gas before re-entering the vortex tube 300. This maximizes the recovery and utilization of carbon dioxide in the purge gas and also maximizes the recovery and utilization of feed gas in the crude methanol product, preventing the feed gas from being carried to the downstream process by the crude methanol, thus avoiding the waste of the effective components of the feed gas. Before entering the stripping tower 410, the high-temperature purge gas can be partially diverted to the outside, mainly discharging the by-product gas, preventing the by-product gas from accumulating in the methanol synthesis system and causing system malfunctions.

[0096] According to an embodiment of the third aspect of this application, a method for synthesizing methanol is provided. Figure 6 A flowchart of a methanol synthesis method according to an embodiment of this application is shown below. Figure 6 As shown, the methanol synthesis method includes steps S610 to S640.

[0097] In step S610, the feed gas, which includes carbon monoxide, carbon dioxide and hydrogen, is subjected to a methanol synthesis reaction, and a low-temperature mixed product, which includes methanol and feed gas, is discharged.

[0098] In step S620, the low-temperature mixed product is separated to obtain methanol condensate, hydrogen-rich gas and hydrogen-lean gas, wherein the hydrogen-rich gas is incorporated into the feed gas.

[0099] In step S630, the hydrogen-deficient gas is subjected to eddy current depressurization treatment to obtain high-temperature purge gas and low-temperature carbon dioxide-rich gas, and the low-temperature carbon dioxide-rich gas is incorporated into the feed gas.

[0100] In step S640, at least part of the high-temperature purge gas is used to strip the raw material gas dissolved in the methanol condensate to obtain medium-temperature purge gas containing the raw material gas and crude methanol.

[0101] By incorporating hydrogen-rich gas and low-temperature carbon dioxide-rich gas into the feed gas, and using at least part of the high-temperature purge gas to strip the feed gas dissolved in the methanol condensate, the utilization rate of the feed gas is improved.

[0102] The methanol synthesis method provided in this application can be implemented using the aforementioned methanol synthesis system. (Refer to...) Figure 4 , Figure 5 and Figure 6 Step S610 can be implemented by methanol synthesis unit 100, step S620 can be implemented by methanol synthesis unit 200, step S630 can be implemented by methanol synthesis unit 300, and step S640 can be implemented by methanol synthesis unit 400.

[0103] According to embodiments of this application, the process may further include compressing and preheating the feed gas before step S610. Compressing the feed gas facilitates its transport in pipelines and ensures thorough mixing of its components. Furthermore, it increases the molecular collision frequency of the feed gas, accelerates the reaction rate, and shifts the reaction towards methanol production. Preheating the feed gas allows the methanol synthesis reaction to proceed under suitable temperature conditions, further accelerating the reaction rate. In some embodiments of this application, the compression of the feed gas can be achieved using a feed gas compressor 140, and the preheating of the feed gas can be achieved using a first heat exchanger 120.

[0104] According to an embodiment of this application, in step S610, the raw material gas including carbon monoxide, carbon dioxide and hydrogen is subjected to a methanol synthesis reaction, and a low-temperature mixed product including methanol and raw material gas is discharged, which may include steps S611 to S613.

[0105] In step S611, the feed gas is subjected to a methanol synthesis reaction and the high-temperature mixed product is discharged. In some embodiments of this application, this step can be implemented by a methanol synthesis reactor 110. The methanol synthesis reactor 110 can be the methanol synthesis reactor provided in any of the above embodiments, or any methanol synthesis reactor available in the related art.

[0106] For example, the methanol synthesis reactor 110 may include a shell, with a feed inlet at the top for receiving feed gas and a product outlet at the bottom for discharging a mixture including methanol; and multiple reaction units connected sequentially from top to bottom. Each reaction unit includes: an upper partition and a lower partition spaced apart within the shell; multiple reaction tubes connected between the upper and lower partitions to receive feed gas from the feed inlet or intermediate products from the previous reaction unit, with a cavity outside the reaction tubes, between the upper and lower partitions, and the shell forming a heat exchange shell side; and a heat exchange medium inlet and a heat exchange medium outlet disposed on the shell, with the heat exchange shell side connected to at least one temperature control device through the heat exchange medium inlet and outlet.

[0107] If the reaction temperature in any reaction unit is higher than a preset value, the temperature of the heat exchange medium in the heat exchange shell side of that reaction unit can be lowered; conversely, if the reaction temperature in any reaction unit is lower than a preset value, the temperature of the heat exchange medium in the heat exchange shell side of that reaction unit can be raised. Therefore, the reaction temperature within the reaction tubes of each reaction unit, i.e., the methanol synthesis temperature, can be controlled separately, improving the utilization rate of the feed gas and thus increasing the methanol yield.

[0108] In step S612, the high-temperature mixed product is heat-exchanged with the feed gas to obtain a medium-temperature mixed product. By exchanging heat with the feed gas, the high-temperature mixed product can be cooled to a medium-temperature mixed product, and the feed gas can be preheated, thereby achieving efficient energy utilization. In some embodiments of this application, this step can be implemented by a first heat exchanger 120.

[0109] In step S613, the intermediate-temperature mixture is cooled to a low-temperature mixture. In some embodiments of this application, this step can be achieved using a cooler 130.

[0110] Cooling high-temperature mixed products into low-temperature mixed products prepares them for subsequent separation operations, which helps improve subsequent separation efficiency, protect equipment, and reduce energy consumption.

[0111] According to an embodiment of this application, in step S620, the low-temperature mixed product is separated to obtain methanol condensate, hydrogen-rich gas and hydrogen-poor gas, which may include steps S621 and S622.

[0112] In step S621, the low-temperature mixed product is subjected to gas-liquid separation to obtain methanol condensate and circulating gas. The methanol condensate may include methanol and feed gas adsorbed and dissolved in methanol. The circulating gas may include unreacted feed gas, by-product gas, and methanol, etc. The circulating gas can be divided into two streams, wherein at least part of the circulating gas can be merged into the feed gas. In some embodiments of this application, this step can be implemented by a gas-liquid separator 210.

[0113] In step S622, at least a portion of the recycle gas is separated into hydrogen-rich gas and hydrogen-lean gas. The hydrogen-lean gas contains less hydrogen than the hydrogen-rich gas and may include by-product gas and feed gas. In some embodiments of this application, this step can be implemented using a hydrogen separator 220.

[0114] In step S630, due to the high boiling point of carbon dioxide, depressurizing the hydrogen-lean gas yields high-temperature purge gas and low-temperature carbon dioxide-rich gas. The high-temperature purge gas may include by-product gas and a small amount of feed gas. The low-temperature carbon dioxide-rich gas can exchange heat with water from outside the boundary, lowering the water temperature. After heating, the low-temperature carbon dioxide-rich gas can become carbon dioxide-rich gas and be incorporated into the feed gas. After cooling, the water from outside the boundary can be used to wash the medium-temperature purge gas.

[0115] According to an embodiment of this application, in step S640, at least a portion of the high-temperature purge gas is used to strip the methanol condensate to obtain medium-temperature purge gas and crude methanol. The high-temperature purge gas can strip the adsorbed and dissolved feed gas in the methanol condensate, and the resulting medium-temperature purge gas will inevitably carry some methanol vapor and feed gas. In some embodiments of this application, this step can be implemented by a stripping tower 410.

[0116] In some embodiments of this application, the low-temperature carbon dioxide-rich gas and the water flowing into the water scrubbing tower 420 can be heat-exchanged to lower the temperature of the water flowing into the water scrubbing tower 420. The low-temperature water helps to further wash away methanol in the medium-temperature purge gas. In some embodiments of this application, this step can be achieved through a second heat exchanger 430.

[0117] In some embodiments of this application, the methanol synthesis method may further include: washing the intermediate-temperature purge gas with water to obtain a separation tail gas and a separation liquid, wherein the separation liquid is incorporated into crude methanol, and the separation tail gas is incorporated into lean hydrogen gas and re-enters the vortex tube. Water washing can remove methanol from the intermediate-temperature purge gas. The separation tail gas may include by-product gas and feed gas, and can be incorporated into lean hydrogen gas before re-entering the vortex tube. The separation liquid may include methanol, and can be incorporated into crude methanol. Therefore, carbon dioxide in the purge gas can be recovered and utilized to the maximum extent, as can feed gas in the crude methanol product, preventing feed gas from being carried to downstream processes by crude methanol and wasting the effective components of the feed gas. In some embodiments of this application, this step can be implemented using a water washing tower 420.

[0118] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this application. It should be understood that the above descriptions are merely specific embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A methanol synthesis reactor, comprising: The housing has a raw material inlet at the top for receiving raw material gas and a product outlet at the bottom for discharging a mixture including methanol. as well as Multiple reaction units connected sequentially from top to bottom, each reaction unit comprising: An upper partition and a lower partition are spaced apart within the housing; Multiple reaction tubes are connected between the upper partition and the lower partition to receive feed gas from the feed inlet or intermediate products from the previous reaction unit. The cavity between the outside of the reaction tubes, the upper partition, the lower partition and the shell forms a heat exchange shell side. A heat exchange medium inlet and a heat exchange medium outlet are disposed on the shell, and the shell side of the heat exchange medium is connected to at least one temperature control device through the heat exchange medium inlet and the heat exchange medium outlet; and A heat exchange assembly is installed around the reaction tubes, and a flow channel is provided between the heat exchange assembly and the reaction tubes.

2. The methanol synthesis reactor according to claim 1, wherein, The heat exchange assembly includes multiple rows of fins arranged along the outer periphery of the reaction tubes. Each row of fins is arranged sequentially in the height direction of the reaction tubes, and one end of each fin is connected to one of the reaction tubes. The flow channel is formed by the multiple rows of fins.

3. The methanol synthesis reactor according to claim 2, wherein, The heat exchange assembly further includes: multiple heat exchange tubes arranged along the outer periphery of one of the reaction tubes, and the other end of each fin is connected to one of the heat exchange tubes, such that each row of fins is arranged sequentially in the height direction of the heat exchange tubes.

4. The methanol synthesis reactor according to claim 3, wherein, Each heat exchange tube is provided with multiple through holes, each through hole being located between two adjacent fins and close to the upper fin.

5. The methanol synthesis reactor according to any one of claims 2 to 4, wherein, Each of the fins forms a downward-opening groove, and / or one end of each fin that connects to the heat exchange tube is located above the end of the fin that connects to the reaction tube.

6. A methanol synthesis system, comprising: The methanol synthesis unit is used to carry out a methanol synthesis reaction on a feed gas including carbon monoxide, carbon dioxide and hydrogen, and to discharge a low-temperature mixed product including methanol and feed gas. The first separation unit is used to separate the low-temperature mixed product to obtain methanol condensate, hydrogen-rich gas and hydrogen-lean gas, wherein the hydrogen-rich gas is incorporated into the raw material gas; A vortex tube is used to depressurize the hydrogen-poor gas to obtain high-temperature purge gas and low-temperature carbon dioxide-rich gas, the low-temperature carbon dioxide-rich gas being incorporated into the feed gas; and The second separation unit includes a stripping tower for stripping the feed gas dissolved in the methanol condensate using at least a portion of the high-temperature purge gas to obtain medium-temperature purge gas containing the feed gas and crude methanol.

7. The methanol synthesis system according to claim 6, wherein, The second separation unit further includes: A water washing tower is used to wash the medium-temperature purge gas with water to obtain a separated tail gas and a separated liquid. The separated liquid is incorporated into the crude methanol, and the separated tail gas is incorporated into the hydrogen-lean gas and then re-enters the vortex tube.

8. The methanol synthesis system according to claim 6, wherein, The first separation unit includes: A gas-liquid separator is used to separate the low-temperature mixture into methanol condensate and recycle gas, wherein at least a portion of the recycle gas is incorporated into the feed gas; and A hydrogen separator for separating at least a portion of the circulating gas into hydrogen-rich and hydrogen-lean gas.

9. The methanol synthesis system according to any one of claims 6 to 8, wherein, The methanol synthesis unit includes a methanol synthesis reactor, which includes: A housing, wherein the upper part of the housing is provided with a raw material inlet for receiving raw material gas, and the lower part is provided with a product outlet for discharging a mixture including methanol; and Multiple reaction units connected sequentially from top to bottom, each reaction unit comprising: An upper partition and a lower partition are spaced apart within the housing; Multiple reaction tubes are connected between the upper partition and the lower partition to receive feed gas from the feed inlet or intermediate products from the previous reaction unit. The cavity between the outside of the reaction tubes, the upper partition, the lower partition and the shell forms a heat exchange shell side. A heat exchange medium inlet and a heat exchange medium outlet are disposed on the shell, and the shell side of the heat exchange medium is connected to at least one temperature control device through the heat exchange medium inlet and the heat exchange medium outlet; and A heat exchange assembly is installed around the reaction tubes, and a flow channel is provided between the heat exchange assembly and the reaction tubes.

10. The methanol synthesis system according to claim 9, wherein, The heat exchange assembly includes multiple rows of fins arranged along the outer periphery of the reaction tubes. Each row of fins is arranged sequentially in the height direction of the reaction tubes, and one end of each fin is connected to one of the reaction tubes. The flow channel is formed by the multiple rows of fins.

11. The methanol synthesis system according to claim 10, wherein, The heat exchange assembly further includes: multiple heat exchange tubes arranged along the outer periphery of one of the reaction tubes, and the other end of each fin is connected to one of the heat exchange tubes, such that each row of fins is arranged sequentially in the height direction of the heat exchange tubes.

12. A method for synthesizing methanol, comprising: The feed gas, which includes carbon monoxide, carbon dioxide and hydrogen, is used to synthesize methanol, and a low-temperature mixed product containing methanol and feed gas is discharged. The low-temperature mixed product is separated to obtain methanol condensate, hydrogen-rich gas and hydrogen-lean gas, wherein the hydrogen-rich gas is incorporated into the feed gas; The hydrogen-poor gas is depressurized to obtain high-temperature purge gas and low-temperature carbon dioxide-rich gas, and the low-temperature carbon dioxide-rich gas is incorporated into the raw material gas. The raw material gas dissolved in the methanol condensate is stripped using at least a portion of the high-temperature purge gas to obtain a medium-temperature purge gas containing the raw material gas and crude methanol.

13. The methanol synthesis method according to claim 12, further comprising: The medium-temperature purge gas is washed with water to obtain a separation tail gas and a separation liquid. The separation liquid is incorporated into the crude methanol, and the separation tail gas is incorporated into the hydrogen-lean gas and then re-enters the vortex tube.

14. The methanol synthesis method according to claim 12 or 13, wherein, The methanol synthesis reaction is carried out in a methanol synthesis reactor, which includes: A housing, wherein the upper part of the housing is provided with a raw material inlet for receiving raw material gas, and the lower part is provided with a product outlet for discharging a mixture including methanol; and Multiple reaction units connected sequentially from top to bottom, each reaction unit comprising: An upper partition and a lower partition are spaced apart within the housing; Multiple reaction tubes are connected between the upper and lower partitions to receive feed gas from the feed inlet or intermediate products from the previous reaction unit. A cavity outside the reaction tubes, between the upper and lower partitions, and the shell forms a heat exchange shell side. A heat exchange medium inlet and a heat exchange medium outlet are provided on the shell, and the heat exchange shell side is connected to at least one temperature control device through the heat exchange medium inlet and the heat exchange medium outlet.

15. The methanol synthesis method according to claim 14, wherein, If the reaction temperature in any reaction unit exceeds a preset value, reduce the temperature of the heat exchange medium in the heat exchange shell side of that reaction unit; or, If the reaction temperature in any reaction unit is lower than the preset value, the temperature of the heat exchange medium in the heat exchange shell side of that reaction unit is increased.

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