Low-pressure methanol synthesis device
By using hollow fiber membrane purge tubes and multi-stage flash tanks in methanol production equipment, the problems of high energy consumption and reduced catalyst activity under high temperature and high pressure are solved, and efficient production of low-pressure synthetic methanol is achieved, and the catalyst life is extended And saves energy consumption.
Patent Information
- Application Number
- CN202421182066.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-28
- Publication Date
- 2025-01-17
- Estimated Expiration
- 2034-05-28
AI Technical Summary
The existing methanol production equipment operates under high temperature and high pressure, resulting in high energy consumption and reduced catalyst activity, and by-product water vapor damages the catalyst.
A purge tube made of hollow fiber membrane is provided in the reactor to absorb some water vapor and to separate gas-liquid through two flash tanks to reduce reaction pressure and catalyst damage.
Reduces reaction pressure and energy consumption, extends the catalyst life, improves reaction conversion rate and methanol refining efficiency, and saves raw material gas compression power consumption.
Smart Images
Figure CN222358464U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to a chemical plant, in particular to a methanol production plant, specifically to a low-pressure methanol synthesis plant. Background Art
[0002] Methanol is an important organic chemical and a carrier of clean renewable energy (H2). In industry, methanol is generally produced by hydrogenation reaction catalyzed by Cu-Zn-based heterogeneous catalysts using synthesis gas as raw material. In recent years, the process of producing methanol by hydrogenation of carbon dioxide using captured CO2 and hydrogen produced by electrolysis of water as raw materials has become an effective way to utilize CO2 resources.
[0003] The existing methanol production device mainly includes a methanol reactor, which is equipped with a catalyst. The raw gas H2 and CO2 enter the reactor after being preheated and pressurized, and react with the catalyst. The reacted gas flows out of the reactor and is separated into gas and liquid after cooling to obtain crude methanol, which is then refined. In the reactor, H2 and CO2 mainly undergo the following reaction: CO2 + 3H2 = CH3OH + H2O.
[0004] As we all know, the above reaction is a reversible reaction. Therefore, the general methanol synthesis reaction needs to be carried out at high temperature (473–573 K) and high pressure (5–10 MPa) to inhibit the reverse reaction and ensure the reaction efficiency. However, this will lead to increased energy consumption and higher requirements for equipment. At the same time, the by-product water vapor will accelerate the aggregation of metal particles in the catalyst, resulting in a decrease in the BET specific surface area of the catalyst, thereby reducing the catalytic activity of the catalyst and affecting the reaction efficiency.
[0005] Therefore, it needs to be improved to better meet production needs. Utility Model Content
[0006] The utility model aims to provide a low-pressure methanol synthesis device to address the deficiencies of the prior art, which can effectively reduce the pressure required for the reaction, extend the service life of the catalyst and reduce energy consumption.
[0007] The technical solution of the utility model is:
[0008] A low-pressure methanol synthesis device comprises a reactor, the reactor comprises a shell, a purge pipe and a catalyst bed are arranged inside the shell, and an air inlet and an air outlet are arranged at two ends of the shell respectively; the purge pipe is a hollow tube, made of a hollow fiber membrane, buried in the catalyst bed, and the two ends of the purge pipe are respectively connected to the air inlet and the air outlet;
[0009] Both ends of the shell are also provided with a feed port and a discharge port; the feed port is connected to a mixing device after passing through the tube side of the heat exchanger; the discharge port is connected to the inlet of a methanol flash tank after passing through the shell side of the heat exchanger; the mixing device is connected to a hydrogen raw gas input pipe and a carbon dioxide raw gas input pipe; the liquid phase outlet of the methanol flash tank is connected to a methanol refining unit, and its gas phase outlet is connected to the mixing device;
[0010] The air inlet is connected to the hydrogen raw gas input pipe through a branch; the air outlet is connected to the inlet of the wastewater flash tank; the liquid phase outlet of the wastewater flash tank is connected to the water treatment unit, and the gas phase outlet is connected to the mixing device.
[0011] Furthermore, a hollow jacket structure is provided on the outer wall of the reactor; the jacket structure is provided with a cooling water inlet and a cooling water outlet which are connected with the inner cavity thereof.
[0012] Furthermore, it also includes a No. 2 water cooler, which is arranged on the pipeline between the shell side outlet of the heat exchanger and the inlet of the methanol flash tank.
[0013] Furthermore, it also includes a No. 1 water cooler, which is arranged on the pipeline between the air outlet and the inlet of the wastewater flash tank.
[0014] Furthermore, a branch regulating valve is provided on the branch.
[0015] Furthermore, the hydrogen raw gas input pipe and the carbon dioxide raw gas input pipe are respectively provided with a hydrogen regulating valve and a carbon dioxide regulating valve.
[0016] Furthermore, it also includes a purge gas pipeline, which is connected to the inlet of the mixer; and a purge gas regulating valve is provided on the purge gas pipeline.
[0017] Furthermore, the mixing device is a static mixer.
[0018] Furthermore, it also includes a temperature sensor capable of detecting the temperature inside the catalyst bed.
[0019] Furthermore, the temperature sensors are in three groups, corresponding to the two ends and the middle of the catalyst bed respectively.
[0020] Beneficial effects of the utility model:
[0021] The utility model sets a purge tube made of a hollow fiber membrane in the synthetic methanol reactor, so that part of the water vapor generated in the synthetic methanol reaction process directly penetrates into the purge tube and flows out of the reactor with the purge gas composed of hydrogen, effectively inhibiting the penetration of hydrogen in the reaction gas, improving the reaction conversion rate, reducing the reaction pressure, reducing the energy consumption of the compressor, and avoiding the damage of water vapor to the catalyst. At the same time, by setting two different flash tanks for gas-liquid separation, the water content in the crude methanol can be reduced while the unreacted raw gas is recovered, and the energy consumption required for the subsequent methanol refining unit is reduced, which is beneficial to energy saving and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 It is a structural schematic diagram of the utility model.
[0023] Figure 2 It is a structural schematic diagram of the reactor of the utility model.
[0024] Among them, 1-carbon dioxide regulating valve, 2-hydrogen regulating valve, 3-mixing device, 4-heat exchanger, 5-branch regulating valve, 6-reactor, 7-temperature sensor, 8-No. 1 water cooler, 9-wastewater flash tank, 10-methanol flash tank, 11-relaxation gas regulating valve, 12-No. 2 water cooler; 6-1-shell; 6-2-air inlet; 6-3-feed port; 6-4-catalyst bed, 6-5-purge pipe, 6-6-cooling water inlet, 6-7-air outlet, 6-8-discharge port, 6-9-jacket structure, 6-10-cooling water outlet. DETAILED DESCRIPTION
[0025] The utility model is further described below in conjunction with the accompanying drawings and embodiments.
[0026] like Figure 1 and 2 shown.
[0027] The utility model discloses a low-pressure methanol synthesis device, which comprises a reactor 6, a heat exchanger 4 and the like.
[0028] The reactor 6 includes a shell 6-1 and a purge pipe 6-5. The shell 6-1 is a closed cylindrical shape, in which a catalyst bed 6-4 is arranged, and a feed port 6-3 and a discharge port 6-8 are arranged at both ends, and a hollow jacket structure 6-9 is wrapped on the outside. The jacket structure 6-9 is provided with a cooling water inlet 6-6 and a cooling water outlet 6-10 which are connected to its inner cavity, and can be connected to an external cooling water circulation pipeline, so that the cooling water flows through the jacket structure and exchanges heat with the inside of the reactor.
[0029] The purge pipe 6-5 is a long straight tube made of membrane material, arranged in the shell 6-1 and buried in the catalyst bed 6-4, and its two ends are respectively connected to the air inlet 6-2 and the air outlet 6-7 arranged at the two ends of the shell 6-1. Preferably, the purge pipe 6-5 can be made of a hollow membrane material based on zeolite, which has obvious advantages in water / hydrogen separation.
[0030] The feed port 6-3 of the reactor 6 is connected to the outlet of the mixing device 3 after passing through the tube side of the heat exchanger 4, and the discharge port 6-8 is connected to the inlet of the methanol flash tank 10 after passing through the shell side of the heat exchanger 4 and the second water cooler 12 in sequence. The mixing device 3 is a static mixer.
[0031] The inlet of the mixing device 3 is connected to the carbon dioxide raw gas input pipe after passing through the carbon dioxide regulating valve 1, and is connected to the hydrogen raw gas input pipe after passing through the hydrogen regulating valve 2.
[0032] The liquid phase outlet of the methanol flash tank 10 is connected to the methanol refining unit, and the gas phase outlet thereof is connected to the inlet of the mixing device 3 .
[0033] The air inlet 6-2 is connected to the outlet of the hydrogen regulating valve 2 through a branch line. The air outlet 6-7 is connected to the inlet of the wastewater flash tank 9 after passing through the first water cooler 8. A branch regulating valve 5 is provided on the branch line.
[0034] The liquid phase outlet of the wastewater flash tank 9 is connected to the water treatment unit, and the gas phase outlet thereof is connected to the inlet of the mixing device 3 .
[0035] Furthermore, it also includes a purge gas pipeline. The purge gas pipeline is connected to the inlet of the mixer 3. At the same time, a purge gas regulating valve 11 is provided on the purge gas pipeline to control the on-off of the purge gas pipeline.
[0036] Furthermore, it also includes a temperature sensor 7 installed in the catalyst bed 6-4 to timely detect the temperature inside the catalyst bed 6-4. Preferably, the temperature sensor 7 is three groups, corresponding to the two ends and the middle of the catalyst bed 6-4 respectively.
[0037] The working process of the utility model is:
[0038] 780 kmol / h of hydrogen and 250 kmol / h of carbon dioxide are adjusted to 2.2 MPa by hydrogen regulating valve 1 and carbon dioxide regulating valve 2 respectively, and then enter static mixer 3 for full mixing. Subsequently, the pipe side flowing through heat exchanger 4 is preheated to 220°C and then flows into reactor 6 to contact with the catalyst for methanol synthesis reaction. At the same time, about 30 kmol / h of the hydrogen adjusted by the hydrogen regulating valve passes through branch regulating valve 5 and flows into the purge pipe as purge gas.
[0039] Part of the water vapor and trace amounts of hydrogen, carbon dioxide and carbon monoxide in the post-reaction gas in the reactor 6 penetrate into the purge pipe through the partial pressure difference and are discharged from the gas outlet 6-7 along with the purge gas.
[0040] The filtered post-reaction gas flows out from the discharge port 6-8, flows through the shell side of the heat exchanger 4 for heat exchange, and is further cooled to 30°C by the second water cooler 12 before flowing into the methanol flash tank 10 for gas-liquid separation. After separation, the bottom discharge liquid is crude methanol with a mass concentration of 75%, about 56 kmol / h, which is sent to the methanol refining unit for methanol purification; the top gas is circulated and used as circulating gas.
[0041] At the same time, three temperature sensors installed in the catalyst bed can monitor the temperature distribution in the reactor and adjust the flow in the external cooling water circulation pipeline accordingly so that the cooling water circulating in the jacket can take away the heat generated in the reaction and keep the temperature of the entire reaction process within 250±15℃.
[0042] After the purge gas is discharged from the gas outlet 6-7, it is first cooled to 30°C by the No. 1 water cooler 8, and then enters the wastewater flash tank 10 for gas-liquid separation. After separation, the bottom discharge liquid is wastewater with a water content of >99%, and contains trace amounts of methanol and other organic matter, which is sent to the water treatment unit for subsequent treatment; the top discharge gas is hydrogen-rich gas, about 34 kmol / h, and the molar fraction of hydrogen is about 97.2%. After this gas merges with the circulating gas from the methanol flash tank 10, about 5% of the gas is first discharged through the relaxation pipe, and then flows into the static mixer 3, mixed with the raw hydrogen and raw carbon dioxide, and then enters the reaction process again. During this period, the supply of fresh hydrogen and fresh carbon dioxide can be adjusted to 120 kmol / h and 50kmol / h, respectively, so that the hydrogen-carbon ratio entering the reactor 6 is maintained at around 2.1.
[0043] The raw hydrogen gas is preferably produced by electrolysis of water, and the hydrogen gas pressure is about 2.2 MPa, and can enter the methanol reactor for reaction without additional compressor pressurization. Alternatively, the raw hydrogen gas can also be derived from coal-to-hydrogen production, etc.
[0044] The source of the raw carbon dioxide is preferably industrial carbon dioxide capture, direct air carbon capture, etc., and may also be replaced by synthesis gas.
[0045] The utility model can selectively separate water vapor while synthesizing methanol, thereby reducing the pressure required for the reaction, saving the compression power consumption of the raw gas, and improving the conversion rate of the synthesis reaction. Moreover, by timely removing water vapor, the catalyst structure can be effectively protected to ensure the normal reaction. In addition, since the water content in the crude methanol at the outlet of the methanol flash tube is significantly reduced, the energy consumption and cost required for subsequent methanol refining can be effectively reduced, which is energy-saving and environmentally friendly.
[0046] The parts not involved in the present invention are the same as the prior art or can be implemented by using the prior art.
Claims
1. A low-pressure methanol synthesis device, comprising a reactor, characterized in that: The reactor comprises a shell, in which a purge pipe and a catalyst bed are arranged, and an air inlet and an air outlet are arranged at two ends thereof respectively; the purge pipe is a hollow tube, made of a hollow fiber membrane, buried in the catalyst bed, and its two ends are respectively connected with the air inlet and the air outlet; Both ends of the shell are also provided with a feed port and a discharge port; the feed port is connected to a mixing device after passing through the tube side of the heat exchanger; the discharge port is connected to the inlet of a methanol flash tank after passing through the shell side of the heat exchanger; the mixing device is connected to a hydrogen raw gas input pipe and a carbon dioxide raw gas input pipe; the liquid phase outlet of the methanol flash tank is connected to a methanol refining unit, and its gas phase outlet is connected to the mixing device; The air inlet is connected to the hydrogen raw gas input pipe through a branch; the air outlet is connected to the inlet of the wastewater flash tank; the liquid phase outlet of the wastewater flash tank is connected to the water treatment unit, and the gas phase outlet is connected to the mixing device.
2. The low-pressure methanol synthesis device according to claim 1, characterized in that: A hollow jacket structure is arranged on the outer wall of the reactor; a cooling water inlet and a cooling water outlet which are connected with the inner cavity of the jacket structure are arranged on the jacket structure.
3. The low-pressure methanol synthesis device according to claim 1, characterized in that: It also includes a No. 2 water cooler, which is arranged on the pipeline between the shell side outlet of the heat exchanger and the inlet of the methanol flash tank.
4. The low-pressure methanol synthesis device according to claim 1, characterized in that: It also includes a No. 1 water cooler, which is arranged on the pipeline between the gas outlet and the inlet of the wastewater flash tank.
5. The low-pressure methanol synthesis device according to claim 1, characterized in that: The branch road is provided with a branch road regulating valve.
6. The low-pressure methanol synthesis device according to claim 1, characterized in that: The hydrogen raw gas input pipe and the carbon dioxide raw gas input pipe are respectively provided with a hydrogen regulating valve and a carbon dioxide regulating valve.
7. The low-pressure methanol synthesis device according to claim 1, characterized in that: It also includes a purge gas pipeline, which is connected to the inlet of the mixing device; a purge gas regulating valve is arranged on the purge gas pipeline.
8. The low-pressure methanol synthesis device according to claim 1, characterized in that: The mixing device is a static mixer.
9. The low-pressure methanol synthesis device according to claim 1, characterized in that: A temperature sensor is also included, which can detect the temperature inside the catalyst bed.
10. The low-pressure methanol synthesis device according to claim 9, characterized in that: The temperature sensors are in three groups, corresponding to the two ends and the middle of the catalyst bed respectively.