Heat exchange coupling type methanol synthesis reactor and methanol synthesis method
By designing the structure of multi-layer catalyst and heat exchanger in the synthetic methanol reactor, the problem of poor temperature equilibrium of the catalyst bed is solved, the reaction efficiency and catalyst utilization rate are improved, the maintenance process is simplified, and the safety and energy utilization efficiency are improved.
Patent Information
- Application Number
- CN202510359405.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-25
- Publication Date
- 2025-06-24
AI Technical Summary
In the prior art, the temperature equilibrium of the catalyst bed is poor, resulting in low methanol synthesis reaction efficiency.
A heat exchange coupled synthetic methanol reactor is designed. By setting up a multi-layer catalyst from top to bottom in the synthesis tower and setting up a multi-layer heat exchanger in the heat exchange tower, the number of layers of the catalyst and the heat exchanger is the same, the uniform temperature distribution and effective utilization of the catalyst are achieved.
It improves the utilization rate of the catalyst and the overall reaction efficiency, simplifies the unloading and loading process of the catalyst, reduces the maintenance workload, and reduces the cold pipe effect, improving the safety and energy utilization efficiency of the reactor.
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Figure CN120189879A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of methanol synthesis, and particularly relates to a heat exchange coupled methanol synthesis reactor and a methanol synthesis method. Background Art
[0002] Methanol is one of the most important chemical products. In 2020, the global consumption was about 132 million tons, and in China it was 82 million tons. In terms of production, China mainly uses the coal-to-methanol process (carbon emission intensity: 3.1 tons of CO2 / ton of methanol), and the industry's carbon emissions are about 200 million tons, which is a typical high-emission industry. In November 2021, five ministries and commissions including the National Development and Reform Commission issued the "Benchmark Levels and Baseline Levels for Energy Efficiency in Key Areas of High-Energy-Consuming Industries (2021 Edition)". For multiple industries including methanol synthesis, transformation and upgrading and elimination shall be implemented in batches within a time limit according to the benchmark levels and baseline levels of energy efficiency. The Global Methanol Association released "Methanol Carbon Footprint" in 2022. The full life cycle carbon emission of methanol produced by CO2 plus photovoltaic hydrogen is only 0.086 t / t of methanol. Therefore, the CO2 hydrogenation to methanol process is an important path to achieve the dual carbon goals of the methanol synthesis industry. In March 2022, the National Development and Reform Commission and the National Energy Administration jointly issued the "Medium- and Long-Term Development Plan for the Hydrogen Energy Industry (2021-2035)", proposing to actively guide industries such as methanol synthesis to transform from high-carbon processes to low-carbon processes, and promote the green and low-carbon development of high-energy-consuming industries.
[0003] In addition, when methanol is used as a fuel, it has the advantages of low storage and transportation costs, relatively high volume energy density, and good safety compared with hydrogen, ammonia, etc. It is suitable for the energy demand in scenarios with long endurance and sensitive space.
[0004] IMO (International Maritime Organization) plan: Based on 2008, by 2030, carbon emission intensity will be reduced by 40%; by 2050, total carbon emissions will be reduced by at least 50%, and carbon emission intensity will be reduced by 70%. To achieve this emission reduction plan, fuel upgrades and substitutions are needed. Methanol, as a fuel for ocean-going shipping, has the advantages of low modification cost, high safety, sound regulations, sound refueling facilities, and flexible fuel tank layout. Many companies in the shipping industry have launched fuel substitution plans: Maersk announced strategic cooperation with 6 companies in April 2022, including a joint Chinese company (Jidian shares participated) to provide it with 300,000 tons of green methanol per year, and plans to reach 6 million tons per year in 2030; COSCO Shipping plans to complete the transformation of 22 23,000 container-class ships in 2030, with a demand of more than 2.1 million tons per year. From the end of 2022 to date, France's CMA CGM has accumulated orders for 24 methanol-fueled ships. According to existing methanol-powered ship orders, the demand for methanol as a shipping fuel is expected to reach 3 million tons in 2027. The International Renewable Energy Agency (IRENA) predicts that the global annual demand for green methanol will reach 250 million tons by 2050. It can be seen that methanol is not only a basic chemical raw material, but also a new energy carrier, and has a large demand for application scenarios. The synthesis of green methanol from CO2 and electrolytic green hydrogen is one of the important technical routes for green electricity conversion, and an efficient and stable synthetic methanol reactor is a key technology.
[0005] At present, the main process for synthesizing methanol is to produce methanol from synthesis gas, which mainly uses water-cooled reactors. In contrast, the CO2 hydrogenation to produce methanol has a mild reaction and a low calorific value, and it is impossible to achieve the tower inlet temperature required by the water-cooled reactor. Therefore, an air-cooled reactor is usually used to place the heat exchange pipeline inside the synthesis tower to reduce the tower inlet temperature. However, the structure of the air-cooled reactor is complex, which makes the catalyst unloading and loading inconvenient, and it is easy to cause the local area to be not dense enough during loading, resulting in uneven catalyst bed temperature, affecting the overall reaction efficiency. Summary of the invention
[0006] The present invention aims to provide a heat exchange coupling type methanol synthesis reactor and a methanol synthesis method to solve the problem of low methanol synthesis reaction efficiency caused by poor temperature balance of the catalyst bed in the prior art.
[0007] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a heat exchange coupling synthetic methanol reactor, comprising a heat exchange tower and a synthesis tower connected by pipelines, wherein multiple layers of heat exchangers are arranged from top to bottom in the heat exchange tower, and a steam heat exchanger is arranged at the bottom of the heat exchanger; multiple layers of catalysts are arranged from top to bottom in the synthesis tower, and the number of layers of the catalyst is the same as the number of layers of the heat exchanger.
[0008] Preferably, as an improvement, the number of layers of the catalyst and the heat exchanger are the same, both of which are 2 to 10 layers.
[0009] Preferably, as an improvement, both the number of layers of the catalyst and the heat exchanger is 3 layers.
[0010] Preferably, as an improvement, a flow equalizing plate is provided on the upper part of the catalyst, and a grid plate is provided on the lower part of the catalyst.
[0011] Preferably, as an improvement, the steam heat exchanger is a plate heat exchanger or a tubular heat exchanger.
[0012] Preferably, as an improvement, the heat exchange mode of the steam heat exchanger is countercurrent heat exchange.
[0013] Preferably, as an improvement, a heat exchange coupled methanol synthesis method includes the following steps:
[0014] S1. Adsorb CO2 molecules on the surface of the catalyst;
[0015] S2. Introduce hydrogen from the lower part of the third-layer heat exchanger into the heat exchange tower, flow from bottom to top, and finally heat it to 210 °C;
[0016] S3. Lead the heated hydrogen out from the upper part of the heat exchange tower to the upper part of the synthesis tower;
[0017] S4. The hydrogen entering the synthesis tower reacts on the first-layer catalyst and heats up; it is led to the first-layer heat exchanger through a pipeline, cooled and then introduced into the second-layer catalyst again to continue heating up; it is led to the second-layer heat exchanger through a pipeline again, cooled and then introduced into the third-layer catalyst again to continue the reaction and heating up; then it is led to the bottom of the heat exchange tower through a pipeline and enters the heat exchange tower;
[0018] S5. The gas introduced into the heat exchange tower exchanges heat with water in a countercurrent manner to desorb methanol and generate steam at the same time.
[0019] Preferably, as an improvement, it further includes step S6. Continuously introduce the steam into the third-layer heat exchanger through a pipeline, reduce the temperature to 40 °C, and discharge it along the heat exchange tower.
[0020] Preferably, as an improvement, in step S1, the catalyst is a Cu-based catalyst, and the Cu-based catalyst is a mixture of CuO, ZnO, and Al2O3.
[0021] Preferably, as an improvement, in step S2, the inlet temperature of hydrogen is 30 °C.
[0022] The principle and advantages of this solution are as follows: In view of the problem of low methanol synthesis reaction efficiency caused by poor temperature uniformity in the catalyst bed layer in the prior art, the traditional method is to place heat exchange tubes inside the reactor, which can timely remove the heat of the reaction to maintain the reaction temperature. However, this method has the problems of complex structure, high manufacturing cost of the reactor, large workload for catalyst replacement, and inconvenient maintenance. Moreover, there is a cold tube effect on the catalyst near the heat exchange tubes (the catalyst cannot be activated due to the low temperature around the heat exchange tubes, and the catalyst activation temperature is about 190°C), resulting in ineffective use of this part of the catalyst and low effective utilization rate of the catalyst.
[0023] The beneficial effects of this technical solution are as follows:
[0024] 1. The structure inside the synthesis tower of this technical solution is simple, which is convenient for catalyst unloading and loading: The structure inside the synthesis tower is simple, without complex heat exchange tube bundles. The catalyst unloading and loading are relatively convenient, reducing the maintenance workload. Moreover, the catalyst inside the tower is more uniform, filled more densely, and there is no cold tube effect (the catalyst cannot be activated due to the low temperature around the heat exchange tubes), thereby improving the catalyst utilization rate and overall efficiency.
[0025] 2. The catalyst is designed in layers, and the axial temperature difference is small: In this technical solution, the catalyst is designed in layers, and the adiabatic temperature rise is realized in sections, thereby reducing the axial temperature rise and keeping the catalyst always in a suitable temperature range, thus improving the overall reaction efficiency.
[0026] 3. This technical solution integrates multiple heat exchangers into one heat exchange tower, reducing the number of pressure vessels in the process system, improving safety. Moreover, four heat exchangers are integrated into one heat exchange tower, reducing the number of pressure vessels in the process system, facilitating centralized management and maintenance of pressure vessels, and reducing operating costs.
[0027] 4. In this technical solution, a steam heat exchanger is arranged at the bottom of the heat exchange tower, which can produce steam at about 130°C for other sections, realizing the full utilization of energy. Description of the Drawings
[0028] Figure 1 It is a schematic structural diagram of a heat exchange-coupled methanol reactor in an embodiment of the present invention.
[0029] Figure 2 It is a schematic diagram of the operation mode of a heat exchange-coupled methanol reactor in an embodiment of the present invention.
[0030] Figure 3 It is an actual operation diagram (application example) of an embodiment of the present invention.
[0031] Figure 4 It is a schematic structural diagram of a conventional reactor.
[0032] Figure 5It is a cold tube effect diagram of a conventional reactor. Detailed implementation manners
[0033] The following is a further detailed description through specific implementation manners, but the implementation manners of the present invention are not limited thereto. Unless otherwise specified, the technical means used in the following implementation manners are conventional means well-known to those skilled in the art; the experimental methods used are all conventional methods; the materials, reagents, etc. used can all be obtained from commercial channels.
[0034] The reference numerals in the accompanying drawings of the specification include: heat exchange tower 1, synthesis tower 2, first-layer heat exchanger 3, second-layer heat exchanger 4, third-layer heat exchanger 5, steam heat exchanger 6, pipeline 7, first-layer catalyst 8, second-layer catalyst 9, third-layer catalyst 10, charging port 11, and discharging port 12.
[0035] Example 1
[0036] A heat exchange-coupled methanol synthesis reactor includes a heat exchange tower 1 and a synthesis tower 2 connected by a pipeline 7.
[0037] Inside the heat exchange tower 1, a first-layer heat exchanger 3, a second-layer heat exchanger 4, a third-layer heat exchanger 5, and a steam heat exchanger 6 are arranged from top to bottom. A partition for separation is arranged between the third-layer heat exchanger 5 and the steam heat exchanger 6, and the first-layer heat exchanger 3, the first-layer heat exchanger 3, the third-layer heat exchanger 5, and the steam heat exchanger 6 are parallel to each other. In actual application, the number of heat exchanger layers can be set to 2 - 10 layers, and the heat exchanger is a plate heat exchanger or a tubular heat exchanger; the heat exchange mode of the steam heat exchanger 6 is countercurrent heat exchange.
[0038] Inside the synthesis tower 2, a first-layer catalyst 8, a second-layer catalyst 9, and a third-layer catalyst 10 are arranged from top to bottom. A partition is arranged between the catalysts for separation; and a flow equalizing plate is arranged above each layer of catalyst, and a grid plate is arranged below each layer of catalyst. In actual application, the number of catalyst layers can be set to 2 - 10 layers, and is the same as the number of heat exchanger layers. A plurality of charging ports 11 and discharging ports 12 corresponding to these three layers of catalysts 10 are arranged on the side of the synthesis tower 2.
[0039] A heat exchange-coupled methanol synthesis method includes the following steps:
[0040] S1. Adsorb CO2 molecules on the surface of the catalyst. The catalyst is a Cu-based catalyst, and the main components are a mixture of CuO, ZnO, and Al2O3.
[0041] S2. The inlet gas (mixed gas, including hydrogen, CO2, CO, etc., at a temperature of 30°C) enters the heat exchange tower from the lower part of the third-layer heat exchanger, flows from bottom to top, and is heated to about 170°C by the high-temperature gas in the third-layer heat exchanger; then enters the second-layer heat exchanger and is heated to about 190°C, and the first-layer heat exchanger, and after being heated step by step, reaches about 210°C, meeting the conditions of catalyst activity.
[0042] S3. Lead the heated tower gas from the upper pipeline of the heat exchange tower to the upper part of the synthesis tower.
[0043] S4. The tower gas entering the synthesis tower reacts on the first layer of catalyst. Due to the exothermic reaction, the temperature rises by about 20°C; it is led to the first layer of heat exchanger through a pipeline, and after the temperature drops by 20°C, it is introduced into the second layer of catalyst again, and the temperature continues to rise by 20°C; it is led to the second layer of heat exchanger through a pipeline again, and after the temperature drops by 20°C, it is introduced into the third layer of catalyst again, and the reaction continues to rise by 20°C; it is led to the bottom of the heat exchange tower through a pipeline and enters the heat exchange tower.
[0044] S5. The gas introduced into the heat exchange tower exchanges heat with water in reverse, condensing the methanol into liquid state, facilitating the subsequent gas-liquid separation into products, and generating steam at the same time.
[0045] S6. The steam is further introduced into the third-layer heat exchanger through the pipeline, the temperature is reduced to about 40°C, and is discharged along the heat exchange tower.
[0046] Example 2
[0047] The difference between this embodiment and embodiment 1 is that in this embodiment, the number of layers of the catalyst and the heat exchanger are both 2.
[0048] Example 3
[0049] The difference between this embodiment and embodiment 1 is that the number of layers of the catalyst and the heat exchanger in this embodiment are both 10.
[0050] Application Examples
[0051] The operation diagram of the actual application of Example 1 is as follows Figure 3 As shown, Figure 3 The three reactors (B1\B2\B3) correspond to Figure 1 The first layer catalyst 8, the second layer catalyst 9, and the third layer catalyst 10; the four heat exchangers H1, H2, H3, and H4 correspond to Figure 1 The first layer heat exchanger 3, the second layer heat exchanger 4, the third layer heat exchanger 5, and the steam heat exchanger 6.
[0052] In addition, with conventional reactors in the prior art (structure such as Figure 4 ) was used as a comparative example and the actual operation was carried out. The results are shown in Table 1.
[0053] As can be seen from Table 1 below, the temperature of each layer of catalyst in the application example of the present invention is more balanced, which is beneficial to improving the efficiency of the catalyst. In addition, the application example does not have a cold pipe effect, which further improves the effectiveness of the catalyst. The application example has a cold pipe effect, and the cold pipe effect schematic diagram is shown in FIG. Figure 5 As shown, the blue area is the low temperature area, and the temperature of about 5% of the catalyst area is low, and the catalyst cannot be activated.
[0054] Table 1
[0055]
[0056] The above are only embodiments of the present invention, and common general technical solutions and / or characteristics in the solutions are not described in detail herein. It should be noted that for those skilled in the art, without departing from the technical solutions of the present invention, several modifications and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicability of the patent. The protection scope required by this application shall be subject to the content of its claims, and the specific implementation manners and the like recorded in the specification can be used to interpret the content of the claims.
Claims
1. A heat exchange coupled synthetic methanol reactor, characterized in that: It comprises a heat exchange tower and a synthesis tower connected by pipelines. The heat exchange tower is provided with multiple layers of heat exchangers from top to bottom, and a steam heat exchanger is provided at the bottom of the heat exchanger. The synthesis tower is provided with multiple layers of catalysts from top to bottom, and the number of layers of the catalysts is the same as that of the heat exchangers.
2. The heat exchange coupled synthetic methanol reactor according to claim 1, characterized in that: The number of layers of the catalyst and the heat exchanger is the same, both of which are 2 to 10 layers.
3. A heat exchange coupling type synthetic methanol reactor according to claim 2, characterized in that: The number of layers of the catalyst and the heat exchanger are both 3.
4. The heat exchange coupled synthetic methanol reactor according to claim 3, characterized in that: The upper part of the catalyst is provided with a flow balancing plate, and the lower part of the catalyst is provided with a grid plate.
5. The heat exchange coupling type synthetic methanol reactor according to claim 4, characterized in that: The steam heat exchanger is a plate heat exchanger or a tube heat exchanger.
6. The heat exchange coupling type synthetic methanol reactor according to claim 5, characterized in that: The heat exchange mode of the steam heat exchanger is countercurrent heat exchange.
7. A heat exchange coupling methanol synthesis method, characterized in that: The synthesis using the heat exchange coupling type synthetic methanol reactor described in any one of claims 1 to 6 comprises the following steps: S1, adsorbing CO2 molecules on the catalyst surface; S2, hydrogen enters the heat exchange tower from the lower part of the third layer heat exchanger, flows from bottom to top, and is finally heated to 210°C; S3, leading the heated hydrogen from the upper part of the heat exchange tower to the upper part of the synthesis tower; S4, the hydrogen entering the synthesis tower reacts and heats up on the first layer of catalyst; is led to the first layer of heat exchanger through a pipeline, and is introduced into the second layer of catalyst again after cooling, and continues to heat up; is led to the second layer of heat exchanger through a pipeline again, and is introduced into the third layer of catalyst again after cooling, and continues to react and heat up; and then is led to the bottom of the heat exchange tower through a pipeline and enters the heat exchange tower; S5. The gas introduced into the heat exchange tower exchanges heat with water in reverse to desorb methanol and generate steam at the same time.
8. A heat exchange coupling methanol synthesis method according to claim 7, characterized in that: The method further includes step S6, wherein the steam is continuously introduced into the third-layer heat exchanger through the pipeline, the temperature of the steam is reduced to 40° C., and the steam is discharged along the heat exchange tower.
9. A heat exchange coupling methanol synthesis method according to claim 8, characterized in that: In step S1, the catalyst is a Cu-based catalyst, and the Cu-based catalyst is a mixture of CuO, ZnO, and Al2O3.
10. A heat exchange coupling methanol synthesis method according to claim 9, characterized in that: In step S2, the inlet temperature of hydrogen is 30°C.