A shell-and-tube pyrolysis reactor

Abstract

This utility model discloses a tubular pyrolysis reactor, which includes a reactor shell and a first tube sheet, a second tube sheet, and several tubes disposed within the reactor shell. The first tube sheet and the second tube sheet are arranged sequentially from top to bottom within the reactor shell, dividing the inner cavity of the reactor shell into independent first chambers, second chambers, and third chambers. The first tube sheet is provided with a first connecting hole, and the second tube sheet is provided with a second connecting hole. In this utility model, the material flowing inside the reaction tubes of the tubular pyrolysis reactor is the pyrolysis reaction medium, and the material flowing outside the tubes is the heating medium. Through heat exchange and heat transfer in the reaction heat exchange tubes, the reaction tubes are enveloped by the heating medium, resulting in uniform heat transfer. Furthermore, the flow direction of the heating medium and the pyrolysis reaction medium is countercurrent, which allows the catalyst in the lower part of the tubes to be fully utilized, resulting in complete pyrolysis reaction and high conversion rate.

Description

Technical Field

[0001] This utility model relates to a tubular pyrolysis reactor. Background Technology

[0002] Currently, in the chemical, green hydrogen, and hydrogen energy industries, methanol-to-hydrogen production facilities using methanol cracking reactors vary in type, but their production capacity is generally small. These facilities are limited to skid-mounted equipment, with a single unit producing less than 800 Nm³ / h of hydrogen, making them unsuitable for large-scale applications, especially in resource-poor regions. Furthermore, methanol cracking for hydrogen production requires external heating, creating a temperature difference between the heating medium and the reaction medium. These reactors also have limitations in managing thermal stress.

[0003] One patent proposes installing atomizing nozzles in a methanol cracking reactor to inject methanol into the reactor for vaporization and hydrogen production. However, since methanol and water are miscible in any proportion, improper operation during methanol injection and vaporization can result in low pressure differentials at the nozzle or nozzle damage, leading to poor vaporization. This can cause water droplets to enter the reactor, causing dew point corrosion of the metal equipment, which can damage the equipment over time. Furthermore, using high-quality anhydrous methanol would result in excessively high raw material costs.

[0004] One patent proposes using a square methanol cracking reactor for hydrogen production. Methanol cracking for hydrogen production is most economical and suitable when operating at a pressure of 2.0 MPa to 2.5 MPa and a temperature of 240℃ to 280℃. However, this requires higher pressures and temperatures, necessitates a square reactor with thicker metal casings, leading to higher equipment costs and a larger footprint.

[0005] In the methanol cracking hydrogen production reactors currently used in production facilities, the spent catalyst cannot be automatically discharged after the catalyst reaches its service life during production operation. It can only be discharged by lifting the equipment out, removing the top cover, and inverting the equipment. Utility Model Content

[0006] The purpose of this invention is to address the problems of existing methanol cracking hydrogen production reactors, such as small production scale, high equipment manufacturing costs, potential corrosion risks, and the inability to self-unload the catalyst. This invention provides a tubular cracking reactor. The tubular cracking reactor of this invention features a simple structure, uniform heat transfer, no dew point corrosion, complete catalyst self-unloading, and can be designed to meet different production scale requirements.

[0007] This utility model solves the above-mentioned technical problems through the following technical solutions:

[0008] This utility model provides a tubular pyrolysis reactor, which includes a reactor shell and a first tube sheet, a second tube sheet and a plurality of tubes disposed within the reactor shell;

[0009] The first tube sheet and the second tube sheet are arranged sequentially from top to bottom inside the reactor shell, and the first tube sheet and the second tube sheet divide the inner cavity of the reactor shell into independent first chamber, second chamber and third chamber; the first tube sheet is provided with a first connection hole, and the second tube sheet is provided with a second connection hole;

[0010] A plurality of tubes are arranged side by side in the second chamber. The tubes are used to fill the cracking catalyst. One end of the tube is sealed and connected to the first connecting hole of the first tube sheet and communicates with the first chamber. The other end of the tube is sealed and connected to the second connecting hole of the second tube sheet and communicates with the third chamber. The third chamber is used to fill the inert filler. An interlayer space for the flow of heat exchange medium is formed between the tubes and between the tubes and the inner wall of the second chamber. A heat exchange medium inlet and a heat exchange medium outlet are respectively provided on the lower and upper parts of the shell wall of the second chamber. Both the heat exchange medium inlet and the heat exchange medium outlet communicate with the interlayer space.

[0011] The reactor shell is provided with a feed inlet at the top, which is connected to the first chamber; the reactor shell is provided with a discharge pipe at the bottom, one end of which is connected to the third chamber, and the other end of which is provided with a discharge port. A blind flange is connected to the discharge port, and a condensate outlet is provided on the blind flange. A discharge port is provided on the side wall of the discharge pipe.

[0012] An expansion joint is provided on the shell wall of the second chamber between the heat exchange medium inlet and the heat exchange medium outlet.

[0013] In this invention, preferably, the heat exchange medium outlet is arranged symmetrically about the vertical axis of the reactor shell, and the heat exchange medium inlet is also arranged symmetrically about the vertical axis of the reactor shell. Furthermore, the heat exchange medium inlet and outlet are staggered at equal intervals on the horizontal projection plane of the reactor shell. This further ensures a uniform flow path for the heating medium and eliminates dead zones in heat delivery.

[0014] In this invention, the reactor shell preferably includes a cylindrical body and an upper end cap and a lower end cap connected to both ends of the cylindrical body. The first tube sheet is connected to the connection between the cylindrical body and the upper end cap, and the second tube sheet is disposed at the connection between the cylindrical body and the lower end cap, which facilitates the installation and welding of the reactor shell.

[0015] Preferably, the upper end cap is a hemispherical shell, and the feed inlet is provided at the center of the top of the upper end cap.

[0016] Preferably, the lower end cap is a hemispherical shell, and the discharge pipe is located at the bottom center of the lower end cap, which is conducive to the complete discharge of materials.

[0017] Preferably, both the upper and lower end caps are provided with manholes to facilitate equipment maintenance. The manhole at the upper end cap can also be used for loading catalysts.

[0018] The positive and progressive effects of this utility model are as follows:

[0019] (1) The reaction tube of the tubular pyrolysis reactor of this utility model contains a pyrolysis reaction medium inside the tube and a heating medium outside the tube. The heat transfer is achieved by heat exchange through the reaction heat exchange tube, which encloses the reaction tube with the heating medium, resulting in uniform heat transfer. Furthermore, the flow direction of the heating medium and the pyrolysis reaction medium is countercurrent, which allows the catalyst in the lower part of the tube to be fully utilized, resulting in a complete pyrolysis reaction and a high conversion rate.

[0020] (2) By setting a condensate drain outlet, this utility model ensures that when the temperature of the catalyst bed drops due to start-up, unplanned forced shutdown, emergency shutdown, or interruption of heat transfer oil or failure to reach the required temperature, the steam condenses into condensate and can be discharged in time, thus avoiding dew point corrosion and damage to the equipment.

[0021] (3) By concentrating the discharge port, outlet and condensate outlet on a single discharge pipe, this utility model can reduce the impact of the opening on the stress at the bottom of the reactor shell; at the same time, the discharge pipe allows the catalyst to be automatically removed while the equipment remains intact, reducing damage to the reactor shell, enabling the reactor to be reused, reducing fixed asset investment and production costs.

[0022] (4) By setting up a first chamber, the reaction gas enters the first chamber and is buffered and stays briefly, so that the gas pressure at the inlet of the tube is equal and the gas volume entering each tube is equal, thereby making the gas distribution uniform and the catalyst utilization rate high.

[0023] (5) By setting an expansion joint, this utility model ensures that the metal expansion of the reactor shell and tube is consistent when heated, protects the equipment and extends the service life of the equipment, making the equipment safer and more stable; in addition, when in use, the reaction medium can be introduced into the tube and the heating medium can be introduced into the shell. The operating pressure of the shell heating medium is close to the atmospheric pressure. Only the reaction tube is under pressure, and the reactor shell is not under pressure, so the wall thickness of the reactor shell can be thinner and it is convenient to install the expansion joint.

[0024] (6) The tubular pyrolysis reactor of this utility model can be designed to meet the needs of different production scales. The equipment structure is simple, the process flow is simple, the reaction temperature of the catalyst bed is easy to control, and it is convenient for safe and stable production management.

[0025] (7) In the tubular pyrolysis reactor of this utility model, the pyrolysis reaction side (i.e., the first chamber, the third chamber and the inner side of the tube body) is the high pressure area. The shells corresponding to the first chamber and the third chamber of this utility model have fewer openings, greater pressure resistance, and higher equipment safety. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of a tubular pyrolysis reactor according to a preferred embodiment of the present invention.

[0027] Explanation of reference numerals in the attached figures:

[0028] 1-Reactor shell, 2-First tube sheet, 3-Second tube sheet, 4-Tube body, 5-Discharge pipe, 6-Blind flange, 7-Expansion joint;

[0029] 101-First chamber, 102-Second chamber, 103-Third chamber, 104-Heat exchange medium inlet, 105-Heat exchange medium outlet, 106-Feed inlet, 107-Cylinder body, 108-Upper head, 109-Lower head, 110-Manhole;

[0030] 201 - First connecting hole; 301 - Second connecting hole;

[0031] 501 - Unloading port, 502 - Discharge port;

[0032] 601 - Condensate drain outlet. Detailed Implementation

[0033] The present invention is further illustrated below by way of embodiments, but these embodiments do not limit the present invention to the scope of the embodiments described. Experimental methods in the following embodiments that do not specify specific conditions are performed according to conventional methods and conditions, or as selected according to the product instructions.

[0034] A specific embodiment of this utility model discloses a tubular pyrolysis reactor, such as... Figure 1 As shown, it includes a reactor shell 1 and a first tube sheet 2, a second tube sheet 3 and several tube bodies 4 disposed inside the reactor shell 1.

[0035] The first tube sheet 2 and the second tube sheet 3 are arranged sequentially from top to bottom inside the reactor shell 1. The first tube sheet 2 and the second tube sheet 3 divide the inner cavity of the reactor shell 1 into a first chamber 101, a second chamber 102 and a third chamber 103, respectively. The first tube sheet 2 is provided with a first connecting hole 201 and the second tube sheet 3 is provided with a second connecting hole 301.

[0036] Several tubes 4 are arranged side by side in the second chamber 102. The tubes 4 are used to fill the cracking catalyst. One end of the tube 4 is sealed and connected to the first connection hole 201 of the first tube sheet 2 and communicates with the first chamber 101. The other end of the tube 4 is sealed and connected to the second connection hole 301 of the second tube sheet 3 and communicates with the third chamber 103. The third chamber 103 is used to fill the inert filler. A sandwich space for the flow of heat exchange medium is formed between the tubes 4 and between the tubes 4 and the inner wall of the second chamber 102.

[0037] The lower and upper parts of the shell wall of the second chamber 102 are respectively provided with a heat exchange medium inlet 104 and a heat exchange medium outlet 105, and both the heat exchange medium inlet 104 and the heat exchange medium outlet 105 are connected to the interlayer space. The heat exchange medium outlet 105 is arranged symmetrically with the vertical axis of the reactor shell 1 as the center, and the heat exchange medium inlet 104 is arranged symmetrically with the vertical axis of the reactor shell 1 as the center. The heat exchange medium inlet 104 and the heat exchange medium outlet 105 are arranged at equal intervals and staggered on the horizontal projection plane of the reactor shell 1.

[0038] The reactor shell 1 is provided with a feed inlet 106 at the top, which is connected to the first chamber 101; the reactor shell 1 is provided with a discharge pipe 5 at the bottom, one end of which is connected to the third chamber 103, and the other end of which is provided with a discharge port 501. A blind flange 6 is connected to the discharge port 501, and a condensate outlet 601 is provided on the blind flange 6. A discharge port 502 is provided on the side wall of the discharge pipe 5.

[0039] In this embodiment, the reactor shell 1 includes a cylindrical body 107 and an upper end cap 108 and a lower end cap 109 connected to both ends of the cylindrical body 107. A first tube sheet 2 is connected to the connection between the cylindrical body 107 and the upper end cap 108, and a second tube sheet 3 is disposed at the connection between the cylindrical body 107 and the lower end cap 109. The upper end cap 108 is a hemispherical shell, and a feed inlet 106 is disposed at the center of its top. The lower end cap 109 is also a hemispherical shell, and a discharge pipe 5 is disposed at the center of its bottom. Both the upper end cap 108 and the lower end cap 109 are provided with manholes 110 for convenient equipment maintenance; the manhole at the upper end cap can also be used for loading catalyst.

[0040] An expansion joint 7 is provided on the shell wall of the second chamber 102 between the heat exchange medium inlet 104 and the heat exchange medium outlet 105.

[0041] Example of effect:

[0042] In the third chamber 103, the tube body is filled with inert packing material (quartz sand or small ceramic balls). The tube body 4 is filled with a catalyst, which is a copper-based catalyst (specifically, the K3-110 methanol decomposition hydrogen production catalyst). In the K3-110 catalyst, CuO is 50 wt%, ZnO is 30 wt%, Al2O3 is 15 wt%, ZrO2 is 5 wt%, and the particles are cylindrical with a diameter of φ4 × 4 mm and a specific surface area of ​​90~110 m². 2 / g, bulk density is 1.3~1.5 g / cm³ 3 The compressive strength is ≥50 N / cm. The methanol and water mixture has a pressure of approximately 2.0 MPa and a temperature of approximately 260℃. This mixture enters the first chamber 101 through inlet 106, briefly resides, and then enters the catalyst bed in each tube 4 to carry out methanol cracking and carbon monoxide conversion reactions, producing hydrogen and carbon dioxide. As the cracking reaction progresses, the temperature of the catalyst bed decreases. External heat transfer oil (approximately 280–300℃) is introduced into the second chamber 102 through heat exchange medium inlet 104 to heat the catalyst bed in the tube 4, maintaining the reaction temperature required for the cracking reaction. The heat transfer oil, after heat exchange, flows out from heat exchange medium outlet 105 at approximately 260–280℃. After the methanol cracking and carbon monoxide conversion reactions are completed, the cracked hydrogen and carbon dioxide enter the third chamber 103 at approximately 250–270℃ and then leave the reactor through outlet 502 of discharge pipe 5.

[0043] When the methanol cracking catalyst becomes ineffective, after the nitrogen purging is completed and the shutdown is successful, open the blind flange 6 and automatically discharge the waste catalyst through the discharge port 501.

[0044] The methanol cracking conversion rate (molar ratio) is greater than 99.5%, and the carbon monoxide conversion rate (molar ratio) is greater than 99.3%.

Claims

1. A shell-and-tube pyrolysis reactor characterized by, It includes a reactor shell and a first tube sheet, a second tube sheet, and several tubes disposed within the reactor shell; The first tube sheet and the second tube sheet are arranged sequentially from top to bottom inside the reactor shell, and the first tube sheet and the second tube sheet divide the inner cavity of the reactor shell into independent first chamber, second chamber and third chamber; the first tube sheet is provided with a first connection hole, and the second tube sheet is provided with a second connection hole; A plurality of tubes are arranged side by side in the second chamber. The tubes are used to fill the cracking catalyst. One end of the tube is sealed and connected to the first connecting hole of the first tube sheet and communicates with the first chamber. The other end of the tube is sealed and connected to the second connecting hole of the second tube sheet and communicates with the third chamber. The third chamber is used to fill the inert filler. An interlayer space for the flow of heat exchange medium is formed between the tubes and between the tubes and the inner wall of the second chamber. A heat exchange medium inlet and a heat exchange medium outlet are respectively provided on the lower and upper parts of the shell wall of the second chamber. Both the heat exchange medium inlet and the heat exchange medium outlet communicate with the interlayer space. The reactor shell is provided with a feed inlet at the top, which is connected to the first chamber; the reactor shell is provided with a discharge pipe at the bottom, one end of which is connected to the third chamber, and the other end of which is provided with a discharge port. A blind flange is connected to the discharge port, and a condensate outlet is provided on the blind flange. A discharge port is provided on the side wall of the discharge pipe. An expansion joint is provided on the shell wall of the second chamber between the heat exchange medium inlet and the heat exchange medium outlet.

2. The tubular pyrolysis reactor as described in claim 1, characterized in that, The heat exchange medium outlet is arranged symmetrically with respect to the vertical axis of the reactor shell, and the heat exchange medium inlet is arranged symmetrically with respect to the vertical axis of the reactor shell. The heat exchange medium inlet and the heat exchange medium outlet are arranged at equal intervals and staggered on the horizontal projection plane of the reactor shell.

3. The tubular pyrolysis reactor as described in claim 1, characterized in that, The reactor shell includes a cylindrical body and an upper end cap and a lower end cap connected to both ends of the cylindrical body. The first tube sheet is connected to the connection between the cylindrical body and the upper end cap, and the second tube sheet is disposed at the connection between the cylindrical body and the lower end cap.

4. The tubular pyrolysis reactor as described in claim 3, characterized in that, The upper end cap is a hemispherical shell, and the feed port is provided at the center of the top of the upper end cap.

5. The tubular pyrolysis reactor as described in claim 3, characterized in that, The lower end cap is a hemispherical shell, and the unloading pipe is located at the bottom center of the lower end cap.

6. The tubular pyrolysis reactor as described in claim 3, characterized in that, Both the upper and lower end caps are provided with manholes.

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