Sleeve type reactor suitable for gas-solid strong exothermic catalytic reaction

Abstract

The invention discloses a double-pipe reactor suitable for gas-solid strong heat release catalytic reaction. The double-pipe reactor comprises an upper sealing head, a cylinder body, a lower sealing head, an inner pipe medium discharging pipe inserted into the upper sealing head, an inner pipe medium feeding pipe inserted into the lower sealing head and a plurality of outer pipes arranged in the cylinder body, a shell pass medium outlet is formed in the upper part of the barrel, a shell pass medium inlet is formed in the lower part of the barrel, and a gas outlet is formed in the lower end socket; an upper tube plate is arranged between the upper end socket and the cylinder, a lower tube plate is arranged between the lower end socket and the cylinder, the upper end of each outer tube is embedded into the upper tube plate to be fixed, and the lower end of each outer tube is embedded into the lower tube plate to be fixed. According to the sleeve type structure, the heat exchange area is greatly increased, the hot-spot temperature of a bed layer is obviously reduced, and the temperature control capability is obviously superior to that of a traditional tubular reactor; the inner pipe structure and the gas collecting structure are arranged, so that filling of a catalyst is facilitated; and meanwhile, double heat transfer medium channels are arranged, so that working condition operation is more flexible.

Description

Technical Field

[0001] This invention belongs to the field of reactor technology, specifically relating to a shell-and-tube reactor suitable for gas-solid strongly exothermic catalytic reactions. Background Technology

[0002] Tubular fixed-bed reactors are widely used in exothermic reaction systems, such as methanol synthesis reactors, ethylene glycol synthesis reactors, and ethylene oxide reactors. Their characteristic is that the catalyst is generally packed inside the reaction tube. The heat released by the reaction in the catalyst bed inside the tube is carried away by the heat transfer medium outside the tube, i.e., the shell side, thereby reducing the temperature inside the reaction tube and allowing the catalyst to react at a suitable temperature.

[0003] The design philosophy for reactors used in exothermic reactions is to maximize the heat exchange area per unit catalyst bed. For tubular fixed-bed reactors, the specific surface area of ​​the reaction tubes is inversely proportional to the tube diameter; therefore, reducing the tube diameter helps increase the heat exchange area per unit bed. However, the equivalent particle size of industrial catalysts is typically in the millimeter range. Excessively small tube diameters can lead to catalyst bridging, increased bed porosity and inhomogeneity, and severely weakened reaction efficiency.

[0004] To increase the heat exchange area per unit bed, shell-and-tube reactors have emerged. Patent CN202510640689.2 discloses a shell-and-tube reactor where the outer and inner tubes are integral, and the bottom of the outer tube has a separate outlet capillary. However, this design is complex and has a high failure rate. Patent CN202511256151.8 discloses a tubular reactor where the tops of the inner and outer tubes are fixed to two tube sheets, but this hinders catalyst loading, and the poor flow of the medium between the inner and outer tubes prevents effective heat exchange. Summary of the Invention

[0005] To address the technical shortcomings of traditional tubular reactors, such as small heat exchange area per unit catalyst bed and complex structure and difficulty in loading catalysts in traditional shell-and-tube reactors, this invention provides a shell-and-tube reactor with a large heat exchange area and simple structure, suitable for gas-solid strongly exothermic catalytic reactions.

[0006] To achieve the above objectives, the present invention provides a shell-and-tube reactor suitable for gas-solid strongly exothermic catalytic reactions, comprising an upper head, a cylinder, a lower head, an inner tube medium outlet pipe inserted into the upper head, an inner tube medium inlet pipe inserted into the lower head, and multiple outer tubes arranged within the cylinder; the upper head has an air inlet, the upper part of the cylinder has a shell-side medium outlet, the lower part has a shell-side medium inlet, and the lower head has an air outlet; an upper tube sheet is arranged between the upper head and the cylinder, and a lower tube sheet is arranged between the lower head and the cylinder, with the upper end of each outer tube embedded in and fixed to the upper tube sheet, and the lower end embedded in and fixed to the lower tube sheet.

[0007] Furthermore, each of the outer tubes is internally arranged with an inner tube, which includes a straight tube arranged coaxially with the outer tube and a bent tube extending from both ends of the outer tube; the upper end of the straight tube of the inner tube extends out of the upper tube sheet until the bent tube connects and communicates with the upper ring tube, and the lower end extends out of the lower tube sheet until the bent tube connects and communicates with the lower ring tube; the upper ring tube is connected to the inner tube medium outlet pipe, and the lower ring tube is connected to the inner tube medium inlet pipe.

[0008] Furthermore, an annular space for catalyst loading is formed between the outer tube and the inner tube, and the radial distance between the inner wall surface of the outer tube and the outer wall surface of the inner tube is 5 to 12 times the average particle size of the catalyst; the space between the outer tube and the cylinder is the shell-side medium flow region, and the interior of the inner tube is the inner tube medium flow region.

[0009] Furthermore, the straight tube of the inner tube and the outer wall surface inside the outer tube are provided with 2-10 sets of fin assemblies along the axial direction, each set of fin assemblies including 2-6 fins, which are evenly arranged along the circumferential direction.

[0010] Furthermore, the gap between the radially outer end face of each fin and the inner wall of the outer tube is greater than 0.5 times the average particle size of the catalyst and less than 1.5 times the average particle size of the catalyst.

[0011] Furthermore, the opening of the upper end cap is lined with a distribution plate, which is located 1-2 cm above the upper tube sheet. The upper end of the straight tube of each inner tube passes through the distribution plate and connects with the upper ring tube. The distribution plate has first openings, the diameter of which is 0.5-1 mm larger than the outer diameter of the inner tube, and the number of first openings is equal to the number of inner tubes. Second openings are evenly distributed around each first opening along the circumference, and the diameter of the second openings is no greater than 0.5 times the average particle size of the catalyst. The distribution plate is assembled into a circle by splicing sections.

[0012] Furthermore, the top of the lower end cap is lined with a support plate, which is installed below the lower ring pipe. The inner tube medium feed pipe passes through the support plate and connects with the lower ring pipe. The support plate has third openings, the diameter of which is larger than the outer diameter of the inner tube medium feed pipe, and the number of third openings is equal to the number of inner tube medium feed pipes. Around each third opening, fourth openings are evenly distributed along the circumference, the diameter of which is not less than 1 times the average particle size of the catalyst and not more than 3 times the average particle size of the catalyst. The support plate is assembled into a circle by splicing sections.

[0013] Furthermore, the multiple outer tubes are evenly distributed along the circumference.

[0014] Furthermore, the inner tube extends 2-20 cm beyond both the upper and lower tube sheets.

[0015] Furthermore, the spacing between any two adjacent sets of the fin assemblies may be equal or unequal.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1) The heat exchange area is significantly increased, and the bed hot spot temperature is significantly reduced. Traditional tubular reactors rely solely on the outer wall of the reaction tubes for heat exchange with the shell-side heat transfer medium. This invention, by installing a sleeve inside the reaction tubes, greatly increases the heat exchange area and can effectively control the bed hot spot temperature.

[0017] 2) The outer wall of the inner tube is provided with fins, which helps the catalyst to maintain good flowability when it falls from top to bottom and avoids the catalyst bridging in the annular cavity between the inner and outer tubes during loading; at the same time, the fins limit the inner tube and prevent the inner tube from deforming too much at high temperature and squeezing the catalyst; on the other hand, the addition of fins further increases the heat exchange area.

[0018] 3) The use of annular gas collection structures such as upper and lower annular pipes provides sufficient space for catalyst loading operations.

[0019] 4) Dual heat transfer medium channel design. The inner tube and the shell between the outer tube and the cylinder are two separate heat transfer medium flow spaces, so different types of heat transfer media can be used, making operation more flexible.

[0020] 5) The overall structure of the reactor is extremely simple. For existing traditional tubular reactors, the modification can be completed by adding inner tubes and upper and lower annular tubes and increasing the number of openings, which can significantly improve the heat exchange efficiency. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of the shell-and-tube reactor of the present invention; Figure 2 for Figure 1 Schematic diagram of the inner tube structure; Figure 3 for Figure 1 Schematic diagram of the upper and middle ring pipe structure; Figure 4 This is a comparison chart of the catalyst bed temperature distribution curves for Example 1, Example 2, and Comparative Example 1. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments to facilitate a clearer understanding of the invention, but these descriptions do not constitute a limitation on the invention.

[0023] like Figure 1 , 2The shell-and-tube reactor shown is suitable for gas-solid exothermic catalytic reactions. It includes an upper head 3, a cylinder 10, a lower head 14, an inner tube medium outlet pipe 2 inserted into the upper head 3, an inner tube medium inlet pipe 16 inserted into the lower head 14, and multiple outer tubes 9 arranged inside the cylinder 10, which are evenly distributed along the circumference. The upper head 3 has an air inlet 1, the upper part of the cylinder 10 has a shell-side medium outlet 7, the lower part has a shell-side medium inlet 11, and the lower head 14 has an air outlet 17. An upper tube sheet 6 is arranged between the upper head 3 and the cylinder 10, and a lower tube sheet 12 is arranged between the lower head 14 and the cylinder 10. The upper end of each outer tube 9 is embedded in the upper tube sheet 6 and fixed, and the lower end is embedded in the lower tube sheet 12 and fixed.

[0024] Each outer tube 9 has an inner tube 8 inserted inside. The inner tube 8 includes a straight tube 8.1 coaxially arranged with the outer tube 9 and bent tubes 8.2 extending from both ends of the outer tube 9 (i.e., bent tubes 8.2 are located at both ends of the straight tube 8.1). The upper end of the straight tube 8.1 of the inner tube 8 extends out of the upper tube plate 6 until the bent tube 8.2 connects and communicates with the upper ring tube 4, and the lower end extends out of the lower tube plate 12 until the bent tube 8.2 connects and communicates with the lower ring tube 13. The straight tube 8.1 extends 2-20cm beyond both the upper tube plate 6 and the lower tube plate 12. The upper ring tube 4 is connected to the inner tube medium outlet tube 2, and the lower ring tube 13 is connected to the inner tube medium inlet tube 16. The number of inner tube medium outlet tubes 2 and inner tube medium inlet tubes 16 is at least one each. Figure 3 As shown, preferably two, both arranged symmetrically.

[0025] The catalyst is packed in the annular space between the outer tube 9 and the inner tube 8, and the radial distance between the inner wall of the outer tube 9 and the outer wall of the inner tube 8 is 5 to 12 times the average particle size of the catalyst. The space between the outer tube 9 and the cylinder 10 is the shell-side medium flow region, and the interior of the inner tube 8 is the inner tube medium flow region. The feed gas flows in from the inlet 1, the inner tube heat transfer medium enters from the inner tube medium feed pipe 16, and the shell-side heat transfer medium enters from the shell-side medium inlet 11. The feed gas and the heat transfer medium flow in countercurrent.

[0026] like Figure 2 Each inner tube 8, as shown, has 2-10 sets of fin assemblies arranged axially on its straight tube 8.1 inside the outer tube 9. The spacing between any two adjacent sets of fin assemblies may be equal or unequal. Each set of fin assemblies includes 2-6 fins 81, which are uniformly arranged circumferentially. The gap between the radially outer end face of each fin 81 and the inner wall of the outer tube 9 is greater than 0.5 times the average particle size of the catalyst and less than 1.5 times the average particle size of the catalyst.

[0027] A distribution plate 5 is placed at the opening of the upper end cap 3. The distribution plate 5 is located 1-2 cm above the upper tube plate 6, and the upper end of the straight tube 8.1 of each inner tube 8 passes through the distribution plate 5 and connects to the upper ring tube 4. The distribution plate 5 has first openings, the diameter of which is 0.5-1 mm larger than the outer diameter of the inner tube 8, and the number of first openings is equal to the number of inner tubes 8. Second openings are evenly distributed around each first opening along its circumference, and the diameter of the second openings is no greater than 0.5 times the average particle size of the catalyst. In this embodiment, the distribution plate 5 is assembled into a circle by splicing sections.

[0028] The top of the lower end cap 14 is lined with a support plate 15, which is installed below the lower ring pipe 13. The inner tube medium feed pipe 16 passes through the support plate 15 and connects to the lower ring pipe 13. The support plate 15 has third openings, the diameter of which is larger than the outer diameter of the inner tube medium feed pipe 16, and the number of third openings is equal to the number of inner tube medium feed pipes 16. Around each third opening, fourth openings are evenly distributed along the circumference, with a diameter not less than 1 times the average particle size of the catalyst and not greater than 3 times the average particle size of the catalyst. In this embodiment, the support plate 15 is assembled into a circle by splicing sections.

[0029] The working principle of this invention is as follows: 1) Catalyst and inert packing filling. First, inert ceramic balls are filled. After disassembling the distribution plate 5 above the filling area piece by piece, the ceramic balls are poured into the annular cavity between the straight pipe 8.1 of the inner tube 8 and the outer tube 9 by tilting. The ceramic balls are piled up on the bottom support plate 15 until they cover the entire lower end cap 14 and are higher than the lower tube sheet 12, at which point the filling of ceramic balls is stopped. Next, the catalyst is filled. The catalyst is poured into the annular cavity between the straight pipe 8.1 of the inner tube 8 and the outer tube 9 by tilting until the filling height is close to the lower surface of the upper tube sheet 6. Finally, ceramic balls are filled to fill the cavity between the upper tube sheet 6 and the distribution plate 5.

[0030] 2) Feed gas flow path. The feed gas enters from the top inlet 1, filling the cavity enclosed by the upper end cap 3 and the distribution plate 5. Then, the feed gas passes through the openings on the distribution plate 5 and enters the annular catalyst bed region between the inner tube 8 and the outer tube 9. The reacted product gas flows out from the annular catalyst bed region between the inner tube 8 and the outer tube 9 at the bottom, passes through the openings on the support plate 15, and exits the reactor through the outlet 17.

[0031] 3) Flow path of heat transfer medium. The reactor of the present invention contains two heat transfer media: the first heat transfer medium enters the lower ring pipe 13 from the inner tube medium inlet pipe 16, then enters the inner tube 8 connected to the lower ring pipe 13, passes through the inner tube 8 from bottom to top and enters the top upper ring pipe 4, and flows out of the reactor from the top inner tube medium outlet pipe 2; the second heat transfer medium enters the shell formed between the outer tube 9 and the cylinder 10 from the shell side medium inlet 11, flows in the opposite direction of gravity, fills the entire shell and flows out from the top shell side medium outlet 7.

[0032] Example 1 Reactor structure as follows Figure 1 As shown, the feed gas enters the reactor through inlet 1 at a flow rate of 3000 Nm³. 3 The feed gas consists of hydrogen and carbon dioxide, with a hydrogen to carbon dioxide molar ratio of 4. The first heat transfer medium is heat transfer oil with an inlet temperature of 473 K and a model number of BARRELTHERM400. It enters the lower annular pipe 13 from the inner tube medium inlet pipe 16, then enters the inner tube 8 connected to the lower annular pipe 13, passes through the inner tube 8 from bottom to top, enters the upper annular pipe 4, and flows out of the reactor from the upper inner tube medium outlet pipe 2. The second heat transfer medium is also heat transfer oil with an inlet temperature of 473 K and a model number of BARRELTHERM400. It enters the shell between the outer tube 9 and the cylinder 10 from the shell-side medium inlet 11, flows against gravity, fills the entire shell, and then flows out from the top shell-side medium outlet 7. The mass flow rate ratio of the second heat transfer medium to the first heat transfer medium is 35. The outer tube 9 has a height of 2m, an outer diameter of 35.8mm, and a wall thickness of 3mm. The straight section of the inner tube 8 has a height of 2.1m, an outer diameter of 10mm, and a wall thickness of 1.5mm. There are 1000 inner tubes 8 and 1000 outer tubes 9 in the reactor. Both the inner tube 8 and the outer tube 9 are made of austenitic stainless steel SUS316.

[0033] The reactor's total packing space consists of three parts: the first part is the cavity between the distribution plate 5 and the upper tube sheet 6; the second part is the annular space between the inner tube 8 and the outer tube 9; and the third part is the cavity between the lower tube sheet 12 and the support plate 15. The methanation catalyst is packed in the annular space between the inner tube 8 and the outer tube 9 to a height of 1.5 m, located in the middle of the reactor. The remaining packing space is filled with inert alumina ceramic balls. The catalyst loading per single reaction tube is 9.28... 10 -4 m 3 .

[0034] Figure 4The dashed line represents the temperature distribution of the catalyst bed along the axis of a single reaction tube in the reactor described in this embodiment. The hot spot temperature of the catalyst bed is 702K, the outlet temperature of the first heat transfer medium is 482K, and the outlet temperature of the second heat transfer medium is 473.6K. The carbon dioxide conversion rate at the reactor outlet is greater than 99%.

[0035] Example 2 The reactor structure and dimensions, feed gas flow rate and composition, second heat transfer medium type and inlet temperature, catalyst type and loading method are the same as in Example 1. The difference is that the product gas flowing out of the reactor from the outlet 17 is introduced into the inner tube medium feed pipe 16 as the first heat transfer medium. The application scenario of this example is: the product gas from the first stage reactor needs to be heated to enter the second stage reactor for further reaction.

[0036] Figure 4 The dashed line indicates the temperature distribution of the catalyst bed along the axis of a single reaction tube in the reactor described in this embodiment. The hot spot temperature of the catalyst bed is 788K, the outlet temperature of the first heat transfer medium is 523K, and the outlet temperature of the second heat transfer medium is 473.8K. The carbon dioxide conversion rate at the reactor outlet is greater than 99%.

[0037] Comparative Example 1 Assuming a conventional tubular reactor exists as a comparison with the reactor of this invention, this conventional tubular reactor has a shell-and-tube structure, with no sleeves or other internal components inside the reaction tubes. The space between the reaction tubes and the shell is the shell side, and this reactor contains only one heat transfer medium. The reaction tubes of this conventional tubular reactor are 2m long, 34mm in outer diameter, and 3mm thick. The methanation catalyst is loaded at a height of 1.5m in the middle of the reaction tube, and the alumina ceramic balls are loaded at each of the two ends for 0.25m lengths. The catalyst loading in a single reaction tube of the conventional tubular reactor is 9.24g. 10 -4 m 3 The conventional tubular reactor contains 1000 reaction tubes. The feed gas flow rate and composition, heat transfer medium type and inlet temperature are the same as in Example 1.

[0038] Figure 4 The solid line represents the temperature distribution of the catalyst bed in a single reaction tube within the reactor described in this comparative example along the axis of the reaction tube. The hot spot temperature of the catalyst bed is 886 K, the outlet temperature of the heat transfer medium is 473.8 K, and the carbon dioxide conversion rate at the reactor outlet is greater than 99%.

[0039] By comparing Example 1 with Comparative Example 1, it can be seen that, under the premise that the catalyst loading amount and feed gas flow rate are the same, the reactor of the present invention can significantly reduce the catalyst bed temperature and demonstrate good temperature control capability.

[0040] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A shell-and-tube reactor suitable for gas-solid strongly exothermic catalytic reactions, characterized in that: It includes an upper end cap (3), a cylinder (10), a lower end cap (14), an inner tube medium outlet pipe (2) inserted into the upper end cap (3), an inner tube medium inlet pipe (16) inserted into the lower end cap (14), and multiple outer tubes (9) arranged in the cylinder (10); the upper end cap (3) has an air inlet (1), the upper part of the cylinder (10) has a shell side medium outlet (7), the lower part has a shell side medium inlet (11), and the lower end cap (14) has an air outlet (17); an upper tube sheet (6) is arranged between the upper end cap (3) and the cylinder (10), and a lower tube sheet (12) is arranged between the lower end cap (14) and the cylinder (10). The upper end of each outer tube (9) is embedded in the upper tube sheet (6) and fixed, and the lower end is embedded in the lower tube sheet (12) and fixed.

2. The shell-and-tube reactor suitable for gas-solid strongly exothermic catalytic reactions according to claim 1, characterized in that: Each of the outer tubes (9) has an inner tube (8) inside. The inner tube (8) includes a straight tube (8.1) arranged coaxially with the outer tube (9) and a bent tube (8.2) extending from both ends of the outer tube (9). The upper end of the straight tube (8.1) of the inner tube (8) extends out of the upper tube plate (6) until the bent tube (8.2) is connected to the upper ring tube (4) and communicates with it. The lower end extends out of the lower tube plate (12) until the bent tube (8.2) is connected to the lower ring tube (13) and communicates with it. The upper ring tube (4) is connected to the inner tube medium outlet pipe (2), and the lower ring tube (13) is connected to the inner tube medium inlet pipe (16).

3. The shell-and-tube reactor suitable for gas-solid strongly exothermic catalytic reactions according to claim 2, characterized in that: An annular space for catalyst loading is formed between the outer tube (9) and the inner tube (8), and the radial distance between the inner wall surface of the outer tube (9) and the outer wall surface of the inner tube (8) is 5 to 12 times the average particle size of the catalyst; the outer tube (9) and the cylinder (10) are the shell-side medium flow area, and the inside of the inner tube (8) is the inner tube medium flow area.

4. The shell-and-tube reactor suitable for gas-solid strongly exothermic catalytic reactions according to claim 2, characterized in that: Each inner tube (8) has 2-10 sets of fin assemblies arranged along the axial direction on the outer wall surface of the straight tube (8.1) inside the outer tube (9). Each set of fin assemblies includes 2-6 fins (81) and is evenly arranged along the circumferential direction.

5. The shell-and-tube reactor suitable for gas-solid strongly exothermic catalytic reactions according to claim 4, characterized in that: The gap between the radial outer end face of each fin (81) and the inner wall of the outer tube (9) is greater than 0.5 times the average particle size of the catalyst and less than 1.5 times the average particle size of the catalyst.

6. The shell-and-tube reactor suitable for gas-solid strongly exothermic catalytic reactions according to claim 2, characterized in that: The opening of the upper end cap (3) is lined with a distribution plate (5). The distribution plate (5) is located 1-2 cm above the upper tube plate (6). The upper end of the straight tube (8.1) of each inner tube (8) passes through the distribution plate (5) and is connected to the upper ring tube (4). The distribution plate (5) has a first opening. The diameter of the first opening is 0.5-1 mm larger than the outer diameter of the inner tube (8). The number of first openings is equal to the number of inner tubes (8). A second opening is evenly distributed around each first opening along the circumference. The diameter of the second opening is not greater than 0.5 times the average particle size of the catalyst. The distribution plate (5) is assembled into a circle by splicing blocks.

7. The shell-and-tube reactor suitable for gas-solid strongly exothermic catalytic reactions according to claim 1 or 2, characterized in that: The top of the lower end cap (14) is lined with a support plate (15). The support plate (15) is installed below the lower ring pipe (13). The inner tube medium feed pipe (16) passes through the support plate (15) and is connected to the lower ring pipe (13). The support plate (15) has a third opening. The diameter of the third opening is larger than the outer diameter of the inner tube medium feed pipe (16), and the number of third openings is equal to the number of inner tube medium feed pipes (16). A fourth opening is evenly distributed around each third opening along the circumference. The diameter of the fourth opening is not less than 1 times the average particle size of the catalyst and not more than 3 times the average particle size of the catalyst. The support plate (15) is assembled into a circle by splicing blocks.

8. The shell-and-tube reactor according to claim 1, suitable for gas-solid strongly exothermic catalytic reactions, characterized in that: The multiple outer tubes (9) are evenly distributed along the circumference.

9. The shell-and-tube reactor suitable for gas-solid strongly exothermic catalytic reactions according to claim 2, characterized in that: The inner tube (8) extends 2-20cm beyond the upper tube sheet (6) and the lower tube sheet (12).

10. The shell-and-tube reactor suitable for gas-solid strongly exothermic catalytic reactions according to claim 4, characterized in that: The spacing between any two adjacent sets of the fin assemblies may be equal or unequal.

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