A shell and tube fixed bed isothermal reactor

Abstract

The present invention discloses an isothermal axial shell-and-tube reactor, comprising a shell, an upper tube box, an upper end cap, a lower end cap also serving as a lower tube box, a heat exchange tube bundle and a lower fixed tube sheet, wherein the upper end cap and the lower end cap also serving as a lower tube box are fixed at both ends of the shell respectively; the lower fixed tube sheet is fixed between the lower end of the shell and the lower end cap, and further comprises an upper tube box and a plurality of flexible reaction gas delivery pipes and an upper floating tube sheet, wherein the upper tube box and the upper floating tube sheet are floatingly located in the middle and upper part of the shell, the upper floating tube sheet is fixedly connected to the bottom of the upper tube box, and the upper and lower ends of the heat exchange tube bundle are fixedly connected to the upper floating tube sheet and the lower fixed tube sheet respectively; the first ends of the plurality of flexible reaction gas delivery pipes are connected to the upper tube box so as to feed the reaction gas to the upper tube box, and the second ends are connected to the upper end cap or / the shell and extend to the outside so as to allow the reaction gas from the outside to enter each flexible reaction gas delivery pipe. The present invention solves the problem of temperature difference and thermal stress in the shell-and-tube process of the traditional fixed tube sheet shell-and-tube reactor.

Description

Technical Field

[0001] The present invention belongs to the technical field of coal chemical industry and natural gas chemical industry, and relates to a shell-and-tube fixed bed isothermal reactor suitable for fixed bed gas-solid phase exothermic catalytic reaction, in which the reaction gas of the shell-and-tube fixed bed isothermal reactor passes through the catalyst along the axial direction of the heat exchange tube, the reaction heat is quickly taken away and saturated steam is produced as a by-product, and the bed layer is basically at a uniform temperature. It is particularly suitable for CO shift reaction, methanol synthesis, ethylene glycol synthesis, methane synthesis, etc. Background Art

[0002] With the development of chemical production, in order to adapt to different heat transfer requirements and heat transfer methods, a variety of fixed bed reactor structures have emerged. Among them, the gas-solid catalytic reactor that utilizes gaseous reactants to react through a bed composed of solid catalysts is the most widely used in chemical production.

[0003] Fixed bed reactors can be divided into two categories based on reaction principle: adiabatic type and heat exchange type.

[0004] Adiabatic fixed bed reactors have a simple structure and are widely used. However, in actual operation, adiabatic reactors cannot achieve very high efficiency, mainly due to two limitations:

[0005] ① Limitation of chemical equilibrium; for exothermic reactions, the higher the temperature, the less favorable it is for the reaction to approach equilibrium, while lowering the temperature will reduce the reaction rate;

[0006] ② The reaction temperature rise makes the catalyst bed temperature far beyond the catalyst use range, which will cause the active components on the catalyst surface to sinter, the specific surface area to drop significantly, the activity to drop, the side reactions to intensify, and even cause temperature runaway and damage the equipment; therefore, for exothermic catalytic reaction devices, in order to achieve a deeper reaction, a multi-stage adiabatic bed process with heat exchange is usually adopted. The process is lengthy and the heat exchange network is complex. It is constrained by the energy balance of the whole plant and has a greater impact on load fluctuations and changes in the composition of the raw gas, which is not conducive to the long-term stable and safe operation of the device.

[0007] The isothermal reactor uses heat exchange elements to remove the reaction heat in time and keep the bed basically at a constant temperature. Its main advantages are:

[0008] ①Isothermal operation makes the actual reaction temperature curve close to the maximum reaction rate curve, greatly improving the reaction rate and making the reaction tend to equilibrium;

[0009] ②Isothermal reaction provides a mild operating environment for the catalyst, thus extending the life of the catalyst;

[0010] ③ The method of using water circulation by-product steam to remove the reaction heat of the catalyst bed has been proven to be effective through decades of practice. It has strong controllability and can effectively control the catalyst bed temperature by adjusting the by-product steam pressure;

[0011] ④ Isothermal reaction effectively prevents the occurrence of catalyst bed overheating, while avoiding possible side reactions in certain reactions, thereby improving the safety of the device.

[0012] With the characteristics of large-scale equipment and diversified coal gasification technology, the use of isothermal reactors, or the combined use of isothermal reactors and adiabatic reactors will be more suitable for certain process requirements.

[0013] In the prior art, the commonly used axial isothermal reactor is a fixed tube sheet type isothermal tube reactor, in which the catalyst is loaded in the heat exchange tube, the tube sheet is welded to the shell, the reaction gas flows axially in the tube, and the water vapor on the shell side removes the reaction heat and produces steam as a by-product. Considering the temperature difference between the tube and shell, the heat exchange tube is made of duplex steel, and the catalyst is supported by alumina balls in the lower tube box. However, in engineering practice, problems such as failure of the heat exchange tube joints, cracks in the tube sheet, and failure of the welds between the tube sheet and the shell have occurred due to the uncoordinated deformation of the heat exchange tube and the tube sheet; at the same time, with the enlargement of the reactor specifications, alumina balls are used in large quantities, which brings about problems such as heavy equipment operation weight and difficulty in sorting when replacing catalysts.

[0014] Purpose of the Invention

[0015] The present invention is aimed at the above problems existing in the above-mentioned existing fixed tube plate type isothermal tube reactor and discloses an isothermal axial tube shell reactor.

[0016] In order to achieve the above object, the technical solution adopted by the present invention is:

[0017] An isothermal axial shell and tube reactor comprises a shell, an upper tube box, an upper head, a lower head also serving as a lower tube box, a heat exchange tube bundle and a lower fixed tube sheet, wherein the upper head and the lower head also serving as the lower tube box are respectively fixed at the upper and lower ends of the shell in the axial direction; the lower fixed tube sheet is fixed between the lower end of the shell in the axial direction and the lower head also serving as the lower tube box, and is characterized in that it also comprises an upper tube box and a plurality of flexible reaction gas delivery pipes and an upper floating tube sheet, wherein the upper tube box and the upper floating tube sheet are floatingly located in the middle and upper part of the shell, the upper floating tube sheet is fixedly connected to the bottom of the upper tube box, the upper and lower ends of the heat exchange tube bundle are respectively fixedly connected to the upper floating tube sheet and the lower fixed tube sheet and are parallel to the axis of the shell; the first ends of the plurality of flexible reaction gas delivery pipes are connected to the upper tube box so as to feed the reaction gas into the upper tube box, and the second ends of the plurality of flexible reaction gas delivery pipes are connected to the upper head or / the shell and extend to the outside so that the reaction gas from the outside enters each flexible reaction gas delivery pipe.

[0018] In a preferred embodiment of the present invention, a plurality of heat exchange tube support plates are arranged in the shell between the upper floating tube plate and the lower fixed tube plate at intervals along the axial direction of the shell, each heat exchange tube support plate is provided with heat exchange tube holes whose number is the same as the number of heat exchange tubes in the heat exchange tube bundle, the outer periphery of each heat exchange tube support plate is fixedly connected to the shell, each heat exchange tube in the heat exchange tube bundle passes through the corresponding heat exchange tube holes on all the heat exchange tube support plates, and the outer diameter of each heat exchange tube is slidably matched with the inner diameter of the corresponding heat exchange tube hole.

[0019] In a preferred embodiment of the present invention, a water hole is provided on each heat exchange tube support plate.

[0020] In a preferred embodiment of the present invention, a plurality of flexible reaction gas delivery pipes are bent and spiraled along the interior of the upper cover and the interior of the shell to the upper pipe box, leaving an intermediate channel space.

[0021] In a preferred embodiment of the present invention, there are four flexible reaction gas delivery pipes, and the first ends of the four flexible reaction gas delivery pipes are evenly connected to the upper pipe box to deliver the reaction gas to the upper pipe box. The second ends of every two flexible reaction gas delivery pipes are connected to a reaction gas pipe joint after being connected in parallel. The two reaction gas pipe joints are evenly connected to the upper head or / and the shell and extend to the outside so that the reaction gas from the outside can enter each flexible reaction gas delivery pipe.

[0022] In a preferred embodiment of the present invention, each heat exchange tube is filled with a catalyst, and a catalyst support structure is provided at the bottom of the lower fixed tube sheet to support the catalyst in each heat exchange tube.

[0023] In a preferred embodiment of the present invention, a compressed metal mesh is provided in the section of each heat exchange tube located in the lower fixed tube plate, the compressed metal mesh is used to support the catalyst in each heat exchange tube, and the lower end of the compressed metal mesh is supported on the catalyst support structure.

[0024] In a preferred embodiment of the present invention, the catalyst support structure is a V-shaped mesh catalyst support structure; the V-shaped mesh catalyst support structure includes a plurality of V-shaped meshes and a plurality of support plates, each support plate is provided with a plurality of V-shaped grooves, all the support plates are fixed on the inner wall of the lower head which also serves as the lower pipe box, and each V-shaped mesh is inserted into the corresponding V-shaped grooves of all the support plates.

[0025] In a preferred embodiment of the present invention, a V-shaped mesh gap is left between adjacent V-shaped meshes to allow air to flow without causing the catalyst to fall.

[0026] In a preferred embodiment of the present invention, all the V-shaped nets and all the supporting plates can be combined in a split structure or fixed to form a whole.

[0027] Due to the adoption of the above technical solution, the present invention fixes the lower fixed tube sheet with the shell, the upper floating tube sheet with the upper tube box, the upper tube box is floatingly arranged in the shell and connected to the upper head through a flexible reaction gas delivery pipe, and the shell, the upper floating tube sheet, the lower fixed tube sheet, the upper tube box and the heat exchange tube bundle constitute the basic heat transfer elements. Compared with the traditional fixed tube sheet shell and tube reactor, it first solves the problem of temperature difference thermal stress in the shell and tube process of the traditional fixed tube sheet shell and tube reactor. Compared with the traditional fixed tube sheet reactor, the temperature difference stress and deformation can be released, avoiding the failure of the heat exchange tube joints, tube sheet welds and the like, and enhancing the reliability of the equipment. Secondly, it solves the problem that the traditional fixed tube sheet shell and tube reactor usually uses dual-phase steel materials to reduce the thermal expansion difference between the heat exchange tube and the shell, and the reaction temperature is controlled below 300°C. The use of the present invention can reduce the material selection, and only the material selection is based on the corrosion characteristics of the reaction gas, and chemical reactions with larger temperature differences can be accepted.

[0028] In addition, by arranging a compressed metal wire mesh in the section of each heat exchange tube located in the lower fixed tube sheet and cooperating with the V-net catalyst support structure arranged at the bottom of the lower fixed tube sheet, the catalyst can be well supported without affecting the gas flow, avoiding the traditional reactor using a large number of stacked alumina balls to support the catalyst, which not only greatly reduces the operating weight of the reactor but also avoids the problem of difficulty in sorting alumina balls when unloading the catalyst. The V-net used is high in strength, controllable in opening rate, and can be installed in blocks. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic structural diagram of the isothermal axial shell and tube reactor of the present invention.

[0030] Figure 2 for Figure 1 An enlarged schematic diagram of point I.

[0031] Figure 3 for Figure 2 AA section view.

[0032] Figure 4 for Figure 2 BB cross-sectional view.

[0033] Figure 5 It is a schematic diagram of the catalyst in the heat exchange tube of the present invention being supported by a compressed metal wire mesh and a V-shaped mesh catalyst support structure.

[0034] Figure 6 It is a three-dimensional schematic diagram of the V-net catalyst support structure of the present invention.

[0035] Figure 7 It is a front view of the V-net catalyst support structure of the present invention.

[0036] Figure 8 It is a top view of the V-net catalyst support structure of the present invention. DETAILED DESCRIPTION

[0037] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0038] See also Figure 1 An isothermal axial shell and tube reactor shown in the figure comprises a shell 10, an upper head 30, a lower head 40 also serving as a lower tube box, a heat exchange tube bundle 50 and a lower fixed tube sheet 60. The upper head 30 and the lower head 40 also serving as a lower tube box are respectively fixed to the upper and lower ends of the shell 10 in the axial direction by welding; the lower fixed tube sheet 60 is fixed between the lower end of the shell 10 in the axial direction and the lower head 40 also serving as the lower tube box, and an operation manhole 31 and a plurality of saturated water vapor outlets 32 are provided on the upper head 30.

[0039] Compared with the traditional fixed tube sheet shell and tube reactor, the present invention has the following characteristics:

[0040] It also includes an upper tube box 20, a plurality of flexible reaction gas delivery pipes 80 and an upper floating tube sheet 70. The upper tube box 20 and the upper floating tube sheet 70 are floatingly located in the middle and upper part of the shell 10. The upper tube box 20 is a hemispherical shell. The upper floating tube sheet 70 is fixedly connected to the bottom of the upper tube box 20 (or called the inner tube box) (that is, the bottom of the hemispherical shell) by welding, so that the upper tube box 20 and the upper floating tube sheet 70 form a pressure-bearing cavity. The pressure-bearing cavity should consider sufficient space and set an operating manhole 21 on the top of the upper tube box 20 to facilitate catalyst loading and equipment maintenance.

[0041] The upper and lower ends of the heat exchange tube bundle 50 are respectively fixedly connected with the upper floating tube sheet 70 and the lower fixed tube sheet 60 by welding and are parallel to the axis of the shell 10; since the upper tube box 20 and the upper floating tube sheet 70 are also located in the upper middle part of the shell 10 by floating, the thermal expansion difference between the heat exchange tube bundle 50 and the shell 10 can be absorbed, which solves the problem of thermal stress of the tube shell of the traditional fixed tube sheet shell reactor. Compared with the traditional fixed tube sheet reactor, the thermal stress and deformation of the heat exchange tube joint and the tube sheet weld are released, and the failure of the heat exchange tube joint and the tube sheet weld is avoided, and the reliability of the equipment is enhanced. In addition, the problem that the traditional fixed tube sheet shell reactor usually uses dual-phase steel materials to reduce the thermal expansion difference between the heat exchange tube and the shell and the reaction temperature is controlled below 300°C is solved. Therefore, the various parts of the present invention can reduce the material selection, and only the material selection is based on the corrosion characteristics of the reaction gas, and chemical reactions with larger temperature differences can be accepted.

[0042] In addition, an annular gap A is left between the upper floating tube sheet 70 and the interior of the shell 10, so that water vapor can flow upward through the annular gap after heat exchange is completed.

[0043] In order to enable the pressure chamber surrounded by the upper tube box 20 and the upper floating tube sheet 70 to float up and down, the present invention uses a plurality of flexible reaction gas delivery pipes 80 to input reaction gas into the pressure chamber surrounded by the upper tube box 20 and the upper floating tube sheet 70 .

[0044] As a preferred solution of the present invention, there are four flexible reaction gas delivery pipes 80 (of course, it is not limited to four and may also be one, two, three or more than four, but the number of flexible reaction gas delivery pipes 80 should be matched according to the process requirements, but must have sufficient strength and absorb thermal expansion). When configuring the flexible reaction gas delivery pipe 80, the thermal expansion difference between the heat exchange tube bundle 50 and the shell 10 should be considered, especially special operating conditions such as starting and stopping.

[0045] See especially Figures 2 to 4 The first ends of the four flexible reaction gas delivery pipes 80 are evenly connected to the upper tube box 90 so as to deliver the reaction gas into the pressure-bearing cavity surrounded by the upper tube box 20 and the upper floating tube plate 70. The second ends of every two flexible reaction gas delivery pipes 80 are connected in parallel to a reaction gas pipe connector 81. The two reaction gas pipe connectors 81 are evenly connected to the upper head 30 and extended to the outside (of course, they can also be evenly connected to the shell 10 and extended to the outside) so that the reaction gas from the outside can enter each flexible reaction gas delivery pipe 80.

[0046] The first ends of the four flexible reaction gas delivery pipes 80 are each provided with a reaction gas inlet distributor 82 , and the reaction gas is evenly distributed through the reaction gas inlet distributor 82 into the pressure-bearing cavity surrounded by the upper tube box 20 and the upper floating tube sheet 70 .

[0047] Four flexible reaction gas delivery pipes 80 are bent and spiraled along the interior of the upper head 30 and the interior of the shell 10 to the upper pipe box 20, leaving an intermediate channel space to facilitate catalyst loading and equipment maintenance.

[0048] Continue to see Figure 1In the shell 10 between the upper floating tube sheet 70 and the lower fixed tube sheet 60, a plurality of heat exchange tube support plates are arranged at intervals along the axial direction of the shell 10. Each heat exchange tube support plate 100 is provided with heat exchange tube holes (not shown in the figure) the same as the number of heat exchange tubes 51 in the heat exchange tube bundle 50. The outer periphery of each heat exchange tube support plate 100 is fixedly connected to the shell 10 by welding. Each heat exchange tube 51 in the heat exchange tube bundle 50 passes through the corresponding heat exchange tube hole on the heat exchange tube support plate 100. The outer diameter of each heat exchange tube 51 is slidably matched with the inner diameter of the corresponding heat exchange tube hole. In addition, a water hole (not shown in the figure) is provided on each heat exchange tube support plate 100. Further, a plurality of heat exchange tube support plates 100 can be connected by a tie rod (not shown in the figure).

[0049] The present invention further comprises a downcomer assembly 90 . To ensure uniform distribution of water vapor on the shell side, the downcomer assembly 90 has a plurality of water supply inlets (not shown in the figure). The water supply inlets are evenly distributed on the shell 10 and communicate with the interior of the shell 10 .

[0050] A gas outlet collector 41 and an operating manhole are provided on the lower head 40 which also serves as the lower pipe box. The gas inlet of the gas outlet collector 41 is connected with the interior of the lower head 40 which also serves as the lower pipe box to collect the reaction gas after the reaction. The gas outlet of the gas outlet collector 41 is connected with the outside to send the gas out of the reactor to the next process.

[0051] See also Figures 5 to 8 In order to allow the reaction gas entering the heat exchange tube 51 to fully undergo a catalytic reaction, each heat exchange tube 51 is filled with a catalyst 52 .

[0052] In order to provide good support for the catalyst 52 in each heat exchange tube 51 and not affect the gas flow, a compressed metal mesh 53 is provided in the section of each heat exchange tube 51 located in the lower fixed tube sheet 60, and a catalyst support structure 54 is provided at the bottom of the lower fixed tube sheet 60. The compressed metal mesh 53 is used to support the catalyst 52 in each heat exchange tube 51, and the lower end of the compressed metal mesh 51 is supported on the catalyst support structure 54. The height of the compressed metal mesh 51 is determined by the distance from the upper surface of the fixed tube sheet 60 to the upper surface of the catalyst support structure 54.

[0053] The catalyst support structure 54 is a V-net catalyst support structure; the V-net catalyst support structure includes a plurality of V-nets 54a and a plurality of support plates 54b, each support plate 54b is provided with a plurality of V-grooves 54ba, all support plates 54b are fixed on the inner wall of the lower head 40 which also serves as the lower pipe box, and each V-net 54a is inserted into the corresponding V-grooves 54ba of all support plates 54b. A V-net gap 54ab is left between adjacent V-nets 54a to allow air to flow without causing the catalyst to fall.

[0054] All the V-shaped nets 54a and all the supporting plates 54b can be combined in a split structure or fixed to form a whole.

[0055] The above-mentioned compressed metal wire mesh 53 combined with the catalyst support structure 54 can provide good support for the catalyst without affecting the gas circulation, avoiding the traditional reactor using a large number of stacked alumina balls to support the catalyst, greatly reducing the operating weight of the reactor and avoiding the problem of difficulty in sorting alumina balls when unloading the catalyst.

[0056] The loading of the catalyst 52 of the isothermal axial shell and tube reactor is the same as that of the conventional tube reactor, and the unloading is considered to adopt the top vacuum suction method, which is highly efficient and avoids dust pollution.

[0057] When the catalyst 50 is loaded in the heat exchange tube 51, in order to allow the reaction heat to be quickly taken away by the water vapor outside the heat exchange tube 52, the catalyst 50 is loaded to the upper floating tube sheet 70. Considering the shrinkage rate of the catalyst, the loading height is higher than the upper floating tube sheet 70, and it is ensured that the catalyst enters under the upper floating tube sheet 70 after shrinkage.

[0058] The working principle of the isothermal axial shell and tube reactor of the present invention is as follows:

[0059] The reaction gas enters the four flexible reaction gas delivery pipes 80 from the two reaction gas pipe joints 110 provided on the upper end cap 30, and is evenly distributed through the four flexible reaction gas delivery pipes 80 and the reaction gas inlet distributor 120 to enter the pressure-bearing cavity surrounded by the upper tube box 20 and the upper floating tube sheet 70. The reaction gas entering the pressure-bearing cavity surrounded by the upper tube box 20 and the upper floating tube sheet 70 enters the heat exchange tube 51 containing the catalyst 52 for catalytic reaction. The reaction heat generated by the catalytic reaction is removed in time by the saturated water vapor outside the heat exchange tube 51.

[0060] After the reaction is completed through the heat exchange tube 51, the reaction gas enters the lower head 40 which also serves as the lower tube box, is collected by the gas outlet collector 41, and is sent out from the gas outlet of the gas outlet collector 41 to enter the next process.

[0061] At the same time, boiler feed water and steam drum downcomer feed water are evenly distributed into the shell 10 from several water feed inlets of the downcomer assembly 90 arranged at the lower part of the shell 10. The water vapor absorbs the reaction heat in the heat exchange tube 51 and flows from bottom to top through the water holes on each heat exchange tube support plate 200. After completing the heat exchange, the water vapor continues to enter the upper head 30 upward through the annular gap between the upper floating tube plate 70 and the interior of the shell 10, and is finally sent out through several saturated water vapor outlets 32 arranged on the upper head 30 to enter the steam-water separation (steam drum) equipment.

[0062] The isothermal axial shell-and-tube reactor is used for a methanol synthesis tower with a capacity of 500,000 tons / year. The diameter of the shell 10 in the isothermal axial shell-and-tube reactor is DN4000mm, the length of the heat exchange tube bundle 50 is 8000mm, and the catalyst 52 is loaded with 52m 3 The metal net weight of the isothermal axial shell and tube reactor is ~185 tons, and the weight of the catalyst 52 is ~68 tons. The bottom of the catalyst 52 is not supported by alumina balls, which can reduce the operating weight by ~40 tons compared with the traditional methanol synthesis tower that uses alumina balls to support the catalyst. The shell side produces 2.5MPag~4.0MPag medium-pressure saturated steam (pressure adjustable), the reaction hot spot temperature is ~280℃, and the thermal expansion difference between the heat exchange tube bundle 50 and the shell 10 is absorbed by the upper floating tube sheet 60 and the flexible reaction gas delivery pipe 80. The equipment is safe and reliable.

Claims

1. An isothermal axial shell and tube reactor, comprising a shell, an upper head, a lower head also serving as a lower tube box, a heat exchange tube bundle and a lower fixed tube sheet, wherein the upper head and the lower head also serving as a lower tube box are respectively fixed at the upper and lower ends of the shell in the axial direction; the lower fixed tube sheet is fixed between the lower end of the shell in the axial direction and the lower head also serving as the lower tube box, characterized in that: It also includes an upper tube box, a plurality of flexible reaction gas delivery pipes and an upper floating tube sheet, wherein the upper tube box and the upper floating tube sheet are floatingly located in the middle and upper part of the shell, the upper floating tube sheet is fixedly connected to the bottom of the upper tube box, and the upper and lower ends of the heat exchange tube bundle are respectively fixedly connected to the upper floating tube sheet and the lower fixed tube sheet and are parallel to the axis of the shell; The first ends of a plurality of flexible reaction gas delivery pipes are connected to the upper pipe box so as to deliver reaction gas to the upper pipe box, and the second ends of a plurality of flexible reaction gas delivery pipes are connected to the upper head or the shell and extend to the outside so that reaction gas from the outside can enter each flexible reaction gas delivery pipe; Each heat exchange tube of the heat exchange tube bundle is filled with a catalyst, and a catalyst support structure is arranged at the bottom of the lower fixed tube sheet to support the catalyst in each heat exchange tube; A compressed metal mesh is arranged in the section of each heat exchange tube located in the lower fixed tube sheet, the compressed metal mesh is used to support the catalyst in each heat exchange tube, and the lower end of the compressed metal mesh is supported on the catalyst support structure; The catalyst support structure is a V-shaped mesh catalyst support structure; the V-shaped mesh catalyst support structure includes a plurality of V-shaped meshes and a plurality of support plates, each support plate is provided with a plurality of V-shaped grooves, all the support plates are fixed on the inner wall of the lower head which also serves as the lower pipe box, and each V-shaped mesh is inserted into the V-shaped groove corresponding to all the support plates; A V-shaped mesh gap is left between adjacent V-shaped meshes to allow air to flow without causing the catalyst to fall.

2. An isothermal axial shell and tube reactor according to claim 1, characterized in that: A plurality of heat exchange tube support plates are arranged in the shell between the upper floating tube plate and the lower fixed tube plate at intervals along the axial direction of the shell. Each heat exchange tube support plate is provided with heat exchange tube holes whose number is the same as the number of heat exchange tubes in the heat exchange tube bundle. The outer periphery of each heat exchange tube support plate is fixedly connected to the shell. Each heat exchange tube in the heat exchange tube bundle passes through the corresponding heat exchange tube holes on all the heat exchange tube support plates. The outer diameter of each heat exchange tube is slidably matched with the inner diameter of the corresponding heat exchange tube hole.

3. An isothermal axial shell and tube reactor according to claim 2, characterized in that: A water hole is provided on each heat exchange tube support plate.

4. The isothermal axial shell and tube reactor according to claim 1, characterized in that: A plurality of flexible reaction gas delivery pipes are bent and spiraled along the interior of the upper cover head and the interior of the shell to the upper pipe box, leaving an intermediate channel space.

5. An isothermal axial shell and tube reactor according to claim 4, characterized in that: There are four flexible reaction gas delivery pipes, and the first ends of the four flexible reaction gas delivery pipes are evenly connected to the upper pipe box to deliver the reaction gas to the upper pipe box. The second ends of every two flexible reaction gas delivery pipes are connected to a reaction gas pipe joint after being connected in parallel. The two reaction gas pipe joints are evenly connected to the upper head or the shell and extend to the outside, so that the reaction gas from the outside can enter each flexible reaction gas delivery pipe.

6. The isothermal axial shell and tube reactor according to claim 1, characterized in that: All V-shaped nets and all supporting plates are combined with a split structure, or fixed to form a whole.

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