Fixed bed reactor for catalyzing gas-phase reaction by solid-phase catalyst

Abstract

The invention provides a fixed bed reactor for catalyzing gas phase reaction by a solid phase catalyst, the fixed bed reactor comprises a reactor body and a heat transfer device arranged in the reactor body, the heat transfer device is a screw of which the length is matched with the internal height of the reactor body, and the pitch of a thread on the surface of the screw is a variable pitch. The interiors of the screw rod and the thread are hollow structures and are communicated with each other, two ends of the screw rod are respectively provided with a first heat transfer medium inlet and a first heat transfer medium outlet, and a gap between the interior of the reactor body and the exterior of the heat transfer device is used for filling a catalyst. According to the fixed bed reactor, by arranging the variable-pitch screw with the hollow interior, a heat transfer medium in the variable-pitch screw is distributed in the fixed bed reactor in the axial direction and the radial direction, the heat exchange area is increased, the retention time is prolonged, efficient and uniform heat transfer is achieved, and the temperature runaway phenomenon is avoided; meanwhile, the discharge amount of the catalyst is quantitatively controlled by controlling the number of turns of rotation of the screw, operation is easy and convenient, and replacement is rapid.

Description

Technical Field

[0001] The invention relates to the technical field of chemical equipment, and in particular to a fixed bed reactor for catalyzing gas phase reaction with a solid phase catalyst. Background Art

[0002] In recent years, with the vigorous development of the domestic chemical industry, a new round of large-scale synthesis process technology has been indirectly driven. Among various types of chemical synthesis equipment, fixed bed reactors are a common type of reactor equipment used for multiphase catalytic reactions, such as solid-phase catalysts catalyzing gas-phase reactions or catalyzing liquid-phase reactions. Generally, granular solid-phase catalysts or solid reactants are loaded inside the reactor to form a stacked bed layer of a certain height, and then the gas-phase or liquid-phase materials are allowed to flow through the static fixed bed layer through the gaps between the particles to achieve a heterogeneous reaction process. The characteristic of this type of reactor is that the solid particles loaded in the equipment are fixed, which is different from the moving bed reactor and fluidized bed reactor in which the solid particles move in the reactor, so it is also called a packed bed reactor.

[0003] The existing traditional fixed bed reactor has poor and uneven internal heat transfer. When the reaction releases a lot of heat, it is very easy for the reaction temperature to lose control, rise sharply, and exceed the allowable range. In addition, there are problems such as the inactivated catalyst cannot be replaced in time, which prolongs the process cycle and leads to a long production synthesis cycle. It can be seen that as an important core device for chemical production, the structure of the fixed bed reactor has a relatively large impact on chemical production. It is also extremely necessary to reasonably construct its internal facilities and optimize the equipment size parameters. As a device that mainly affects and controls the internal heat transfer effect of the fixed bed reactor, the heat transfer device installed inside the fixed bed reactor is its core device, and its research, development and improvement have also attracted much attention.

[0004] Existing traditional fixed bed reactors generally use two methods: external heat exchange and internal heat exchange. For the external heat exchange method, due to the low thermal conductivity of most catalysts, the temperature in the central area of ​​the fixed bed reactor often fails to meet the expected requirements; for the internal heat exchange method, there are many tube bundles involved inside the fixed bed reactor. When one or more of the tube bundles leak, it is difficult to be discovered and repaired in time, resulting in the catalyst being contaminated by the heat transfer medium and losing its function, resulting in a high loss cost. Regarding the problem of replacing the catalyst in the fixed bed reactor, at this stage, the method of filling the fixed bed reactor with excess catalyst is generally adopted to achieve the purpose of extending the catalyst replacement time, but this method also increases the operating cost of the equipment in disguise to a certain extent.

[0005] In addition, there are many studies on optimizing the internal heat transfer of fixed bed reactors at home and abroad, such as a tube-type fixed bed reactor (CN 116251541A) with a component introduced into the tube pass, which uses internal components to strengthen the radial heat transfer in the tube pass of the tube-type fixed bed reactor, reduce the temperature difference in the tube pass, and thus optimize the reaction conditions and catalytic activity; and a patent for a mixed flow tube-type fixed bed reactor (CN 116272686A), which provides a mixed flow tube-type fixed bed reactor with strong heat exchange in the upper cross-flow and low pressure drop in the small parallel flow, and meets the characteristics of strong heat exchange, low pressure loss, and low energy consumption. Although the above scheme can improve the heat exchange efficiency by increasing the disturbance, it cannot ensure that the temperature distribution inside the fixed bed reactor is uniform. Therefore, for a fixed bed reactor used for solid-phase catalyst catalytic gas phase reaction, designing a device that can efficiently and uniformly transfer heat and reduce the cost of catalyst replacement is of great significance to actual chemical production. Summary of the invention

[0006] The present invention aims to provide a fixed bed reactor for solid-phase catalyst-catalyzed gas phase reaction, which solves the shortcomings of traditional fixed bed reactors, such as poor heat transfer effect, uneven heat transfer, difficulty in replacing catalysts, and long time consumption.

[0007] To achieve the above object, the present invention proposes the following technical solutions:

[0008] A fixed bed reactor for solid-phase catalyst catalyzed gas phase reaction, comprising a reactor body and a heat transfer device arranged inside the reactor body, wherein the heat transfer device is a screw having a length adapted to the internal height of the reactor body, the pitch of the thread on the surface of the screw is a variable pitch, the interior of the screw and the thread are both hollow structures and the two are interconnected, and a first heat transfer medium inlet and a first heat transfer medium outlet are respectively arranged at both ends of the screw;

[0009] The gap between the inside of the reactor body and the outside of the heat transfer device is used to fill the catalyst, and the opposite ends of the reactor body are respectively provided with a catalyst inlet and a catalyst outlet.

[0010] As a preferred technical solution of the present invention, the pitch of the thread gradually increases from the catalyst inlet side to the catalyst outlet side.

[0011] As a preferred technical solution of the present invention, the initial pitch of the thread is 1 / 2-1 / 200 of the length of the screw located inside the reactor body.

[0012] As a preferred technical solution of the present invention, the side walls at opposite ends of the reactor body are respectively provided with a reactant inlet and a product outlet;

[0013] The thickness of the thread decreases from the reactant inlet side to the product outlet side, and the thickness of the thread is 1 / 20-1 / 20000 of the inner height of the reactor body.

[0014] As a preferred technical solution of the present invention, the thread is any one of a common thread, a trapezoidal thread, a serrated thread, a pipe thread, a rectangular thread, a circular arc thread, and a triangular thread.

[0015] As a preferred technical solution of the present invention, the shape of the catalyst is any one of spherical, cylindrical, three-leaf clover, and four-leaf clover, or a mixture of more than one of them.

[0016] As a preferred technical solution of the present invention, the maximum equivalent diameter of the catalyst is 0.1 mm-10 mm.

[0017] As a preferred technical solution of the present invention, the reactor body comprises an outer shell and an inner shell, the outer shell and the inner shell enclose a closed heat exchange interlayer, and the radius ratio of the outer shell to the inner shell is 1.05-1.50;

[0018] The shell is provided with a second heat transfer medium inlet and a second heat transfer medium outlet which are in communication with the heat exchange interlayer;

[0019] The reactant inlet and the product outlet are respectively arranged on the bottom side and the top side of the inner container.

[0020] As a preferred technical solution of the present invention, a plurality of array-like uniformly distributed fins are provided on the outer side wall of the inner liner, and the maximum height of the fins is not greater than the difference between the radius of the outer shell and the radius of the inner liner. The length direction is the direction in which the fins are parallel to the axial direction of the inner liner, the width direction is the direction in which the fins extend along the circumferential direction of the inner liner side wall, and the height direction is the direction in which the fins extend toward the inner wall of the outer shell.

[0021] As a preferred technical solution of the present invention, the cross-sectional shape of the fin is any one of a triangle, a rectangle and a trapezoid.

[0022] Compared with the prior art, the fixed bed reactor for solid-phase catalyst-catalyzed gas-phase reaction provided by the technical solution of the present invention has at least the following beneficial effects:

[0023] First, a hollow variable pitch screw is arranged inside the reactor body, so that the first heat transfer medium flows inside the screw and the screw thread, so that the first heat transfer medium is distributed not only in the axial direction inside the fixed bed reactor, but also in the radial direction thereof, so that the first heat transfer medium is distributed in both the axial and radial directions inside the fixed bed reactor, which not only increases the heat exchange area between the first heat transfer medium and the reaction materials, but also achieves the effect of uniform heat transfer, thereby ensuring uniform temperature distribution inside the reactor body;

[0024] Second, the pitch of the thread gradually increases from the catalyst inlet to the catalyst outlet, thereby being able to prolong the residence time of the first heat transfer medium in the screw and the thread. In this way, the use of the screw with variable pitch threads increases the heat transfer contact area and residence time of the first heat transfer medium at the same time, thereby improving the heat exchange capacity of the first heat transfer medium, improving the heat exchange efficiency of the heat transfer device, achieving efficient and uniform heat transfer, and stabilizing the temperature inside the reactor body within the desired ideal value, reducing the hazards of catalyst deactivation and increase of by-products caused by local overheating;

[0025] Third, when the catalyst inside the reactor body is always in excess, the variable pitch and variable thread thickness settings of the threads, compared with the equal pitch settings, affect the flow trend of the gas-phase reactant fluid to a certain extent, prolonging the residence time of the gas-phase reactants inside the reactor body, which is equivalent to prolonging the reaction time of the gas-phase reactants in contact with the catalyst, thereby increasing the yield of the product. Although more heat will be released, the excess heat will be absorbed by the heat exchange capacity of the variable pitch screw, so that the temperature inside the reactor body is stabilized within the desired ideal value;

[0026] Fourth, the reactor body is also provided with a heat exchange interlayer and a plurality of array-type uniformly distributed fins therein, wherein the base end of the fin is connected to the outer wall of the inner tank, that is, the base end of the fin is in direct contact with the high-temperature side, and the heat of the high-temperature side can be extracted from the base end thereof and released to the heat exchange interlayer for heat exchange with the second heat transfer medium, thereby achieving the heat transfer effect of the heat exchange interlayer enhanced by the fins, further enhancing the heat transfer effect of the entire fixed bed reactor, and avoiding the occurrence of temperature runaway phenomenon;

[0027] Fifth, in addition, the rotation of the screw can be used to squeeze the catalyst out of the reactor body to replace the catalyst, and the emission of the catalyst can be quantitatively controlled by controlling the number of rotation turns. The operation is simple and convenient, and the replacement is quick and timely, which greatly shortens the production synthesis cycle.

[0028] It should be appreciated that all combinations of the foregoing concepts, as well as additional concepts described in greater detail below, may be considered to be part of the inventive subject matter of the present disclosure, provided such concepts are not mutually inconsistent.

[0029] The foregoing and other aspects, embodiments and features of the present invention can be more fully understood from the following description in conjunction with the accompanying drawings. Other additional aspects of the present invention, such as the features and / or beneficial effects of the exemplary embodiments, will be apparent from the following description or learned from the practice of the specific embodiments according to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings are not drawn to scale according to actual reference objects. In the accompanying drawings, each identical or nearly identical component shown in various figures may be represented by the same reference numeral. For the sake of clarity, not every component is labeled in each figure. Now, embodiments of various aspects of the present invention will be described by way of example and with reference to the accompanying drawings, in which:

[0031] Figure 1 A schematic diagram of the internal structure of a fixed bed reactor according to an embodiment of the present invention;

[0032] Figure 2 Schematic diagram of the thread structure of a screw rod according to an embodiment of the present invention;

[0033] Figure 3 is a schematic diagram of the ratio of the radius of the outer shell and the inner liner of an embodiment of the present invention;

[0034] Figure 4 A schematic diagram of the connection between the triangular fin and the inner container according to an embodiment of the present invention;

[0035] Figure 5 It is a schematic diagram of the connection between the rectangular fins and the inner container according to an embodiment of the present invention.

[0036] The meanings of the reference numerals in the figures are as follows:

[0037] 1-screw 2-thread 3-shell 4-liner 5-first heat transfer medium inlet 6-first heat transfer medium outlet 7-reactant inlet 8-product outlet 9-second heat transfer medium inlet 10-second heat transfer medium outlet 11-catalyst inlet 12-catalyst outlet 13-rib DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be the common meaning understood by people with general skills in the field to which the present invention belongs.

[0039] The words "first", "second" and similar words used in the patent application specification and claims of the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, unless the context clearly indicates otherwise, the singular forms of "a", "an" or "the" and similar words do not indicate a quantitative limitation, but indicate the existence of at least one. Words such as "include" or "comprise" mean that the elements or objects appearing before "include" or "comprise" cover the features, wholes, steps, operations, elements and / or components listed after "include" or "comprise", and do not exclude the existence or addition of one or more other features, wholes, steps, operations, elements, components and / or their collections. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0040] The embodiment of the present invention provides a fixed bed reactor for solid-phase catalyst catalyzed gas phase reaction, comprising a reactor body and a heat transfer device, wherein the heat transfer device is arranged inside the reactor body. Figure 1 As shown, the heat transfer device is a screw 1 whose length is adapted to the internal height of the reactor body, and the outer surface of the screw 1 is provided with a spirally continuously raised thread 2 along its length direction, and the pitch of the thread 2 is a variable pitch, and the interior of the screw 1 and the thread 2 are both hollow structures and the two are connected to each other, and the two ends of the screw 1 are respectively provided with a first heat transfer medium inlet 5 and a first heat transfer medium outlet 6. The first heat transfer medium is introduced into the screw 1 and the thread 2 through the first heat transfer medium inlet 5, and the first heat transfer medium is discharged from the first heat transfer medium outlet 6 after heat transfer between the first heat transfer medium and the material.

[0041] The gap between the inside of the reactor body and the outside of the heat transfer device is used to fill the catalyst. The opposite ends of the reactor body are respectively provided with a catalyst inlet 11 and a catalyst outlet 12. The pitch of the screw thread 2 gradually increases from the catalyst inlet 11 side to the catalyst outlet 12 side, so that the catalyst can be squeezed out from the catalyst outlet 12. The catalyst enters the reactor body from the catalyst inlet 11 and fills the gap between the inside of the reactor body and the outside of the heat transfer device. After the catalyst is deactivated, it is squeezed out from the catalyst outlet by the screw 1, and a new catalyst is loaded into the catalyst inlet 11 to replace the catalyst. The operation is simple and convenient, the replacement is fast, and the discharge amount of the catalyst can be quantitatively controlled by controlling the number of rotation turns of the screw 1, so as to realize quantitative control of the replacement amount of the catalyst.

[0042] In the embodiment of the present invention, the reactor body is a cylindrical structure, a reactant inlet is provided on the bottom side of the reactor body, and a product outlet is provided on the top side. The screw 1 is arranged in the middle of the reactor body, and the thread 2 is continuously extended in a spiral shape along the length direction of the screw 1 and protrudes from the outer surface of the screw 1, so that the thread 2 is not only extended axially inside the reactor body, but also extended radially inside the reactor body, so that the first heat transfer medium inside the thread 2 is in contact with the axial and radial materials inside the reactor body for heat exchange, which not only increases the heat transfer area of ​​the first heat transfer medium, but also realizes uniform heat transfer everywhere inside the reactor body, thereby achieving efficient and uniform heat transfer effect.

[0043] In the embodiment of the present invention, the pitch of the thread 2 gradually increases from the catalyst inlet 11 to the catalyst outlet 12, so that after the first heat transfer medium enters from the first heat transfer medium inlet, the more it flows toward the first heat transfer medium outlet, the longer its residence time inside the screw 1 and the thread 2, and the longer the contact time with the reaction material, so as to fully exchange heat and improve the heat exchange capacity of the first heat transfer medium. The initial pitch of the thread (starting from the end with the smaller pitch) is 1 / 2-1 / 200 of the length of the screw located inside the reactor body.

[0044] The thickness of the thread 2 shows a decreasing trend from the reactant inlet 7 side to the product outlet 8 side. In the embodiment of the present invention, the reactant inlet 7 is arranged at the bottom of the reactor body and the product outlet 8 is arranged at the top of the reactor body, so the thread 2 shows an increasing trend from bottom to top. The thickness of the thread 2 is 1 / 20-1 / 20000 of the internal height of the reactor body. In the embodiment of the present invention, the synthesis of methanol from carbon monoxide and hydrogen is an exothermic reaction. The high-temperature area of ​​the reaction is mainly concentrated in the reactant inlet section. In this section, the thickness of the thread 2 is designed to be larger, which can increase the surface area of ​​the thread 2 here, thereby increasing the heat exchange area, and further enhancing the heat exchange effect of the first heat exchange medium in this section; while the heat release near the reactant outlet section is slightly weaker, and therefore the heat exchange requirement is also slightly weaker, so the thickness of the thread 2 in this section can be reduced to make the volume of the thread 2 smaller, which can increase the filling amount of the catalyst in this section, and further increase the filling amount of the catalyst in the entire reactor body, so that the catalyst is always kept in an overfilled state. Figure 2 As shown, the thread 2 is any one of a common thread, a trapezoidal thread, a serrated thread, a pipe thread, a rectangular thread, an arc thread, and a triangular thread, but is not limited to the above-mentioned types of threads.

[0045] In an embodiment of the present invention, the shape of the catalyst is any one of spherical, cylindrical, clover-shaped, and four-leaf clover-shaped, or a mixture of more than one of them, but is not limited to the above shapes. Regardless of the shape, the maximum equivalent diameter of the catalyst is 0.1mm-10mm.

[0046] In the embodiment of the present invention, the material of the reactor body is preferably a metal or alloy material with good thermal conductivity or corrosion resistance, including but not limited to copper, iron-based alloy materials and nickel-based corrosion-resistant alloy materials. The reactor body includes an outer shell 3 and an inner liner 4, and the outer shell 3 and the inner liner 4 are enclosed to form a closed heat exchange interlayer, such as Figure 3 As shown, the radius ratio of the outer shell 3 to the inner liner 4 is 1.05-1.50. The outer wall of the inner liner 4 is provided with a plurality of array-like evenly distributed fins 13, and the maximum height of the fins 13 is not greater than the difference between the radius of the outer shell 3 and the radius of the inner liner 4. Figure 4 and Figure 5 As shown, the cross-sectional shape of the fin 13 is any one of a triangle, a rectangle and a trapezoid. The length direction is the direction in which the fin 13 is parallel to the axial direction of the inner tank 4, the width direction is the direction in which the fin 13 extends along the circumferential direction of the side wall of the inner tank 4, and the height direction is the direction in which the fin 13 extends toward the inner wall of the shell 3. The heat transfer capacity of the heat exchange interlayer is enhanced by the fin 13, and the heat transfer effect of the entire fixed bed reactor is further enhanced, so as to avoid the phenomenon that the reaction temperature of the fixed bed reactor loses control, rises sharply, and exceeds the allowable range.

[0047] The shell 3 is provided with a second heat transfer medium inlet 9 and a second heat transfer medium outlet 10 connected to the heat exchange interlayer, and the second heat transfer medium inlet 9 is used to add the second heat transfer medium into the heat exchange interlayer, and discharge it from the second heat transfer medium outlet 10 after heat exchange. The bottom side and the top side of the inner tank 4 are respectively provided with a reactant inlet 7 and a product outlet 8.

[0048] The first heat transfer medium inlet 5 and the first heat transfer medium outlet 6 are respectively located in the middle of the top and the middle of the bottom of the inner liner 4. The first heat transfer medium inlet 5 and the first heat transfer medium outlet 6 are directly arranged at the top and the bottom of the screw 1, and the two pass through the top and the bottom of the inner liner 4 respectively, completely isolating the interior of the heat transfer device from the internal space of the inner liner 4, so that the first heat transfer medium inside the heat transfer device and the materials and catalysts in the inner liner 4 are not mixed. The catalyst inlet 11 and the catalyst outlet 12 are respectively arranged at the top side and the bottom side of the inner liner 4. When the screw 1 rotates, the catalyst entering from the catalyst inlet 11 is pushed to the catalyst outlet 12 side through the thread, and finally the deactivated catalyst can be squeezed out from the inside of the reactor body. The reactant inlet 7 is arranged on the side of the inner liner 4 0.1m-1.5m away from the bottom of the inner liner 4, and the product outlet 8 is arranged on the top side of the inner liner 4 0.1m-1.5m away from the top of the inner liner 4. The second heat transfer medium inlet 9 is arranged on the bottom side of the shell 3 at a distance of 0.1m-1.5m from the bottom of the shell 3, and the second heat transfer medium outlet 10 is arranged on the top side of the shell 3 at a distance of 0.1m-1.5m from the top of the shell 3; the second heat transfer medium enters the heat exchange interlayer from the second heat transfer medium inlet 9, and is discharged from the second heat transfer medium outlet 10 after heat exchange.

[0049] As can be seen from the above, in the embodiment of the present invention, the first heat transfer medium flows in the countercurrent direction relative to the reaction material, and has a higher average temperature difference and a more uniform temperature distribution, because the countercurrent operation can ensure that the temperature of the heat transfer medium is close to the temperature of the heat transfer medium, making the average temperature difference larger, thereby improving the heat transfer efficiency; at the same time, it can make the heat be transferred to the heat transfer medium more evenly, reducing the temperature gradient and temperature non-uniformity. The second heat transfer medium flows in the forward direction relative to the reaction material, and its advantage is that compared with the relatively complex internal hollow structure inside the heat transfer device, the heat exchange interlayer structure is relatively simple and easy to maintain. Among them, the first heat transfer medium and the second heat transfer medium can be selected according to the needs to play a heat transfer or heat conduction role. Heat transfer medium, such as but not limited to water, clean air and oil, etc.

[0050] Example 1

[0051] In this embodiment, the synthesis of methanol by hydrogenation of carbon monoxide is taken as an example. The screw length is 12m, the thread shape is rectangular, the maximum thickness of the thread is 0.2m, the initial thread pitch is 1m, the ratio of the shell of the reactor body to the radius of the inner shell is 1.25, and the catalyst shape is spherical and the equivalent diameter is 5mm. Under these parameters, the geometric model is established and a three-dimensional steady-state simulation is performed in COMSOL software. The first heat transfer medium in the heat transfer device is water, with an initial temperature of 490K and a mass flow rate of 0.5kg / s; the second heat transfer medium in the heat exchange interlayer is also water, with an initial temperature of 490K and a mass flow rate of 0.7kg / s. The internal pressure of the reactor body is 50bar, and the reactants are a mixture of carbon monoxide, carbon dioxide, hydrogen and nitrogen, with an initial temperature of 500K and a mass flow rate of 5kg / s. Through simulation, it is found that when the heat transfer reaches stability, the average temperature drop of the reactor liner is about 6.7% of the temperature before heat dissipation, and the average temperature drop of the reactor wall is about 8.3% of the temperature before heat dissipation, and the heat exchange effect is more obvious.

[0052] Example 2

[0053] This embodiment adopts the same reaction system as that of Example 1, except that the thread is set to a triangle, and other experimental conditions are consistent with its simulation conditions. Through simulation, it is found that when the heat transfer reaches stability, the average temperature drop of the inner tank is about 6.3% of the temperature before heat dissipation, the average temperature drop of the wall of the fixed bed reactor is about 7.4% of the temperature before heat dissipation, and the outlet methanol concentration is about 5% higher than the outlet methanol concentration of Example 1, indicating that the methanol yield of this embodiment is higher than the methanol yield of Example 1. Since the catalyst filled in the inner tank is always excessive, the change in the thread shape of the screw affects the flow trend of the gas-phase reactant fluid to a certain extent, thereby affecting the residence time of the gas-phase reactant in the catalyst, which has a certain effect on the progress of the synthesis reaction. In order to realize the smooth rotation of the variable pitch screw and realize the transmission function of the catalyst, a thread of a suitable shape can be selected according to actual needs.

[0054] Example 3

[0055] This embodiment adopts the same reaction system as that of Example 1, except that the initial thread pitch is 0.5m, and the other experimental conditions are consistent with the simulation conditions of Example 1. Through simulation, it is found that when the heat transfer reaches stability, the temperature of the fixed bed reactor drops significantly, wherein the average temperature of the inner tank drops by about 11.9% of the temperature before heat dissipation, the average temperature of the wall of the fixed bed reactor drops by about 10.2% of the temperature before heat dissipation, and the outlet methanol concentration is about 10% higher than the outlet methanol concentration of Example 1. Therefore, it is explained that reducing the initial thread pitch in the fixed bed reactor can extend the residence time of the first heat transfer medium in the variable pitch screw and its thread interior, thereby improving its heat exchange capacity and enhancing the heat exchange effect. Therefore, when the catalyst inside the fixed bed reactor is always in excess, reducing the initial thread pitch will affect the flow trend of the reaction gas, extend the residence time of the reaction gas in the reactor, thereby extending the reaction time of the reaction gas in contact with the catalyst, thereby improving the yield of the product and releasing more heat, and the additional heat released is offset by the heat exchange capacity further improved by the variable pitch screw.

[0056] Example 4

[0057] This embodiment adopts the same reaction system as Example 1, the screw length is 12m, the thread shape is rectangular, the maximum thickness of the thread is 0.3m, the initial thread pitch is 1m, the radius ratio of the shell to the liner of the fixed bed reactor is 1.5, the catalyst shape is spherical and the equivalent diameter is 3mm. Under this parameter, the geometric model is established and a three-dimensional steady-state simulation is performed in COMSOL software, wherein the first heat transfer medium is water, the initial temperature is 490K, and the mass flow rate is 1.0kg / s; the second heat transfer medium is water, the initial temperature is 490K, and the mass flow rate is 1.0kg / s. The internal pressure of the reactor body is 60bar, and the reactants are a mixture of carbon monoxide, carbon dioxide, hydrogen and nitrogen, with an initial temperature of 500K and a mass flow rate of 5kg / s. Through simulation, it is found that when the heat transfer reaches stability, the average temperature drop of the reactor liner is about 12.77% of the temperature before heat dissipation, and the average temperature drop of the reactor wall is about 14.97% of the temperature before heat dissipation. By comparing Example 1, Example 2 and Example 3, it is found that under the process conditions adopted in Example 4, the heat exchange effect of the heat transfer medium is optimal, and the reaction gas has a longer residence time in the reactor, thereby obtaining a higher product yield, indicating that increasing the thickness of the thread can increase the heat transfer area of ​​the first heat transfer medium at the reactant inlet, thereby improving the heat exchange capacity, maintaining the reaction temperature in this area at a normal level, and avoiding deactivation of the catalyst in this area due to high temperature, thereby affecting the reaction.

[0058] Example 5

[0059] This example uses the same reaction system as Example 1, except that fins are added to the outer wall of the inner tank to enhance heat transfer, and other experimental conditions are consistent with the simulation conditions. Through simulation, it is found that when the heat transfer reaches stability, the average temperature drop of the inner tank of the fixed bed reactor is about 7.85% of the temperature before heat dissipation, and the average temperature drop of the wall of the fixed bed reactor is about 9.17% of the temperature before heat dissipation. It is explained that compared with Example 1, adding fins in the heat exchange interlayer and utilizing the heat conduction effect of the fins to enhance the heat exchange capacity of the heat exchange interlayer, thereby improving the overall heat exchange capacity of the fixed bed reactor.

[0060] Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. A person with ordinary knowledge in the technical field to which the present invention belongs may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the definition of the claims.

Claims

1. A fixed bed reactor for solid-phase catalyst catalyzed gas phase reaction, comprising a reactor body and a heat transfer device arranged inside the reactor body, characterized in that: The heat transfer device is a screw (1) whose length is adapted to the internal height of the reactor body, the pitch of the thread (2) on the surface of the screw (1) is a variable pitch, the interior of the screw (1) and the thread (2) are both hollow structures and are interconnected, and the two ends of the screw (1) are respectively provided with a first heat transfer medium inlet (5) and a first heat transfer medium outlet (6); The gap between the inside of the reactor body and the outside of the heat transfer device is used to fill the catalyst, and the opposite ends of the reactor body are respectively provided with a catalyst inlet (11) and a catalyst outlet (12).

2. The fixed bed reactor for solid-phase catalyst-catalyzed gas phase reaction according to claim 1, characterized in that: The pitch of the thread (2) gradually increases from the catalyst inlet (11) side to the catalyst outlet (12) side.

3. The fixed bed reactor for solid phase catalyst catalyzed gas phase reaction according to claim 1, characterized in that: The initial pitch of the thread (2) is 1 / 2-1 / 200 of the length of the screw (1) located inside the reactor body.

4. The fixed bed reactor for solid phase catalyst catalyzed gas phase reaction according to claim 1, characterized in that: The side walls at opposite ends of the reactor body are respectively provided with a reactant inlet (7) and a product outlet (8); The thickness of the thread (2) decreases from the reactant inlet (7) side to the product outlet (8) side, and the thickness of the thread (2) is 1 / 20-1 / 20000 of the internal height of the reactor body.

5. The fixed bed reactor for solid phase catalyst catalyzed gas phase reaction according to claim 1, characterized in that: The thread (2) is any one of a common thread, a trapezoidal thread, a zigzag thread, a pipe thread, a rectangular thread, a circular arc thread, and a triangular thread.

6. The fixed bed reactor for solid-phase catalyst-catalyzed gas phase reaction according to claim 1, characterized in that: The catalyst is in the shape of any one of sphere, cylinder, clover leaf, and four-leaf clover, or a mixture of more than one of them.

7. The fixed bed reactor for solid-phase catalyst-catalyzed gas phase reaction according to claim 6, characterized in that: The maximum equivalent diameter of the catalyst is 0.1 mm to 10 mm.

8. The fixed bed reactor for solid-phase catalyst-catalyzed gas phase reaction according to claim 4, characterized in that: The reactor body comprises an outer shell (3) and an inner shell (4), wherein the outer shell (3) and the inner shell (4) enclose a closed heat exchange interlayer, and a radius ratio between the outer shell (3) and the inner shell (4) is 1.05-1.50; The shell (3) is provided with a second heat transfer medium inlet (9) and a second heat transfer medium outlet (10) which are in communication with the heat exchange interlayer; The reactant inlet (7) and the product outlet (8) are respectively arranged on the bottom side and the top side of the inner container (4).

9. The fixed bed reactor for solid-phase catalyst-catalyzed gas phase reaction according to claim 8, characterized in that: A plurality of ribs (13) evenly distributed in an array are provided on the outer side wall of the inner container (4), and the maximum height of the ribs (13) is not greater than the difference between the radius of the outer shell (3) and the radius of the inner container (4).

10. The fixed bed reactor for solid-phase catalyst-catalyzed gas phase reaction according to claim 9, characterized in that: The cross-sectional shape of the fin (13) is any one of a triangle, a rectangle and a trapezoid.

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