A mechanism for preventing overheating in a fixed-bed reactor

Abstract

This utility model discloses a mechanism for preventing overheating in a fixed-bed reactor, relating to the field of fixed-bed reactor technology. It includes a fixed-bed shell and a skirt connected to the bottom of the shell. This application, through a distribution shell combined with heating wires and a heating chamber, preheats and evenly distributes the incoming gas, solving the problem of excessive gas accumulation in the inlet area leading to a sudden increase in the catalyst reaction rate. Furthermore, the lack of preheating results in lower gas activity, making it more prone to concentrated bursts in the rear of the bed when reacting with the catalyst layer, thus causing overheating in the fixed-bed reactor. This improves the stability of the fixed-bed reactor. The application also utilizes a buffer tube combined with a flow divider to buffer and divert the incoming gas, solving the problem of direct gas impact through the reaction layer during inlet operation, resulting in low reaction efficiency and easy powder generation due to catalyst particle friction. This improves the reaction efficiency of the fixed-bed reactor and extends the service life of the reaction layer.

Description

Technical Field

[0001] This utility model relates to the field of fixed-bed reactor technology, specifically to a mechanism for preventing overheating in a fixed-bed reactor. Background Technology

[0002] Fixed-bed reactors are key equipment widely used in chemical, energy and other fields. Their core is to fix the catalyst in the bed, and the reactants complete the reaction by contacting the catalyst through the bed. Runaway temperature is a phenomenon in chemical reactions in which the heat released by the reaction far exceeds the heat dissipation capacity, causing heat to accumulate rapidly in a local area and the temperature to rise exponentially. Traditional fixed beds do not have measures for uniform distribution and preheating of the intake air. As a result, excessive accumulation of air in some areas during intake leads to a sudden increase in the reaction rate with the catalyst, and the heat released far exceeds the local heat dissipation capacity, which can easily cause overheating. At the same time, without preheating, the intake air has lower activity and is more likely to react with the catalyst layer in the middle and rear of the bed, which also causes a concentrated burst of heat, resulting in overheating. Moreover, the direct air intake of traditional fixed beds can cause severe catalyst wear in the reaction layer due to the direct impact of the air intake, resulting in a short service life of the reaction layer. At the same time, the direct impact of the air intake through the reaction layer causes uneven and incomplete reaction between the gas and the catalyst layer, resulting in low reaction efficiency of the fixed bed reactor. Utility Model Content

[0003] To address the above problems, this utility model provides a mechanism for preventing overheating in a fixed-bed reactor, thus solving the aforementioned issues.

[0004] To achieve the above objectives, this utility model provides the following technical solution: a mechanism for preventing overheating in a fixed bed reactor, comprising a fixed bed shell and a skirt connected to the bottom of the fixed bed shell, an air outlet connected to the lower part of the fixed bed shell, an air inlet connected to the top of the fixed bed shell, an air inlet pipe connected to the top of the air inlet, and a buffer pipe connected to one end of the air inlet pipe; The buffer tube is installed in the air inlet, and the diameter of the buffer tube decreases from top to bottom. A flow divider is connected to the inner wall of the buffer tube, and a distribution shell is connected to the bottom of the buffer tube. The bottom of the flow divider is installed in the distribution shell. The distribution shell has several partition plates connected inside, one end of each partition plate corresponds to the outer side of the diverter, the bottom of the distribution shell has several distribution holes, and the top of the distribution shell and the outside of the buffer tube are provided with heating wires.

[0005] Preferably, the side of the distribution shell is connected to the inner wall of the fixed bed shell, and the space between the distribution shell and the air inlet is a heating chamber.

[0006] Preferably, the inner wall of the distribution shell is connected to a support frame, and a reaction layer is provided on the top of the support frame.

[0007] Preferably, the reaction layer includes a catalyst layer, and stainless steel mesh is provided at both the upper and lower ends of the catalyst layer.

[0008] Preferably, one end of each of the two stainless steel meshes is provided with a ceramic layer, and the bottom of one of the ceramic layers is connected to the top of the support frame.

[0009] Preferably, a manhole is connected to the outside of the fixed bed shell, and a plurality of thermocouples are connected to one side of the fixed bed shell, with one end of each thermocouple disposed on the catalyst layer.

[0010] Compared with the prior art, the beneficial effects of this utility model are as follows: 1. This application uses a distribution shell, heating wire, and heating chamber to preheat and uniformly distribute the inlet gas, allowing the gas to reach the reaction layer evenly for catalytic reaction. It also increases the inlet gas temperature and reduces the initial temperature difference between the inlet gas and the catalyst layer. This solves the problem of excessive accumulation of gas in some areas of the inlet gas, which leads to a sudden increase in the reaction rate of the catalyst and releases heat far exceeding the local heat dissipation capacity. Furthermore, the inlet gas has low activity and is more likely to concentrate and explode in the middle and rear of the bed when reacting with the catalyst layer without preheating, causing temperature runaway in the fixed bed reactor. This is beneficial to improving the stability of the fixed bed reactor. 2. This application uses a buffer tube in conjunction with a flow divider to buffer and divert the incoming gas, preventing it from directly impacting the reaction layer. This extends the service life of the reaction layer and solves the problem that when the gas directly impacts the reaction layer during the intake of a fixed-bed reactor, the gas does not react fully with the catalyst layer, resulting in low reaction efficiency and easy powdering caused by mutual friction between catalyst particles. This is beneficial to improving the reaction efficiency of the fixed-bed reactor and extending the service life of the reaction layer. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the overall structure of this utility model; Figure 2 This is a schematic cross-sectional view of the fixed bed shell of this utility model; Figure 3 This is a schematic cross-sectional view of the overall structure of this utility model; Figure 4 This is a partial structural schematic diagram of the present invention; Figure 5 This is an exploded view of the buffer tube structure of this utility model; Figure 6 This is a schematic diagram of the flow divider and partition plate structure of this utility model; Figure 7 This is a schematic cross-sectional view of the distribution shell structure of this utility model.

[0012] The diagram shows the following labels: 1. Fixed bed shell; 2. Air outlet; 3. Air inlet; 4. Air inlet pipe; 5. Buffer pipe; 6. Flow divider; 7. Distribution shell; 8. Partition plate; 9. Distribution hole; 10. Heating wire; 11. Heating chamber; 12. Support frame; 13. Reaction layer; 14. Catalyst layer; 15. Stainless steel mesh; 16. Ceramic layer; 17. Skirt; 18. Manhole; 19. Thermocouple. Detailed Implementation

[0013] The embodiments of this utility model will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of this utility model.

[0014] Please see Figures 1 to 7 A mechanism for preventing overheating in a fixed-bed reactor includes a fixed-bed shell 1 and a skirt 17 connected to the bottom of the fixed-bed shell 1. The lower part of the fixed-bed shell 1 is connected to an outlet 2, which is connected to external equipment (the external equipment can be various, such as temporary storage equipment or equipment for subsequent processing; regardless of the type of equipment, it does not affect the normal operation of this fixed-bed reactor, so the external equipment will not be described or shown in detail) to discharge the gas after the reaction. Specifically, the gas to be reacted enters the fixed-bed shell 1 through an inlet pipe 4, a buffer pipe 5, and a distribution shell 7. After undergoing catalytic reaction in the reaction layer 13, it reaches the outlet 2 from the bottom of the reaction layer 13 and is discharged. The top of the fixed-bed shell 1 is connected to an inlet 3, and the top of the inlet 3 is connected to an inlet pipe 4. One end of the inlet pipe 4 is connected to a buffer pipe 5. The buffer tube 5 is installed in the air inlet 3. The diameter of the buffer tube 5 decreases from top to bottom. The inner wall of the buffer tube 5 is connected to the flow divider 6. The air inlet 4 delivers the gas to be reacted to the buffer tube 5. The gas is affected by the flow divider 6 in the buffer tube 5. At this time, the gas will be divided into several streams by the flow divider 6 and continue to enter the buffer tube 5. The flow divider 6 is the first buffer measure, that is, the flow divider 6 buffers and divides the incoming gas to prepare for the subsequent uniform distribution. During the flow of gas through the buffer tube 5, because the diameter of the buffer tube 5 decreases from top to bottom, it is affected by the Venturi effect (the flow velocity increases when the fluid flows through the narrowed section), which can enhance the flowability of the airflow and avoid the problem of airflow stagnation after the intake air is buffered and diverted by the diverter 6. The bottom of the buffer tube 5 is connected to the distribution shell 7, and the bottom of the diverter 6 is set in the distribution shell 7. The gas flows from the diverter 6 to the distribution shell 7. After diversion, the gas in the distribution shell 7 is separated by the partition plate 8 in conjunction with the diverter 6 to maintain the diversion of the intake air. Finally, the gas enters the interior of the fixed bed shell 1 through the distribution hole 9 at the bottom of the distribution shell 7. It is important to note that in order to prevent the reduced flow of the intake air after diversion from failing to reach the distribution holes 9 on the outer ring of the distribution shell 7 for discharge, and instead causing more air to be discharged through the distribution holes 9 on the inner ring, the Venturi effect of the decreasing diameter of the buffer tube 5 from top to bottom is utilized to accelerate the flow of the intake air in the distribution shell 7, so that the gas can quickly reach the outer ring of the distribution shell 7, and thus allow the intake air to enter through the various distribution holes 9 at the bottom of the distribution shell 7. The distribution shell 7 has several partition plates 8 connected inside. One end of the partition plate 8 corresponds to the outer side of the diverter 6. Several distribution holes 9 are opened at the bottom of the distribution shell 7. Heating wires 10 are provided at the top of the distribution shell 7 and outside the buffer tube 5.

[0015] The side of the distribution shell 7 is connected to the inner wall of the fixed bed shell 1. The distribution shell 7 is located in the upper part of the fixed bed shell 1, that is, above the reaction layer 13. The distribution shell 7 is connected to the inner wall of the fixed bed shell 1. Therefore, the space from the top of the distribution shell 7 to the air inlet 3 is a relatively closed space, which is the heating chamber 11. Specifically, the heating wire 10 at the top of the distribution shell 7 and outside the buffer tube 5 generates heat to preheat the intake air through the distribution shell 7 and the buffer tube 5. More specifically, when the heating wire 10 is working, the current passes through it, and the electrical energy is consumed by the resistance and converted into heat energy, thereby preheating the intake air. Its core is to use the resistance characteristics of the material to achieve efficient conversion of electrical energy into heat energy. The space between the distribution shell 7 and the air inlet 3 is the heating chamber 11. It should be further added that when the heating wire 10 is heating, because of the existence of the heating chamber 11, the heating chamber 11 can also maintain a certain temperature, thereby saving the cost of the heating wire 10 during operation and improving its working efficiency. It should be noted that a temperature sensor is provided in the heating chamber 11 to detect the temperature in the heating chamber 11, thereby facilitating the control and adjustment of the temperature of the heating wire 10. The temperature sensor is a conventional means that can be understood and implemented by those skilled in the art based on common sense, and it is very easy for those skilled in the art to implement without any additional mental effort, so it will not be elaborated on here.

[0016] The inner wall of the distribution shell 7 is connected to a support frame 12, and a reaction layer 13 is provided on the top of the support frame 12.

[0017] The reaction layer 13 includes a catalyst layer 14, with stainless steel mesh 15 at both the upper and lower ends of the catalyst layer 14. The ceramic layer 16 is made of porous ceramic and has a large number of interconnected pores inside. It can intercept small particles that may be contained in the intake air and prevent them from entering the catalyst layer 14 and clogging the pores or covering the active sites. Another ceramic layer 16 located in the lower layer suppresses the backflow that may come out at the outlet end through the design of the filling density and pore structure, so as to avoid interfering with the catalyst layer 14 and ensure that the reaction proceeds in the forward direction. Stainless steel mesh 15 is located between ceramic layer 16 and catalyst layer 14. It is used to support ceramic layer 16, prevent ceramic layer 16 from cracking or falling off, and prevent ceramic particles from mixing into catalyst layer 14. The other lower stainless steel mesh 15 focuses on protecting the catalyst layer 14 and fixing the catalyst, preventing the catalyst particles from migrating or being lost due to airflow or vibration, and avoiding them from entering the lower ceramic layer 16 and causing blockage. The catalyst layer 14 is the core area of ​​the reaction layer 13. It is usually composed of particulate, honeycomb or structured catalysts (supported metal catalysts, molecular sieve catalysts, etc.). The reactants in the inlet gas undergo adsorption, activation, reaction and desorption processes at the active sites of the catalyst to be efficiently converted into the target product. The support frame 12 is made of high temperature and high strength materials and is located at the bottom of the reaction layer 13. It is used to support the weight of all the upper bed layers (ceramic layer 16, stainless steel mesh 15, catalyst layer 14) and prevent the overall structure from collapsing due to its own weight or airflow impact. In summary, the airflow first passes through the upper ceramic layer 16 and stainless steel mesh 15 to optimize its state, then enters the catalyst layer 14 to undergo a core reaction. After the reaction, the airflow passes through the lower stainless steel mesh 15 and ceramic layer 16 for stable output. Finally, the support frame 12 supports the overall structure of the reaction layer 13 and ensures that the airflow is discharged evenly (the airflow reaches the bottom of the support frame 12 and is discharged through the air outlet 2).

[0018] Each of the two stainless steel meshes 15 has a ceramic layer 16 at one end, and the bottom of one of the ceramic layers 16 is connected to the top of the support frame 12.

[0019] A manhole 18 is connected to the outside of the fixed bed shell 1. After a period of use, the catalyst filled in the fixed bed reactor needs to be replaced due to decreased activity, coking, etc. The manhole 18 provides a relatively large passage, which facilitates the entry of personnel into the fixed bed shell 1 to unload the old catalyst and fill it with new catalyst. It can also be used for maintenance of the fixed bed reactor. Several thermocouples 19 are connected to one side of the fixed bed shell 1. One end of the thermocouple 19 is set on the catalyst layer 14. The thermocouples 19 can be installed at different positions on the catalyst layer 14. By converting the temperature signal into an electrical signal and transmitting it to the temperature display instrument or control system, the operator can obtain the temperature data of various points in the reactor in real time and intuitively understand the temperature distribution in the reactor. Thermocouples 19 are known technology, and those skilled in the art can and should understand their specific functions and structures, so they will not be described in detail here.

[0020] When using this utility model: First, the intake pipe 4 delivers the gas to be reacted to the buffer pipe 5. The gas is affected by the diverter 6 in the buffer pipe 5. At this time, the gas is divided into several streams by the diverter 6 and continues to enter the buffer pipe 5. The diverter 6 is the first buffer measure, that is, the diverter 6 buffers and divides the intake gas to prepare for subsequent uniform distribution. During the flow of the gas in the buffer pipe 5, because the diameter of the buffer pipe 5 decreases from top to bottom, it is affected by the Venturi effect (the flow velocity increases when the fluid flows through the narrow section), which can enhance the flow of the air and avoid the problem of the airflow being easily stagnant after the intake gas is buffered and divided by the diverter 6. Secondly, the gas flows from the splitter 6 to the distribution shell 7. The split gas in the distribution shell 7 is maintained by the partition plate 8 in conjunction with the splitter 6. Finally, the gas enters the interior of the fixed bed shell 1 through the distribution holes 9 at the bottom of the distribution shell 7. In order to prevent the reduced flow of the gas after splitting from failing to reach the distribution holes 9 on the outer ring of the distribution shell 7 for discharge, and instead discharge through the distribution holes 9 on the inner ring, the Venturi effect of the decreasing diameter of the buffer tube 5 from top to bottom can be used to accelerate the flow of the gas in the distribution shell 7, so that the gas can quickly reach the outer ring of the distribution shell 7, and then the gas can be introduced through the various distribution holes 9 at the bottom of the distribution shell 7. Then, the distribution shell 7 is set in the upper part of the fixed bed shell 1, that is, above the reaction layer 13, and the distribution shell 7 is connected to the inner wall of the fixed bed shell 1. Therefore, the space from the top of the distribution shell 7 to the air inlet 3 is a relatively closed space, which is the heating chamber 11. The heating wire 10 on the top of the distribution shell 7 and the outside of the buffer tube 5 generates heat to preheat the air intake through the distribution shell 7 and the buffer tube 5. More specifically, when the heating wire 10 is working, the current passes through it, and the electrical energy is consumed by the resistance and converted into heat energy, thereby preheating the air intake. Finally, after the airflow enters the fixed bed shell 1, it first passes through the upper ceramic layer 16 and stainless steel mesh 15 to optimize its state, and then enters the catalyst layer 14 to undergo a core reaction. The airflow after the reaction then passes through the lower stainless steel mesh 15 and ceramic layer 16 for stable output. Finally, the support frame 12 supports the overall structure of the reaction layer 13 and ensures that the airflow is discharged evenly (the airflow reaches the bottom of the support frame 12 and is discharged by the air outlet 2).

[0021] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A mechanism for preventing overheating in a fixed-bed reactor, comprising a fixed-bed shell (1) and a skirt (17) connected to the bottom of the fixed-bed shell (1), wherein an air outlet (2) is connected to the lower part of the fixed-bed shell (1) and an air inlet (3) is connected to the top of the fixed-bed shell (1), characterized in that: The top of the air inlet (3) is connected to an air inlet pipe (4), and one end of the air inlet pipe (4) is connected to a buffer pipe (5). The buffer tube (5) is installed in the air inlet (3). The diameter of the buffer tube (5) decreases from top to bottom. A flow divider (6) is connected to the inner wall of the buffer tube (5). A distribution shell (7) is connected to the bottom of the buffer tube (5). The bottom of the flow divider (6) is installed in the distribution shell (7). The distribution shell (7) is internally connected to several partition plates (8), one end of the partition plate (8) corresponds to the outer side of the diverter (6), the bottom of the distribution shell (7) is provided with several distribution holes (9), and the top of the distribution shell (7) and the outside of the buffer tube (5) are provided with heating wires (10).

2. The mechanism for preventing overheating in a fixed-bed reactor according to claim 1, characterized in that: The side of the distribution shell (7) is connected to the inner wall of the fixed bed shell (1), and the space between the distribution shell (7) and the air inlet (3) is a heating chamber (11).

3. The mechanism for preventing overheating in a fixed-bed reactor according to claim 1, characterized in that: The inner wall of the distribution shell (7) is connected to a support frame (12), and a reaction layer (13) is provided on the top of the support frame (12).

4. The mechanism for preventing overheating in a fixed-bed reactor according to claim 3, characterized in that: The reaction layer (13) includes a catalyst layer (14), and stainless steel mesh (15) is provided at both the upper and lower ends of the catalyst layer (14).

5. The mechanism for preventing overheating in a fixed-bed reactor according to claim 4, characterized in that: Both stainless steel meshes (15) have a ceramic layer (16) at one end, and the bottom of one of the ceramic layers (16) is connected to the top of the support frame (12).

6. The mechanism for preventing overheating in a fixed-bed reactor according to claim 1, characterized in that: The fixed bed housing (1) has a manhole (18) connected to its outer side, and a number of thermocouples (19) are connected to one side of the fixed bed housing (1). One end of the thermocouples (19) is placed on the catalyst layer (14).

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