Heat exchanger for bentazone production

Abstract

A heat exchanger used in bentazone production relates to the field of heat exchange equipment, and comprises a main shell, a heat exchange tube and an end socket, the heat exchange tube is arranged in the main shell, a tube fluid flows in the heat exchange tube, a shell fluid flows in a space between the outer wall of the heat exchange tube and the main shell, and the tube fluid and the shell fluid exchange heat through the tube wall of the heat exchange tube. A shell fluid inlet pipe and a shell fluid outlet pipe are arranged on the outer side of the main shell; two inlet branch pipes are arranged on the shell fluid inlet pipe, one ends of the two inlet branch pipes are respectively communicated with the shell fluid inlet pipe, and the other ends of the two inlet branch pipes are respectively communicated with the internal space of the main shell; the two inlet branch pipes and the two outlet branch pipes are arranged in the axis direction of the main shell. The inlet branch pipes and the outlet branch pipes are both provided with switch control devices, switch control over the inlet branch pipes and the outlet branch pipes can be achieved by operating the switch control devices, the passing path of shell fluid in the main shell is changed, and therefore the heat exchange capacity is adjusted.

Description

Technical Field

[0001] The invention belongs to the field of heat exchange equipment, and in particular relates to a heat exchanger used in bentazon production. Background Art

[0002] Bentazone is a chemical pesticide component. During the production of Bentazone, heat exchange of materials is required. In production practice, it is found that the heat exchangers currently used have the following problems: First, the temperature difference in northern my country is relatively large throughout the year, which causes the heat loss of the shell fluid in the heat exchanger to fluctuate greatly with changes in temperature. When the shell fluid flow rate is constant, the heat exchange capacity of the heat exchanger also fluctuates significantly, which in turn has an adverse effect on product quality.

[0003] Second, the heat exchange capacity of existing heat exchangers cannot be adjusted, making it difficult for the same heat exchanger to adapt to production processes with different requirements for heat exchange capacity. Summary of the invention

[0004] The invention provides a heat exchanger used in the production of bentazon, aiming to improve the cleaning effect of a filter screen in a vacuum feeder.

[0005] The technical problem solved by the present invention is achieved by the following technical solution: The present invention provides a heat exchanger for bentazon production, comprising a main shell, a heat exchange tube and a head, the heat exchange tube is arranged in the main shell, a tube fluid flows in the heat exchange tube, a shell fluid flows in the space between the outer wall of the heat exchange tube and the main shell, the tube fluid and the shell fluid exchange heat through the tube wall of the heat exchange tube, and a shell fluid inlet pipe and a shell fluid outlet pipe are arranged on the outer side of the main shell; The shell fluid inlet pipe is provided with two inlet branches, one end of the two inlet branches is respectively connected to the shell fluid inlet pipe, and the other end is respectively connected to the internal space of the main shell; similarly, the fluid outlet pipe is provided with two outlet branches, one end of the two outlet branches is respectively connected to the shell fluid outlet pipe, and the other end is respectively connected to the internal space of the main shell; Two inlet branch pipes are connected to the outside of one end of the main shell, and two outlet branch pipes are connected to the outside of the other end of the main shell; The two inlet branch pipes and the two outlet branch pipes are arranged along the axial direction of the main shell; The inlet branch pipe and the outlet branch pipe are both provided with a switch control device. By operating the switch control device, the switch control of each inlet branch pipe and the outlet branch pipe can be realized, and the passage path of the shell fluid in the main shell can be changed, thereby realizing the adjustment of the heat exchange capacity.

[0006] As a preferred solution, the switch control device is a valve, and each inlet branch pipe and outlet branch pipe is connected in series with one of the valves.

[0007] As a preferred solution, the shell fluid inlet pipe and the shell fluid outlet pipe each include a horizontal pipe section, and the two horizontal pipe sections are coaxial; The switch control device comprises a double-axis motor and two piston assemblies. A lead screw with the same pitch but opposite rotation direction is arranged at each end of the double-axis motor. The two piston assemblies are respectively connected to the two lead screws by threads. At the same time, the two piston assemblies are respectively slidably installed in two horizontal pipe sections and slidably cooperate with the horizontal pipe sections. The piston assembly includes a threaded piston, an end piston and a connecting rod. The end piston is fixedly connected to the threaded piston through the connecting rod. The threaded piston connects the piston assembly as a whole to the lead screw through threads. After the dual-axis motor is started, the rotational motion of the lead screw is converted into linear motion of the piston assembly as a whole, thereby adjusting the positions of the threaded piston and the end piston in the horizontal pipe section, thereby realizing the switch control of each inlet branch pipe and outlet branch pipe.

[0008] As a preferred solution, there are three typical positions of the piston assembly in the horizontal pipe section: The following provisions are made: the two inlet branches are called inlet branch No. 1 and inlet branch No. 2 in order from left to right, and the two outlet branches are called outlet branch No. 1 and outlet branch No. 2 in order from left to right, then: When in the first typical position, the No. 1 inlet branch pipe is connected, the No. 2 inlet branch pipe is blocked by the corresponding threaded piston, the No. 1 outlet branch pipe is blocked by the corresponding outlet branch pipe, and the No. 2 outlet branch pipe is connected; When in the second typical position, the No. 1 inlet branch pipe, the No. 2 inlet branch pipe, the No. 1 outlet branch pipe and the No. 2 outlet branch pipe are all connected; When in the third typical position, the No. 1 inlet branch pipe is blocked by the corresponding end piston, the No. 2 inlet branch pipe is connected, the No. 1 outlet branch pipe is connected, and the No. 2 outlet branch pipe is blocked by the corresponding end piston.

[0009] As a preferred solution, baffles are provided in the main shell, and the baffles are arranged at equal intervals and staggered up and down, so as to form a serpentine flow channel in the main shell for the shell fluid to pass.

[0010] As a preferred solution, a locking mechanism is provided at the connection between the threaded piston and the horizontal pipe section, and the locking mechanism can lock the threaded piston on the horizontal pipe section.

[0011] As a preferred solution, scale lines are provided on the outside of the threaded piston, and by observing the scale lines, the positions of the threaded piston and the end piston in the horizontal pipe section can be known, thereby determining whether each inlet branch and outlet branch is blocked.

[0012] As a preferred solution, there are two groups of scale lines, and the two groups of scale lines respectively show the degree to which the two inlet branches are blocked by the corresponding two pistons, or the degree to which the two outlet branches are blocked by the corresponding two pistons.

[0013] The present invention improves the prior art and produces the following effects: 1. The present invention arranges two inlet branches and two outlet branches at different axial positions on the outside of the main shell. During operation, by opening or closing the inlet branches and outlet branches at different axial positions, the length of the flow path of the shell fluid in the main shell can be changed, that is, the heat exchange time between the shell fluid and the tube fluid is changed, thereby realizing flexible adjustment of the heat exchange capacity of the heat exchanger.

[0014] 2. In the present invention, the shell fluid inlet pipe and the shell fluid outlet pipe each include a horizontal pipe section, the two horizontal pipe sections are coaxial, and the two piston assemblies are respectively installed on the two lead screws at both ends of the double-axis motor. The piston assembly is connected by a threaded piston, a connecting rod and an end piston. This design has the following advantages: First, driven by the dual-axis motor, the two lead screws rotate synchronously at the same time, and then drive the two piston assemblies to slide synchronously at the same time, thereby ensuring that the total diameter of the two inlet branch pipes and the total diameter of the two outlet branch pipes remain the same at all times.

[0015] Second, compared with using valves as switch control devices, using a dual-axis motor to drive the movement of two piston assemblies can more quickly and conveniently control the switch of two inlet branches and two outlet branches at the same time, realizing a variety of changes in the flow path of the shell fluid in the main shell, and greatly improving the convenience of operation.

[0016] Third, after the piston assembly composed of a threaded piston, a connecting rod and an end piston moves, it can not only block or open a certain inlet branch or outlet branch alone, but also open two inlet branches and two outlet branches at the same time, and can also partially open or block a certain inlet branch and outlet branch, thereby providing a variety of different flow paths for the shell fluid. Compared with using a valve as a switch control device, changing the flow path of the shell fluid in this way can more accurately and flexibly adjust the flow path of the shell fluid, thereby realizing accurate and flexible adjustment of the heat exchange capacity of the heat exchanger.

[0017] Fourthly, the pressure from the shell fluid borne by the two threaded pistons connected at both ends of the dual-axis motor acts on both ends of the motor shaft of the dual-axis motor at the same time (the so-called dual-axis motor does not mean that there are two shafts, but that one shaft extends from both ends of the dual-axis motor) and then offsets each other, thereby making it easier to ensure the structural strength of the dual-axis motor.

[0018] 3. By controlling the operation of the dual-axis motor through automated means, the heat exchange capacity of the heat exchanger can be dynamically adjusted, thereby meeting the demand for dynamic adjustment of the heat exchange capacity of the heat exchanger during continuous production. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic structural diagram of the first embodiment of the present invention.

[0020] Figure 2 It is a schematic structural diagram of a second embodiment of the present invention.

[0021] Figure 3 yes Figure 2 Schematic diagram of the position of the middle piston assembly in the shell fluid inlet pipe and the shell fluid outlet pipe.

[0022] Figure 4 Schematic diagram of a second position of the piston assembly in the shell fluid inlet pipe and the shell fluid outlet pipe.

[0023] Figure 5 Schematic diagram of a third position of the piston assembly in the shell fluid inlet pipe and the shell fluid outlet pipe.

[0024] In the figure, 1, head, 2, No. 1 inlet branch, 3, main shell, 4, shell fluid inlet pipe, 5, No. 1 outlet branch, 6, shell fluid outlet pipe, 7, heat exchange tube, 8, baffle, 9, end piston, 10, connecting rod, 11, threaded piston, 12, screw, 13, dual-axis motor, 14, horizontal pipe section, 15, No. 2 inlet branch, 16, No. 2 outlet branch. DETAILED DESCRIPTION

[0025] The present invention is further described below in conjunction with the accompanying drawings: First embodiment like Figure 1 As shown, this embodiment includes a main shell 3, a heat exchange tube 7 and a head 1. The heat exchange tube 7 is arranged in the main shell 3. Tube fluid flows in the heat exchange tube 7. Shell fluid flows in the space between the outer wall of the heat exchange tube 7 and the main shell 3. Tube fluid and shell fluid exchange heat through the tube wall of the heat exchange tube 7. The specific structure is that the heat exchange tube 7 is connected to the head 1 and communicates with the internal space of the head 1. The outside of the head 1 is provided with a tube fluid inlet pipe and a tube fluid outlet pipe for the tube fluid to enter and exit. The outside of the main shell 3 is provided with a shell fluid inlet pipe 4 and a shell fluid outlet pipe 6. The above structure belongs to the mature existing technology, so it will not be repeated here.

[0026] like Figure 1As shown, in this embodiment, two inlet branches are provided on the shell fluid inlet pipe 4, one end of the two inlet branches are respectively connected to the shell fluid inlet pipe 4, and the other end is respectively connected to the internal space of the main shell 3; similarly, two outlet branches are provided on the fluid outlet pipe, one end of the two outlet branches are respectively connected to the shell fluid outlet pipe 6, and the other end is respectively connected to the internal space of the main shell 3; the two inlet branches are connected to the outside of one end of the main shell 3, and the two outlet branches are connected to the outside of the other end of the main shell 3.

[0027] By providing two inlet branches and two outlet branches, and arranging the branches along the axial direction of the main shell 3, during operation, by opening or closing the inlet branches and outlet branches at different axial positions, the length of the flow path of the shell fluid in the main shell 3 can be changed, that is, the heat exchange time between the shell fluid and the tube fluid is changed, thereby realizing flexible adjustment of the heat exchange capacity of the heat exchanger.

[0028] like Figure 1 As shown, in this embodiment, switch control devices are provided at the inlet branch pipe and the outlet branch pipe. By operating the switch control devices, the switch control of each inlet branch pipe and the outlet branch pipe can be achieved, and then each inlet branch pipe and each outlet branch pipe can be opened or closed as needed.

[0029] like Figure 1 As shown, in this embodiment, the switch control device is a traditional valve, and each inlet branch pipe and outlet branch pipe are connected in series with a valve. By changing the switch state and opening degree of the valve, the following functions can be achieved: First, by changing the switch state of the valve, the length of the shell fluid flow path can be adjusted. The longer the flow path, the longer the contact time between the shell fluid and the outer wall of the heat exchange tube 7, and the stronger the heat exchange capacity of the heat exchanger. For example, when the shell fluid enters the main shell 3 from the No. 1 inlet branch pipe 2 and then flows out from the No. 2 outlet branch pipe 16, the flow path of the shell fluid is the longest, and at this time, the heat exchange capacity of the heat exchanger is the strongest. When the shell fluid enters the main shell 3 from the No. 2 inlet branch pipe 15 and then flows out from the No. 1 outlet branch pipe 5, the flow path of the shell fluid is the shortest, and at this time, the heat exchange capacity of the heat exchanger is the weakest.

[0030] Second, by changing the switch state of the valve, the shell fluid can also flow in from two inlet branches at the same time. This dual-channel inflow method can, to a certain extent, break the turbulence of the shell fluid flow, promote heat exchange inside the shell fluid, and thus improve the heat exchange efficiency.

[0031] Third, by changing the degree of opening of the valve, the distribution ratio of the shell fluid between the two inlet branches can be adjusted, so that the heat transfer capacity of the heat exchanger can be continuously adjusted between the "strongest" and "weakest" mentioned in the first point above (different from discrete adjustment), thereby ensuring the accuracy of adjusting the heat transfer capacity of the heat exchanger.

[0032] like Figure 1 As shown, in this embodiment, the main shell 3 is provided with baffles 8, which are arranged at equal intervals and staggered up and down, so as to form a serpentine flow channel in the main shell 3 for the shell fluid to pass through, which can extend the residence time of the shell fluid in the main shell 3 and improve the heat exchange efficiency.

[0033] like Figure 1 As shown, in this embodiment, a locking mechanism is provided at the connection between the threaded piston 11 and the horizontal pipe section 14. After the position of the piston assembly in the horizontal pipe section 14 is adjusted, the threaded piston 11 can be locked on the horizontal pipe section 14 by the locking mechanism, so that the position of the piston assembly remains stable after adjustment.

[0034] Second embodiment like Figure 2 As shown, the difference between this embodiment and the first embodiment is that: in the first embodiment, valves are used as switch control devices at the inlet branch pipe and the outlet branch pipe, while this embodiment provides another switch control device.

[0035] like Figure 2 As shown, in this embodiment, the shell fluid inlet pipe 4 and the shell fluid outlet pipe 6 each include a horizontal pipe section 14, and the two horizontal pipe sections 14 are coaxial.

[0036] like Figure 2 As shown, in this embodiment, the switch control device includes a dual-axis motor 13 and two piston assemblies. A lead screw 12 with the same pitch but opposite rotation direction is respectively provided at both ends of the dual-axis motor 13. The two piston assemblies are respectively connected to the two lead screws 12 by threads. At the same time, the two piston assemblies are respectively slidably installed in two horizontal pipe sections 14 and slidably cooperate with the horizontal pipe sections 14. When in use, driven by the dual-axis motor 13, the two lead screws 12 with the same pitch but opposite rotation direction rotate synchronously at the same time, and then drive the two piston assemblies to slide synchronously at the same time.

[0037] like Figure 2 As shown, in this embodiment, the piston assembly includes a threaded piston 11, an end piston 9 and a connecting rod 10. The threaded piston 11 connects the piston assembly as a whole to the lead screw 12 through a thread, and the end piston 9 is fixedly connected to the threaded piston 11 through the connecting rod 10 so as to move synchronously with the threaded piston 11. After the dual-axis motor 13 is started, the rotational motion of the lead screw 12 is converted into a linear motion of the piston assembly as a whole, thereby adjusting the positions of the threaded piston 11 and the end piston 9 in the horizontal pipe section 14, and realizing the switch control of each inlet branch pipe and outlet branch pipe.

[0038] In this embodiment, in order to reduce the obstruction of the connecting rod 10 to the flow of the shell fluid, the connecting rod 10 can be replaced with a tubular structure, which has the following structural features: 1) The two ends of the tubular structure are respectively fixedly connected to the threaded piston and the end piston to achieve its connection function; 2) The outer wall of the tubular structure is slidably matched with the inner wall of the horizontal pipe section 14 (tolerance fit) to minimize its obstruction to the shell fluid; 3) A sufficiently large window is opened on the side of the tubular structure to ensure that the shell fluid can flow through its interior smoothly during the sliding process of the piston assembly.

[0039] During implementation, attention should be paid to the matching mode between the various parts of the piston assembly and the horizontal pipe section 14. Figure 3 , 4 As shown in Fig. 5, in this embodiment, a sealing ring is installed on the inner side of the horizontal pipe section 14, and the threaded piston 11 in the piston assembly realizes sealing cooperation with the horizontal pipe section 14 through the sealing ring, thereby preventing the shell fluid from leaking to the outside of the horizontal pipe section 14. At the same time, the threaded piston 11 and the end piston 9 do not need to be provided with sealing rings at the plugging points of each branch pipe for two reasons: first, plugging is sufficient without strict sealing; second, after sealing, the piston assembly will not be able to move to the desired position due to the pressure buildup.

[0040] like Figure 3-5 As shown, in this embodiment, when adjusting the conduction state of each inlet branch pipe and outlet branch pipe, the piston assembly has three typical positions in the horizontal pipe section 14: In the first typical position, the No. 1 inlet branch pipe 2 is connected, the No. 2 inlet branch pipe 15 is blocked by the corresponding threaded piston 11, the No. 1 outlet branch pipe 5 is blocked by the corresponding outlet branch pipe, and the No. 2 outlet branch pipe 16 is connected. Figure 3 At this time, the distance between the inlet branch pipe and the outlet branch pipe is the largest, and the heat exchange capacity of the heat exchanger is the strongest.

[0041] In the second typical position, the first inlet branch pipe 2, the second inlet branch pipe 15, the first outlet branch pipe 5 and the second outlet branch pipe 16 are all connected. Figure 4 As shown. At this time, the heat transfer capacity of the heat exchanger is medium.

[0042] In the third typical position, the No. 1 inlet branch pipe 2 is blocked by the corresponding end piston 9, the No. 2 inlet branch pipe 15 is connected, the No. 1 outlet branch pipe 5 is connected, and the No. 2 outlet branch pipe 16 is blocked by the corresponding end piston 9. Figure 5 At this time, the distance between the inlet branch pipe and the outlet branch pipe is the smallest, and the heat exchange capacity of the heat exchanger is the weakest.

[0043] In this embodiment, the outer side of the threaded piston 11 is provided with scale lines. By observing the scale lines, the positions of the threaded piston 11 and the end piston 9 in the horizontal pipe section 14 can be known at the equipment site, and then it can be determined whether each inlet branch pipe and outlet branch pipe is blocked. In this embodiment, there are two groups of scale lines, and the two groups of scale lines respectively show the degree to which the two inlet branch pipes are blocked by the corresponding two pistons, or the degree to which the two outlet branch pipes are blocked by the corresponding two pistons (threaded piston 11 and end piston 9). For example, when a branch pipe (inlet branch pipe and outlet branch pipe) is just completely blocked, the scale value of the branch pipe is displayed as zero. If the flow area of ​​the branch pipe gradually increases with the movement of the piston, then the scale value increases by one value for each unit increase in the flow area.

[0044] During implementation, on the basis of setting the above two groups of scale lines, a third scale line can also be set, and the third scale line uses heat exchange efficiency as the unit of measurement. Under fixed temperature, flow and other environmental conditions, regardless of the blocking state of each inlet branch pipe and outlet branch pipe, each point corresponds to a certain heat exchange efficiency value. Through calibration, the corresponding relationship between each point of the piston assembly in the horizontal pipe section (corresponding to different blocking states) and the heat exchange efficiency value can be calibrated, and the calibrated heat exchange efficiency value is reflected on the third scale line.

[0045] Compared with the first embodiment, the advantages of the technical solution described in this embodiment are: In the first embodiment, four valves are required, and the four valves need to be operated and controlled separately, which is cumbersome to operate. In addition, the opening degree of ordinary valves is difficult to quantify, resulting in poor control accuracy.

[0046] In this embodiment, a switch control device with a special structure is adopted, which produces the following effects: First, driven by the dual-axis motor 13, the two lead screws 12 rotate synchronously at the same time, and then drive the two piston assemblies to slide synchronously at the same time, thereby ensuring that the total diameter of the two inlet branch pipes and the total diameter of the two outlet branch pipes remain the same at all times.

[0047] Second, compared with using a valve as a switch control device, using a dual-axis motor 13 to drive the movement of two piston assemblies can more quickly and conveniently control the switch of two inlet branches and two outlet branches at the same time, thereby realizing a variety of changes in the flow path of the shell fluid in the main shell 3, and greatly improving the convenience of operation.

[0048] Third, after the piston assembly formed by the threaded piston 11, the connecting rod 10 and the end piston 9 moves, it can not only block or open a certain inlet branch or outlet branch alone, but also open two inlet branches and two outlet branches at the same time, and can also partially open or block a certain inlet branch and outlet branch, thereby providing a variety of different flow paths for the shell fluid. Compared with using a valve as a switch control device, changing the flow path of the shell fluid in this way can more accurately and flexibly adjust the flow path of the shell fluid, thereby realizing accurate and flexible adjustment of the heat exchange capacity of the heat exchanger.

[0049] Fourthly, the pressure from the shell fluid borne by the two threaded pistons 11 connected at both ends of the dual-axis motor 13 acts on both ends of the motor shaft of the dual-axis motor 13 at the same time (the so-called dual-axis motor 13 does not mean that there are two shafts, but one shaft extends from both ends of the dual-axis motor 13) and then cancels each other out, thereby making it easier to ensure the structural strength of the dual-axis motor 13.

Claims

1. A heat exchanger for use in the production of bentazon, comprising a main shell (3), a heat exchange tube (7) and a head (1), wherein the heat exchange tube (7) is arranged in the main shell (3), a tube fluid flows in the heat exchange tube (7), a shell fluid flows in the space between the outer wall of the heat exchange tube (7) and the main shell (3), the tube fluid and the shell fluid exchange heat through the tube wall of the heat exchange tube (7), a shell fluid inlet pipe (4) and a shell fluid outlet pipe (6) are arranged on the outer side of the main shell (3), and the characteristics are as follows: The shell fluid inlet pipe (4) is provided with two inlet branch pipes, one end of the two inlet branch pipes is respectively connected to the shell fluid inlet pipe (4), and the other end is respectively connected to the internal space of the main shell (3); similarly, the fluid outlet pipe is provided with two outlet branch pipes, one end of the two outlet branch pipes is respectively connected to the shell fluid outlet pipe (6), and the other end is respectively connected to the internal space of the main shell (3); Two inlet branch pipes are connected to the outside of one end of the main shell (3), and two outlet branch pipes are connected to the outside of the other end of the main shell (3); The two inlet branch pipes and the two outlet branch pipes are arranged along the axial direction of the main shell (3); The inlet branch pipe and the outlet branch pipe are both provided with a switch control device. By operating the switch control device, the switch control of each inlet branch pipe and the outlet branch pipe can be realized, thereby changing the passage path of the shell fluid in the main shell (3), thereby realizing the adjustment of the heat exchange capacity.

2. A heat exchanger for bentazone production according to claim 1, characterized in that: The switch control device is a valve, and each inlet branch pipe and outlet branch pipe is connected in series with a valve.

3. The heat exchanger for bentazone production according to claim 1, characterized in that: The shell fluid inlet pipe (4) and the shell fluid outlet pipe (6) each include a horizontal pipe section (14), and the two horizontal pipe sections (14) are coaxial; The switch control device comprises a dual-axis motor (13) and two piston assemblies. A lead screw (12) having the same pitch but opposite rotation directions is disposed at each end of the dual-axis motor (13). The two piston assemblies are respectively connected to the two lead screws (12) by threads. At the same time, the two piston assemblies are respectively slidably mounted in two horizontal pipe sections (14) and slidably cooperate with the horizontal pipe sections (14). The piston assembly comprises a threaded piston (11), an end piston (9) and a connecting rod (10); the end piston (9) is fixedly connected to the threaded piston (11) via the connecting rod (10); the threaded piston (11) connects the piston assembly as a whole to the lead screw (12) via threads; after the dual-axis motor (13) is started, the rotational motion of the lead screw (12) is converted into linear motion of the piston assembly as a whole, thereby adjusting the positions of the threaded piston (11) and the end piston (9) in the horizontal pipe section (14), thereby realizing the switch control of each inlet branch pipe and outlet branch pipe.

4. A heat exchanger for bentazone production according to claim 3, characterized in that: There are three typical positions of the piston assembly in the horizontal pipe section (14): The following provisions are made: the two inlet branches are respectively called inlet branch No. 1 (2) and inlet branch No. 2 (15) in order from left to right, and the two outlet branches are respectively called outlet branch No. 1 (5) and outlet branch No. 2 (16) in order from left to right, then: When in the first typical position, the No. 1 inlet branch pipe (2) is open, the No. 2 inlet branch pipe (15) is blocked by the corresponding threaded piston (11), the No. 1 outlet branch pipe (5) is blocked by the corresponding outlet branch pipe, and the No. 2 outlet branch pipe (16) is open; When in the second typical position, the No. 1 inlet branch pipe (2), the No. 2 inlet branch pipe (15), the No. 1 outlet branch pipe (5) and the No. 2 outlet branch pipe (16) are all connected; When in the third typical position, the No. 1 inlet branch pipe (2) is blocked by the corresponding end piston (9), the No. 2 inlet branch pipe (15) is connected, the No. 1 outlet branch pipe (5) is connected, and the No. 2 outlet branch pipe (16) is blocked by the corresponding end piston (9).

5. The heat exchanger for bentazone production according to claim 3, characterized in that: Baffles (8) are arranged in the main shell (3), and the baffles (8) are arranged at equal intervals and staggered up and down, so as to form a serpentine flow channel in the main shell (3) for the shell fluid to pass through.

6. A heat exchanger for bentazone production according to claim 3, characterized in that: A locking mechanism is provided at the connection between the threaded piston (11) and the horizontal pipe section (14), and the locking mechanism can lock the threaded piston (11) on the horizontal pipe section (14).

7. The heat exchanger for bentazone production according to claim 3, characterized in that: The outer side of the threaded piston (11) is provided with scale lines, and by observing the scale lines, the positions of the threaded piston (11) and the end piston (9) in the horizontal pipe section (14) can be known, thereby judging whether each inlet branch pipe and outlet branch pipe is blocked.

8. A heat exchanger for bentazone production according to claim 7, characterized in that: There are two groups of scale lines, which respectively show the degree to which the two inlet branches are blocked by the corresponding two pistons, or the degree to which the two outlet branches are blocked by the corresponding two pistons.

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