An overhead condensing device for an extractive distillation column in a benzene hydrogenation process

Abstract

The utility model discloses a kind of extraction distillation column overhead condensing devices in benzene hydrogenation process, including condenser and reflux tank, the shell side of condenser is provided with several heat exchange tubes and several baffles, the shell side of condenser is respectively provided with air inlet and exhaust port, baffle includes side baffle and middle baffle, between side baffle and its nearby tube plate, between two adjacent middle baffles, respectively be provided with round plate, through-hole is machined on round plate, every through-hole is uniformly distributed with multiple air injection holes around, annular soft pad is arranged in the movable gap between through-hole wall and heat exchange tube outer wall, the shell side of condenser shell is provided with lateral cavity on one side, screw rod is arranged in lateral cavity, screw rod is connected with horizontal shift block by screw thread, the shell side shell of condenser is provided with liquid storage cavity in bottom, the bottom of liquid storage cavity is communicated with reflux tank by pipeline. Above all, the utility model has the advantages of liquid film can be eliminated in time, high heat exchange efficiency, good condensing effect.

Description

Technical Field

[0001] This utility model relates to the technical field of top condenser equipment for extractive distillation columns, specifically to a top condenser device for extractive distillation columns in a benzene hydrogenation process. Background Technology

[0002] In the benzene hydrogenation process, the extractive distillation column works by using a selective solvent to alter the relative volatility of the components in the mixture, thereby achieving efficient separation of benzene from cyclohexane and non-aromatic hydrocarbons. The core principle is to change the gas-liquid equilibrium of benzene and cyclohexane by adding a high-boiling-point, polar solvent. This increases the volatility of cyclohexane, making it easier to enter the gas phase, while benzene remains more readily in the liquid phase. Ultimately, high-purity cyclohexane and a small amount of lighter components are obtained at the top of the column, while a mixture of benzene and the solvent is obtained at the bottom. The function of the top condenser is to condense the condensable components, such as cyclohexane, from the top of the column. Part of this condensate is returned to the top of the column as reflux, and the remainder is collected as product. Lighter components, such as hydrogen and methane, remain gases due to their extremely low boiling points and are discharged, possibly to a flare or recovery system.

[0003] Many current extractive distillation columns use horizontal shell-and-tube heat exchangers for their top condensation units. However, these heat exchangers have several problems during use: First, when used for gas condensation, the gas condenses into a liquid, which adheres to the tube walls to form a liquid film. This film thickens and drips down, causing a tube bundle effect. The condensate drips from the upper tubes, thickening the liquid film in the lower tubes and reducing the overall heat exchange performance of the tube bundle. Compensation for this effect often relies on increasing the number and length of heat exchange tubes, increasing manufacturing costs and equipment size. Second... While some heat exchangers employ a method of installing a guide plate and a liquid guide at the bottom of the heat exchange tubes, with the guide plate in close contact with the tubes, allowing the condensate to flow from the outside of the tubes to the guide plate under gravity and surface tension, and then into the liquid guide, ultimately directing the liquid in the guide to both ends of the heat exchange tubes, this method prevents condensate from dripping from the upper heat exchange tubes onto the lower ones, thus avoiding the formation of a liquid film on the lower heat exchange tubes and eliminating the tube bundle effect. However, a problem exists: the liquid film only flows naturally to the guide plate when it reaches a certain thickness. When the liquid film thickness does not reach the critical point for drainage, the liquid film still exists, resulting in unsatisfactory heat exchange efficiency. Therefore, developing a top condenser for the extractive distillation column in the benzene hydrogenation process that can promptly eliminate the liquid film, achieves high heat exchange efficiency, and provides good condensation is objectively necessary. Utility Model Content

[0004] The purpose of this invention is to provide a top condenser for the extraction distillation column in the benzene hydrogenation process, which can promptly eliminate liquid film, has high heat exchange efficiency, and good condensation effect.

[0005] The purpose of this utility model is achieved as follows: It includes a condenser and a reflux tank. The shell side of the condenser is equipped with several heat exchange tubes and several baffles. An air inlet and an exhaust outlet are respectively located on both sides of the shell side of the condenser. The baffles include edge baffles and middle baffles. Circular plates are respectively arranged between the edge baffles and the nearby tube sheet, and between two adjacent middle baffles. Through holes are machined on the circular plates, and multiple air jets are evenly distributed around each through hole. The heat exchange tubes are arranged through the through holes. The edge of the circular plate is flush with the condenser shell. There are movable gaps between the inner walls of the condenser shell and between the wall of the through hole and the outer wall of the heat exchange tube. An annular soft pad is installed in the movable gap between the wall of the through hole and the outer wall of the heat exchange tube. A transverse cavity is provided along the length of one side of the condenser shell. A screw is installed in the transverse cavity. A motor is driven to one end of the screw. A transverse moving block is connected to the screw by a thread. The transverse moving block is connected to a circular plate. A liquid storage chamber is provided at the bottom of the condenser shell. The bottom of the liquid storage chamber is connected to the return tank by a pipeline.

[0006] Furthermore, there are multiple liquid storage chambers, which are arranged at intervals along the shell side of the condenser. The bottom of each liquid storage chamber is connected to a collection pipe through a liquid drain pipe. A solenoid valve is installed on the liquid drain pipe, and the collection pipe is connected to the return trough.

[0007] Furthermore, the exhaust port is connected to the return tank via a pipeline. A wire mesh demister is installed in the upper part of the return tank, an exhaust pipe is installed at the top of the return tank, and a return pipe is installed at the bottom of the return tank.

[0008] Furthermore, L-shaped guide plates are installed on both sides of the circular plate below each row of heat exchange tubes.

[0009] Furthermore, rings are provided on both sides of the circular plate, and drain ports are provided on both sides of the rings of each row of heat exchange tubes, with the drain ports located near the bottom of the guide plate.

[0010] Furthermore, multiple air baffles are spaced apart along the length of the transverse cavity, and the positions of the air baffles correspond one-to-one with the baffles.

[0011] Furthermore, the jet nozzles are angled, with the inlet end facing the air inlet and the outlet end facing the exhaust outlet. The distance between the outlet end and the heat exchange tube is less than the distance between the inlet end and the heat exchange tube.

[0012] This invention relates to the condensation of the gas discharged from the top of the extractive distillation column in the benzene hydrogenation process. During operation, a condensing medium is introduced into the tube side of the condenser, and then the gas discharged from the top of the extractive distillation column is introduced into the shell side of the condenser through the inlet. The gas flows in a generally curved shape under the action of baffles. During the flow, when it encounters a circular plate, it is blocked by the plate and ejected from the jet hole. The heat in the gas is absorbed by the condensing medium through the heat exchange tube wall, and condensable gases such as cyclohexane condense into liquid. Most of the liquid adheres to the heat exchange tube wall and forms a liquid film. After running for a period of time, the electric current is turned on. The motor drives the screw to rotate forward. When the screw rotates, it drives the transverse block, circular plate, and annular soft pad to move through the thread. At this time, the annular soft pad can scrape the surface of the heat exchange tube and remove the water film adhering to the surface of the heat exchange tube. When the circular plate moves to the position of the baffle plate, it stops moving and the motor rotates in reverse, thereby driving the circular plate and annular soft pad to move in the opposite direction. In this way, the motor can rotate forward and reverse periodically as needed, driving the circular plate and annular soft pad to move back and forth, thereby continuously scraping off the liquid film on the surface of the heat exchange tube. After the condensate leaves the heat exchange tube, it drips downward and flows into the liquid storage chamber, and finally is discharged into the return tank for return or extraction. In this invention, the circular plate and annular soft pad are moved back and forth by the forward and reverse rotation of the motor, thereby simultaneously scraping off the liquid film on all heat exchange tubes. This eliminates the tube bundle effect, prevents the liquid film from reducing the heat exchange performance of the tubes, and ensures that the tube walls can directly contact the gas for heat exchange, thus improving the heat exchange efficiency. Secondly, this invention uses a motor-driven method to move the circular plate and annular soft pad laterally to eliminate the liquid film on the heat exchange tubes. This is an active, forced elimination method. Compared to the traditional method of using gravity and surface tension to guide the condensate, it can eliminate the liquid film on the surface of the heat exchange tubes more promptly and completely. This solves the problem in traditional methods where the liquid film only flows naturally when it reaches a certain thickness. It can eliminate the liquid film promptly and thoroughly, significantly improving heat exchange efficiency and providing a better heat exchange effect. In summary, this invention has the advantages of timely liquid film elimination, high heat exchange efficiency, and good condensation effect. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0014] Figure 2 This is a top view of the condenser 1 in this utility model.

[0015] Figure 3 for Figure 1 Schematic diagram of the cross-sectional structure of AA;

[0016] Figure 4 This is a schematic diagram of the structure of the circular plate 8 and the heat exchange tube 3 in this utility model;

[0017] In the diagram: 1-Condenser, 2-Reflux tank, 3-Heat exchange tube, 4-Side baffle, 5-Air inlet, 6-Exhaust port, 7-Central baffle, 8-Circular plate, 9-Annular pad, 10-Jet nozzle, 11-Transverse cavity, 12-Screw, 13-Motor, 14-Transverse block, 15-Liquid storage chamber, 16-Lower liquid pipe, 17-Combination pipe, 18-Wire mesh demister, 19-Guide plate, 20-Ring, 21-Drain port, 22-Air baffle. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings, but this description is not intended to limit the present invention in any way. Any changes or improvements made based on the present invention shall fall within the protection scope of the present invention.

[0019] like Figures 1-4 As shown, this utility model includes a condenser 1 and a reflux tank 2. The condenser 1 is a horizontal shell-and-tube heat exchanger. In this utility model, the tube side of the condenser 1 is circulated with a condensing medium such as cold water, and the shell side is circulated with the mixed gas discharged from the top of the extractive distillation column. The reflux tank 2 is used to store condensate, which can be returned to the extractive distillation column as reflux liquid or directly collected. Several heat exchange tubes 3 and several baffles are arranged in the shell side of the condenser 1. An inlet 5 and an outlet 6 are respectively arranged on both sides of the shell side of the condenser 1. The baffles include edge baffles 4 and middle baffles 7. Circular plates 8 are arranged between the edge baffles 4 and the tube sheet nearby, and between two adjacent middle baffles 7. Through holes are machined on the circular plates 8. Heat pipes 3 are arranged through holes. Movable gaps are left between the edge of the circular plate 8 and the inner wall of the condenser 1 shell, and between the hole wall and the outer wall of the heat exchange tubes 3. An annular soft pad 9 is installed within the movable gap between the hole wall and the outer wall of the heat exchange tubes 3. Multiple jet holes 10 are evenly distributed around each hole. A transverse cavity 11 is provided along the length of one side of the condenser 1 shell-side shell. A screw 12 is installed within the transverse cavity 11, and a motor 13 is driven to one end of the screw 12. A transverse moving block 14 is threaded onto the screw 12 and connected to the circular plate 8. A liquid storage chamber 15 is provided at the bottom of the condenser 1 shell-side shell, and the bottom of the liquid storage chamber 15 is connected to the return trough 2 via a pipeline. Side baffles 4 are baffles located on both sides, one on each side, for a total of two baffles. The central baffles 7 are all the baffles located between the two side baffles 4.

[0020] This invention is used for condensing the gas discharged from the top of the extractive distillation column in the benzene hydrogenation process. During operation, a condensing medium is introduced into the tube side of condenser 1, and then the gas discharged from the top of the extractive distillation column is introduced into the shell side of condenser 1 through inlet 5. The gas flows in a generally curved shape under the action of baffles. During the flow, when it encounters the circular plate 8, it is blocked by the circular plate 8 and the gas is ejected from the jet hole 10. The heat in the gas is absorbed by the condensing medium through the tube wall of the heat exchange tube 3. The condensable gases such as cyclohexane are condensed into liquid, and most of them will adhere to the tube wall of the heat exchange tube 3 and form a liquid film. After running for a period of time, motor 13 is started, and motor 13 drives... When the screw 12 rotates forward, it drives the transverse block 14, the circular plate 8, and the annular soft pad 9 to move via the thread. At this time, the annular soft pad 9 can scrape the surface of the heat exchange tube 3 and remove the water film adhering to the surface of the heat exchange tube 3. When the circular plate 8 moves to the position of the baffle plate, it stops moving. The motor 13 rotates in the reverse direction, thereby driving the circular plate 8 and the annular soft pad 9 to move in the reverse direction. In this way, the motor 13 can rotate forward and reverse periodically as needed, driving the circular plate 8 and the annular soft pad 9 to move back and forth, thereby continuously scraping off the liquid film on the surface of the heat exchange tube 3. After the condensate leaves the heat exchange tube 3, it drips downward and flows into the liquid storage chamber 15, and finally is discharged into the return tank 2 for return or extraction.

[0021] In this invention, the circular plate 8 and the annular soft pad 9 are moved back and forth by the forward and reverse rotation of the motor 13, thereby simultaneously scraping off the liquid film on all the heat exchange tubes 3, eliminating the tube bundle effect, preventing the liquid film from reducing the heat exchange performance of the heat exchange tubes 3, ensuring that the tube wall of the heat exchange tubes 3 can directly contact the gas for heat exchange, and improving the heat exchange efficiency of the heat exchange tubes 3. Secondly, this invention uses the method of moving the circular plate 8 and the annular soft pad 9 by the motor 13 to eliminate the liquid film on the heat exchange tubes 3, which is an active forced elimination method. Compared with the traditional method of using the gravity and surface tension of the condensate to guide the condensate, it can eliminate the liquid film on the surface of the heat exchange tubes 3 more promptly and completely. It solves the problem that in the traditional method, the liquid film on the heat exchange tubes 3 can only flow naturally when it increases to a certain thickness. It can eliminate the liquid film in a timely and thorough manner, greatly improve the heat exchange efficiency, and has a better heat exchange effect.

[0022] There are multiple liquid storage chambers 15, which are arranged at intervals along the shell side length of the condenser 1. The bottom of each liquid storage chamber 15 is connected to a collection pipe 17 through a liquid drain pipe 16. A solenoid valve is installed on the liquid drain pipe 16. The collection pipe 17 is connected to the return tank 2. By setting multiple liquid storage chambers 15, it can be ensured that the condensate is discharged into the nearest liquid storage chamber 15, and then flows into the collection pipe 17 through the liquid drain pipe 16, and finally into the return tank 2. It should be noted that the condensed gas in this invention is the mixed gas discharged from the top of the extractive distillation column in the benzene hydrogenation process. The gas-liquid ratio after condensation is relatively large. If the condensate is discharged directly, the gas-liquid separation efficiency in the subsequent reflux tank 2 may be reduced due to the large gas-liquid ratio, resulting in incomplete condensate recovery and potentially exacerbating erosion of pipelines, valves, or pumps. To prevent this problem, a certain amount of liquid can always be maintained in the storage chamber 15. The flow rate discharged from the storage chamber 15 is controlled by a solenoid valve, thus ensuring that the discharged condensate is relatively pure and free of gas, eliminating the problems associated with a large gas-liquid ratio.

[0023] The exhaust port 6 is connected to the return tank 2 via a pipeline. A wire mesh demister 18 is installed in the upper part of the return tank 2. An exhaust pipe is installed at the top of the return tank 2, and a return pipe is installed at the bottom of the return tank 2. The gas is introduced into the shell side of the condenser 1 for condensation. After condensation, some non-condensable gas will remain. When these non-condensable gases are discharged, they will inevitably carry some liquid droplets, which will not only waste resources but also increase the processing load of non-condensable gases. In order to solve this problem, the gas is discharged into the return tank 2, and the wire mesh demister 18 is used to absorb the liquid droplets in the gas and separate the liquid droplets from the gas. The liquid droplets fall and flow into the condensate, and the gas is discharged for subsequent treatment or utilization.

[0024] Each row of heat exchange tubes 3 has L-shaped guide plates 19 on both sides of the circular plate 8 below it. When the circular plate 8 moves horizontally, the annular soft pad 9 scrapes away the liquid film on the surface of the heat exchange tube 3, and the condensate falls directly onto the heat exchange tube 3 below, causing the droplets to splash and form relatively small droplets. This process may increase the amount of droplets entrained in the gas, thereby reducing the condensation effect of the device. To solve the above problem, guide plates 10 are set up. The guide plates 10 are L-shaped and are installed on the circular plate 8. After installation, the guide plates 10 and the circular plate 8 form an upward-opening guide groove. When the condensate on the heat exchange tube 3 falls, it will fall directly into the guide groove and will not drip onto the heat exchange tube 3 below. Moreover, because the falling distance is small, it is not easy to form splashes and will not increase the amount of droplets entrained in the gas, thereby ensuring the heat exchange effect of the device.

[0025] Both sides of the circular plate 8 are provided with rings 20. Each row of heat exchange tubes 3 has a drain port 21 on both sides of the rings 20, and the drain port 21 is located near the bottom of the guide plate 19. After the guide plate 19 is installed on the circular plate 8, the condensate scraped off from the heat exchange tubes 3 falls onto the guide plate 10 and flows along the guide plate 10 towards both ends of the guide plate 10, and finally falls from both ends of the guide plate 10. In actual operation, it was found that the falling condensate still falls to the bottom. The heat exchange tubes 3 near the edge of the tubes still have a certain impact on the heat exchange effect. To solve this problem, a ring 20 is set up. When the condensate flows to both ends of the guide plate 19, it will flow through the drain port 21 and into the gap between the ring 20 and the shell of the condenser 1. It will then flow downward in the gap until it reaches the liquid storage chamber 15 at the bottom of the condenser 1. The ring 20 prevents the condensate from falling onto the heat exchange tubes 3 below, thus improving the heat exchange effect.

[0026] Multiple baffle blocks 22 are spaced along the length of the transverse cavity 11. The positions of the baffle blocks 22 correspond one-to-one with the baffle plates 7. During the use of this device, it was found that a small amount of gas would enter the transverse cavity 11 and flow directly along it. The entire flow process did not contact or exchange heat with the heat exchange tubes 3, or the contact with the heat exchange tubes 3 was minimal, which would reduce the condensation effect of the gas to a certain extent. To avoid the above problems, baffle blocks 22 are set in the transverse cavity 11. The baffle blocks 22 are fixed in the transverse cavity 11. In actual installation, through holes are machined on them, and the screw 12 is movably inserted into the through holes without affecting the rotation of the screw 12. When the gas enters the transverse cavity 11, it is blocked by the baffle blocks 22, which forces the gas flow out of the transverse cavity 11 and into the shell side of the condenser 1 to participate in heat exchange, thereby improving the heat exchange effect of the device.

[0027] The jet orifice 10 is inclined, with the inlet end facing the inlet 5 and the outlet end facing the outlet 6. The distance between the outlet end and the heat exchange tube 3 is smaller than the distance between the inlet end and the heat exchange tube 3. When gas is sprayed from the jet orifice 10 onto the heat exchange tube 3, it has two effects: first, because the orifice diameter of the jet orifice 10 is small, the gas flow velocity when it is sprayed from the jet orifice 10 is fast and the impact force is large. When it impacts the surface of the heat exchange tube 3, it can break the liquid film on the surface of the heat exchange tube 3, thereby improving the condensation efficiency; second, the gas is sprayed directly onto the surface of the heat exchange tube 3 from the jet orifice 10, so that all the gas can directly contact the surface of the heat exchange tube 3, thereby improving the heat exchange efficiency.

Claims

1. A top condenser device for an extractive distillation column in a benzene hydrogenation process, comprising a condenser (1) and a reflux tank (2), wherein the shell side of the condenser (1) is provided with a plurality of heat exchange tubes (3) and a plurality of baffles, and an inlet (5) and an outlet (6) are respectively provided on both sides of the shell side of the condenser (1), characterized in that: The baffles include a side baffle (4) and a middle baffle (7). Circular plates (8) are respectively arranged between the side baffle (4) and the tube sheet nearby, and between two adjacent middle baffles (7). Through holes are machined on the circular plates (8), and heat exchange tubes (3) are arranged through the through holes. Movable gaps are left between the edge of the circular plate (8) and the inner wall of the condenser (1) shell, and between the wall of the through hole and the outer wall of the heat exchange tube (3). An annular soft pad (9) is arranged in the movable gap between the wall of the through hole and the outer wall of the heat exchange tube (3). Around each through hole... Multiple jet holes (10) are evenly distributed around the circumference of the condenser (1). A transverse cavity (11) is provided on one side of the shell side of the condenser (1) along its length direction. A screw (12) is provided in the transverse cavity (11). A motor (13) is connected to one end of the screw (12). A transverse block (14) is connected to the screw (12) by a thread. The transverse block (14) is connected to the circular plate (8). A liquid storage chamber (15) is provided at the bottom of the shell side of the condenser (1). The bottom of the liquid storage chamber (15) is connected to the return tank (2) through a pipeline.

2. The condenser at the top of the extractive distillation column in a benzene hydrogenation process according to claim 1, characterized in that: The number of liquid storage chambers (15) is multiple, and the multiple liquid storage chambers (15) are arranged at intervals along the shell side length of the condenser (1). The bottom of each liquid storage chamber (15) is connected to a collection pipe (17) through a liquid drain pipe (16). A solenoid valve is installed on the liquid drain pipe (16), and the collection pipe (17) is connected to the return trough (2).

3. The condenser at the top of the extractive distillation column in the benzene hydrogenation process according to claim 1, characterized in that: The exhaust port (6) is connected to the return tank (2) through a pipeline. A wire mesh demister (18) is installed in the upper part of the return tank (2). An exhaust pipe is installed at the top of the return tank (2), and a return pipe is installed at the bottom of the return tank (2).

4. The condenser at the top of the extractive distillation column in the benzene hydrogenation process according to claim 1, characterized in that: Each row of heat exchange tubes (3) has an L-shaped guide plate (19) on both sides of the circular plate (8) below it.

5. The condenser at the top of the extractive distillation column in a benzene hydrogenation process according to claim 4, characterized in that: The circular plate (8) has rings (20) on both sides of its edges. Each row of heat exchange tubes (3) has a drain port (21) on both sides of the rings (20), and the drain port (21) is located near the bottom of the guide plate (19).

6. The condenser at the top of the extractive distillation column in a benzene hydrogenation process according to claim 1, characterized in that: Multiple air baffles (22) are spaced apart along the length of the transverse cavity (11), and the positions of the air baffles (22) correspond one-to-one with the baffles (7).

7. The top condenser of the extractive distillation column in a benzene hydrogenation process according to claim 1, characterized in that: The jet hole (10) is inclined, with the air inlet end of the jet hole (10) facing the air inlet (5) and the air outlet end facing the exhaust port (6). The distance between the air outlet end and the heat exchange tube (3) is less than the distance between the air inlet end and the heat exchange tube (3).

Images