Efficient cooling device for overhead exhaust of stabilizer column in benzene hydrogenation process

Abstract

The utility model discloses a kind of benzene hydrogenation process in stable column overhead exhaust high-efficiency cooling device, including shell side and tube side, several heat exchange tubes are provided in shell side, the upper portion of shell side is provided with air inlet, lower portion is provided with gas outlet and liquid outlet, several arc baffles are arranged in the upper and lower staggered in the shell side between air inlet and liquid outlet, the upper surface of baffle gap end is provided with liquid baffle, the edge of baffle is processed with several liquid discharge openings, the lower surface of baffle gap end is provided with air distribution plate, multiple horizontal strip gas outlet holes are arranged in the upper and lower interval of air distribution plate, the lower end of air distribution plate is fixed with next baffle.The above, the utility model has the advantages of can reduce liquid film, heat exchange efficiency is high, condensation effect is good.

Description

Technical Field

[0001] This utility model relates to the technical field of cooling equipment for exhaust gas at the top of a stabilizer tower, specifically to a high-efficiency cooling device for exhaust gas at the top of a stabilizer tower in a benzene hydrogenation process. Background Technology

[0002] The products of benzene hydrogenation may contain small amounts of unreacted hydrogen, light hydrocarbons (such as methane and ethane), hydrogen sulfide, and other light components. The presence of these light components increases the volatility of benzene, which may not meet the requirements for downstream storage, transportation, and environmental protection. A stabilization tower is installed in the process to remove these low-boiling-point impurities from the benzene product through distillation. When the stabilization tower is running, the impurity gas and a small amount of benzene product vapor will enter the top material condenser of the stabilization tower for cooling. The gas condenses into a liquid, and the hydrogenated oil is separated and returned to the stabilization tower. However, a small amount of light components may still be discharged in gaseous form with non-condensable gases such as hydrogen and methane. In order to further recover these residual light organic components, reduce benzene entrainment losses, and improve the yield, an exhaust cooling device is installed after the top material condenser of the stabilization tower to achieve deep recovery, environmental compliance, and system stability.

[0003] Currently used stabilizer tower top exhaust cooling devices are mostly vertical shell-and-tube condensers, which have the following problems: The condensate flows along the heat exchange tube wall under gravity, forming a liquid film on the outer wall of the tube. This film, however, has a much lower thermal conductivity than the metal tube wall, creating an additional thermal resistance layer and reducing heat transfer efficiency. Statistical calculations show that the liquid film on the outer wall of the heat exchange tube can reduce the heat transfer coefficient by about 30%. Furthermore, the liquid film may adsorb impurities or dissolve salts, accumulating over time to form a fouling layer, further worsening heat transfer and undoubtedly reducing the condensation effect of the gas mixture. Secondly, when the condensate falls onto the baffle plate, the baffle guides it to the edge of the shell, where it falls through a concentrated area. During this fall, it inevitably adheres to nearby heat exchange tubes, thickening the water film and potentially increasing the amount of liquid droplets entrained in the gas mixture, thus reducing the condensation efficiency. Therefore, it is objectively necessary to develop an efficient cooling device for the exhaust gas at the top of the stabilizer tower in the benzene hydrogenation process that can reduce liquid film, has high heat exchange efficiency, and good condensation effect. Utility Model Content

[0004] The purpose of this invention is to provide a high-efficiency cooling device for the exhaust gas at the top of the stabilizer tower in the benzene hydrogenation process, which can reduce 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 shell side and a tube side. Several heat exchange tubes are arranged in the shell side. An air inlet is provided at the upper part of the shell side, and an air outlet and a liquid outlet are provided at the lower part. Several arc-shaped baffles are arranged alternately in the shell side between the air inlet and the liquid outlet. A liquid baffle is provided on the upper surface of the notch end of the baffle. Several liquid drainage openings are machined on the edge of the baffle. An air distribution plate is provided on the lower surface of the notch end of the baffle. Multiple horizontal strip-shaped air outlets are arranged vertically and vertically on the air distribution plate. The lower end of the air distribution plate is fixed to the next baffle.

[0006] Furthermore, a wire mesh is provided on the baffle plate inside the liquid baffle, and the upper end of the wire mesh is fixed to the previous baffle plate.

[0007] Furthermore, the air outlet is inclined, with the lower end of the air outlet connected to the shell side, and a wire mesh demister is installed inside the air outlet.

[0008] Furthermore, the outer wall of the heat exchange tube is coated with a hydrophobic nano-coating.

[0009] Furthermore, several fins are provided on the outer wall of the heat exchange tube.

[0010] Furthermore, the baffle plate is machined with through holes, through which heat exchange tubes are arranged. Annular grooves are machined on the walls of the through holes, and the grooves are filled with a water-swellable material.

[0011] This invention relates to the condensation of exhaust gas at the top of a stabilizer tower in a benzene hydrogenation process. During tower operation, a mixture of light component impurities and a small amount of benzene product vapor is discharged from the top of the stabilizer tower and fed through a pipeline to a material condensation unit for primary condensation. The remaining mixture is then fed into this unit for further condensation. During operation, a cooling medium such as cold water is circulated through the tubes. The mixture is then introduced into the upper shell side of the unit through the inlet. Under the action of several baffles, it flows in a curved pattern from top to bottom. During this flow, the cooling medium in the heat exchange tubes absorbs heat from the mixture, reducing its temperature. The temperature of the gas causes the benzene in the mixture to condense into liquid and separate from the mixture. It falls onto the baffle plate and accumulates there. However, due to the obstruction of the baffle plate, it cannot fall from the notch end of the baffle plate, but falls from the drain opening at the edge of the baffle plate. It falls continuously along the inner wall of the shell side and is eventually discharged from the outlet. The mixture continues to flow downward through the notch of the baffle plate. When it encounters the gas distribution plate, the mixture is divided into multiple streams and flows out from the various horizontal strip outlets of the gas distribution plate. It is cooled by heat exchange again. This process continues until the remaining non-condensable gas is discharged from the outlet. In this invention, when the condensate falls onto the baffle plate, it no longer falls through the baffle plate notch but is discharged through the drain opening. Compared to the traditional baffle plate structure, this device changes the way the condensate falls, preventing it from contacting the heat exchange tubes during its descent. This solves the problem of condensate adhering to the heat exchange tubes and forming and thickening a liquid film, while also solving the problem of liquid droplets entrained in the gas mixture, thus improving the condensation efficiency of the gas mixture. Secondly, this device sets up a gas distribution plate between two adjacent baffle plates to distribute the gas mixture, forming... The airflow is arranged in multiple layers, flowing laterally towards the heat exchange tube. This increases the velocity of the mixed gas and utilizes shear force to disrupt the continuity of the water film, tearing it and accelerating its detachment from the tube wall. Each layer of airflow contributes to tearing the liquid film, and the simultaneous ejection of multiple layers simultaneously tears the liquid film in various parts of the heat exchange tube, minimizing or eliminating it. This ensures direct contact between the mixed gas and the tube wall, and also solves the problem of fouling caused by impurities or dissolved salts adsorbed by the liquid film. This ensures the heat exchange efficiency of the heat exchange tube and improves the condensation effect of the mixed gas. In summary, this invention has the advantages of reducing the liquid film, achieving high heat exchange efficiency, and providing excellent condensation. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0013] Figure 2 for Figure 1 Schematic diagram of the cross-sectional structure of AA;

[0014] Figure 3 This is a schematic diagram of the structure of the air distribution plate 10;

[0015] Figure 4 This is a schematic diagram of the assembly structure of heat exchange tube 3 and baffle 7;

[0016] In the diagram: 1-shell side, 2-tube side, 3-heat exchange tube, 4-air inlet, 5-air outlet, 6-liquid outlet, 7-baffle plate, 8-liquid baffle, 9-drainage opening, 10-air distribution plate, 11-horizontal strip-shaped air outlet, 12-wire mesh, 13-wire mesh demister, 14-hydrophobic nano-coating, 15-water-swellable material. Detailed Implementation

[0017] 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.

[0018] like Figures 1-4 As shown, this utility model includes a shell side 1 and a tube side 2. The overall structure of this device is the existing vertical shell-and-tube heat exchanger structure. Several heat exchange tubes 3 are arranged in the shell side 1. An air inlet 4 is arranged at the upper part of the shell side 1, and an air outlet 5 and a liquid outlet 6 are arranged at the lower part. Several arc-shaped baffles 7 are arranged alternately in the shell side 1 between the air inlet 4 and the liquid outlet 6. A liquid baffle 8 is arranged on the upper surface of the notch end of the baffle 7. Several liquid drainage openings 9 are machined on the edge of the baffle 7. A gas distribution plate 10 is arranged on the lower surface of the notch end of each baffle 7. Multiple horizontal strip-shaped air outlet holes 11 are arranged vertically and vertically on the gas distribution plate 10. The lower end of the gas distribution plate 10 is fixed to the next baffle 7.

[0019] This invention relates to the condensation of exhaust gas at the top of a stabilizer tower in a benzene hydrogenation process. During tower operation, a mixture of light component impurities and a small amount of benzene product vapor is discharged from the top of the stabilizer tower and fed through a pipeline to a material condensation unit for primary condensation. The remaining mixture is then fed into this unit for further condensation. During operation, a cooling medium such as cold water is introduced into the tube side 2, and then the mixture is introduced from the inlet 4 into the upper part of the shell side 1. Under the action of several baffles 7, it flows in a curved pattern from top to bottom. During this flow, the cooling medium in the heat exchange tubes 3 absorbs heat from the mixture, lowering its temperature. Benzene and condensable components in the mixed gas condense into liquid and separate from the mixed gas, falling onto the baffle plate 7 and continuously accumulating on it. However, due to the obstruction of the baffle plate 8, they cannot fall from the notch end of the baffle plate 7, but instead fall from the drain opening 9 at the edge of the baffle plate 7, continuously falling along the inner wall of the shell side 1, and finally being discharged from the outlet 6. Meanwhile, the mixed gas continues to flow downward through the notch of the baffle plate 7. When it encounters the gas distribution plate 10, the mixed gas is divided into multiple streams, which flow out from each of the horizontal strip-shaped gas outlets 11 of the gas distribution plate 10, and are cooled by heat exchange again. This process continues until the remaining non-condensable gas is discharged from the outlet 5.

[0020] In this invention, when the condensate falls onto the baffle plate 7, it no longer falls through the notch in the baffle plate 7, but is discharged from the drain opening 9. Compared with the traditional baffle plate 7 structure, this device changes the way the condensate falls, so that the condensate will no longer contact the heat exchange tube 3 during the falling process. This solves the problem of condensate adhering to the heat exchange tube 3 and forming and thickening the liquid film during the falling process, and also alleviates the problem of liquid droplets entrained in the mixed gas, thus improving the condensation efficiency of the mixed gas. Secondly, this device sets an air distribution plate 10 between two adjacent baffle plates 7 for the air distribution plate 10. The airflow is distributed in a multi-layered pattern, with multiple layers flowing laterally towards the heat exchange tube 3. This increases the velocity of the mixed gas and utilizes shear force to disrupt the continuity of the water film, tearing the liquid film and accelerating its detachment from the tube wall. Each layer of airflow can tear the liquid film, and the simultaneous ejection of multiple layers of airflow can tear the liquid film at various points on the heat exchange tube 3, minimizing or eliminating the liquid film and ensuring that the mixed gas is in direct contact with the tube wall of the heat exchange tube 3. This also solves the problem of fouling caused by the liquid film adsorbing impurities or dissolving salts, ensuring the heat exchange efficiency of the heat exchange tube and improving the condensation effect of the mixed gas.

[0021] A wire mesh 12 is installed on the baffle 7 inside the baffle plate 8. The upper end of the wire mesh 12 is fixed to the previous baffle plate 7. The mixed gas enters the shell side 1 and flows in a curved shape from top to bottom under the action of the baffle plate 7. However, in actual operation, it was found that as the mixed gas continues to condense, the amount of liquid droplets entrained in the mixed gas will continue to increase, thereby reducing the condensation effect of the mixed gas. In order to prevent this problem, the wire mesh 12 is installed. The wire mesh 12 can adsorb and remove most of the liquid droplets in the mixed gas. After these droplets gather, they fall onto the baffle plate 7, while the relatively dry mixed gas continues to flow and condense. In this way, during the flow of the mixed gas, the liquid droplets are continuously removed, thereby improving the condensation effect of the mixed gas.

[0022] The outlet 5 is inclined, and the lower end of the outlet 5 is connected to the shell side 1. A wire mesh demister 13 is installed inside the outlet 5. After the mixed gas is condensed, most of the remaining gas is non-condensable gas. This non-condensable gas is discharged from the outlet 5. However, during the condensation process, some condensate will be carried away by the non-condensable gas. The wire mesh demister 13 can separate this condensate entrained in the non-condensable gas and let it fall into the condensate in the shell side 1 along the inclined outlet 5, thus discharging relatively dry non-condensable gas. This eliminates the need for a subsequent separator or reduces the workload of the subsequent separator.

[0023] The outer wall of the heat exchange tube 3 is coated with a hydrophobic nano-coating 14, which can inhibit the formation of liquid film and allow the condensate to flow through rapidly in the form of droplets.

[0024] The outer wall of the heat exchange tube 3 is provided with several fins, that is, finned tubes are used as heat exchange tubes 3. The fins can effectively disrupt the stability and continuity of the liquid film on the outer wall of the heat exchange tube 3, and make the outer wall of the heat exchange tube 3 in direct contact with the mixed gas as much as possible, thereby improving the condensation effect of the mixed gas.

[0025] The baffle plate 7 has through holes, through which heat exchange tubes 3 are arranged. Annular grooves are machined on the walls of the through holes, and these grooves are filled with a water-swellable material 15. In a shell-and-tube heat exchanger, whether condensate flows through the gap between the baffle plate 7 and the heat exchange tubes 3 depends on the design gap size, operating conditions, and fluid characteristics. However, manufacturing errors or wear can cause the gap to be too large, potentially allowing condensate to flow directly through the gap between the heat exchange tubes 3 and the through holes in the baffle plate 7, thus increasing the liquid film thickness of the lower heat exchange tubes 3. To prevent this, an annular groove is machined within the through holes, and the groove is filled with a water-swellable material 15. The water-swellable material 15 is existing technology. Since the condensate from the gas at the top of the stabilizer contains a certain amount of water, the water-swellable material 15 can absorb this water and expand, tightly filling the annular gap between the heat exchange tubes 3 and the sidewall of the through holes, thus providing a seal and preventing condensate from flowing through the annular gap.

Claims

1. A high-efficiency cooling device for the top exhaust gas of a stabilizer column in a benzene hydrogenation process, comprising a shell side (1) and a tube side (2), wherein a plurality of heat exchange tubes (3) are provided in the shell side (1), characterized in that: The upper part of the shell side (1) is provided with an air inlet (4), and the lower part is provided with an air outlet (5) and a liquid outlet (6). Several bow-shaped baffles (7) are arranged alternately in the shell side (1) between the air inlet (4) and the liquid outlet (6). A liquid baffle (8) is provided on the upper surface of the notch end of the baffle (7). Several liquid discharge openings (9) are processed on the edge of the baffle (7). A gas distribution plate (10) is provided on the lower surface of the notch end of each baffle (7). Multiple horizontal strip-shaped air outlets (11) are arranged on the gas distribution plate (10) at intervals. The lower end of the gas distribution plate (10) is fixed to the next baffle (7).

2. The high-efficiency cooling device for the top exhaust gas of the stabilizer tower in a benzene hydrogenation process according to claim 1, characterized in that: A wire mesh (12) is provided on the baffle plate (7) inside the baffle plate (8), and the upper end of the wire mesh (12) is fixed to the previous baffle plate (7).

3. The high-efficiency cooling device for the top exhaust gas of the stabilizer tower in the benzene hydrogenation process according to claim 1, characterized in that: The air outlet (5) is inclined and the lower end of the air outlet (5) is connected to the shell side (1) shell. A wire mesh demister (13) is provided inside the air outlet (5).

4. The high-efficiency cooling device for the top exhaust gas of the stabilizer tower in a benzene hydrogenation process according to claim 1, characterized in that: The outer wall of the heat exchange tube (3) is coated with a hydrophobic nano-coating (14).

5. The high-efficiency cooling device for the top exhaust gas of the stabilizer tower in a benzene hydrogenation process according to claim 1, characterized in that: The heat exchange tube (3) has several fins on its outer wall.

6. The high-efficiency cooling device for the top exhaust gas of the stabilizer tower in a benzene hydrogenation process according to claim 1, characterized in that: The baffle plate (7) has through holes, and the heat exchange tube (3) is arranged through the through holes. The through hole wall has an annular groove, and the annular groove is filled with a water-swellable material (15).

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