A solvent recovery system for a water washing tower

Abstract

This utility model relates to the technical field of petrochemical production equipment and discloses a solvent recovery system for a water washing tower, comprising a water washing tower, a solvent recovery feed buffer tank, and a solvent recovery tower connected in sequence. The solvent recovery feed buffer tank has a gas phase discharge port at its top and a liquid phase discharge port at its bottom, which is connected to the solvent recovery tower. The gas phase discharge port is connected to a cooler, and a cooling product recovery tank is connected downstream of the cooler. This utility model achieves the following technical effects: by setting up a cooler and a cooling product recovery tank, volatile hydrocarbons and their entrained water washing solvents can be cooled, liquefied, and temporarily stored in the cooling product recovery tank for reuse. This reduces the loss of recovered solvent, lowers production costs, and also reduces the volatilization and emission of volatile hydrocarbons and water washing solvents, reducing the adverse effects of the production process on the environment and human health.

Description

Technical Field

[0001] This utility model belongs to the technical field of petrochemical production equipment, specifically relating to a solvent recovery system for a water washing tower. Background Technology

[0002] In the production process of petroleum resins, byproduct fractions (such as C5 or C9) generated from petroleum cracking can be processed into petroleum resins (C5 or C9, etc.) through a series of pretreatment, polymerization, and distillation processes. After polymerization, the byproduct fractions typically require further washing to remove oligomers from the polymerized product. For example, a dimer washing tower can be installed downstream of the polymerization reactor, using acetonitrile as the washing solvent. The dimers in the polymerized product are washed away by thorough mixing and contact between acetonitrile and the polymerized product within the dimer washing tower.

[0003] In existing technologies, a solvent recovery tower is usually set up downstream of the water washing tower for the recovery and reuse of the washing solvent. A solvent recovery feed buffer tank is installed between the water washing tower and the solvent recovery tower. Since the vent valve of the solvent recovery feed buffer tank needs to be kept open for a long time, volatile hydrocarbons will be discharged into the flare system along with a small amount of solvent, resulting in the loss of recovered solvent and increasing production costs. At the same time, the combustion emissions of volatile hydrocarbons and washing solvents will pollute the external environment and endanger human health. Utility Model Content

[0004] To address the shortcomings of the existing technology, this invention provides a solvent recovery system for a water washing tower. A cooler is connected to the gas phase emission port, and a cooling product recovery tank is installed downstream of the cooler. This system allows volatile hydrocarbons and their entrained washing solvents to be cooled, liquefied, and temporarily stored in the cooling product recovery tank for reuse. This reduces solvent loss, lowers production costs, and also reduces the emission of volatile hydrocarbons and washing solvents, minimizing the adverse environmental and health impacts of the production process.

[0005] The technical effects to be achieved by this utility model are realized through the following technical aspects: This utility model provides a solvent recovery system for a water washing tower, comprising a water washing tower, a solvent recovery feed buffer tank, and a solvent recovery tower connected in sequence. The solvent recovery feed buffer tank is provided with a gas phase discharge port at the top and a liquid phase discharge port at the bottom. The liquid phase discharge port is connected to the solvent recovery tower. The gas phase discharge port is connected to a cooler. The downstream of the cooler is connected to a cooling product recovery tank.

[0006] As a further description of the technical solution of this utility model, the top of the cooling product recovery tank is provided with a first inlet, the bottom of the cooling product recovery tank is provided with a first outlet, the first inlet is connected to the cooling product discharge port of the cooler, and the first outlet is connected to the water washing tower.

[0007] As a further description of the technical solution of this utility model, the first discharge port is connected to a first conveying pump, and the outlet of the first conveying pump is connected to the water washing tower.

[0008] As a further description of the technical solution of this utility model, the upper end of the water washing tower is provided with an oil phase output port, the lower end of the water washing tower is provided with a water washing waste liquid output port and a circulation input port, the water washing waste liquid output port is connected to the solvent recovery feed buffer tank, and the outlet of the first delivery pump is connected to the circulation input port.

[0009] As a further description of the technical solution of this utility model, the cooler is a shell-and-tube heat exchanger, the shell side of the cooler is used for the flow of cooling water, and the tube side of the cooler is used for the flow of gas phase discharged from the gas phase outlet.

[0010] As a further description of the technical solution of this utility model, the liquid phase discharge port is connected to a second transfer pump, and the outlet of the second transfer pump is connected to the solvent recovery tower.

[0011] As a further description of the technical solution of this utility model, the solvent recovery system of the water washing tower also includes a solvent recovery storage tank, the upper end of the solvent recovery tower is provided with a solvent recovery output port, the lower end of the solvent recovery tower is provided with a wastewater discharge port, the solvent recovery output port is connected to the solvent recovery storage tank, and the wastewater discharge port is connected to an external sewage treatment system.

[0012] As a further description of the technical solution of this utility model, the top of the recovered solvent storage tank is provided with a second inlet, the bottom of the recovered solvent storage tank is provided with a second outlet, the second inlet is connected to the recovered solvent output port, and the second outlet is connected to a recovered solvent extraction pump.

[0013] As a further description of the technical solution of this utility model, the water washing tower is a dimer water washing tower.

[0014] As a further description of the technical solution of this utility model, the solvent recovery tower is an acetonitrile recovery tower.

[0015] In summary, this utility model has at least the following advantages: The solvent recovery system for a water washing tower provided by this invention uses a cooler to cool the volatile gaseous materials, causing the volatile hydrocarbons and their entrained washing solvents to cool, liquefy, and temporarily store them in a cooling product recovery tank for reuse. This significantly reduces the amount of gas directly emitted into the flare system, minimizes solvent loss, and achieves efficient recovery of the washing solvent. The efficient recovery and reuse of the washing solvent effectively reduces production costs and improves production efficiency. Simultaneously, reducing the emission of volatile hydrocarbons and washing solvents also prevents the release of harmful volatile substances (such as VOCs) that could pollute the environment, thus reducing the adverse effects of the production process on the environment and human health. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the solvent recovery system of the water washing tower in Embodiment 1 of this utility model; Figure 2 This is a schematic diagram of the solvent recovery system of the water washing tower in Embodiment 2 of this utility model; Figure 3 This is a schematic diagram of the solvent recovery system of the water washing tower in Embodiment 3 of this utility model.

[0017] Marked in the image: 1. Water washing tower; 11. Oil phase output port; 12. Water washing waste liquid output port; 13. Circulation input port; 2. Solvent recovery feed buffer tank; 21. Gas phase discharge port; 22. Liquid phase discharge port; 3. Solvent recovery tower; 31. Recovered solvent output port; 32. Wastewater discharge port; 4. Cooler; 5. Cooling product recovery tank; 51. First feed inlet; 52. First discharge outlet; 6. First transfer pump; 7. Second transfer pump; 8. Recovered solvent storage tank; 81. Second inlet; 82. Second outlet; 9. Recovered solvent extraction pump. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. The described embodiments are some, but not all, of the embodiments of this utility model.

[0019] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0020] Example 1 refer to Figure 1 The solvent recovery system for the washing tower provided in this embodiment includes a washing tower 1, a solvent recovery feed buffer tank 2, and a solvent recovery tower 3 connected in sequence. The washing waste liquid discharged from the washing tower 1 can pass through the solvent recovery feed buffer tank 2 and enter the solvent recovery tower 3 for the recovery of washing solvent.

[0021] The solvent recovery feed buffer tank 2 has a gas phase discharge port 21 at the top and a liquid phase discharge port 22 at the bottom. The liquid phase discharge port 22 is connected to the solvent recovery tower 3. The gas phase discharge port 21 is connected to a cooler 4, and the downstream of the cooler 4 is connected to a cooling product recovery tank 5. The wastewater discharged from the water washing tower 1 enters the solvent recovery feed buffer tank 2. The liquid portion enters the solvent recovery tower 3 through the liquid phase discharge port 22 for the recovery of the water washing solvent. Volatile hydrocarbons, carrying a small amount of water washing solvent, are discharged from the gas phase discharge port 21 and enter the cooler 4 for cooling and liquefaction. Afterward, they enter the cooling product recovery tank 5 for temporary storage. The cooling product in the cooling product recovery tank 5 contains some water washing solvent. It can be recycled back to the water washing tower 1 for further water washing or directly sent to the solvent recovery tower 3 for the recovery of the water washing solvent.

[0022] By installing cooler 4 to cool the volatile gaseous materials, volatile hydrocarbons and their entrained washing solvents are cooled, liquefied, and temporarily stored in cooling product recovery tank 5 for reuse. This significantly reduces the amount of gas directly emitted into the flare system, minimizes solvent loss, achieves efficient recovery and reuse of washing solvents, effectively reduces production costs, and improves production efficiency. Reducing the emission of volatile hydrocarbons and washing solvents also prevents the release of harmful volatile substances (such as VOCs) that could pollute the environment, thus mitigating the adverse effects of the production process on the environment and human health. By adding cooler 4 and cooling product recovery tank 5, the solvent recovery rate of the solvent recovery system can be increased from 72% to 89%, and the emission concentration of volatile organic compounds (VOCs) can be reduced from 120 mg / m³. 3 Reduced to 15 mg / m 3 This effectively reduces pollutant emissions and also lowers subsequent treatment costs.

[0023] In one embodiment, the cooling product recovery tank 5 has a first inlet 51 at its top and a first outlet 52 at its bottom. The first inlet 51 is connected to the cooling product discharge port of the cooler 4, and the first outlet 52 is connected to the water washing tower 1. Therefore, the cooling product generated after cooling by the cooler 4 can be returned to the water washing tower 1 for further water washing, which can further improve the utilization rate of the washing solvent.

[0024] In this embodiment, the water washing tower 1 is a dimer water washing tower, used to wash away dimers in the polymerization product; the solvent recovery tower 3 is an acetonitrile recovery tower, that is, acetonitrile is used as the water washing solvent, which can effectively wash away dimers in the polymerization product.

[0025] Example 2 As a further optimization of Example 1, in Figure 1 Based on, refer to Figure 2 The first discharge port 52 is connected to the first conveying pump 6, and the outlet of the first conveying pump 6 is connected to the water washing tower 1. The first conveying pump 6 can provide more power for conveying the cooled product, and at the same time, it is also helpful to balance the pressure difference between the cooled product recovery tank 5 and the water washing tower 1, so as to improve the safety of the production process.

[0026] In some embodiments, the upper end of the water washing tower 1 is provided with an oil phase output port 11, which can be connected to the finished product tank of the target product. The lower end of the water washing tower 1 is provided with a water washing waste liquid output port 12 and a circulation input port 13. The water washing waste liquid output port 12 is connected to the solvent recovery feed buffer tank 2, and the outlet of the first delivery pump 6 is connected to the circulation input port 13.

[0027] In a preferred embodiment, the cooler 4 is a shell-and-tube heat exchanger. The shell side of the cooler 4 is used for the flow of cooling water, and the tube side is used for the flow of gaseous material discharged from the gas phase discharge port 21. Using a shell-and-tube heat exchanger as the cooler 4 helps to reduce production energy consumption and further control production operating costs. In this embodiment, the cooler 4 is specifically a U-tube heat exchanger. The initial temperature of the cooling water flowing through the shell side of the heat exchanger is 25°C, and the initial temperature of the gaseous material flowing through the tube side is 100±5°C. After the circulating cooling water and the gaseous material exchange heat through counter-current flow, the temperature of the gaseous material can be reduced to below 45°C and liquefaction occurs. The cooling products generated by liquefaction will enter the cooling product recovery tank 5 for temporary storage.

[0028] In some embodiments, the liquid phase discharge port 22 is connected to a second transfer pump 7, and the outlet of the second transfer pump 7 is connected to the solvent recovery tower 3. The second transfer pump 7 can provide more power for the transfer of liquid phase materials, and also helps to balance the pressure difference between the solvent recovery feed buffer tank 2 and the solvent recovery tower 3, further improving the safety of the production process.

[0029] Example 3 As a further optimization of Example 2, in Figures 1 to 2 Based on, refer to Figure 3 The solvent recovery system of the washing tower also includes a solvent recovery storage tank 8, which is used to store the acetonitrile recovered by the solvent recovery tower 3. The upper end of the solvent recovery tower 3 is provided with a solvent recovery output port 31, and the lower end of the solvent recovery tower 3 is provided with a wastewater discharge port 32. The solvent recovery output port 31 is connected to the solvent recovery storage tank 8, and the wastewater discharge port 32 is connected to an external sewage treatment system. After the solvent recovery tower 3 recovers the acetonitrile from the washing waste liquid, the remaining waste liquid can be discharged to the external sewage treatment system through the wastewater discharge port 32 for further treatment.

[0030] In some embodiments, the top of the recovered solvent storage tank 8 is provided with a second inlet 81, and the bottom of the recovered solvent storage tank 8 is provided with a second outlet 82. The second inlet 81 is connected to the recovered solvent output port 31, and the second outlet 82 is connected to a recovered solvent extraction pump 9. The recovered solvent extraction pump 9 can extract acetonitrile from the recovered solvent storage tank 8 to the water washing tower 1 or other production systems for reuse, thereby realizing the reuse of production resources, which is conducive to reducing production consumables, effectively reducing production costs, and improving production efficiency.

[0031] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0032] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this utility model is in use. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. In addition, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0033] In this invention, unless otherwise expressly specified and limited, "above or below" the first feature may include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on" the first feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the first feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0034] Although the description of this utility model has been given in conjunction with the specific embodiments described above, it is obvious to those skilled in the art that many substitutions, modifications, and variations can be made based on the above description. Therefore, all such substitutions, modifications, and variations are included within the spirit and scope of the appended claims.

Claims

1. A solvent recovery system for a water washing tower, characterized in that, It includes a water washing tower (1), a solvent recovery feed buffer tank (2) and a solvent recovery tower (3) connected in sequence; The solvent recovery feed buffer tank (2) is provided with a gas phase discharge port (21) at the top and a liquid phase discharge port (22) at the bottom. The liquid phase discharge port (22) is connected to the solvent recovery tower (3). The gas phase discharge port (21) is connected to a cooler (4). The cooler (4) is connected to a cooling product recovery tank (5) downstream.

2. The solvent recovery system for the water washing tower according to claim 1, characterized in that, The top of the cooling product recovery tank (5) is provided with a first feed inlet (51), and the bottom of the cooling product recovery tank (5) is provided with a first discharge outlet (52). The first feed inlet (51) is connected to the cooling product discharge outlet of the cooler (4), and the first discharge outlet (52) is connected to the water washing tower (1).

3. The solvent recovery system for the water washing tower according to claim 2, characterized in that, The first discharge port (52) is connected to the first conveying pump (6), and the outlet of the first conveying pump (6) is connected to the water washing tower (1).

4. The solvent recovery system for the water washing tower according to claim 3, characterized in that, The upper end of the water washing tower (1) is provided with an oil phase output port (11), and the lower end of the water washing tower (1) is provided with a water washing waste liquid output port (12) and a circulation input port (13). The water washing waste liquid output port (12) is connected to the solvent recovery feed buffer tank (2), and the outlet of the first delivery pump (6) is connected to the circulation input port (13).

5. The solvent recovery system for a water washing tower according to claim 1, characterized in that, The cooler (4) is a shell-and-tube heat exchanger. The shell side of the cooler (4) is used for the flow of cooling water, and the tube side of the cooler (4) is used for the flow of gas phase discharged from the gas phase outlet (21).

6. The solvent recovery system for the water washing tower according to claim 1, characterized in that, The liquid phase discharge port (22) is connected to a second transfer pump (7), and the outlet of the second transfer pump (7) is connected to the solvent recovery tower (3).

7. The solvent recovery system for a water washing tower according to claim 1, characterized in that, It also includes a solvent recovery storage tank (8), the upper end of the solvent recovery tower (3) is provided with a solvent recovery output port (31), the lower end of the solvent recovery tower (3) is provided with a wastewater discharge port (32), the solvent recovery output port (31) is connected to the solvent recovery storage tank (8), and the wastewater discharge port (32) is connected to an external sewage treatment system.

8. The solvent recovery system for the water washing tower according to claim 7, characterized in that, The top of the recycled solvent storage tank (8) is provided with a second inlet (81), and the bottom of the recycled solvent storage tank (8) is provided with a second outlet (82). The second inlet (81) is connected to the recycled solvent output port (31), and the second outlet (82) is connected to a recycled solvent extraction pump (9).

9. The solvent recovery system for a water washing tower according to claim 1, characterized in that, The washing tower (1) is a dimer washing tower.

10. The solvent recovery system for the water washing tower according to claim 9, characterized in that, The solvent recovery tower (3) is an acetonitrile recovery tower.

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