Dichloroethane dehydration system
By using a multi-layer tray structure and a precisely controlled dichloroethane dehydration system, the problems of low dehydration efficiency and high energy consumption in existing technologies have been solved, achieving efficient and stable dichloroethane dehydration, reducing production costs and improving system safety.
Patent Information
- Application Number
- CN202520442638.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-14
- Publication Date
- 2026-03-03
- Estimated Expiration
- 2035-03-14
AI Technical Summary
Existing technologies for the dehydration of dichloroethane are inefficient, energy-intensive, and complex to operate, making it difficult to meet the needs of modern chemical production, especially in large-scale continuous production.
The dehydration tower adopts a multi-layer tray structure, combined with precise flow control and pressure regulation. It achieves efficient separation of dichloroethane and water through the design of a top condenser and reflux tank. It is equipped with tail gas treatment equipment to reduce the emission of harmful gases and prevents corrosion through alkaline treatment.
It achieves efficient dehydration of dichloroethane, reduces energy consumption, simplifies the operation process, reduces the difficulty of solid waste treatment and harmful gas emissions, and improves the safety and economic benefits of the system.
Smart Images
Figure CN223959208U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of distillation and purification technology, specifically relating to a dichloroethane dehydration system. Background Technology
[0002] Vinyl chloride is an important organic chemical product, obtained by cracking dichloroethane. Dichloroethane is a crucial intermediate or raw material in the vinyl chloride production process. To prevent its volatilization and leakage, dichloroethane requires a water seal during transportation. Therefore, arriving dichloroethane often contains a small amount of water, approximately 2000 ppm at room temperature. When dichloroethane contains water, it slowly hydrolyzes at room temperature or slightly above room temperature to produce HCl. Trace amounts of hydrogen chloride can corrode dichloroethane storage tanks and related pipelines, causing equipment corrosion damage. Furthermore, the corrosion of storage tanks and pipelines by hydrogen chloride also generates iron ions. For the dichloroethane cracking reaction in vinyl chloride production, the presence of iron ions accelerates the deep cracking reaction of dichloroethane, which is detrimental to vinyl chloride formation. Therefore, vinyl chloride plants generally require the iron content in dichloroethane to not exceed 0.3 ppm and the water content to not exceed 10 ppm. Traditional dichloroethane dehydration methods have many shortcomings, such as low dehydration efficiency, high energy consumption, and complex operation. Especially in the context of continuous, large-scale production, traditional dehydration methods are no longer sufficient to meet the demands of modern chemical production. Therefore, developing a highly efficient, energy-saving, and easy-to-operate dichloroethane dehydration system is of paramount importance. Utility Model Content
[0003] This invention provides a dichloroethane dehydration system, which has the advantages of high separation efficiency, continuous, stable and reliable operation, and significant economic benefits.
[0004] The technical solution of this utility model is as follows:
[0005] The dichloroethane dehydration system includes a purified dichloroethane cooler, a dehydration tower inlet / outlet heat exchanger and a dehydration tower, a dehydration tower bottom reboiler, a dehydration tower top condenser, a mixer, a dehydration tower top reflux tank and a controller;
[0006] The inlet of the dehydration tower's inlet / outlet heat exchanger is connected to a wet dichloroethane feed line, which is equipped with a flow transmitter and a flow regulating valve. The outlet of the dehydration tower's inlet / outlet heat exchanger is connected to the dehydration tower via a pipeline. The bottom of the dehydration tower is connected to the bottom reboiler, which is equipped with a temperature transmitter. The bottom reboiler uses low-pressure steam as the heat medium, and a steam regulating valve and a flow transmitter are installed on the low-pressure steam feed line. The steam regulating valve is controlled in cascade with a flow transmitter; the bottom of the dehydration tower is also connected to a purified dichloroethane discharge pipeline, which is equipped with a dehydration tower bottom discharge pump, a purified dichloroethane cooler, a discharge regulating valve, a flow transmitter, and a water analyzer. A level transmitter is installed at the bottom of the dehydration tower. The level transmitter, the flow transmitter, and the discharge regulating valve are all electrically connected to the controller. The level transmitter, the flow transmitter, and the discharge regulating valve are controlled in cascade.
[0007] The top of the dehydration tower is connected to the top condenser via a top pipeline. The top pipeline is equipped with a pressure transmitter. A vent pipeline is installed at the side outlet of the top condenser. The vent pipeline is connected in sequence to a tail gas cooler and a tail gas condensate separator. The vent pipeline is equipped with a pressure regulating valve. Both the pressure transmitter and the pressure regulating valve are electrically connected to the controller, which can discharge non-condensable gas according to the pressure.
[0008] The bottom of the tail gas condensate separator is connected to the top reflux tank of the dehydration tower via a pipeline. The bottom of the top condenser of the dehydration tower is connected to the top reflux tank of the dehydration tower via the top condenser discharge pipeline. The top condenser discharge pipeline is equipped with a mixer. The top condenser discharge pipeline is connected to an alkali feed pipeline. The alkali feed pipeline is equipped with a flow transmitter and a flow regulating valve.
[0009] The dehydration tower top reflux tank is connected to the aqueous phase outlet pipeline and the tower top reflux pipeline. The tower top reflux pipeline is connected to the top tray of the dehydration tower. A pH analyzer is installed on the aqueous phase outlet pipeline.
[0010] The top reflux tank of the dehydration tower is equipped with a first baffle and a second baffle, which divide the tank into an oil-water separation zone and a reflux zone. In the oil-water separation zone, dichloroethane and water are separated. An overflow port is located at the top; when the aqueous phase level reaches a certain height, the aqueous phase automatically flows out from the overflow port through the aqueous phase outlet pipeline. Dichloroethane enters the area between the first and second baffles through the lower gap between the first baffle and the top reflux tank, and then overflows into the reflux zone through the upper part of the second baffle. A certain gap is left between the lower part of the first baffle and the bottom of the tank to ensure that the heavy dichloroethane liquid phase enters the channel between the two baffles. A small gap is left between the upper part of the first baffle and the tank wall of the top reflux tank to ensure gas-air communication inside the tank. The lower part of the second baffle is completely sealed to the bottom of the tank, while a larger gap is left between the upper part of the second baffle and the top reflux tank to ensure the overflow of dichloroethane.
[0011] The top reflux pipeline is equipped with a dehydration tower top reflux pump, a reflux flow regulating valve, and a flow transmitter four. The top reflux tank of the dehydration tower is equipped with a level transmitter two. The level transmitter two, the flow transmitter four, and the reflux flow regulating valve are all electrically connected to the controller. The level transmitter two and the flow transmitter four cascade control the reflux flow regulating valve.
[0012] Preferably, the dehydration tower is a plate tower with 40 plates. A differential pressure transmitter is installed between the first plate and the last plate. The differential pressure transmitter is electrically connected to the controller and monitors the differential pressure between the plates.
[0013] Preferably, the dehydration tower top condenser is a vertical heat exchanger, and the shell side of the dehydration tower top condenser is provided with a circulating water inlet pipeline and a circulating water outlet pipeline. The gaseous material at the top of the tower enters from the upper tube box of the heat exchanger, is condensed in the tube side of the heat exchanger, and then flows out from the bottom of the lower tube box and is sent to the dehydration tower top reflux tank through the pipeline.
[0014] Preferably, a vent is provided in the lower tube box of the dehydration tower top condenser, and a baffle is installed at the vent to prevent the liquid phase from entering the vent pipeline along the pipeline.
[0015] Preferably, the cooling medium of the exhaust gas cooler is chilled water.
[0016] Preferably, the pipeline connecting the top condenser of the dehydration tower to the top reflux tank of the dehydration tower, and the pipeline connecting the tail gas condensate separator to the top reflux tank of the dehydration tower, are all connected to the liquid phase of the oil-water separation zone of the top reflux tank of the dehydration tower.
[0017] Compared with the prior art, this utility model has the following advantages:
[0018] 1. This utility model can realize large-scale continuous production, and also avoids the problems of difficult solid waste treatment caused by molecular sieve drying and dehydration. In addition, this system has the advantages of high separation effect, continuous, stable and reliable operation, and significant economic benefits.
[0019] 2. The dehydration tower of this invention adopts a multi-layer tray structure, which provides sufficient mass transfer area, enabling water and dichloroethane to be effectively separated, thereby improving the dehydration efficiency.
[0020] 3. This utility model reduces unnecessary energy consumption and lowers production costs through precise flow control and pressure regulation.
[0021] 4. This utility model incorporates exhaust gas treatment equipment such as an exhaust gas cooler and an exhaust gas condensate separator, effectively reducing the emission of harmful gases and protecting the environment. Furthermore, safety measures such as vents and baffles further enhance the system's safety. Attached Figure Description
[0022] Figure 1 This is a schematic diagram of the structure of this utility model.
[0023] Figure 2 This is a schematic diagram of the structure of the dehydration tower top reflux tank of this utility model.
[0024] In the diagram, 1. Dichloroethane cooler; 2. Dehydration tower inlet / outlet heat exchanger; 3. Dehydration tower; 4. Dehydration tower bottom reboiler; 5. Dehydration tower bottom discharge pump; 6. Dehydration tower top condenser; 7. Mixer; 8. Dehydration tower top reflux tank; 9. Dehydration tower top reflux pump; 10. Tail gas cooler; 11. Tail gas condensate separator; 12. Baffle; 13. Water analyzer; 14. Flow transmitter one; 15. Flow regulating valve one; 16. Level transmitter one; 17. Flow transmitter two; 18. Discharge regulating valve; 19. Pressure regulating valve; 20. Pressure transmitter; 21. First baffle; 22. 23. Second partition; 24. Flow transmitter three; 25. Flow regulating valve two; 26. pH analyzer; 27. Reflux flow regulating valve; 28. Flow transmitter four; 29. Liquid level transmitter two; 30. Regulating valve; 31. Flow transmitter five; 32. Temperature transmitter; 83. Differential pressure transmitter; 84. Oil-water separation zone; 85. Reflux zone; 36. Wet dichloroethane feed line; 37. Refined dichloroethane discharge line; 38. Tower top line; 39. Vent line; 40. Tower top condenser discharge line; 31. Alkali feed line; 31. Aqueous phase discharge line; 42. Tower top reflux line. Detailed Implementation
[0025] To enable those skilled in the art to better understand the technical solutions of this utility model, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of this utility model.
[0026] Example 1
[0027] like Figure 1-2 As shown, this embodiment provides a dichloroethane dehydration system, including a purified dichloroethane cooler 1, a dehydration tower inlet / outlet heat exchanger and a dehydration tower 3, a dehydration tower bottom reboiler 4, a dehydration tower top condenser 6, a mixer 7, a dehydration tower top reflux tank 8, and a controller.
[0028] The inlet of the dehydration tower inlet / outlet heat exchanger 2 is connected to a wet dichloroethane feed line 33. The wet dichloroethane feed line 33 is equipped with a flow transmitter 14 and a flow regulating valve 15. The outlet of the dehydration tower inlet / outlet heat exchanger 2 is connected to the dehydration tower 3 via a pipeline. The bottom of the dehydration tower 3 is connected to the bottom reboiler 4. The bottom of the dehydration tower 3 is equipped with a temperature transmitter 31. The bottom reboiler 4 uses low-pressure steam as the heat medium. A steam regulating valve 29 and a flow transmitter 30 are installed on the low-pressure steam feed line. The temperature transmitter 31, the flow transmitter 30, and the steam regulating valve 29 are all connected to a control system. The equipment is electrically connected, and the temperature transmitter 31 and the flow transmitter 30 cascade control the steam regulating valve 29; the bottom of the dehydration tower 3 is also connected to the purified dichloroethane discharge pipeline 34, which is equipped with the dehydration tower bottom discharge pump 5, the purified dichloroethane cooler 1, the discharge regulating valve 18, the flow transmitter 17 and the water analyzer 13. At the bottom of the dehydration tower 3, there is a level transmitter 16. The level transmitter 16, the flow transmitter 17 and the discharge regulating valve 18 are all electrically connected to the controller, and the level transmitter 16 and the flow transmitter 17 cascade control the discharge regulating valve 18;
[0029] The top of the dehydration tower 3 is connected to the top condenser 6 via a top pipeline 35. A pressure transmitter 20 is installed on the top pipeline 35. A vent pipeline 36 is installed at the side outlet of the top condenser 6. A tail gas cooler 10 and a tail gas condensate separator 11 are installed in sequence on the vent pipeline 36. A pressure regulating valve 19 is installed on the vent pipeline 36. Both the pressure transmitter 20 and the pressure regulating valve 19 are electrically connected to the controller.
[0030] The bottom of the tail gas condensate separator 11 is connected to the top reflux tank 8 of the dehydration tower via a pipeline. The bottom of the top condenser 6 of the dehydration tower is connected to the top reflux tank 8 of the dehydration tower via the top condenser discharge pipeline 37. The top condenser discharge pipeline 37 is equipped with a mixer 7. The top condenser discharge pipeline 37 is connected to an alkali feed pipeline 38. The alkali feed pipeline 38 is equipped with a flow transmitter 23 and a flow regulating valve 24.
[0031] The dehydration tower top reflux tank 8 is connected to the aqueous phase outlet pipeline 39 and the tower top reflux pipeline 40. The tower top reflux pipeline 40 is connected to the top of the dehydration tower. The aqueous phase outlet pipeline 39 is equipped with a pH analyzer 25.
[0032] The dehydration tower top reflux tank 8 is equipped with a first baffle 21 and a second baffle 22, which divide the dehydration tower top reflux tank 8 into two areas: an oil-water separation zone 81 and a reflux zone 82. In the oil-water separation zone 81, dichloroethane and water are separated. An overflow port is provided at the top. When the water phase level reaches a certain height, the water phase automatically flows out from the overflow port through the water phase outlet pipe 39. Dichloroethane enters the area between the first baffle 21 and the dehydration tower top reflux tank 8 through the lower gap between the first baffle 21 and the second baffle 22, and then overflows from the top of the second baffle 22 into the reflux zone 82. The lower part of the first partition 21 has a certain gap with the bottom of the tank to ensure that the heavy liquid phase enters the channel between the two partitions. The upper part of the first partition 21 has a small gap with the tank wall of the dehydration tower top reflux tank 8 to ensure that the gas connection inside the dehydration tower top reflux tank 8 is maintained. The lower part of the second partition 22 is completely sealed with the bottom of the tank, and the upper part of the second partition 22 has a large gap with the dehydration tower top reflux tank to ensure the overflow of dichloroethane.
[0033] The top return pipeline 40 is equipped with a dehydration tower top return pump 9, a return flow regulating valve 26, and a flow transmitter 27. The top return tank 8 is equipped with a level transmitter 28. The level transmitter 28, the flow transmitter 27, and the return flow regulating valve 26 are all electrically connected to the controller. The level transmitter 28 and the flow transmitter 27 cascade control the return flow regulating valve 26.
[0034] The dehydration tower 3 is a plate tower with 40 layers of plates. A differential pressure transmitter 32 is installed between the first and last layers of plates, and the differential pressure transmitter 32 is electrically connected to the controller.
[0035] The dehydration tower top condenser 6 is a vertical heat exchanger. The shell side of the dehydration tower top condenser 6 is equipped with a circulating water inlet pipeline and a circulating water outlet pipeline. The gaseous material at the top of the tower enters from the upper tube box of the heat exchanger, is condensed in the tube side of the heat exchanger, and then flows out from the bottom of the lower tube box and is sent to the dehydration tower top reflux tank 8 through the pipeline.
[0036] A vent is provided in the lower tube box of the top condenser 6 of the dehydration tower, and a baffle 12 is provided at the vent to prevent the liquid phase from entering the vent pipeline 36 along the pipeline.
[0037] The cooling medium of the exhaust gas cooler 10 is chilled water.
[0038] The pipelines connecting the top condenser 6 of the dehydration tower to the top reflux tank 8 of the dehydration tower, and the pipelines connecting the tail gas condensate separator 11 to the top reflux tank 8 of the dehydration tower, are all connected to the liquid phase in the oil-water separation zone 81 of the top reflux tank 8 of the dehydration tower.
[0039] The process is described as follows:
[0040] Wet dichloroethane from outside the dehydration tower is preheated by the inlet / outlet heat exchanger 2 and then enters the first tray of the dehydration tower 3 (tray numbers are from top to bottom). Because dichloroethane and water form an azeotrope during distillation, the vapor phase at the top of the tower (the azeotrope formed by dichloroethane and water) is condensed by the top condenser 6 and enters the top reflux tank 8. Since the solubility of water and dichloroethane is relatively low, dichloroethane and water are separated in the top reflux tank 8. Dichloroethane has a higher density than water; the upper part of the top reflux tank 8 contains the aqueous phase, and the lower part contains the dichloroethane oil phase. The water separated from the top reflux tank 8 overflows from the top of the tank and is discharged outside the boundary via the aqueous phase outlet pipeline 39. The dichloroethane at the bottom of the top reflux tank 8 is pressurized by the top reflux pump 9 and returned to the upper part of the dehydration tower 3 for reflux. After dehydration, the purified dichloroethane is sequentially sent to the dehydration tower inlet / outlet heat exchanger 2 and the purified dichloroethane cooler 1 via the bottom discharge pump 5 of the dehydration tower for cooling before being discharged out of the boundary area. Since dichloroethane decomposes slightly when heated to produce HCl and non-condensable gas, and HCl can cause corrosion of equipment and pipelines, an alkali feed pipeline 38 is installed on the pipeline between the top condenser 6 of the dehydration tower and the top reflux tank 8 of the dehydration tower. A tail gas vent and a vent pipeline 36 are installed on one side of the lower pipe box of the top condenser 6 of the dehydration tower. A tail gas cooler 10 and a tail gas condensate separator 11 are sequentially installed on the vent pipeline 36. The non-condensable gas is led out from the top of the tail gas condensate separator 11 through the pipeline and sent to the outside area for treatment.
[0041] Although the present invention has been described in detail with reference to the accompanying drawings and preferred embodiments, it is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the present invention by those skilled in the art without departing from the spirit and essence of the present invention, and all such modifications or substitutions should be within the scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.
Claims
1. A dichloroethane dehydration system, characterized in that, It includes a connected dichloroethane cooler (1), a dehydration tower inlet / outlet heat exchanger and dehydration tower (3), a dehydration tower bottom reboiler (4), a dehydration tower top condenser (6), a mixer (7), a dehydration tower top reflux tank (8), and a controller; The inlet of the dehydration tower inlet / outlet heat exchanger (2) is connected to a wet dichloroethane feed line (33). The wet dichloroethane feed line (33) is equipped with a flow transmitter (14) and a flow regulating valve (15). The outlet of the dehydration tower inlet / outlet heat exchanger (2) is connected to the dehydration tower (3) via a pipeline. The bottom of the dehydration tower (3) is connected to the bottom reboiler (4). The bottom of the dehydration tower (3) is equipped with a temperature transmitter (31). The bottom of the dehydration tower is also connected to... A dichloroethane discharge pipeline (34) is connected. The dichloroethane discharge pipeline (34) is equipped with a dehydration tower bottom discharge pump (5), a dichloroethane cooler (1), a discharge regulating valve (18), a flow transmitter (17) and a water analyzer (13). A level transmitter (16) is installed at the bottom of the dehydration tower (3). The level transmitter (16), the flow transmitter (17) and the discharge regulating valve (18) are all electrically connected to the controller. The top of the dehydration tower (3) is connected to the top condenser (6) of the dehydration tower via a top pipeline (35). A pressure transmitter (20) is installed on the top pipeline (35). A vent pipeline (36) is installed at the side outlet of the top condenser (6). A tail gas cooler (10) and a tail gas condensate separator (11) are installed in sequence on the vent pipeline (36). A pressure regulating valve (19) is installed on the vent pipeline (36). Both the pressure transmitter (20) and the pressure regulating valve (19) are electrically connected to the controller. The bottom of the tail gas condensate separator (11) is connected to the top reflux tank (8) of the dehydration tower via a pipeline. The bottom of the top condenser (6) of the dehydration tower is connected to the top reflux tank (8) of the dehydration tower via the top condenser discharge pipeline (37). The top condenser discharge pipeline (37) is equipped with a mixer (7). The top condenser discharge pipeline (37) is connected to an alkali feed pipeline (38). The alkali feed pipeline (38) is equipped with a flow transmitter (23) and a flow regulating valve (24). The dehydration tower top reflux tank (8) is connected to the aqueous phase outlet pipeline (39) and the tower top reflux pipeline (40). The tower top reflux pipeline (40) is connected to the top of the dehydration tower (3). The aqueous phase outlet pipeline (39) is equipped with a pH analyzer (25). The dehydration tower top reflux tank (8) is provided with a first baffle (21) and a second baffle (22), which divide the dehydration tower top reflux tank (8) into an oil-water separation zone (81) and a reflux zone (82). The top reflux pipeline (40) is equipped with a top reflux pump (9), a reflux flow regulating valve (26), and a flow transmitter four (27). The top reflux tank (8) is equipped with a level transmitter two (28). The level transmitter two (28), the flow transmitter four (27), and the reflux flow regulating valve (26) are all electrically connected to the controller.
2. The dichloroethane dehydration system as described in claim 1, characterized in that, The dehydration tower (3) is a plate tower, and a differential pressure transmitter (32) is installed between the first plate and the last plate. The differential pressure transmitter (32) is electrically connected to the controller.
3. The dichloroethane dehydration system as described in claim 1, characterized in that, The dehydration tower top condenser (6) is a vertical heat exchanger, and the shell side of the dehydration tower top condenser (6) is equipped with a circulating water inlet pipeline and a circulating water outlet pipeline.
4. The dichloroethane dehydration system as described in claim 1, characterized in that, A vent is provided in the lower tube box of the dehydration tower top condenser (6), and a baffle (12) is provided at the vent.
5. The dichloroethane dehydration system as described in claim 1, characterized in that, The cooling medium of the exhaust gas cooler (10) is chilled water.
6. The dichloroethane dehydration system as described in claim 1, characterized in that, The pipelines connecting the top condenser (6) of the dehydration tower to the top reflux tank (8) and the pipelines connecting the tail gas condensate separator (11) to the top reflux tank (8) of the dehydration tower are all connected to the liquid phase of the oil-water separation zone (81) of the top reflux tank (8).