Dichloroethane rectification device

Abstract

The utility model relates to the technical field of dichloroethane production, in particular to a dichloroethane rectification device. Comprising a dehydrating tower, a tower kettle of the dehydrating tower is connected with a reboiler, two lower packing layers are arranged in the lower portion of the dehydrating tower in the axial direction of the dehydrating tower, an upper packing layer is fixed in the upper portion of the dehydrating tower, a distribution exchanger is fixed in the dehydrating tower above the upper packing layer, and the dehydrating tower part between the two lower packing layers is communicated with the feeding end of a dichloroethane condenser. The discharge end of the dichloroethane condenser is communicated with the dichloroethane buffer tank, the gas outlet end of the tower top of the dehydrating tower is communicated with the feed end of the tower top condenser, the discharge end of the tower top condenser is communicated with the return tank, the upper end of the return tank is communicated with the wastewater tank, and the lower end of the return tank is communicated with the distribution exchanger through the delivery pump. According to the utility model, tower top steam is pre-cooled by utilizing the low-temperature characteristic of a backflow oil phase, so that the cooling load of the tower top condenser is obviously reduced, and the consumption of condensate water is reduced.

Description

Technical Field

[0001] This utility model relates to the field of dichloroethane production technology, specifically to a dichloroethane distillation apparatus. Background Technology

[0002] Dichloroethane, an important chemical raw material, is widely used in the synthesis of products such as vinyl chloride and ethylenediamine. During its production, crude dichloroethane typically contains moisture and other impurities, requiring purification through distillation. However, traditional distillation equipment suffers from high energy consumption, high condensate consumption, and low wastewater treatment efficiency.

[0003] In existing technologies, the overhead vapor typically enters the condenser directly for cooling, failing to fully utilize the system's internal waste heat or reflux material for pre-cooling, resulting in high condensate consumption. Traditional distillation columns employ a single gas-liquid contact method, such as ordinary packing or tray structures, leading to low mass and heat transfer efficiency. Some improved solutions use multi-layer packing, which enhances separation, but does not optimize energy exchange between the overhead vapor and reflux material, still resulting in heat waste. In existing systems, wastewater after phase separation is often discharged via manual valves, which is prone to overflow or equipment corrosion due to untimely liquid level monitoring, and also poses low operational safety risks.

[0004] However, technologies that enhance heat exchange through built-in coils or ejectors are prone to creating cooling dead zones under low flow conditions, resulting in problems such as localized overheating of heavy components or insufficient pre-cooling of steam.

[0005] To address the aforementioned issues, there is an urgent need for a dichloroethane distillation unit that integrates efficient heat exchange, condensate recycling, and automated control. Utility Model Content

[0006] The main objective of this invention is to provide a dichloroethane distillation apparatus that can reduce the consumption of condensate.

[0007] To achieve the above objectives, the technical solution provided by this utility model is as follows:

[0008] A dichloroethane distillation apparatus includes a dehydration tower, the reboiler of which is connected to a reboiler. Two lower packing layers are arranged along the axial direction in the lower part of the dehydration tower, and an upper packing layer is fixed in the upper part of the dehydration tower. A distribution exchanger is fixed in the dehydration tower above the upper packing layer. The portion of the dehydration tower between the two lower packing layers is connected to the feed end of a dichloroethane condenser. The discharge end of the dichloroethane condenser is connected to a dichloroethane buffer tank. The gas outlet at the top of the dehydration tower is connected to the feed end of the top condenser. The discharge end of the top condenser is connected to a reflux tank. The upper end of the reflux tank is connected to a wastewater tank, and the lower end of the reflux tank is connected to the distribution exchanger via a transfer pump. During the flow of the oil phase discharged from the lower end of the reflux tank through the distribution exchanger, the top vapor flowing through the distribution exchanger can be pre-cooled.

[0009] Specifically, a level sensor is installed at the upper end of the wastewater tank, and a solenoid valve is installed at the lower end of the wastewater tank. The level sensor, the solenoid valve, and the controller are electrically connected.

[0010] Specifically, the distribution exchanger includes a housing, which is fixedly and sealed inside the dehydration tower. An inlet pipe is fixedly connected to the housing, and the inlet pipe is connected to the lower end of the return tank through a delivery pump. Multiple air risers pass through the housing and are fixedly and sealed to the housing. Each air riser section below the housing is fitted with a sleeve, which is concentric with the air riser inside it. The annular cavity between the sleeve and the air riser is connected to the inside of the housing.

[0011] Specifically, the lower end of the riser pipe passes through the lower end of the sleeve, and a conical ring is fixed on the outer side of the lower end of the riser pipe. The diameter of the upper end of the conical ring is smaller than the diameter of the lower end of the conical ring.

[0012] Specifically, a cross plate is fixed inside the air riser pipe.

[0013] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0014] 1. Through the innovative structure of the distribution exchanger, the low-temperature characteristics of the reflux oil phase are used to pre-cool the overhead steam, significantly reducing the cooling load on the overhead condenser, decreasing condensate consumption, and achieving energy recycling. The built-in distribution exchanger replaces the traditional external heat exchanger, avoiding additional energy input and further reducing the overall system energy consumption.

[0015] 2. The dehydration tower is equipped with a double lower packing layer and a single upper packing layer to extend the gas-liquid contact path, enhance the separation efficiency of water and light components, and suppress the entrainment of high-boiling-point impurities, thereby improving the purity of dichloroethane. The bushing, conical ring, and cross plate structure of the distribution exchanger promotes the dispersion of the oil phase into a uniform liquid film, increases the contact area with steam, strengthens the heat and mass transfer process, and avoids local overheating or cooling dead zones.

[0016] 3. The integrated layout of the distribution exchanger and dehydration tower simplifies piping connections, reduces pressure drop and leakage risks, and minimizes equipment footprint. The dynamic balance between oil phase reflux and steam precooling buffers pressure fluctuations within the tower, maintains the stability of the distillation process, and reduces tower pressure runaway problems caused by changes in steam load.

[0017] 4. The liquid level sensor of the wastewater tank is linked with the solenoid valve to realize real-time monitoring and automatic discharge of wastewater level, avoiding the risk of overflow or equipment corrosion caused by manual operation delay.

[0018] 5. The cross plate inside the riser pipe can break up liquid droplets in the steam and prevent the riser pipe from becoming blocked; the conical ring structure optimizes the oil phase flow path, inhibits flooding, and ensures safe operation over long periods.

[0019] 6. By using efficient phase separation and automatic discharge, the retention time of wastewater containing organic matter is reduced, thereby reducing the difficulty and cost of subsequent treatment.

[0020] 7. Oil phase precooling reduces steam temperature and slows down condenser scaling; the synergistic effect of the packing layer and the distribution exchanger reduces the thermal decomposition of heavy components and delays equipment aging. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the distillation apparatus.

[0022] Figure 2 This is a schematic diagram of a distribution switch.

[0023] Figure 3 A cross-sectional view of the distribution switch.

[0024] Figure 4 This is a schematic diagram of the cross plate inside the riser pipe.

[0025] The components in the attached diagram are named as follows: 1. Dehydration tower, 2. Reboiler, 3. Dichloroethane condenser, 4. Top condenser, 5. Reflux tank, 6. Wastewater tank, 7. Dichloroethane buffer tank, 8. Lower packing layer, 9. Upper packing layer, 10. Distribution exchanger, 11. Shell, 12. Inlet pipe, 13. Riser pipe, 14. Sleeve, 15. Conical ring, 16. Cross plate. Detailed Implementation

[0026] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments.

[0027] Example 1: Refer to Figure 1 As shown, a dichloroethane distillation apparatus includes a dehydration tower 1, the bottom of which is connected to a reboiler 2.

[0028] Two lower packing layers 8 are arranged along the axial direction in the lower part of the dehydration tower 1, and an upper packing layer 9 is fixed in the upper part of the dehydration tower 1. A distribution exchanger 10 is fixed in the dehydration tower 1 above the upper packing layer 9.

[0029] The dehydration tower 1 between the two packing layers 8 is connected to the feed end of the dichloroethane condenser 3, and the discharge end of the dichloroethane condenser 3 is connected to the dichloroethane buffer tank 7.

[0030] The gas outlet at the top of the dehydration tower 1 is connected to the feed inlet of the top condenser 4, the discharge outlet of the top condenser 4 is connected to the reflux tank 5, and the upper end of the reflux tank 5 is connected to the wastewater tank 6.

[0031] A liquid level sensor is installed at the upper end of the wastewater tank 6, and a solenoid valve is installed at the lower end of the wastewater tank 6. The liquid level sensor, the solenoid valve, and the controller are electrically connected. The controller adjusts the opening degree of the solenoid valve in real time through a PID algorithm.

[0032] The lower end of the reflux tank 5 is connected to the distribution exchanger 10 via a transfer pump.

[0033] Crude 1,2-dichloroethane feedstock enters dehydration tower 1. The gas phase at the top of dehydration tower 1 enters the top condenser 4 and is condensed before entering the reflux tank 5, where it undergoes phase separation. The water phase in the upper part of reflux tank 5 flows into wastewater tank 6, while the oil phase is in the lower part of reflux tank 5.

[0034] The oil phase is mainly composed of 1,2-dichloroethane, containing small amounts of incompletely separated high-boiling-point impurities and trace azeotropic entrainments. During distillation, water and vinyl chloride are discharged as vapors at the top of the column, while high-boiling-point components such as 1,2-dichloroethane are enriched within the column. After the vapors at the top of the column condense, due to the higher density of 1,2-dichloroethane (1.235 g / cm³) compared to water, it separates into an upper aqueous phase and a lower oil phase in the reflux tank 5.

[0035] The oil phase is pressurized by a transfer pump and flows downward in the dehydration tower 1 after passing through the distribution exchanger 10. As the oil phase discharged from the lower end of the reflux tank 5 flows through the distribution exchanger 10, it can pre-cool the overhead steam flowing through the distribution exchanger 10, thereby reducing the amount of condensate used in the overhead condenser 4 and reducing energy consumption.

[0036] When the liquid level in wastewater tank 6 is high, the level sensor sends a signal to the controller, which then opens the solenoid valve at the bottom of wastewater tank 6, thereby achieving automatic wastewater discharge. When the liquid level is low, the solenoid valve closes.

[0037] The dichloroethane material between the two lower packing layers 8 in the dehydration tower 1 enters the dichloroethane condenser 3, and after condensation and cooling, flows into the dichloroethane buffer tank 7.

[0038] The bottom of the dehydration tower 1 is connected to the reboiler 2, which can heat the crude 1,2-dichloroethane feedstock in the bottom of the dehydration tower 1.

[0039] Example 2: Based on Example 1, referring to... Figures 2-3 As shown, the distribution exchanger 10 includes a housing 11, which is fixedly and sealed inside the dehydration tower 1. An inlet pipe 12 is fixedly connected to the housing 11, and the inlet pipe 12 is connected to the lower end of the return tank 5 through a delivery pump.

[0040] Multiple air risers 13 penetrate the housing 11 and are fixedly and sealed to the housing 11. Each air riser 13 portion below the housing 11 is fitted with a sleeve 14, the sleeve 14 is concentric with the air riser 13 inside it, and the annular cavity between the sleeve 14 and the air riser 13 communicates with the interior of the housing 11.

[0041] The oil phase discharged from the lower end of the reflux tank 5 enters the shell 11 and descends between the sleeve 14 and the riser pipe 13. The overhead steam in the dehydration tower 1 rises through the riser pipe 13. The oil phase absorbs the heat from the overhead steam, and its own temperature rises before entering the dehydration tower 1 to participate in the reflux. The descending oil phase can pre-cool the ascending overhead steam, which can reduce the amount of condensate used in the overhead condenser 4 and reduce energy consumption.

[0042] Example 3: Based on Example 1, referring to... Figures 2-4 As shown, the lower end of the riser pipe 13 passes through the lower end of the sleeve 14, and a conical ring 15 is fixed to the outer side of the lower end of the riser pipe 13. The diameter of the upper end of the conical ring 15 is smaller than the diameter of the lower end of the conical ring 15.

[0043] When the downward-flowing oil phase comes into contact with the conical ring 15, it can disperse the oil phase, thereby increasing the dispersion rate of the oil phase, improving the heat exchange efficiency between the upward-flowing steam and the oil phase in the dehydration tower 1, and thus improving the distillation efficiency.

[0044] Example 4: Based on Example 1, referring to... Figure 4 As shown, a cross plate 16 is fixed inside the riser pipe 13.

[0045] When the top vapor rises in the riser 13, the cross plate 16 can increase the heat exchange area between the downward oil phase and the top vapor, thereby improving the pre-cooling efficiency of the top vapor.

[0046] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A dichloroethane distillation apparatus, comprising a dehydration tower (1), characterized in that, Two lower packing layers (8) are arranged along the axial direction in the lower part of the dehydration tower (1). An upper packing layer (9) is fixed in the upper part of the dehydration tower (1). A distribution exchanger (10) is fixed in the dehydration tower (1) above the upper packing layer (9). The part of the dehydration tower (1) between the two lower packing layers (8) is connected to the feed end of the dichloroethane condenser (3). The discharge end of the dichloroethane condenser (3) is connected to the dichloroethane buffer tank (7). The gas outlet at the top of the tower (1) is connected to the feed inlet of the top condenser (4), the discharge outlet of the top condenser (4) is connected to the reflux tank (5), the upper end of the reflux tank (5) is connected to the wastewater tank (6), and the lower end of the reflux tank (5) is connected to the distribution exchanger (10) via a transfer pump. During the process of the oil phase discharged from the lower end of the reflux tank (5) flowing through the distribution exchanger (10), the top steam flowing through the distribution exchanger (10) can be pre-cooled.

2. The dichloroethane distillation apparatus according to claim 1, characterized in that, The bottom of the dehydration tower (1) is connected to the reboiler (2).

3. The dichloroethane distillation apparatus according to claim 1, characterized in that, A liquid level sensor is installed at the upper end of the wastewater tank (6), and a solenoid valve is installed at the lower end of the wastewater tank (6). The liquid level sensor, the solenoid valve, and the controller are electrically connected.

4. The dichloroethane distillation apparatus according to claim 1, characterized in that, The distribution exchanger (10) includes a housing (11), which is fixedly and sealed inside the dehydration tower (1). An inlet pipe (12) is fixedly connected to the housing (11). The inlet pipe (12) is connected to the lower end of the return tank (5) through a delivery pump. Multiple air risers (13) pass through the housing (11) and are fixedly and sealed to the housing (11). Each air riser (13) below the housing (11) is fitted with a sleeve (14). The sleeve (14) is concentric with the air riser (13) inside it. The annular cavity between the sleeve (14) and the air riser (13) is connected to the inside of the housing (11).

5. The dichloroethane distillation apparatus according to claim 4, characterized in that, The lower end of the riser pipe (13) passes through the lower end of the sleeve (14), and a conical ring (15) is fixed on the outer side of the lower end of the riser pipe (13).

6. The dichloroethane distillation apparatus according to claim 5, characterized in that, The diameter of the upper end of the cone ring (15) is smaller than the diameter of the lower end of the cone ring (15).

7. The dichloroethane distillation apparatus according to claim 4, characterized in that, A cross plate (16) is fixed inside the riser pipe (13).

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