A recovery isopropyl alcohol purification device

Abstract

The utility model relates to a kind of recovery isopropyl alcohol purification device, mainly solve the problem that water content in isopropyl alcohol solution is higher and higher in the production process of polymer polyol, seriously affect the continuous production polymer polyol product quality problem.The utility model passes through using a kind of recovery isopropyl alcohol purification device, including processing kettle (1), recovery isopropyl alcohol A tank (2-1), recovery isopropyl alcohol B tank (2-2), superheater (3), membrane module (4), first heat exchanger (5-1), second heat exchanger (5-2), first gas-liquid separator (6-1), second gas-liquid separator (6-2), water seal tank (7), vacuum pump (8), ceramic tube membrane (9) and screw (10) technical scheme, better solve the problem, can be used in the industrial production application of polymer polyol.

Description

Technical Field

[0001] This utility model relates to an apparatus for recovering and purifying isopropanol. Background Technology

[0002] In the production of polymeric polyols (POPs), a certain amount of vinyl-containing macromonomer polyether is typically added during blending. A chain transfer agent is also added during POP production to control the molecular weight of the polymer during synthesis, reduce cross-linking, and improve the solubility of the vinyl polymer in the base polyether. This significantly improves the dispersion stability of the POP system and increases the stability of the polymeric polyol, making it an indispensable part of the polymerization process. The commonly used chain transfer agent is isopropanol.

[0003] The continuous process for synthesizing polymer polyols involves mixing multiple raw materials and continuously adding them to a reactor. This reduces the residence time of the vinyl polymer in the reactor, resulting in a wide particle size distribution and enabling the production of high-solids-content, low-viscosity polymer polyols. The process is highly continuous and automated, leading to high production efficiency and low unit product production costs. Isopropanol, acting as a chain transfer agent in the polymer polyol, does not participate in the reaction. Its addition before the reaction helps to ensure more uniform and stable grafting of POP. After the reaction, isopropanol, unreacted styrene, and acrylonitrile are distilled off through a flash evaporation system and recovered through a condensation recovery system. However, the recovery system is affected by factors such as the temperature of the coolant, scaling in the heat exchanger, and the efficiency of the vacuum pump, resulting in an isopropanol recovery efficiency of only about 70%. As isopropanol is lost, the water content gradually increases to over 12%. Without adjusting the mixing ratio, the isopropanol concentration in the polymer polyol will decrease, affecting the molecular weight of the grafted polymer macromonomers in POP, thus impacting the viscosity of POP and subsequent filtration. Therefore, in our daily production process, we need to control the water content of the isopropanol solution to below 12% and increase the isopropanol content to ≥60% to ensure production stability. Because the boiling points of the components in the isopropanol aqueous solution are close, it is difficult to remove water from the isopropanol solution through distillation.

[0004] Currently, the process usually relies on adding pure isopropanol to increase the concentration of the isopropanol solution. However, this increases production costs and cannot reduce the total water content of the entire system. As isopropanol is lost, the total water content in the system will increase rapidly, which seriously affects the product quality of continuously produced polymer polyols. Therefore, there is an urgent need in industrial production for a process to purify the isopropanol solution.

[0005] Chinese patent CN221815334U provides a device for the recovery and treatment of isopropanol waste liquid, including: a deweighting tower, a pervaporation membrane module, a purification tower, a first reboiler, and a second reboiler; the deweighting tower is connected to the isopropanol waste liquid inlet pipe, the bottom of the deweighting tower is connected to the first reboiler, the top of the deweighting tower is connected to the shell-side inlet of the pervaporation membrane module through a top component conveying pipe, the shell-side outlet of the pervaporation membrane module is connected to the inlet of the purification tower, the bottom of the purification tower is connected to the second reboiler, and the bottom of the purification tower is connected to the isopropanol product discharge pipe; however, the deweighting tower has high energy consumption, complex operation, and large investment amount, and is not the optimal solution. Summary of the Invention

[0006] The technical problem this invention aims to solve is that during the production of polymer polyols, the water content in the isopropanol solution increases, seriously affecting the quality of continuously produced polymer polyol products. This invention provides an isopropanol recovery and purification device, which has the advantages of improving the purity of recovered isopropanol and saving costs.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows: A device for recovering and purifying isopropanol, characterized in that it includes a processing vessel 1, a recovery isopropanol A tank 2-1, a recovery isopropanol B tank 2-2, a superheater 3, a membrane module 4, a first heat exchanger 5-1, a second heat exchanger 5-2, a first gas-liquid separator 6-1, a second gas-liquid separator 6-2, a water seal tank 7, a vacuum pump 8, a ceramic membrane tube 9, and screws 10; wherein, the top of the processing vessel 1 is connected to a feed valve and a vacuum pump for separation. The bottom of the isopropanol recovery tank 2-1 and isopropanol recovery tank 2-2 should not be connected. The polymerization inhibitor inlet is located before the feed valve at the top of the treatment vessel 1. The tops of isopropanol recovery tanks 2-1 and 2-2 are connected via a first gas-liquid separator 6-1 and a second heat exchanger 5-2. Steam is introduced from the side of the treatment vessel 1 through a regulating valve. The top of the treatment vessel 1 is connected to the bottom of the superheater 3 through a vacuum valve. The superheater 3 is used to heat the material in the pipeline. Steam is introduced from the superheater 3 through the vacuum valve. The superheater 3 is connected to the top of the membrane module 4 via a side inlet. The bottom of the membrane module 4 is connected to the second heat exchanger 5-2, which is used to cool the isopropanol after membrane treatment and recover it to the isopropanol storage tank. The membrane module 4 is connected to the first heat exchanger 5-1, which is used to vacuum separate the water vapor generated during the membrane treatment process. The bottom of the first heat exchanger 5-1 is connected to the second gas-liquid separator 6-2. The gas in the pipeline flows from the top of the second gas-liquid separator 6-2 through a vacuum pump. 8. The liquid in the pipeline is transported from the bottom of the second gas-liquid separator 6-2 to the water seal tank 7. The purified recovered isopropanol flows back to the recovered isopropanol A tank 2-1 and the recovered isopropanol B tank 2-2 through the first gas-liquid separator 6-1. The membrane module 4 includes a ceramic tube membrane 9 and screws 10. The pores of the ceramic tube membrane 9 are 0.5nm to 0.7nm, and the number is 1000 to 1200, which are evenly distributed in the membrane module 4. The screws 10 are used to fix the membrane module 4.

[0008] In the above technical solution, the number of membrane modules is 2 to 6, which are connected in parallel.

[0009] In the above technical solution, the membrane module 4 has an operating temperature of 100-130℃, an in-membrane working pressure of ≤0.3Mpa, and a post-membrane working pressure of 0--0.09Mpa.

[0010] In the above technical solution, a pressure gauge is provided at the top of the treatment vessel 1, a membrane thermometer is provided in the outlet pipe at the top of the superheater 3, and a membrane pressure gauge is provided in the pipe of the membrane module 4.

[0011] In the above technical solution, the number of the first heat exchangers 5-1 is 2 to 4, and the number of the second heat exchangers 5-2 is 3 to 5.

[0012] In the above technical solution, the operating temperature of the superheater 3 is 100-160℃, the operating temperature of the first heat exchanger 5-1 is 40-140℃, and the operating temperature of the second heat exchanger 5-2 is 0-140℃.

[0013] In the above technical solution, the isopropanol recovery tank A 2-1 and the isopropanol recovery tank B 2-2 are respectively equipped with level gauges on the tank body.

[0014] This invention provides a device for recovering and purifying isopropanol. A mixed solution of recovered isopropanol is added to a stainless steel autoclave. Heating causes the volatilized vapor to be forced into a membrane separator. In the membrane separator, recovered isopropanol vapor (a mixture of organic solvent and water) is introduced onto one side of the membrane, while a vacuum is used on the other side to remove trace amounts of water, achieving separation and purification. The organic solvent outside the membrane is forced into a heat exchanger for condensation, yielding a water-free recovered isopropanol mixture. This method offers high water removal efficiency, minimal loss of effective components, and cost savings. The higher-purity recovered isopropanol solution can be reused in the continuous production of polymer polyols, significantly reducing impurity particles in the finished product, lowering and stabilizing the product's viscosity, accelerating subsequent filtration, and effectively reducing energy consumption in filtration, achieving excellent technical results. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the isopropanol recovery and purification device provided by this utility model.

[0016] Figure 2 This is a cross-sectional view of the membrane module in the isopropanol recovery and purification device provided by this utility model.

[0017] Appendix Figure 1 In the diagram, 1 is the processing vessel, 2-1 is the isopropanol recovery tank A, 2-2 is the isopropanol recovery tank B, 3 is the superheater, 4 is the membrane module, 5-1 is the first heat exchanger, 5-2 is the second heat exchanger, 6-1 is the first gas-liquid separator, 6-2 is the second gas-liquid separator, 7 is the water seal tank, and 8 is the vacuum pump.

[0018] Appendix Figure 2 In the diagram, 9 represents a ceramic membrane tube, and 10 represents a screw. Detailed Implementation

[0019] The following are merely preferred embodiments of this utility model and are not intended to limit the scope of protection of this utility model. All technical solutions that fall within the scope of this utility model should be included in the scope of protection of this utility model. For those skilled in the art, minor improvements and modifications made to this utility model without departing from the principle of this utility model should also be included in the scope of protection of this utility model.

[0020] Examples 1-4

[0021] An isopropanol recovery and purification apparatus, characterized in that it comprises a processing vessel 1, a recovery isopropanol A tank 2-1, a recovery isopropanol B tank 2-2, a superheater 3, a membrane module 4, a first heat exchanger 5-1, a second heat exchanger 5-2, a first gas-liquid separator 6-1, a second gas-liquid separator 6-2, a water seal tank 7, a vacuum pump 8, a ceramic membrane tube 9, and screws 10; wherein the top of the processing vessel 1 is connected to the recovery isopropanol A tank 2-1 and the recovery isopropanol B tank 2-2 via a feed valve and a vacuum pump, respectively. The bottom of tank 2-2 is connected to the reactor. The feed valve at the top of the treatment vessel 1 is the inlet for the polymerization inhibitor. The tops of isopropanol recovery tank 2-1 and isopropanol recovery tank 2-2 are connected via a first gas-liquid separator 6-1 and a second heat exchanger 5-2. Steam is introduced from the side of the treatment vessel 1 through a regulating valve. The top of the treatment vessel 1 is connected to the bottom of the superheater 3 through a vacuum valve. The superheater 3 is used to heat the material in the pipeline. Steam is introduced from the side of the superheater 3 through a vacuum valve. The top of the superheater 3... The membrane module 4 is connected to the bottom of the membrane module 4 and the second heat exchanger 5-2. The second heat exchanger 5-2 is used to cool the isopropanol after membrane treatment and recover it to the isopropanol recovery storage tank. The pipeline of the membrane module 4 is connected to the first heat exchanger 5-1. The first heat exchanger 5-1 is used to vacuum separate the water vapor generated during the membrane treatment process. The bottom of the first heat exchanger 5-1 is connected to the second gas-liquid separator 6-2. The gas in the pipeline is transported from the top of the second gas-liquid separator 6-2 to the tail gas treatment device through the vacuum pump 8. The liquid in the pipeline is transported from the bottom of the second gas-liquid separator 6-2 to the water seal tank 7. The purified recovered isopropanol flows back to the recovered isopropanol A tank 2-1 and the recovered isopropanol B tank 2-2 through the first gas-liquid separator 6-1. The membrane module 4 includes a ceramic tube membrane 9 and screws 10. The pores of the ceramic tube membrane 9 are 0.5nm to 0.7nm, and the number is 1000 to 1200, which are evenly distributed in the membrane module 4. The screws 10 are used to fix the membrane module 4.

[0022] In the above technical solution, the number of membrane modules is 2 to 6, which are connected in parallel.

[0023] In the above technical solution, the membrane module 4 has an operating temperature of 100-130℃, an in-membrane working pressure of ≤0.3Mpa, and a post-membrane working pressure of 0--0.09Mpa.

[0024] In the above technical solution, a pressure gauge is provided at the top of the treatment vessel 1, a membrane thermometer is provided in the outlet pipe at the top of the superheater 3, and a membrane pressure gauge is provided in the pipe of the membrane module 4.

[0025] In the above technical solution, the number of the first heat exchangers 5-1 is 2 to 4, and the number of the second heat exchangers 5-2 is 3 to 5.

[0026] In the above technical solution, the operating temperature of the superheater 3 is 100-160℃, the operating temperature of the first heat exchanger 5-1 is 40-140℃, and the operating temperature of the second heat exchanger 5-2 is 0-140℃.

[0027] In the above technical solution, the isopropanol recovery tank A 2-1 and the isopropanol recovery tank B 2-2 are respectively equipped with level gauges on the tank body.

[0028] Purification process:

[0029] Turn on the circulation pumps at the isopropanol recovery tank A 2-1 and the isopropanol recovery tank B 2-2 to feed material into the processing vessel 1 (tank B receives material when tank A is feeding, and tank A receives material when tank B is feeding). When the liquid level reaches 20%, start stirring. After the feeding of processing vessel 1 is completed, notify the external operator to close the processing feed valve, turn off the circulation pump, and stop feeding. Calculate the feeding amount based on the liquid level of the isopropanol recovery tank, and add polymerization inhibitor according to the feeding amount.

[0030] After the feeding of the treatment vessel 1 is completed, open the steam regulating valve of the outer jacket of the treatment vessel 1 and set the temperature of the treatment vessel 1 to 115℃ to heat the recovered isopropanol in the vessel. Before heating, drain the condensate in the jacket of the treatment vessel 1. After heating, drain the condensate every 2 hours.

[0031] When the temperature inside the treatment vessel 1 rises to 100°C, the circulating water, general cooling, and deep cooling of the heat exchanger 5 are turned on to cool down the vacuum control system in advance. The vacuum pump and the manual valve of the membrane module 4 to the vacuum system are turned on to draw negative pressure after the membrane is drawn. After the vacuum system is turned on, the steam condensate bypass manual valve of the superheater 3 is opened to drain the steam condensate in the pipeline and then the manual valve is closed. The steam manual valve is then opened to heat up the superheater 3. When the pressure inside the treatment vessel is ≥0.3MPa and the pressure inside membrane module 4 is 0.001MPa, slowly open the membrane inlet manual valve and membrane outlet manual valve, and slowly open the vacuum and condensate manual valves of treatment vessel 1. On the outside of the membrane, water molecules preferentially adsorb onto the membrane surface and pass through membrane module 4 under the pressure difference of water vapor on both sides of the membrane, and vaporize into water vapor inside the membrane. After the isopropanol treated by membrane module 4 enters the isopropanol recovery storage tank A / B, adjust the membrane outlet valve to slowly increase the pressure inside membrane module 4 and maintain it at 0.125MPa, so that membrane module 4 maintains stable pressure operation. Check the water content of the finished product at regular intervals (2h / time).

[0032] When the temperature and pressure of treatment vessel 1 drop to a certain value and no longer change, and after a period of time, the temperature of treatment vessel 1 begins to rise, the stirring current decreases compared to the beginning, the recovery liquid level curves of isopropanol recovery tank A 2-1 and isopropanol recovery tank B 2-2 slow down significantly, and the pressure in the membrane module drops to 0.05 MPa and the temperature drops below 80℃, it indicates that the treatment is complete. Stop stirring and close the vacuum valve, vacuum condensate valve, and feed valve of the treatment vessel. Open the drain valve at the bottom of treatment vessel 1 to drain the high-boiling-point residual liquid at the bottom of the vessel into an iron drum for collection.

[0033] Comparative Example 1

[0034] The parameters of the recovered isopropanol solution without membrane treatment are shown in Table 1.

[0035] Table 1. Parameters of the recovered isopropanol solution in Examples 1-4 and Comparative Example 1

[0036] Moisture % 4.13 2.24 3.58 3.58 12.53 Isopropanol content % 67.07 66.26 62.06 62.87 50.45 tert-amyl alcohol residue % 11.83 15.84 11.04 11.68 10.81 Acrylonitrile residue % 6.7 4.22 8.51 7.44 8.2 Ethylbenzene residue % 0.96 1.26 1.09 1.07 1.64 styrene residue % 5.43 5.92 6.81 6.5 8.48 % of effective components 96.12 95.74 93.09 92.94 92.11

[0037] As can be seen from the data in Table 1, the device provided by this utility model effectively improves the utilization rate of isopropanol in the continuous process of polymer polyol recycling, saves costs, reduces the impact of moisture on product quality, improves product quality, and ensures continuous production when producing polymer polyols.

Claims

1. A device for recovering and purifying isopropanol, characterized in that, The system includes a processing vessel (1), a recovery tank for isopropanol A (2-1), a recovery tank for isopropanol B (2-2), a superheater (3), a membrane module (4), a first heat exchanger (5-1), a second heat exchanger (5-2), a first gas-liquid separator (6-1), a second gas-liquid separator (6-2), a water seal tank (7), a vacuum pump (8), a ceramic membrane tube (9), and screws (10); wherein, the top of the processing vessel (1) is connected to the bottom of the recovery tank for isopropanol A (2-1) and the recovery tank for isopropanol B (2-2) via a feed valve and a vacuum pump, respectively. The parts are connected. The feed valve at the top of the treatment vessel (1) is the inlet for the polymerization inhibitor. The tops of the isopropanol recovery tank A (2-1) and the isopropanol recovery tank B (2-2) are connected through the first gas-liquid separator (6-1) and the second heat exchanger (5-2). Steam is introduced from the side of the treatment vessel (1) through the regulating valve. The top of the treatment vessel (1) is connected to the bottom of the superheater (3) through the vacuum valve. The superheater (3) is used to heat the material in the pipeline. Steam is introduced from the side of the superheater (3) through the vacuum valve. The top of the superheater (3) and the membrane module ( 4) The bottom of the membrane module (4) is connected to the second heat exchanger (5-2). The second heat exchanger (5-2) is used to cool the isopropanol after membrane treatment and recover it to the isopropanol storage tank. The pipeline of the membrane module (4) is connected to the first heat exchanger (5-1). The first heat exchanger (5-1) is used to vacuum separate the water vapor generated during the membrane treatment process. The bottom of the first heat exchanger (5-1) is connected to the second gas-liquid separator (6-2). The gas in the pipeline is transported from the top of the second gas-liquid separator (6-2) to the tail gas treatment unit through the vacuum pump (8). The liquid in the pipeline is transported from the bottom of the second gas-liquid separator (6-2) to the water seal tank (7). The purified isopropanol is returned to the isopropanol recovery tank A (2-1) and the isopropanol recovery tank B (2-2) through the first gas-liquid separator (6-1). The membrane module (4) includes a ceramic tube membrane (9) and screws (10). The ceramic tube membrane (9) has pores of 0.5nm to 0.7nm and 1000 to 1200 pores, which are evenly distributed in the membrane module (4). The screws (10) are used to fix the membrane module (4).

2. The isopropanol recovery and purification apparatus according to claim 1, characterized in that, The number of membrane modules (4) is 2 to 6, which are connected in parallel.

3. The isopropanol recovery and purification apparatus according to claim 1, characterized in that, The membrane module (4) operates at a temperature of 100-130°C, with a pre-membrane working pressure of ≤0.3 MPa and a post-membrane working pressure of 0--0.09 MPa.

4. The isopropanol recovery and purification apparatus according to claim 1, characterized in that, The processing vessel (1) is equipped with a pressure gauge at the top, the superheater (3) is equipped with a membrane thermometer at the top outlet pipe, and the membrane module (4) is equipped with a membrane pressure gauge.

5. The isopropanol recovery and purification apparatus according to claim 1, characterized in that, The number of the first heat exchangers (5-1) is 2 to 4, and the number of the second heat exchangers (5-2) is 3 to 5.

6. The isopropanol recovery and purification apparatus according to claim 1, characterized in that, The superheater (3) operates at a temperature of 100-160°C, the first heat exchanger (5-1) operates at a temperature of 40-140°C, and the second heat exchanger (5-2) operates at a temperature of 0-140°C.

7. The isopropanol recovery and purification apparatus according to claim 1, characterized in that, The isopropanol recovery tank A (2-1) and the isopropanol recovery tank B (2-2) are each equipped with a level gauge on the tank body.

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