A recovery apparatus for separating acetic acid and water by multi-effect rectification
By using a multi-effect distillation column to separate acetic acid and water by utilizing boiler steam heat in stages, and generating electricity using the steam at the top of the column, the problem of increased costs and energy waste caused by the use of azeotropic agents is solved, achieving efficient heat utilization and reduced energy consumption.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- ZHEJIANG DONGJIANG GREEN PETROCHEMICAL TECHNOLOGY INNOVATION CENTER CO LTD
- Filing Date
- 2025-04-10
- Publication Date
- 2026-06-09
AI Technical Summary
In existing PTA plants, azeotropic agents are required during the separation of acetic acid and water, which increases separation costs. Furthermore, the heat energy of the organic vapor at the top of the column is carried away by the circulating cooling water, resulting in energy waste.
A multi-effect distillation system is used to separate acetic acid and water. The system utilizes the heat from steam generated by the boiler in a series of distillation columns, including a first-effect column, a second-effect column, and a third-effect column. The steam at the top of the columns is used for power generation, avoiding the use of azeotropic agents. The heat is further recovered by using a heat exchanger at the top of the columns.
It improves thermal energy utilization, reduces energy and material consumption, reduces the use of circulating cooling water, and achieves efficient separation of acetic acid and water for power generation.
Smart Images
Figure CN224331528U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of PTA production technology, and more specifically, to a multi-effect distillation device for the recovery of acetic acid and water. Background Technology
[0002] Currently, most PTA (acetic acid and water) units use azeotropic distillation for acetic acid and water separation. The organic vapor temperature at the top of the column is approximately 80–90°C, rich in azeotropic agents and water. To allow the azeotropic agent to be refluxed back into the distillation column for reuse, the azeotropic agent and water need to be separated, and the temperature of the organic vapor at the top of the distillation column needs to be cooled to 40–60°C. Currently, the organic vapor at the top of the acetic acid and water azeotropic distillation column is cooled by circulating water, resulting in most of the heat energy of the organic vapor at the top of the column being carried away by the circulating cooling water, causing energy waste.
[0003] For example, Chinese Patent Publication No. CN215505567U, published on January 14, 2022, is entitled "Acetic Acid Recovery System for PTA Units." In this application, the steam in the distillation column is extracted using a vacuum pump, and the distillation column is distilled and dehydrated under negative pressure, which can vaporize the azeotropic agent and separate it from acetic acid at low temperature. However, it requires the use of an azeotropic agent, which increases the separation cost. Utility Model Content
[0004] This invention overcomes the shortcomings of existing PTA units that require the use of azeotropic agents in the acetic acid recovery process, which increases separation costs. It provides a multi-effect distillation device for separating acetic acid and water recovery without the use of azeotropic agents, thus reducing production costs. Furthermore, this application effectively utilizes the organic vapor in the distillation column, eliminating the need for circulating cooling water. Instead, it uses the heat energy of the vapor to generate steam, which is then used to drive a steam turbine for power generation, significantly improving heat utilization and reducing energy and material consumption.
[0005] To solve the above-mentioned technical problems, this utility model adopts the following technical solution: a multi-effect distillation device for separating acetic acid and water, comprising:
[0006] A single-effect distillation column is equipped with a single-effect reboiler at the bottom;
[0007] The double-effect distillation column is equipped with a double-effect reboiler at the bottom; the top of the single-effect distillation column is connected to the double-effect reboiler.
[0008] The triple-effect distillation column is equipped with a triple-effect reboiler at the bottom; the top of the double-effect distillation column is connected to the triple-effect reboiler.
[0009] Steam from the top of the triple-effect distillation column enters the top heat exchanger for heat exchange, and the steam generated after heat exchange in the top heat exchanger enters the steam turbine generator to generate electricity.
[0010] In this application, steam generated by a boiler heats a first-effect reboiler. The first-effect reboiler distills acetic acid and water in a first-effect distillation column. The organic vapor generated in the first-effect distillation column flows out from the top of the column. After passing through a second-effect reboiler, the second-effect reboiler is heated. The second-effect reboiler distills acetic acid and water in a second-effect distillation column. The organic vapor generated in the second-effect distillation column flows out from the top of the column. After passing through a third-effect reboiler, the third-effect reboiler is heated. The third-effect reboiler distills acetic acid and water in a third-effect distillation column. The organic vapor generated in the third-effect distillation column flows out from the top of the column. The organic vapor then passes through a heat exchanger at the top of the column, where it exchanges heat with the organic vapor generated in the third-effect distillation column to produce steam. The steam then powers a steam turbine generator unit to generate electricity. In the above process, the steam generated by the boiler serves as the heat source for the entire unit. The heat is utilized in stages through the first-effect distillation column, the second-effect distillation column, and the third-effect distillation column, thereby improving the utilization rate of thermal energy. Finally, the thermal energy is used to generate electricity, which significantly improves the utilization rate of heat. Moreover, no azeotropic agent is required in the entire process, which reduces energy and material consumption.
[0011] Preferably, the upper part of the single-effect distillation column is connected to the first feed pipe;
[0012] The bottom of the single-effect distillation column is connected to the first acid discharge pipe, and the first acid discharge pipe is equipped with a first column bottom feed heat exchanger.
[0013] Before the mixture of acetic acid and water enters the first-effect distillation column through the first feed pipe, it exchanges heat with concentrated acid in the bottom feed heat exchanger of the first column.
[0014] Before entering the first-effect distillation column, the mixture of acetic acid and water exchanges heat with the concentrated acid flowing out of the first-effect distillation column in the bottom feed heat exchanger. The mixture of acetic acid and water absorbs some of the heat from the concentrated acid, thereby improving the heat utilization rate and reducing the loss of some of the concentrated acid's heat.
[0015] Preferably, the upper part of the double-effect distillation column is connected to the second feed pipe;
[0016] The bottom of the double-effect distillation column is connected to the second acid drain pipe, and the second acid drain pipe is equipped with a second bottom feed heat exchanger.
[0017] Before the mixture of acetic acid and water enters the double-effect distillation column through the second feed pipe, it exchanges heat with concentrated acid in the bottom feed heat exchanger of the second column.
[0018] Before entering the double-effect distillation column, the mixture of acetic acid and water exchanges heat with the concentrated acid flowing out of the double-effect distillation column in the bottom feed heat exchanger of the second column. The mixture of acetic acid and water absorbs part of the heat from the concentrated acid, thereby improving the heat utilization rate and reducing the loss of some of the heat from the concentrated acid.
[0019] Preferably, the upper part of the triple-effect distillation column is connected to the third feed pipe;
[0020] The bottom of the triple-effect distillation column is connected to the third acid drain pipe, and the third acid drain pipe is equipped with a third column bottom feed heat exchanger.
[0021] Before the mixture of acetic acid and water enters the triple-effect distillation column through the third feed pipe, it exchanges heat with concentrated acid in the bottom feed heat exchanger of the third column.
[0022] Before entering the triple-effect distillation column, the mixture of acetic acid and water exchanges heat with the concentrated acid flowing out of the triple-effect distillation column in the bottom feed heat exchanger of the third column. The mixture of acetic acid and water absorbs some of the heat from the concentrated acid, thereby improving the heat utilization rate and reducing the loss of some of the heat from the concentrated acid.
[0023] As a preferred option, the top dilute acid main pipe is also included;
[0024] The steam flowing out from the top of the first-effect distillation column exchanges heat in the second-effect reboiler and then flows into the dilute acid header at the top of the column.
[0025] The steam flowing out from the top of the double-effect distillation column is heated in the triple-effect reboiler and then flows into the dilute acid header at the top of the column.
[0026] The steam flowing out from the top of the triple-effect distillation column is heated by the heat exchanger at the top of the column and then flows into the dilute acid header at the top of the column.
[0027] The top dilute acid header is used to collect organic vapors flowing from the top of the first-effect, second-effect, and third-effect distillation columns. After passing through their corresponding reboilers or top heat exchangers, the organic vapors condense into liquids and enter the top dilute acid header for overall collection of the organic vapors at the top of the columns.
[0028] Preferably, the system also includes a concentrated acid header at the bottom of the column; the concentrated acid in the reboiler of the first-effect distillation column, the reboiler of the second-effect distillation column, and the reboiler of the third-effect distillation column is discharged from the concentrated acid header at the bottom of the column.
[0029] It can collect concentrated acid discharged from the first-effect distillation column, the second-effect distillation column, and the third-effect distillation column at the same time, which facilitates further processing and treatment of concentrated acid.
[0030] Preferably, a concentrated acid cooler is installed on the concentrated acid main pipe at the bottom of the tower.
[0031] The concentrated acid discharged from the bottom of the first-effect distillation column, the bottom of the second-effect distillation column, and the bottom of the third-effect distillation column can have its temperature reduced when it passes through the concentrated acid cooler at the bottom of the column.
[0032] As a preferred option, pressure monitoring gauges are installed in the single-effect distillation column, the double-effect distillation column, and the triple-effect distillation column.
[0033] The pressure gauge can monitor the pressure in the first-effect, second-effect, and third-effect distillation columns in real time, thereby adjusting the opening of the corresponding valves and adjusting the pressure in the first-effect, second-effect, and third-effect distillation columns to keep the pressure within the optimal range and ensure the operating efficiency of the entire unit.
[0034] As a preferred option, temperature monitoring meters are installed in the single-effect distillation column, the double-effect distillation column, and the triple-effect distillation column.
[0035] The temperature sensor can monitor the temperature inside the first-effect distillation column, the second-effect distillation column, and the third-effect distillation column in real time. Based on the detected temperature, the steam exchanging heat with the first-effect reboiler, the organic steam exchanging heat with the second-effect reboiler, and the organic steam exchanging heat with the third-effect reboiler are adjusted to keep their temperature within the optimal range and ensure the operating efficiency of the entire unit.
[0036] As a preferred option, level gauges are installed in the single-effect distillation column, the double-effect distillation column, and the triple-effect distillation column.
[0037] The liquid level gauge can monitor the liquid level in the first-effect, second-effect, and third-effect distillation columns in real time, thereby adjusting the opening of the corresponding valves, the amount of acetic acid and water mixture entering the first-effect, second-effect, and third-effect distillation columns, and the amount of concentrated acid flowing out of the first-effect, second-effect, and third-effect distillation columns, so that the liquid level can be maintained within the optimal range, ensuring that the entire unit operates at its best efficiency.
[0038] Compared with the prior art, the beneficial effects of this utility model are: it can fully recover the heat of organic vapor at the top of the acetic acid and water distillation column and use it for power generation, while reducing the amount of circulating water used and reducing consumption. In addition, with the structure of this application, the separation of acetic acid and water no longer requires an azeotropic agent, and the consumption of azeotropic agent is not considered.
[0039] In existing technologies, acetic acid and water separation uses azeotropic distillation. For a water processing capacity of 100 t / h, cooling the organic vapor at the top of the column to 60 degrees Celsius consumes approximately 8000–9000 t / h of circulating cooling water and approximately 80 kg / h of azeotropic agent. However, with the structure of this application, the organic vapor at the top of the triple-effect distillation column no longer needs circulating cooling water; instead, its thermal energy is used to generate steam, which drives a steam turbine to generate electricity, estimated at approximately 8400 kWh per hour. Using a multi-effect distillation column to separate acetic acid and water eliminates the need for azeotropic agents and eliminates the consideration of azeotropic agent consumption losses. The process of this invention reduces energy and material consumption. Attached Figure Description
[0040] Figure 1 This is a schematic diagram of the structure of this utility model.
[0041] Figure 2 yes Figure 1 A partial schematic diagram of region I in the middle.
[0042] Figure 3 yes Figure 1 A partial schematic diagram of region II.
[0043] In the diagram: 1. Single-effect distillation column; 11. Single-effect reboiler;
[0044] 2. Double-effect distillation column; 21. Double-effect reboiler;
[0045] 3. Triple-effect distillation column; 31. Triple-effect reboiler;
[0046] 4. Tower top heat exchanger;
[0047] 5. Steam turbine generator;
[0048] 6. Main feed pipe; 61. First feed pipe; 62. Second feed pipe; 63. Third feed pipe;
[0049] 7. Main acid discharge pipe at the bottom of the tower; 71. First acid discharge pipe; 711. First bottom feed heat exchanger at the bottom of the tower; 72. Second acid discharge pipe; 721. Second bottom feed heat exchanger at the bottom of the tower; 73. Third acid discharge pipe; 731. Third bottom feed heat exchanger at the bottom of the tower; 74. Concentrated acid cooler at the bottom of the tower.
[0050] 8. Top dilute acid main pipe;
[0051] 91. Pressure monitoring gauge; 92. Temperature monitoring gauge; 93. Liquid level monitoring gauge; 94. Bottom water concentration monitoring gauge; 95. Power generation detection instrument; 96. Flow meter.
[0052] 10. Acetic acid and water organic vapor feed pipe. Detailed Implementation
[0053] The technical solution of this utility model will be further described in detail below through specific embodiments and with reference to the accompanying drawings:
[0054] Example 1: Refer to Figures 1 to 3 As shown, a multi-effect distillation apparatus for separating acetic acid and water includes:
[0055] A single-effect distillation column 1 is provided with a single-effect reboiler 11 at the bottom;
[0056] The double-effect distillation column 2 is equipped with a double-effect reboiler 21 at the bottom; the top of the single-effect distillation column 1 is connected to the double-effect reboiler 21.
[0057] The triple-effect distillation column 3 is equipped with a triple-effect reboiler 31 at the bottom; the top of the double-effect distillation column 2 is connected to the triple-effect reboiler 31.
[0058] The steam at the top of the triple-effect distillation column 3 enters the top heat exchanger 4 for heat exchange, and the steam generated after heat exchange in the top heat exchanger 4 enters the steam turbine generator 5 to generate electricity.
[0059] Steam generated by the boiler heats a first-effect reboiler 11. The first-effect reboiler 11 distills acetic acid and water within a first-effect distillation column 1. The organic vapor generated in the first-effect distillation column 1 exits from the top of the column and then passes through a second-effect reboiler 21, which heats the second-effect reboiler 21. The second-effect reboiler 21 then distills acetic acid and water within a second-effect distillation column 2. The organic vapor generated in the second-effect distillation column 2 exits from the top of the column. After passing through the triple-effect reboiler 31, the triple-effect reboiler 31 is heated. The triple-effect reboiler 31 distills acetic acid and water in the triple-effect distillation column 3. The organic vapor generated in the triple-effect distillation column 3 flows out from the top of the triple-effect distillation column 3. Then, when the organic vapor passes through the top heat exchanger 4, it exchanges heat in the top heat exchanger 4. The top heat exchanger 4 exchanges the heat from the organic vapor generated in the triple-effect distillation column 3 to generate steam. The steam generates electricity for the steam turbine generator 5.
[0060] In the above process, the steam generated by the boiler serves as the heat source for the entire device. The heat is utilized step by step through the first-effect distillation column 1, the second-effect distillation column 2, and the third-effect distillation column 3, which improves the utilization rate of thermal energy. Finally, the thermal energy is used to generate electricity, which significantly improves the utilization rate of heat. Moreover, no azeotropic agent is required in the entire process, which reduces energy and material consumption.
[0061] In one embodiment, the upper part of the single-effect distillation column 1 is connected to the first feed pipe 61; the bottom of the single-effect distillation column 1 is connected to the first acid discharge pipe 71, and a first bottom feed heat exchanger 711 is provided on the first acid discharge pipe 71; before the mixture of acetic acid and water enters the single-effect distillation column 1 through the first feed pipe 61, it exchanges heat with the concentrated acid flowing out of the first acid discharge pipe 711 in the first bottom feed heat exchanger 711.
[0062] Before entering the first-effect distillation column 1, the mixture of acetic acid and water exchanges heat with the concentrated acid flowing out of the first-effect distillation column 1 in the first bottom feed heat exchanger 711. The mixture of acetic acid and water absorbs part of the heat from the concentrated acid, thereby improving the heat utilization rate and reducing the loss of some of the concentrated acid's heat.
[0063] In one embodiment, the upper part of the double-effect distillation column 2 is connected to the second feed pipe 62; the bottom of the double-effect distillation column 2 is connected to the second acid discharge pipe 72, and a second bottom feed heat exchanger 721 is provided on the second acid discharge pipe 72; before the mixture of acetic acid and water enters the double-effect distillation column 2 through the second feed pipe 62, it exchanges heat with the concentrated acid flowing out from the second acid discharge pipe 72 in the second bottom feed heat exchanger 721.
[0064] Before entering the double-effect distillation column 2, the mixture of acetic acid and water exchanges heat with the concentrated acid flowing out of the double-effect distillation column 2 in the bottom feed heat exchanger 721. The mixture of acetic acid and water absorbs part of the heat from the concentrated acid, thereby improving the heat utilization rate and reducing the loss of some of the concentrated acid's heat.
[0065] In one embodiment, the upper part of the triple-effect distillation column 3 is connected to the third feed pipe 63; the bottom of the triple-effect distillation column 3 is connected to the third acid discharge pipe 73, and a third bottom feed heat exchanger 731 is provided on the third acid discharge pipe 73; before the mixture of acetic acid and water enters the triple-effect distillation column 3 through the third feed pipe 63, it exchanges heat with concentrated acid in the third bottom feed heat exchanger 731.
[0066] Before entering the triple-effect distillation column 3, the mixture of acetic acid and water exchanges heat with the concentrated acid flowing out of the triple-effect distillation column 3 in the bottom feed heat exchanger 731. The mixture of acetic acid and water absorbs part of the heat from the concentrated acid, thereby improving the heat utilization rate and reducing the loss of some of the heat from the concentrated acid.
[0067] The first feed pipe 61, the second feed pipe 62, and the third feed pipe 63 are all connected to the main feed pipe 6.
[0068] In one embodiment, the system also includes a concentrated acid header 7 at the bottom of the column; concentrated acid from the reboilers of the first-effect distillation column 1, the second-effect distillation column 2, and the third-effect distillation column 3 is discharged from the concentrated acid header 7 at the bottom of the column. Specifically, the first acid discharge pipe 71, the second acid discharge pipe 72, and the third acid discharge pipe 73 are all connected to the concentrated acid header 7 at the bottom of the column, thereby enabling the concentrated acid discharged from the first-effect distillation column 1, the second-effect distillation column 2, and the third-effect distillation column 3 to be collected simultaneously, facilitating further processing and treatment of the concentrated acid.
[0069] A concentrated acid cooler 74 is installed on the concentrated acid main pipe 7 at the bottom of the column. The concentrated acid discharged from the bottom of the first-effect distillation column 1, the bottom of the second-effect distillation column 2, and the bottom of the third-effect distillation column 3 can have its temperature reduced when it passes through the concentrated acid cooler 74 at the bottom of the column.
[0070] In one embodiment, a top dilute acid header 8 is also included. The top dilute acid header 8 is used to collect organic vapors flowing from the top of the first-effect distillation column 1, the second-effect distillation column 2, and the third-effect distillation column 3. After passing through their corresponding reboilers or top heat exchangers 4, the organic vapors condense into liquid and enter the top dilute acid header 8, thus collecting the organic vapors from the top of the columns. Specifically:
[0071] The steam flowing out from the top of the first-effect distillation column 1 exchanges heat in the second-effect reboiler 21 and then flows into the dilute acid header 8 at the top of the column.
[0072] The steam flowing out from the top of the double-effect distillation column 2 exchanges heat in the triple-effect reboiler 31 and then flows into the dilute acid main pipe 8 at the top of the column.
[0073] The steam flowing out from the top of the triple-effect distillation column 3 is heated by the heat exchanger 4 at the top of the column and then flows into the dilute acid header 8 at the top of the column.
[0074] In one embodiment, pressure monitoring gauges 91 are installed in the first-effect distillation column 1, the second-effect distillation column 2, and the third-effect distillation column 3. The pressure monitoring gauges 91 can monitor the pressure in the first-effect distillation column 1, the second-effect distillation column 2, and the third-effect distillation column 3 in real time, thereby adjusting the opening degree of the corresponding valves and regulating the pressure in these columns to maintain them within the optimal range, ensuring the overall operating efficiency of the device.
[0075] In one embodiment, temperature monitoring gauges 92 are installed in the first-effect distillation column 1, the second-effect distillation column 2, and the third-effect distillation column 3. The temperature monitoring gauges 92 can monitor the temperature inside the first-effect distillation column 1, the second-effect distillation column 2, and the third-effect distillation column 3 in real time. Based on the detected temperature, the steam exchanging heat with the first-effect reboiler 11, the organic steam exchanging heat with the second-effect reboiler 21, and the organic steam exchanging heat with the third-effect reboiler 31 are adjusted to maintain their temperatures within the optimal range, ensuring the overall operating efficiency of the device.
[0076] In one embodiment, each of the first-effect distillation column 1, the second-effect distillation column 2, and the third-effect distillation column 3 is equipped with a liquid level monitoring gauge 93. The liquid level monitoring gauge 93 can monitor the liquid level in the first-effect distillation column 1, the second-effect distillation column 2, and the third-effect distillation column 3 in real time, thereby adjusting the opening degree of the corresponding valves, adjusting the amount of acetic acid and water mixture entering the first-effect distillation column 1, the second-effect distillation column 2, and the third-effect distillation column 3, and adjusting the amount of concentrated acid flowing out of the first-effect distillation column 1, the second-effect distillation column 2, and the third-effect distillation column 3, so that the liquid level can be maintained within the optimal range, ensuring that the entire device is operating at its best efficiency.
[0077] In one embodiment, bottom water concentration monitoring gauges 94 are installed on the first acid discharge pipe 71, the second acid discharge pipe 72, and the third acid discharge pipe 73. The bottom water concentration monitoring gauges 94 monitor the concentration of concentrated acid when it is discharged to the bottom concentrated acid main pipe 7 to ensure that the concentration of concentrated acid reaches a certain standard.
[0078] In one embodiment, the steam turbine generator 5 is equipped with a power generation monitoring instrument 95 to monitor the generator's operating status, and flow monitoring meters and temperature detection meters are also installed on the pipelines of the entire device as needed.
[0079] In this invention, the heat from the organic vapor at the top of the acetic acid and water distillation column can be fully recovered and used for power generation, while reducing the amount of circulating water used and thus reducing consumption. Furthermore, using the structure of this application, the separation of acetic acid and water no longer requires an azeotropic agent, eliminating the need to consider azeotropic agent consumption.
[0080] Specifically, in existing technologies, acetic acid and water separation uses azeotropic distillation. For a water processing capacity of 100 t / h, cooling the organic vapor at the top of the column to 60 degrees Celsius consumes approximately 8000–9000 t / h of circulating cooling water and approximately 80 kg / h of azeotropic agent. However, with the structure of this application, the organic vapor at the top of the third-effect distillation column no longer needs circulating cooling water; instead, its thermal energy is used to generate steam, which drives a turbine to generate electricity, estimated at approximately 8400 kWh per hour. Using a multi-effect distillation column to separate acetic acid and water eliminates the need for azeotropic agents and eliminates the consideration of azeotropic agent consumption losses. The process of this invention reduces energy and material consumption.
[0081] Example 2: Refer to Figures 1 to 3 As shown, a multi-effect distillation apparatus for separating acetic acid and water includes:
[0082] A single-effect distillation column 1 is provided with a single-effect reboiler 11 at the bottom;
[0083] The double-effect distillation column 2 is equipped with a double-effect reboiler 21 at the bottom; the top of the single-effect distillation column 1 is connected to the double-effect reboiler 21.
[0084] The triple-effect distillation column 3 is equipped with a triple-effect reboiler 31 at the bottom; the top of the double-effect distillation column 2 is connected to the triple-effect reboiler 31.
[0085] The steam at the top of the triple-effect distillation column 3 enters the top heat exchanger 4 for heat exchange, and the steam generated after heat exchange in the top heat exchanger 4 enters the steam turbine generator 5 to generate electricity.
[0086] Steam generated by the boiler heats a first-effect reboiler 11. The first-effect reboiler 11 distills acetic acid and water within a first-effect distillation column 1. The organic vapor generated in the first-effect distillation column 1 exits from the top of the column and then passes through a second-effect reboiler 21, which heats the second-effect reboiler 21. The second-effect reboiler 21 then distills acetic acid and water within a second-effect distillation column 2. The organic vapor generated in the second-effect distillation column 2 exits from the top of the column. After passing through the triple-effect reboiler 31, the triple-effect reboiler 31 is heated. The triple-effect reboiler 31 distills acetic acid and water in the triple-effect distillation column 3. The organic vapor generated in the triple-effect distillation column 3 flows out from the top of the triple-effect distillation column 3. Then, when the organic vapor passes through the top heat exchanger 4, it exchanges heat in the top heat exchanger 4. The top heat exchanger 4 exchanges the heat from the organic vapor generated in the triple-effect distillation column 3 to generate steam. The steam generates electricity for the steam turbine generator 5.
[0087] In the above process, the steam generated by the boiler serves as the heat source for the entire device. The heat is utilized step by step through the first-effect distillation column 1, the second-effect distillation column 2, and the third-effect distillation column 3, which improves the utilization rate of thermal energy. Finally, the thermal energy is used to generate electricity, which significantly improves the utilization rate of heat. Moreover, no azeotropic agent is required in the entire process, which reduces energy and material consumption.
[0088] In one embodiment, the upper part of the single-effect distillation column 1 is connected to the first feed pipe 61; the bottom of the single-effect distillation column 1 is connected to the first acid discharge pipe 71, and a first bottom feed heat exchanger 711 is provided on the first acid discharge pipe 71; before the mixture of acetic acid and water enters the single-effect distillation column 1 through the first feed pipe 61, it exchanges heat with the concentrated acid flowing out of the first acid discharge pipe 711 in the first bottom feed heat exchanger 711.
[0089] Before entering the first-effect distillation column 1, the mixture of acetic acid and water exchanges heat with the concentrated acid flowing out of the first-effect distillation column 1 in the first bottom feed heat exchanger 711. The mixture of acetic acid and water absorbs part of the heat from the concentrated acid, thereby improving the heat utilization rate and reducing the loss of some of the concentrated acid's heat.
[0090] In one embodiment, the upper part of the double-effect distillation column 2 is connected to the second feed pipe 62; the bottom of the double-effect distillation column 2 is connected to the second acid discharge pipe 72, and a second bottom feed heat exchanger 721 is provided on the second acid discharge pipe 72; before the mixture of acetic acid and water enters the double-effect distillation column 2 through the second feed pipe 62, it exchanges heat with the concentrated acid flowing out from the second acid discharge pipe 72 in the second bottom feed heat exchanger 721.
[0091] Before entering the double-effect distillation column 2, the mixture of acetic acid and water exchanges heat with the concentrated acid flowing out of the double-effect distillation column 2 in the bottom feed heat exchanger 721. The mixture of acetic acid and water absorbs part of the heat from the concentrated acid, thereby improving the heat utilization rate and reducing the loss of some of the concentrated acid's heat.
[0092] In one embodiment, the upper part of the triple-effect distillation column 3 is connected to the third feed pipe 63; the bottom of the triple-effect distillation column 3 is connected to the third acid discharge pipe 73, and a third bottom feed heat exchanger 731 is provided on the third acid discharge pipe 73; before the mixture of acetic acid and water enters the triple-effect distillation column 3 through the third feed pipe 63, it exchanges heat with concentrated acid in the third bottom feed heat exchanger 731.
[0093] Before entering the triple-effect distillation column 3, the mixture of acetic acid and water exchanges heat with the concentrated acid flowing out of the triple-effect distillation column 3 in the bottom feed heat exchanger 731. The mixture of acetic acid and water absorbs part of the heat from the concentrated acid, thereby improving the heat utilization rate and reducing the loss of some of the heat from the concentrated acid.
[0094] The first feed pipe 61, the second feed pipe 62, and the third feed pipe 63 are all connected to the main feed pipe 6.
[0095] In one embodiment, the system also includes a concentrated acid header 7 at the bottom of the column; concentrated acid from the reboilers of the first-effect distillation column 1, the second-effect distillation column 2, and the third-effect distillation column 3 is discharged from the concentrated acid header 7 at the bottom of the column. Specifically, the first acid discharge pipe 71, the second acid discharge pipe 72, and the third acid discharge pipe 73 are all connected to the concentrated acid header 7 at the bottom of the column, thereby enabling the concentrated acid discharged from the first-effect distillation column 1, the second-effect distillation column 2, and the third-effect distillation column 3 to be collected simultaneously, facilitating further processing and treatment of the concentrated acid.
[0096] A concentrated acid cooler 74 is installed on the concentrated acid main pipe 7 at the bottom of the column. The concentrated acid discharged from the bottom of the first-effect distillation column 1, the bottom of the second-effect distillation column 2, and the bottom of the third-effect distillation column 3 can have its temperature reduced when it passes through the concentrated acid cooler 74 at the bottom of the column.
[0097] In one embodiment, a top dilute acid header 8 is also included. The top dilute acid header 8 is used to collect organic vapors flowing from the top of the first-effect distillation column 1, the second-effect distillation column 2, and the third-effect distillation column 3. After passing through their corresponding reboilers or top heat exchangers 4, the organic vapors condense into liquid and enter the top dilute acid header 8, thus collecting the organic vapors from the top of the columns. Specifically:
[0098] The steam flowing out from the top of the first-effect distillation column 1 exchanges heat in the second-effect reboiler 21 and then flows into the dilute acid header 8 at the top of the column.
[0099] The steam flowing out from the top of the double-effect distillation column 2 exchanges heat in the triple-effect reboiler 31 and then flows into the dilute acid main pipe 8 at the top of the column.
[0100] The steam flowing out from the top of the triple-effect distillation column 3 is heated by the heat exchanger 4 at the top of the column and then flows into the dilute acid header 8 at the top of the column.
[0101] In one embodiment, pressure monitoring gauges 91 are installed in the first-effect distillation column 1, the second-effect distillation column 2, and the third-effect distillation column 3. The pressure monitoring gauges 91 can monitor the pressure in the first-effect distillation column 1, the second-effect distillation column 2, and the third-effect distillation column 3 in real time, thereby adjusting the opening degree of the corresponding valves and regulating the pressure in these columns to maintain them within the optimal range, ensuring the overall operating efficiency of the device.
[0102] In one embodiment, temperature monitoring gauges 92 are installed in the first-effect distillation column 1, the second-effect distillation column 2, and the third-effect distillation column 3. The temperature monitoring gauges 92 can monitor the temperature inside the first-effect distillation column 1, the second-effect distillation column 2, and the third-effect distillation column 3 in real time. Based on the detected temperature, the steam exchanging heat with the first-effect reboiler 11, the organic steam exchanging heat with the second-effect reboiler 21, and the organic steam exchanging heat with the third-effect reboiler 31 are adjusted to maintain their temperatures within the optimal range, ensuring the overall operating efficiency of the device.
[0103] In one embodiment, each of the first-effect distillation column 1, the second-effect distillation column 2, and the third-effect distillation column 3 is equipped with a liquid level monitoring gauge 93. The liquid level monitoring gauge 93 can monitor the liquid level in the first-effect distillation column 1, the second-effect distillation column 2, and the third-effect distillation column 3 in real time, thereby adjusting the opening degree of the corresponding valves, adjusting the amount of acetic acid and water mixture entering the first-effect distillation column 1, the second-effect distillation column 2, and the third-effect distillation column 3, and adjusting the amount of concentrated acid flowing out of the first-effect distillation column 1, the second-effect distillation column 2, and the third-effect distillation column 3, so that the liquid level can be maintained within the optimal range, ensuring that the entire device is operating at its best efficiency.
[0104] In one embodiment, bottom water concentration monitoring gauges 94 are installed on the first acid discharge pipe 71, the second acid discharge pipe 72, and the third acid discharge pipe 73. The bottom water concentration monitoring gauges 94 monitor the concentration of concentrated acid when it is discharged to the bottom concentrated acid main pipe 7 to ensure that the concentration of concentrated acid reaches a certain standard.
[0105] In one embodiment, the steam turbine generator 5 is equipped with a power generation monitoring instrument 95 to monitor the generator's operating status, and flow monitoring instruments 96, temperature monitoring instruments 92, and pressure monitoring instruments 91 are also installed on the pipelines of the entire device as needed.
[0106] In this invention, the heat from the organic vapor at the top of the acetic acid and water distillation column can be fully recovered and used for power generation, while reducing the amount of circulating water used and thus reducing consumption. Furthermore, using the structure of this application, the separation of acetic acid and water no longer requires an azeotropic agent, eliminating the need to consider azeotropic agent consumption.
[0107] This embodiment is similar in structure to that in Embodiment 1, except that acetic acid and water vapor feed pipes 10 are provided at the top of both the double-effect distillation column 2 and the triple-effect distillation column 3. Based on the temperature and pressure changes inside the triple-effect distillation column 3 and the double-effect distillation column 2, the heated acetic acid and water vapor are promptly replenished into the triple-effect distillation column 3 and the double-effect distillation column 2 to ensure the efficiency of acetic acid separation in the triple-effect distillation column 3 and the double-effect distillation column 2, so that the entire equipment is in a highly efficient operating state.
[0108] Specifically, in existing technologies, acetic acid and water separation uses azeotropic distillation. For a water processing capacity of 100 t / h, cooling the organic vapor at the top of the column to 60 degrees Celsius consumes approximately 8000–9000 t / h of circulating cooling water and approximately 80 kg / h of azeotropic agent. However, with the structure of this application, the organic vapor at the top of the third-effect distillation column no longer needs circulating cooling water; instead, its thermal energy is used to generate steam, which drives a turbine to generate electricity, estimated at approximately 8400 kWh per hour. Using a multi-effect distillation column to separate acetic acid and water eliminates the need for azeotropic agents and eliminates the consideration of azeotropic agent consumption losses. The process of this invention reduces energy and material consumption.
[0109] The embodiments described above are merely preferred solutions of this utility model and are not intended to limit this utility model in any way. Other variations and modifications are possible without departing from the technical solutions described in the claims.
Claims
1. A multi-effect distillation apparatus for separating acetic acid and water, characterized in that it comprises: A single-effect distillation column is equipped with a single-effect reboiler at the bottom; The double-effect distillation column is equipped with a double-effect reboiler at the bottom; The top of the single-effect distillation column is connected to the double-effect reboiler; The triple-effect distillation column is equipped with a triple-effect reboiler at the bottom; the top of the double-effect distillation column is connected to the triple-effect reboiler. The steam at the top of the triple-effect distillation column enters the top heat exchanger for heat exchange, and the steam generated after heat exchange in the top heat exchanger enters the steam turbine generator to generate electricity. The upper part of the single-effect distillation column is connected to the first feed pipe; The bottom of the single-effect distillation column is connected to the first acid discharge pipe, and the first acid discharge pipe is equipped with a first column bottom feed heat exchanger. Before the mixture of acetic acid and water enters the first-effect distillation column through the first feed pipe, it exchanges heat with concentrated acid in the bottom feed heat exchanger of the first column.
2. The multi-effect distillation and separation device for acetic acid and water recovery according to claim 1, characterized in that, The upper part of the double-effect distillation column is connected to the second feed pipe; The bottom of the double-effect distillation column is connected to the second acid drain pipe, and the second acid drain pipe is equipped with a second bottom feed heat exchanger. Before the mixture of acetic acid and water enters the double-effect distillation column through the second feed pipe, it exchanges heat with concentrated acid in the bottom feed heat exchanger of the second column.
3. The multi-effect distillation apparatus for separating acetic acid and water according to claim 1, characterized in that, The upper part of the triple-effect distillation column is connected to the third feed pipe; The bottom of the triple-effect distillation column is connected to the third acid drain pipe, and the third acid drain pipe is equipped with a third column bottom feed heat exchanger. Before the mixture of acetic acid and water enters the triple-effect distillation column through the third feed pipe, it exchanges heat with concentrated acid in the bottom feed heat exchanger of the third column.
4. The multi-effect distillation and water recovery device according to claim 1, characterized in that, This also includes the top dilute acid main pipe; The steam flowing out from the top of the first-effect distillation column exchanges heat in the second-effect reboiler and then flows into the dilute acid header at the top of the column. The steam flowing out from the top of the double-effect distillation column is heated in the triple-effect reboiler and then flows into the dilute acid header at the top of the column. The steam flowing out from the top of the triple-effect distillation column is heated by the heat exchanger at the top of the column and then flows into the dilute acid header at the top of the column.
5. The multi-effect distillation apparatus for separating acetic acid and water according to any one of claims 1 to 4, characterized in that, It also includes the concentrated acid header at the bottom of the column; the concentrated acid in the bottom of the first-effect distillation column, the bottom of the second-effect distillation column, and the bottom of the third-effect distillation column is discharged from the concentrated acid header at the bottom of the column.
6. The multi-effect distillation apparatus for separating acetic acid and water according to claim 5, characterized in that, A concentrated acid cooler is installed on the concentrated acid main pipe at the bottom of the tower.
7. The multi-effect distillation apparatus for separating acetic acid and water according to any one of claims 1 to 4, characterized in that, Pressure monitoring gauges are installed in the single-effect distillation column, the double-effect distillation column, and the triple-effect distillation column.
8. The multi-effect distillation apparatus for separating acetic acid and water according to any one of claims 1 to 4, characterized in that, Temperature monitoring meters are installed in the single-effect distillation column, the double-effect distillation column, and the triple-effect distillation column.
9. The multi-effect distillation apparatus for separating acetic acid and water according to any one of claims 1 to 4, characterized in that, Liquid level gauges are installed in the single-effect, double-effect, and triple-effect distillation columns.