Comprehensive utilization system for benzoic acid wastewater
By using a multi-tower distillation system and azeotropic agent separation technology, the problems of low concentration of acetic acid and benzoic acid and high COD in PTA residue treatment were solved, achieving efficient separation and recovery and improving the comprehensive utilization rate.
Patent Information
- Application Number
- CN202422979069.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-04
- Publication Date
- 2025-10-31
- Estimated Expiration
- 2034-12-04
AI Technical Summary
In existing technologies, the formic acid water produced during PTA residue treatment has low concentrations of benzoic acid and acetic acid, but high COD content, resulting in low comprehensive utilization rate and inability to be directly recycled or sold.
A multi-tower distillation system, including a first distillation column, a second distillation column, and a third distillation column, is adopted. Combined with azeotropic agents and reflux technology, acetic acid and benzoic acid are separated through a phase separation tank and a condenser. The parallel pipeline structure of a vacuum buffer tank and an electromagnetic control valve is used to achieve efficient separation and recovery.
This method achieves efficient separation of acetic acid and benzoic acid, reduces COD content, improves comprehensive utilization rate, and increases the recovery concentration of acetic acid and benzoic acid.
Smart Images
Figure CN223496228U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of wastewater treatment, specifically a comprehensive utilization system for benzoic acid wastewater. Background Technology
[0002] In PTA residue treatment, the formic acid water distilled from the intermediate benzoic acid section is wastewater containing benzoic acid and acetic acid. The benzoic acid content in this wastewater is low, and the treatment of this wastewater is mostly done by direct distillation to recover benzoic acid and acetic acid. However, the recovered benzoic acid and acetic acid have low concentrations and high COD content, making them unsuitable for direct recycling or sale, resulting in low overall utilization rate. Summary of the Invention
[0003] This invention provides a comprehensive utilization system for benzoic acid wastewater that can efficiently separate acetic acid while taking into account acetic acid concentration and COD content, ensuring comprehensive utilization rate.
[0004] The technical solution adopted in this utility model is: a comprehensive utilization system for benzoic acid wastewater, comprising a first distillation column connected to a feed pipe by a feed pump, the feed pipe being connected to wastewater containing acetic acid and benzoic acid treated by PTA residue, characterized in that: a preheater is connected to the feed pipe, an azeotropic agent storage tank is connected to the first distillation column, the top of the first distillation column is connected to a phase separation tank via a first top condenser and a first cooler, the upper part of the phase separation tank is connected to the upper part of the first distillation column via a return pump, the lower part of the phase separation tank is pumped to a second distillation column, and the bottom of the second distillation column is pumped to a preheater for heat exchange. The solution then flows through a second cooler to a biochemical tank. The top of the second distillation column is condensed at the top and connected to a first reflux tank. The first reflux tank splits into two streams: one pumps to the upper part of the second distillation column, and the other pumps to a phase separation tank. The bottom of the first distillation column is pumped to a third distillation column, and the bottom of the third distillation column is pumped to a benzoic acid intermediate tank. The top of the third distillation column is condensed at the top and connected to a second reflux tank. The second reflux tank splits into two streams: one pumps to the upper part of the third distillation column, and the other pumps, after connecting to the third cooler, to an acetic acid intermediate tank.
[0005] The lower part of the first, second and third distillation columns is connected to a reboiler.
[0006] Both the first and second reflux tanks are connected to vacuum buffer tanks.
[0007] The first cooler is connected to the phase separation tank via a bend, which includes a lower section and an upper section. The lower section is connected to the discharge outlet of the first tower top condenser. The next stage is raised by the upper section and then connected to the phase separation tank. The highest point of the upper section is at the same height as the highest point of the first cooler.
[0008] All pump pipelines adopt a parallel pipeline structure with two sets of pumps equipped with electromagnetic control valves.
[0009] The first, second, and third tower top condensers and the first and second coolers all use cooling water heat exchange.
[0010] Wastewater containing acetic acid and benzoic acid is preheated in a preheater and then pumped into the middle of the first distillation column. An azeotropic agent is pumped from the storage tank to the top of the first distillation column. A mixture of acetic acid, benzoic acid, and water is collected from the bottom of the first distillation column. The vapor phase from the top of the first distillation column is condensed in the first top condenser, cooled in the first cooler, and then flows to the phase separation tank. In the phase separation tank, water and the azeotropic agent separate into phases. The upper phase, the azeotropic agent, is directly returned to the first distillation column via a return pump. The lower phase, the aqueous phase, is pumped into the middle of the second distillation column. The vapor phase from the top of the second distillation column is condensed in the second top condenser. The acetic acid then enters the first reflux tank. A portion is refluxed to the second distillation column, while the other portion is pumped to the phase separation tank. The aqueous phase from the bottom of the second distillation column is sent to the preheater for waste heat utilization, and after being cooled by the second cooler, it is directly discharged into the biochemical tank. The liquid phase from the bottom of the first distillation column is pumped to the middle section of the third distillation column. The vapor phase from the top of the third distillation column is condensed by the third column's top condenser and sent to the second reflux tank. A portion is refluxed to the third distillation column, and the other portion is pumped to the acetic acid intermediate tank, resulting in acetic acid with a high acetic acid content and low COD. The liquid phase from the bottom of the third distillation column is directly pumped into the benzoic acid intermediate tank for benzoic acid recovery. This system has a simple structure and can efficiently separate acetic acid and benzoic acid that can be comprehensively utilized. Attached Figure Description
[0011] Figure 1 This is a schematic diagram of the structure of this utility model;
[0012] In the diagram: 1. Feed pipe; 2. Feed pump; 3. Preheater; 4. First distillation column; 5. Azeotropic agent storage tank; 6. First column top condenser; 7. First cooler; 8. Phase separation tank; 9. Return pump; 10. Second distillation column; 11. Second cooler; 12. Biochemical tank; 13. Second column top condenser; 14. First reflux tank; 15. Third distillation column; 16. Benzoic acid intermediate tank; 17. Third column top condenser; 18. Second reflux tank; 19. Third cooler; 20. Acetic acid intermediate tank; 21. Bend. Detailed Implementation
[0013] The following explanation, in conjunction with the accompanying drawings, will provide further details.
[0014] Figure 1 As shown: A comprehensive utilization system for benzoic acid wastewater includes a feed pipe 1, a feed pump 2, a preheater 3, a first distillation column 4, an azeotropic agent storage tank 5, a first column top condenser 6, a first cooler 7, a phase separation tank 8, a return pump 9, a second distillation column 10, a second cooler 11, a biochemical tank 12, a second column top condenser 13, a first reflux tank 14, a third distillation column 15, a benzoic acid intermediate tank 16, a third column top condenser 17, a second reflux tank 18, a third cooler 19, an acetic acid intermediate tank 20, and a bend 21.
[0015] Wastewater containing acetic acid and benzoic acid from PTA residue treatment is fed into the middle of the first distillation column 4 via a feed pipe. A feed pump 2 and a preheater 3 are sequentially installed on the feed pipe 1. An azeotropic agent storage tank 5 is connected to the top of the first distillation column 4. The top of the first distillation column 4 is connected to a phase separation tank 8 via a first top condenser 6 and a first cooler 7. The upper layer of the phase separation tank 8 is returned to the upper part of the first distillation column 4 via a return pump 9. The lower layer of the phase separation tank 8 is pumped to the second distillation column 10. The bottom of the second distillation column 10 is pumped to the preheater 3 for heat exchange, then connected to the biochemical tank 12 via a second cooler 11. The top of the second distillation column 10 is connected to... The solution exits through the second column top condenser 13 and connects to the first reflux tank 14. The first reflux tank 14 is divided into two streams: one stream pumps to the upper part of the second distillation column 10, and the other stream pumps to the phase separation tank 8. The bottom of the first distillation column 4 is pumped to the third distillation column 15. The bottom of the third distillation column 15 is pumped to the benzoic acid intermediate tank 16. The top of the third distillation column 15 is connected to the third column top condenser 17. The top of the third column top condenser is connected to the second reflux tank 18. The second reflux tank is divided into two streams: one stream pumps to the upper part of the third distillation column, and the other stream is pumped to the third cooler 19 and then pumped to the acetic acid intermediate tank 20.
[0016] In this invention, reboilers are connected to the lower part of the first, second, and third distillation columns. Vacuum buffer tanks are connected to the first and second reflux tanks.
[0017] In this embodiment, the first cooler 7 is connected to the phase separation tank 8 via a bend 20. The bend includes a lower section and an upper section. The lower section is connected to the discharge point of the first tower top condenser. The next stage is raised by the upper section and then connected to the phase separation tank. The highest point of the upper section is at the same height as the highest point of the first cooler.
[0018] In this embodiment, pumps and electromagnetic control valves are installed on the pipelines involving liquid transportation between each structure. This technology is commonly used in existing chemical production.
[0019] In this embodiment, the first, second, and third tower top condensers and the first and second coolers are all cooling water heat exchangers.
[0020] Based on this embodiment, all pump pipelines can adopt a parallel pipeline structure with two sets of pumps equipped with electromagnetic control valves. This technology is commonly used in existing chemical production to ensure that the pump set is in standby mode and improves safety.
Claims
1. A comprehensive utilization system for benzoic acid wastewater, comprising a first distillation column connected to a feed pipe by a feed pump, the feed pipe being connected to wastewater containing acetic acid and benzoic acid treated with PTA residue, characterized in that: The feed pipe passes through a preheater, and the first distillation column is connected to an azeotropic agent storage tank. The top of the first distillation column is connected to a phase separation tank via a first top condenser and a first cooler. The upper part of the phase separation tank is connected to the upper part of the first distillation column via a return pump. The lower part of the phase separation tank is pumped to the second distillation column. The bottom of the second distillation column is pumped to the preheater for heat exchange, and then connected to the biochemical tank via the second cooler. The top of the second distillation column is connected to the first reflux tank via a second top condenser. The first reflux tank is split into two branches: one branch is pumped to the upper part of the second distillation column, and the other branch is pumped to the phase separation tank. The bottom of the first distillation column is pumped to the third distillation column. The bottom of the third distillation column is pumped to the benzoic acid intermediate tank. The top of the third distillation column is connected to the third top condenser. The third top condenser is connected to the second reflux tank. The second reflux tank is split into two branches: one branch is pumped to the upper part of the third distillation column, and the other branch is pumped to the acetic acid intermediate tank after connecting to the third cooler.
2. The benzoic acid wastewater comprehensive utilization system according to claim 1, characterized in that: The lower part of the first, second and third distillation columns is connected to a reboiler.
3. The benzoic acid wastewater comprehensive utilization system according to claim 1, characterized in that: Both the first and second reflux tanks are connected to vacuum buffer tanks.
4. The benzoic acid wastewater comprehensive utilization system according to claim 1, characterized in that: The first cooler is connected to the phase separation tank via a bend, which includes a lower section and an upper section. The lower section is connected to the discharge outlet of the first tower top condenser. The next stage is raised by the upper section and then connected to the phase separation tank. The highest point of the upper section is at the same height as the highest point of the first cooler.
5. The benzoic acid wastewater comprehensive utilization system according to claim 1, characterized in that: All pump pipelines adopt a parallel pipeline structure with two sets of pumps equipped with electromagnetic control valves.
6. The benzoic acid wastewater comprehensive utilization system according to claim 1, characterized in that: The first, second, and third tower top condensers and the first and second coolers all use cooling water heat exchange.