Membrane separation device for sodium carbonate and sodium bromide in PTA tail gas washing water
Through the membrane separation device and treatment process, the problem of low separation efficiency of sodium carbonate and sodium bromide in PTA exhaust washing water is solved, efficient separation and resource reuse are achieved, and the service life of the device is extended.
Patent Information
- Application Number
- CN202421824770.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-31
- Publication Date
- 2025-07-11
- Estimated Expiration
- 2034-07-31
AI Technical Summary
The separation efficiency of sodium carbonate and sodium bromide in the exhaust gas washing water of existing PTA production is low, resulting in waste of resources and increased difficulty in processing.
The membrane separation device is adopted, including pretreatment, ultrafiltration, nanofiltration membrane and reverse osmosis membrane systems, and sodium carbonate and sodium bromide are separated by nanofiltration membranes and RO membranes of different pore sizes, combined with sodium hydroxide treatment to adjust the pH value to achieve effective separation.
It improves the separation efficiency of sodium carbonate and sodium bromide, reduces resource waste, extends the life of the membrane device, reduces the failure rate, and improves resource utilization rate.
Smart Images
Figure CN223087707U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the field of wastewater treatment, in particular to a membrane separation device for sodium carbonate and sodium bromide in PTA tail gas washing water. Background Art
[0002] The existing PTA production adopts the xylene air oxidation method. Its tail gas is organic waste gas containing many pollutants. The conventional method is to use tail gas washing to remove pollutants in the waste gas. The washing water contains a large amount of sodium carbonate and sodium bromide salts. Directly discharging it as sewage requires extremely high treatment requirements for the sewage treatment system and also causes a large waste of sodium carbonate and sodium bromide resources. Summary of the Invention
[0003] The utility model provides a membrane separation device with a simple structure, which can effectively separate sodium carbonate and sodium bromide in PTA tail gas washing water.
[0004] The technical solution adopted by the utility model is: a membrane separation device for sodium carbonate and sodium bromide in PTA tail gas washing water, including a stock solution tank for PTA tail gas washing water, characterized in that: the stock solution tank is sequentially connected to a first nanofiltration membrane device through a pretreatment tank, ultrafiltration and COD purification device. The pretreatment tank is connected to a sodium hydroxide storage tank. The filtrate of the first nanofiltration membrane device is connected to a second nanofiltration membrane device. The concentrated solutions of the first and second nanofiltration membrane devices are both connected to a third nanofiltration membrane device. The concentrated solution of the third nanofiltration membrane device is connected to a sodium carbonate storage tank, and the filtrate of the third nanofiltration membrane device is connected to the stock solution tank; the filtrate of the second nanofiltration membrane device is connected to an RO membrane system. The concentrated solution of the RO membrane system is connected to a sodium bromide storage tank, and the filtrate is connected to a waste water tank or a recycled water tank or directly discharged.
[0005] Further, the nanofiltration membrane pore diameter of the second nanofiltration membrane device is not greater than that of the first nanofiltration membrane device.
[0006] Further, the nanofiltration membrane pore diameter of the third nanofiltration membrane device is smaller than that of the first and second nanofiltration membrane devices.
[0007] Further, the RO membrane system includes a first RO membrane device and a second RO membrane device. The filtrate of the second nanofiltration membrane device is connected to the first RO membrane device. The concentrated solution of the first RO membrane device is connected to the second RO membrane device. The concentrated solution of the second RO membrane device is connected to a sodium bromide storage tank, and the filtrate of the second RO membrane device is connected to a waste water tank or a recycled water tank or directly discharged.
[0008] Further, the filtrate of the first RO membrane device is connected to a waste water tank or a recycled water tank or directly discharged.
[0009] Further, the first RO membrane device is a low-pressure RO membrane device, and the second RO membrane device is a high-pressure RO membrane device.
[0010] Furthermore, intermediate tanks and intermediate pumps are provided on the connecting pipelines between each tank, membrane device, and membrane system.
[0011] Furthermore, the first, second, and third nanofiltration membrane devices purchase S-NF200 / S-NF160 / S-NF100 series pollution-resistant and antioxidant membrane elements from Langji Company.
[0012] Furthermore, the first and second RO membrane devices purchase S-RO alkali-resistant membrane elements from Langji Company.
[0013] Furthermore, the ultrafiltration purchases the C-UF20 model from Langji Company, and the COD purification device purchases the OMRP combined module from Langji Company.
[0014] During operation, the PTA tail gas washing water is sent to the raw liquid tank, and the raw liquid tank is sent to the liquid pretreatment tank. Sodium hydroxide solution is added through the sodium hydroxide storage tank to control the pH value to be 10.5 - 12.5, so that sodium bicarbonate is converted into sodium carbonate; then it is sent to the ultrafiltration to remove the insoluble solid colloid substances; then it is sent to the COD purification device to remove various COD component substances that cause membrane pollution; then it is sent to the first nanofiltration membrane device. The first nanofiltration membrane device intercepts most of the sodium carbonate through the nanofiltration membrane and sends the concentrated liquid to the third nanofiltration membrane device. The concentrated liquid of the third nanofiltration membrane device with a high content of sodium carbonate is sent to the sodium carbonate storage tank or returned to the CRU unit. The filtrate of the third nanofiltration membrane device is sent back to the raw liquid tank. A small part of the sodium carbonate and most of the sodium bromide in the first nanofiltration membrane device pass through the nanofiltration membrane and are sent to the second nanofiltration membrane device with the filtrate. The concentrated liquid of the second nanofiltration membrane device is sent to the third nanofiltration membrane device to further recover a small amount of sodium carbonate, thereby achieving the full recovery of sodium carbonate in the PTA tail gas washing water; the filtrate of the second nanofiltration membrane device is sent to the first and second RO membrane devices in sequence. The concentrated liquid with a high content of sodium bromide after low-pressure reverse osmosis and high-pressure reverse osmosis is sent to the sodium bromide storage tank, and the filtrate is sent to wastewater or directly discharged or reused, thereby achieving the full recovery of sodium bromide in the PTA tail gas washing water.
[0015] The present utility model uses nanofiltration membrane filtration, which has excellent anti-pollution ability and strong anti-pollution ability: it is not easily blocked by COD pollutants in the wastewater, reduces the risk of membrane pollution, and extends the service life of the membrane. The nanofiltration membrane and RO membrane are respectively used to effectively separate sodium carbonate and sodium bromide substances in a targeted manner. It has good separation selectivity for sodium carbonate and sodium bromide in the PTA tail gas washing water, meets the requirements of efficient separation of the washing water, facilitates the full separation and reuse of the PTA tail gas washing water, and improves the resource utilization rate. The operation failure rate of various membrane elements is low, and the abilities of resistance to compaction, abrasion, chemical degradation, and microbial attack are high. The device has stable performance and a long service life. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 It is a structural schematic diagram of the present utility model.
[0017] In the figure: stock solution tank 1, transfer tank 2, transfer pump 3, pretreatment tank 4, sodium hydroxide storage tank 5, ultrafiltration unit 6, COD purification device 7, first nanofiltration membrane device 8, second nanofiltration membrane device 9, third nanofiltration membrane device 10, sodium carbonate storage tank 11, first RO membrane device 12, second RO membrane device 13, sodium bromide storage tank 14, drain pipe 15. Specific embodiments
[0018] The following is further described in conjunction with the drawings and embodiments.
[0019] Figure 1 As shown: A membrane separation device for sodium carbonate and sodium bromide in PTA tail gas washing water, including a stock solution tank 1, a transfer tank 2, a transfer pump 3, a pretreatment tank 4, a sodium hydroxide storage tank 5, an ultrafiltration unit 6, a COD purification device 7, a first nanofiltration membrane device 8, a second nanofiltration membrane device 9, a third nanofiltration membrane device 10, a sodium carbonate storage tank 11, a first RO membrane device 12, a second RO membrane device 13, and a sodium bromide storage tank 14. The PTA tail gas washing water is sent from the stock solution tank 1, and the stock solution tank 1 is connected to the first nanofiltration membrane device 8 through the pretreatment tank 4, the ultrafiltration unit 6, and the COD purification device 7 in sequence. The pretreatment tank 4 is connected to the sodium hydroxide storage tank 5. The filtrate of the first nanofiltration membrane device 8 is connected to the second nanofiltration membrane device 9. The concentrated solutions of the first and second nanofiltration membrane devices 8 and 9 are both connected to the third nanofiltration membrane device 10. The concentrated solution of the third nanofiltration membrane device 10 is connected to the sodium carbonate storage tank 11, and the filtrate of the third nanofiltration membrane device 10 is connected to the stock solution tank 1; the filtrate of the second nanofiltration membrane device 9 is connected to the first RO membrane device 12 for low-pressure reverse osmosis, the concentrated solution of the first RO membrane device 12 is connected to the second RO membrane device 13 for high-pressure reverse osmosis, the concentrated solution of the second RO membrane device 13 is connected to the sodium bromide storage tank 14, and the filtrates of the first and second RO membrane devices 12 and 13 are connected to the drain pipe 15.
[0020] In this embodiment, the pore size of the nanofiltration membrane of the second nanofiltration membrane device is not greater than that of the first nanofiltration membrane device, and the pore size of the nanofiltration membrane of the third nanofiltration membrane device is smaller than that of the first and second nanofiltration membrane devices.
[0021] In this embodiment, transfer tanks 2 and transfer pumps 3 are provided on the connecting pipelines between each tank, membrane device, and membrane system. This technology is a conventional technology in chemical industrial production.
[0022] On the basis of this embodiment, the filtrates of the first and second RO membrane devices 12 and 13 can also be connected to a waste water tank or a recycled water tank.
Claims
1. A membrane separation device for sodium carbonate and sodium bromide in PTA tail gas washing water, comprising a stock solution tank for PTA tail gas washing water, characterized in that: The stock solution tank is connected to the first nanofiltration membrane device through a pretreatment tank, ultrafiltration, and COD purification device in sequence. The pretreatment tank is connected to a sodium hydroxide storage tank. The filtrate of the first nanofiltration membrane device is connected to the second nanofiltration membrane device. The concentrated solutions of the first and second nanofiltration membrane devices are both connected to the third nanofiltration membrane device. The concentrated solution of the third nanofiltration membrane device is connected to a sodium carbonate storage tank. The filtrate of the third nanofiltration membrane device is connected to the stock solution tank. The filtrate of the second nanofiltration membrane device is connected to the RO membrane system. The concentrated solution of the RO membrane system is connected to a sodium bromide storage tank, and the filtrate is connected to a wastewater tank or a recycled water tank or discharged directly.
2. The membrane separation device for sodium carbonate and sodium bromide in PTA tail gas washing water according to claim 1, wherein: The nanofiltration membrane pore size of the second nanofiltration membrane device is not greater than that of the first nanofiltration membrane device.
3. The membrane separation device for sodium carbonate and sodium bromide in PTA tail gas washing water according to claim 1 or 2, characterized in that: The nanofiltration membrane pore size of the third nanofiltration membrane device is smaller than that of the first and second nanofiltration membrane devices.
4. The membrane separation device for sodium carbonate and sodium bromide in PTA tail gas washing water according to claim 1, wherein: The RO membrane system includes a first RO membrane device and a second RO membrane device. The filtrate of the second nanofiltration membrane device is connected to the first RO membrane device. The concentrated solution of the first RO membrane device is connected to the second RO membrane device. The concentrated solution of the second RO membrane device is connected to a sodium bromide storage tank. The filtrate of the second RO membrane device is connected to a wastewater tank or a recycled water tank or discharged directly.
5. The membrane separation device for sodium carbonate and sodium bromide in PTA tail gas washing water according to claim 4, characterized in that: The filtrate of the first RO membrane device is connected to a wastewater tank or a recycled water tank or discharged directly.
6. The membrane separation device for sodium carbonate and sodium bromide in PTA tail gas washing water according to claim 4 or 5, characterized in that: The first RO membrane device is a low-pressure RO membrane device, and the second RO membrane device is a high-pressure RO membrane device.
7. The membrane separation device for sodium carbonate and sodium bromide in PTA tail gas washing water according to claim 1, characterized in that: Transfer tanks and transfer pumps are provided on the connecting pipelines between each tank, membrane device, and membrane system.
8. The membrane separation device for sodium carbonate and sodium bromide in PTA tail gas washing water according to claim 1, characterized in that: The first, second, and third nanofiltration membrane devices purchase S-NF200 / S-NF160 / S-NF100 series anti-pollution and anti-oxidation membrane elements from Langji Company.
9. A membrane separation device for sodium carbonate and sodium bromide in PTA tail gas washing water according to claim 4, characterized in that: The first and second RO membrane devices purchase S-RO alkali-resistant membrane elements from Langji Company.
10. The membrane separation device for sodium carbonate and sodium bromide in PTA tail gas washing water according to claim 1, characterized in that: The ultrafiltration purchases the C-UF20 model from Langji Company, and the COD purification device purchases the OMRP combined module from Langji Company.