Recovery device for oxidation wastewater of pta device

Abstract

The utility model relates to PTA oxidation wastewater recovery technical field, is a kind of PTA device oxidation wastewater recycling device, it includes feed heater, azeotrope recovery column, wastewater cooler and spray cooling tower, first feed pipeline is connected to the left side import of feed heater, second feed pipeline is communicated between the right side export of feed heater and azeotrope recovery column, first wastewater pipeline is fixedly communicated between the bottom export of azeotrope recovery column and the bottom import of feed heater, second wastewater pipeline is communicated between the upper export of feed heater and wastewater cooler, third wastewater pipeline is fixed between wastewater cooler and spray cooling tower, incineration tail gas pipeline is communicated in the middle import of spray cooling tower.The utility model is reasonable and compact in structure, convenient to use, it is used as the spray cooling fluid of incineration tail gas by the oxidation wastewater after processing, eliminates peculiar smell in spray cooling fluid, reduces material consumption, with safe, simple, efficient characteristics.

Description

Technical Field

[0001] This utility model relates to the field of PTA oxidation wastewater recovery technology, and is a device for recovering and utilizing PTA plant oxidation wastewater. Background Technology

[0002] The production process of purified terephthalic acid (PTA) can be broadly divided into an oxidation unit and a purification unit. The oxidation unit reaction is carried out in a reaction system with acetic acid (HAC) as solvent, cobalt acetate and manganese acetate as catalysts, and hydrobromic acid as promoter. The raw material p-xylene (PX) reacts with oxygen (O2) in compressed air under certain pressure and temperature conditions to produce terephthalic acid (TA).

[0003] After the waste heat from the oxidation reaction is utilized and the temperature is reduced, the gas enters a high-pressure absorption tower. The reaction tail gas is then washed with acetic acid and demineralized water and heated before entering the tail gas incineration system, where harmful organic compounds are removed through catalytic combustion. After incineration, a portion of the tail gas is washed in a spray cooling tower and then sent to a tail gas drying system for drying. The dried tail gas is used in the unit for pneumatic conveying, purging, and inertial protection. Most of the tail gas is sent to a tail gas expander to provide power for the air compressor. The expanded tail gas is then washed in a tail gas venting scrubber and vented at a high point. Currently, the spray cooling tower uses medium-pressure sealing water supplied by a sealed water system as the spraying fluid. The acetic acid concentration in this medium-pressure sealing water is 3% to 4%, causing odor in the venting pipelines of subsequent treatment units. Furthermore, the emission of acetic acid and organic matter increases the unit's material consumption.

[0004] Therefore, it is essential to research and invent a device for recycling oxidation wastewater from PTA plants. Summary of the Invention

[0005] This utility model provides a PTA plant oxidation wastewater recycling device, which overcomes the shortcomings of the prior art. It can effectively solve the problems of acetic acid and organic matter in the spray cooling liquid during the existing PTA production incineration tail gas treatment process, which leads to strong odor of the spray cooling liquid, large emissions of acetic acid and organic matter, and increased material consumption of the device.

[0006] The technical solution of this utility model is achieved through the following measures: A PTA unit oxidation wastewater recovery and utilization device includes a feed heater, an azeotropic agent recovery tower, a wastewater cooler, and a spray cooling tower. A first feed pipeline is fixedly connected to the left inlet of the feed heater. A second feed pipeline is fixedly connected to the right outlet of the feed heater and the upper inlet of the azeotropic agent recovery tower. A gas phase pipeline is fixedly connected to the top outlet of the azeotropic agent recovery tower. A first wastewater pipeline is fixedly connected to the bottom outlet of the azeotropic agent recovery tower and the bottom inlet of the feed heater. A second wastewater pipeline is fixedly connected to the upper outlet of the feed heater and the left inlet of the wastewater cooler. A third wastewater pipeline is fixedly connected to the right outlet of the wastewater cooler and the upper inlet of the spray cooling tower. A combustion exhaust gas pipeline is fixedly connected to the middle inlet of the spray cooling tower. A purified exhaust gas pipeline is fixedly connected to the top outlet of the spray cooling tower. A fourth wastewater pipeline is fixedly connected to the bottom outlet of the spray cooling tower.

[0007] The following are further optimizations and / or improvements to the above-mentioned utility model technical solution: The inlet of the aforementioned azeotropic agent recovery tower is fixedly connected to a steam pipeline.

[0008] The wastewater cooler has a fixed connection between its upper inlet and a circulating water supply pipeline, and a fixed connection between its lower outlet and a circulating return water pipeline.

[0009] The first wastewater transfer pump and the second wastewater transfer pump are fixedly installed on the second wastewater pipeline and the third wastewater pipeline, respectively.

[0010] A fifth wastewater pipeline is fixedly connected to the third wastewater pipeline between the aforementioned wastewater cooler and the second wastewater transfer pump.

[0011] A first thermometer is fixedly installed on the aforementioned azeotropic agent recovery tower, a second thermometer is fixedly installed on the second feed pipeline, a temperature regulating valve and a third thermometer are fixedly installed on the steam pipeline in sequence according to the medium flow direction, a first control valve is fixedly installed on the third wastewater pipeline between the second wastewater transfer pump and the spray cooling tower, and a second control valve is fixedly installed on the fifth wastewater pipeline.

[0012] The above also includes a PLC controller, a first wastewater transfer pump, a second wastewater transfer pump, a first thermometer, a second thermometer, a temperature regulating valve, a third thermometer, a first control valve, and a second control valve, all of which are electrically connected to the PLC controller. An interlock is provided between the third thermometer and the temperature regulating valve.

[0013] This utility model has a reasonable and compact structure and is easy to use. It treats oxidation wastewater containing small amounts of n-butyl acetate (NBA), methyl acetate (MA), and p-xylene (PX) and uses it as a spray cooling liquid for incineration tail gas. This eliminates the odor in the spray cooling liquid and reduces the consumption of 50% liquid alkali used to neutralize acetic acid, the amount of demineralized water used for alkali preparation, and the amount of oxidation wastewater discharged in subsequent processes of the production unit. It is safe, labor-saving, simple, and efficient. Attached Figure Description

[0014] Appendix Figure 1 This is a schematic diagram of the process flow of this utility model.

[0015] Appendix Figure 1 The codes in the diagram are as follows: 1 is the feed heater, 2 is the azeotropic agent recovery tower, 3 is the wastewater cooler, 4 is the spray cooling tower, 5 is the first conveying pipeline, 6 is the second conveying pipeline, 7 is the first wastewater pipeline, 8 is the second wastewater pipeline, 9 is the third wastewater pipeline, 10 is the incineration tail gas pipeline, 11 is the purified tail gas pipeline, 12 is the fourth wastewater pipeline, 13 is the first gas phase pipeline, 14 is the steam pipeline, 15 is the circulating water supply pipeline, 16 is the circulating return water pipeline, 17 is the first wastewater transfer pump, 18 is the second wastewater transfer pump, 19 is the fifth wastewater pipeline, 20 is the first thermometer, 21 is the second thermometer, 22 is the temperature regulating valve, 23 is the first control valve, and 24 is the second control valve. Detailed Implementation

[0016] This utility model is not limited to the following embodiments, and the specific implementation method can be determined according to the technical solution of this utility model and the actual situation.

[0017] Unless otherwise specified, all equipment and devices used in this invention are existing, publicly known, and commonly used equipment and devices in the field.

[0018] In this utility model, for ease of description, the description of the relative positions of the components is based on the appendix to the specification. Figure 1 The layout is described using a diagrammatic method, such as the positional relationships of front, back, top, bottom, left, and right, which are based on the instructions attached. Figure 1 The orientation of the layout is determined by the direction of the map.

[0019] The present invention will be further described below with reference to the embodiments and accompanying drawings: Example 1: As shown in the attached document Figure 1As shown, the PTA unit's oxidation wastewater recovery and utilization device includes a feed heater 1, an azeotropic agent recovery tower 2, a wastewater cooler 3, and a spray cooling tower 4. The left inlet of the feed heater 1 is fixedly connected to a first feed pipeline 5. The right outlet of the feed heater 1 is fixedly connected to the upper inlet of the azeotropic agent recovery tower 2 via a second feed pipeline 6. The top outlet of the azeotropic agent recovery tower 2 is fixedly connected to a gas phase pipeline 13. The bottom outlet of the azeotropic agent recovery tower 2 is fixedly connected to the bottom inlet of the feed heater 1 via a first wastewater pipeline 7. The upper outlet of the feed heater 1 is fixedly connected to the left inlet of the wastewater cooler 3 via a second wastewater pipeline 8. The right outlet of the wastewater cooler 3 is fixedly connected to the upper inlet of the spray cooling tower 4 via a third wastewater pipeline 9. The middle inlet of the spray cooling tower 4 is fixedly connected to an incineration tail gas pipeline 10. The top outlet of the spray cooling tower 4 is fixedly connected to a purified tail gas pipeline 11. The bottom outlet of the spray cooling tower 4 is fixedly connected to a fourth wastewater pipeline 12.

[0020] In this invention, the oxidation wastewater (containing small amounts of organic matter such as n-butyl acetate (NBA), methyl acetate (MA), and p-xylene (PX)) from the solvent dehydration tower reflux tank in the PTA production process enters the feed heater 1 via the first feed pipeline 5. After exchanging heat with the bottom liquid of the azeotropic agent recovery tower 2 and being heated, it enters the azeotropic agent recovery tower 2 for separation of water and organic matter. The bottom liquid obtained after separation enters the feed heater 1 via the first wastewater pipeline 7. After exchanging heat with the oxidation wastewater and cooling, it enters the wastewater cooler 3 for further cooling to obtain low-temperature wastewater. The low-temperature wastewater is sent to the spray cooling tower 4 via the third wastewater pipeline 9 to wash and cool the combustion exhaust gas entering the spray cooling tower 4. The washed and cooled wastewater enters the sewage treatment unit, and the purified combustion exhaust gas enters the subsequent exhaust gas drying unit via the purified exhaust gas pipeline 11.

[0021] As needed, the gaseous organic matter separated in the azeotropic agent recovery tower 2 enters the subsequent processing unit via the gas phase pipeline 13 to recover most of the methyl acetate. Finally, the non-condensable gas enters the tail gas recovery system.

[0022] The contents of acetic acid and other trace organic matter in the above-mentioned low-temperature wastewater are as follows: HAc (≤1Wt / %): not detected; MA (≤0.01Wt / %): <0.01; NBA (≤0.01Wt / %): <0.01; PX (≤0.01%): <0.01.

[0023] The above-mentioned PTA unit oxidation wastewater recovery and utilization device can be further optimized and / or improved according to actual needs: Example 2: Its difference from Example 1 is as follows: (See attached) Figure 1 As shown, the inlet of the azeotropic agent recovery tower 2 is fixedly connected to a steam pipeline 14.

[0024] As needed, after the oxidized wastewater exchanges heat with the bottom liquid of the azeotropic agent recovery tower 2, the temperature reaches 48°C. Steam is then introduced into the azeotropic agent recovery tower 2 through the steam pipeline 14 to bring the temperature of the azeotropic agent recovery tower 2 to its operating temperature.

[0025] Example 3: Its difference from Examples 1 to 2 is as follows: (See attached) Figure 1 As shown, the upper inlet of the wastewater cooler 3 is fixedly connected to a circulating water supply pipeline 15, and the lower outlet of the wastewater cooler 3 is fixedly connected to a circulating return water pipeline 16.

[0026] Example 4: Its difference from Examples 1 to 3 is as follows: (See attached) Figure 1 As shown, a first wastewater transfer pump 17 and a second wastewater transfer pump 18 are fixedly installed on the second wastewater pipeline 8 and the third wastewater pipeline 9, respectively.

[0027] Example 5: It differs from Examples 1 to 4 in that, as shown in the appendix... Figure 1 As shown, a fifth wastewater pipeline 19 is fixedly connected to the third wastewater pipeline 9 between the wastewater cooler 3 and the second wastewater transfer pump 18.

[0028] As needed, unrecycled post-treatment oxidation wastewater enters the wastewater treatment unit via the fifth wastewater pipeline 19.

[0029] Example 6: Its difference from Examples 1 to 5 is as follows: (See attached) Figure 1 As shown, a first thermometer 20 is fixedly installed on the azeotropic agent recovery tower 2, a second thermometer 21 is fixedly installed on the second conveying pipeline 6, a temperature regulating valve 22 and a third thermometer 23 are fixedly installed on the steam pipeline 14 in sequence according to the medium flow direction, a first control valve 24 is fixedly installed on the third wastewater pipeline 9 between the second wastewater conveying pump 18 and the spray cooling tower 4, and a second control valve 25 is fixedly installed on the fifth wastewater pipeline 19.

[0030] Example 7: Its difference from Examples 1 to 6 is as follows: (See attached) Figure 1 As shown, it also includes a PLC controller, a first wastewater transfer pump 17, a second wastewater transfer pump 18, a first thermometer 20, a second thermometer 21, a temperature regulating valve 22, a third thermometer 23, a first control valve 24, and a second control valve 25, all of which are electrically connected to the PLC controller. An interlock is provided between the third thermometer 23 and the temperature regulating valve 22.

[0031] As needed, the operating temperature of the azeotropic agent recovery tower 2 (the temperature displayed by the first thermometer 20) is 95℃ to 105℃. When the temperature displayed by the first thermometer 20 is lower than 95℃, the opening of the temperature regulating valve 22 is increased. When the temperature displayed by the first thermometer 20 is higher than 105℃, the opening of the temperature regulating valve 22 is decreased. By adjusting the opening of the temperature regulating valve 22, the amount of steam introduced into the azeotropic agent recovery tower 2 is controlled.

[0032] Depending on the needs, the pipelines and equipment of the PTA unit's oxidation wastewater recovery and utilization device may also be equipped with conventional valves, thermometers, and pressure gauges known in the art, according to production requirements. The PLC controller can be a Siemens S7-1500, which is equipped with a Yokogawa CS3000 DCS control system.

[0033] Before and after use: The spray cooling tower 4 sprays cooling water with a flow rate of 2t / h. Before use, there was an odor in the purification tail gas pipeline 11. Due to the emission of acetic acid and organic matter, the material consumption of the unit increased, with acetic acid consumption increasing by 60kg / h, 50% liquid alkali consumption increasing by 80kg / h, and demineralized water consumption increasing by 720kg / h. After use, the odor in the purification tail gas pipeline 11 was eliminated, the 50% liquid alkali used to neutralize acetic acid in the subsequent process of the production unit was reduced by 80kg / h, the demineralized water used for alkali preparation was reduced by 720kg / h, and the discharge of oxidation wastewater was reduced by 800kg / h.

[0034] The above technical features constitute various embodiments of this utility model, which have strong adaptability and implementation effect. Unnecessary technical features can be added or removed according to actual needs to meet the needs of different situations.

[0035] The usage process of this utility model is as follows: First, the oxidizing wastewater is heated by heat exchange in the feed heater 1 and then enters the azeotropic agent recovery tower 2 for separation of water and organic matter. The gaseous organic matter separated in the azeotropic agent recovery tower 2 enters the subsequent treatment unit through the gas phase pipeline 13. Next, the bottom liquid separated in the azeotropic agent recovery tower 2 enters the feed heater 1 through the first wastewater pipeline 7, and after heat exchange and cooling with the oxidizing wastewater, it enters the wastewater cooler 3 for further cooling to obtain low-temperature wastewater. Finally, the low-temperature wastewater is sent to the spray cooling tower 4 by the second wastewater transfer pump 18 to wash and cool the combustion exhaust gas entering the spray cooling tower 4. The washed and cooled wastewater enters the sewage treatment unit through the fourth wastewater pipeline 12, and the combustion exhaust gas enters the subsequent exhaust gas drying unit through the purified exhaust gas pipeline 11 after purification.

Claims

1. A device for recycling oxidation wastewater from a PTA plant, characterized in that... The system includes a feed heater, an azeotropic agent recovery tower, a wastewater cooler, and a spray cooling tower. The feed heater has a first feed pipeline fixedly connected to its left inlet. The feed heater has a second feed pipeline fixedly connected to its right outlet and the upper inlet of the azeotropic agent recovery tower. The azeotropic agent recovery tower has a gas phase pipeline fixedly connected to its top outlet. The azeotropic agent recovery tower has a first wastewater pipeline fixedly connected to its bottom outlet and the bottom inlet of the feed heater. The feed heater has a second wastewater pipeline fixedly connected to its upper outlet and the left inlet of the wastewater cooler. The wastewater cooler has a third wastewater pipeline fixedly connected to its right outlet and the upper inlet of the spray cooling tower. The spray cooling tower has a combustion exhaust gas pipeline fixedly connected to its middle inlet. The spray cooling tower has a purified exhaust gas pipeline fixedly connected to its top outlet. The spray cooling tower has a fourth wastewater pipeline fixedly connected to its bottom outlet.

2. The PTA plant oxidation wastewater recovery and utilization device according to claim 1, characterized in that... A steam pipeline is fixedly connected to the inlet of the azeotropic agent recovery tower in the middle.

3. The PTA plant oxidation wastewater recovery and utilization device according to claim 1 or 2, characterized in that... The upper inlet of the wastewater cooler is fixedly connected to a circulating water supply pipeline, and the lower outlet of the wastewater cooler is fixedly connected to a circulating return water pipeline.

4. The PTA plant oxidation wastewater recovery and utilization device according to claim 1 or 2, characterized in that... The first wastewater transfer pump and the second wastewater transfer pump are fixedly installed on the second wastewater pipeline and the third wastewater pipeline, respectively.

5. The PTA plant oxidation wastewater recovery and utilization device according to claim 3, characterized in that... The first wastewater transfer pump and the second wastewater transfer pump are fixedly installed on the second wastewater pipeline and the third wastewater pipeline, respectively.

6. The PTA plant oxidation wastewater recovery and utilization device according to claim 4, characterized in that... A fifth wastewater pipeline is fixedly connected to the third wastewater pipeline between the wastewater cooler and the second wastewater transfer pump.

7. The PTA plant oxidation wastewater recovery and utilization device according to claim 5, characterized in that... A fifth wastewater pipeline is fixedly connected to the third wastewater pipeline between the wastewater cooler and the second wastewater transfer pump.

8. The PTA plant oxidation wastewater recovery and utilization device according to claim 7, characterized in that... A first thermometer is fixedly installed on the azeotropic agent recovery tower, a second thermometer is fixedly installed on the second feed pipeline, a temperature regulating valve and a third thermometer are fixedly installed on the steam pipeline in sequence according to the medium flow direction, a first control valve is fixedly installed on the third wastewater pipeline between the second wastewater transfer pump and the spray cooling tower, and a second control valve is fixedly installed on the fifth wastewater pipeline.

9. The PTA plant oxidation wastewater recovery and utilization device according to claim 8, characterized in that... It also includes a PLC controller, a first wastewater transfer pump, a second wastewater transfer pump, a first thermometer, a second thermometer, a temperature regulating valve, a third thermometer, a first control valve, and a second control valve, all of which are electrically connected to the PLC controller. An interlock is provided between the third thermometer and the temperature regulating valve.

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