Bromide ion recovery treatment device in PTA (pure terephthalic acid) production

Abstract

The utility model relates to the technical field of post-treatment in PTA (terephthalic acid) production, in particular to a bromine ion recovery treatment device in PTA (pure terephthalic acid) production, which comprises a filter, a sodium carbonate conversion tank, a nanofiltration membrane device, a weak cation resin bed layer, a strong cation resin bed layer, a dilute hydrobromic acid heater, a hydrobromic acid tank and a hydrochloric acid storage tank. The device is reasonable and compact in structure and convenient to use, after impurities in the tail gas alkali wash solution are filtered out, a sodium hydroxide solution is introduced, the pH value of the solution is adjusted, the tail gas alkali wash solution is subjected to nanofiltration, the weak cation resin bed layer and the strong cation resin bed layer to remove salt ions in the solution, a dilute hydrobromic acid solution is obtained, and then the dilute hydrobromic acid solution is concentrated to obtain high-concentration hydrobromic acid for reuse. According to the utility model, the bromide ions in the tail gas alkali wash water are recovered in the form of hydrobromic acid through the separation technology of nanofiltration and ion exchange resin, so that the safe, stable and efficient operation of the bromide ion recovery treatment device in PTA production is ensured, and the production cost is also reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of post-treatment of terephthalic acid production, and is a device for recovering and treating bromide ions in PTA production. Background Technique

[0002] Terephthalic acid is an important basic chemical raw material with broad application prospects, and is widely used in the production of the chemical industry and the polyester industry. The traditional industrial production method of terephthalic acid mainly uses p-xylene as the raw material, acetic acid as the solvent, cobalt acetate and manganese acetate as the catalysts, and hydrobromic acid as the promoter to react with air for oxidation to produce crude terephthalic acid; then the crude terephthalic acid is subjected to hydrogenation refining to remove impurities, and then through a series of treatment processes such as separation and drying to obtain purified terephthalic acid. In the production process of PTA, the waste gas generated is mainly the organic waste gas containing p-xylene, acetic acid, and acetic acid esters generated in the oxidation stage, as well as the vent gas discharged from separation, filtration, drying, and the silo. A small part of these tail gases is used for transporting materials and process air in the pneumatic conveying system of the terephthalic acid unit after drying and purification; most of them pass through the tail gas expansion turbine and then are directly discharged into the atmosphere through the chimney. Although the pollutant concentration of these waste gases is not high, the values of benzene, xylene, non-methane total hydrocarbons, etc. still exceed the national emission standards, and the gas volume is very large, causing great pollution to the surrounding environment.

[0003] In the existing production of terephthalic acid, hydrobromic acid is used as the promoter. Some bromide ions generate organic bromine in the reactor and are lost with the tail gas. They burn in the tail gas catalytic combustion reactor to form bromide ions, and enter the expander to do work and then be discharged together with the tail gas. In order to meet the environmental protection standards, the tail gas is subjected to alkali washing before emission. After the bromide ions form sodium bromide, they are discharged into the sewage or sodium bromide is recovered, and the hydrobromic acid is not effectively recovered and reused. Summary of the Invention

[0004] The utility model provides a device for recovering and treating bromide ions in PTA production, which overcomes the above-mentioned deficiencies of the prior art, and can effectively solve the problems that the hydrobromic acid in the alkali washing solution of the existing terephthalic acid production tail gas is not effectively recovered and reused and the production cost is relatively high.

[0005] The technical solution of the utility model is realized by the following measures: A bromide ion recovery and treatment device in PTA production, including a filter, a sodium carbonate conversion tank, a nanofiltration membrane device, a weak cation resin bed, a strong cation resin bed, a dilute hydrobromic acid heater, and a hydrobromic acid tank. The upper inlet of the filter is fixedly connected to a tail gas caustic scrubbing liquid pipeline. There is a first caustic liquid pipeline fixedly connected between the lower outlet of the filter and the top inlet of the sodium carbonate conversion tank. The upper inlet of the sodium carbonate conversion tank is fixedly connected to a sodium hydroxide pipeline. There is a second caustic liquid pipeline fixedly connected between the bottom outlet of the sodium carbonate conversion tank and the bottom inlet of the nanofiltration membrane device. There is a third caustic liquid pipeline fixedly connected between the upper outlet of the nanofiltration membrane device and the upper inlet of the weak cation resin bed. There is a first feeding pipeline fixedly connected between the lower outlet of the weak cation resin bed and the top inlet of the strong cation resin bed. There is a second feeding pipeline fixedly connected between the bottom outlet of the strong cation resin bed and the first feed inlet of the dilute hydrobromic acid heater. There is a third feeding pipeline fixedly connected between the first discharge outlet of the dilute hydrobromic acid heater and the upper inlet of the hydrobromic acid tank. The lower outlet of the hydrobromic acid tank is fixedly connected to a hydrobromic acid recycling pipeline.

[0006] The following is a further optimization or / and improvement of the above-mentioned technical solution of the utility model:

[0007] An alkali liquid pump and a hydrobromic acid transfer pump are respectively fixedly installed on the above-mentioned second caustic liquid pipeline and the second feeding pipeline.

[0008] The bottom inlet of the above-mentioned weak cation resin bed is fixedly connected to a first hydrochloric acid pipeline. The inlet of the first hydrochloric acid pipeline is fixedly connected to a hydrochloric acid storage tank. A hydrochloric acid transfer pump is fixedly installed on the first hydrochloric acid pipeline. There is a second hydrochloric acid pipeline fixedly connected between the first hydrochloric acid pipeline between the hydrochloric acid transfer pump and the weak cation resin bed and the bottom inlet of the strong cation resin bed.

[0009] A first on-line pH detector is fixedly arranged on the above-mentioned first feeding pipeline. A second on-line pH detector is fixedly arranged on the second caustic liquid pipeline between the sodium carbonate conversion tank and the alkali liquid pump. A sodium ion on-line detection device is fixedly arranged on the second feeding pipeline between the dilute hydrobromic acid heater and the hydrobromic acid transfer pump.

[0010] The top outlet of the above-mentioned nanofiltration membrane device is fixedly connected to a sodium carbonate conveying pipeline. There is an alkali liquid reflux pipeline fixedly connected between the second caustic liquid pipeline between the nanofiltration membrane device and the alkali liquid pump and the middle inlet of the sodium carbonate conversion tank.

[0011] The second feed inlet of the above-mentioned dilute hydrobromic acid heater is fixedly connected to a steam pipeline. The second discharge outlet of the dilute hydrobromic acid heater is fixedly connected to a steam condensate pipeline.

[0012] A pressure regulating valve is fixedly arranged on the above-mentioned lye reflux pipeline, a remote pressure gauge is fixedly arranged on the second lye pipeline between the lye reflux pipeline and the nanofiltration membrane device, a steam regulating valve is fixedly arranged on the steam pipeline, a remote thermometer is fixedly arranged on the third feeding pipeline, and a remote flowmeter and a flow regulating valve are fixedly arranged on the hydrobromic acid recycling pipeline in sequence according to the medium flow direction. Interlocks are respectively arranged between the pressure regulating valve and the remote pressure gauge, the steam regulating valve and the remote thermometer, and the remote flowmeter and the flow regulating valve.

[0013] The above-mentioned device further includes a DCS controller. The hydrobromic acid delivery pump, hydrochloric acid delivery pump, lye pump, pressure regulating valve, remote pressure gauge, first on-line pH detector, sodium ion on-line detection device, steam regulating valve, remote thermometer, second on-line pH detector, remote flowmeter, and flow regulating valve are all electrically connected to the DCS controller.

[0014] In the present utility model, the tail gas lye after-washing liquid passes through a filter to filter out mechanical impurities and then enters a sodium carbonate conversion tank. At the same time, a sodium hydroxide solution is introduced to adjust the pH value of the solution, and sodium bicarbonate in the tail gas lye after-washing liquid is converted into sodium carbonate. The converted tail gas lye after-washing liquid first passes through a nanofiltration membrane device and then sequentially passes through a weak cation resin bed layer and a strong cation resin bed layer to remove salt ions in the solution, obtaining a dilute hydrobromic acid solution. Then, a distillation membrane device is used to concentrate the dilute hydrobromic acid to obtain a higher-concentration hydrobromic acid, which is recycled to the mother liquor system of the terephthalic acid device. The present utility model also includes a resin bed layer backwashing and regeneration device to ensure the safe, stable, and efficient operation of the bromide ion recovery and treatment device. Through a series of filtration, separation, and concentration processes, the recovery rate of bromide ions in the tail gas lye after-washing liquid can reach more than 85%. Brief Description of the Drawings

[0015] Appendix Figure 1 is a schematic process flow diagram of the present utility model.

[0016] The codes in the attached drawings are as follows: 1 is a filter, 2 is a sodium carbonate conversion tank, 3 is a nanofiltration membrane device, 4 is a weak cation resin bed, 5 is a strong cation resin bed, 6 is a dilute hydrobromic acid heater, 7 is a hydrobromic acid tank, 8 is a hydrobromic acid transfer pump 8, 9 is a hydrochloric acid transfer pump, 10 is an alkali solution pump, 11 is a hydrochloric acid storage tank, 12 is a tail gas alkali scrubbing liquid pipeline, 13 is a first alkali solution pipeline, 14 is a second alkali solution pipeline, 15 is a third alkali solution pipeline, 16 is a first hydrochloric acid pipeline, 17 is a first feeding pipeline, 18 is a second feeding pipeline, 19 is a third feeding pipeline, 20 is a hydrobromic acid recycling pipeline, 21 is a sodium hydroxide pipeline, 22 is an alkali solution reflux pipeline, 23 is a sodium carbonate transfer pipeline, 24 is a steam pipeline, 25 is a steam condensate pipeline, 26 is a second hydrochloric acid pipeline, 27 is a pressure regulating valve, 28 is a remote pressure gauge, 29 is a first on-line pH detector, 30 is a sodium ion on-line detection device, 31 is a steam regulating valve, 32 is a remote thermometer, 33 is a second on-line pH detector, 34 is a remote flowmeter, 35 is a flow regulating valve. Detailed implementation mode

[0017] The present utility model is not limited by the following embodiments, and the specific implementation mode can be determined according to the technical solution of the present utility model and the actual situation.

[0018] In the present utility model, unless otherwise specified, the equipment and devices used are the existing publicly known and commonly used equipment and devices in the art.

[0019] In the present utility model, for the convenience of description, the description of the relative position relationship of each component is carried out according to the layout mode of the attached drawings of the specification. Figure 1 For example, the position relationships such as front, back, up, down, left, and right are determined according to the layout direction of the attached drawings of the specification. Figure 1

[0020] The present utility model will be further described below in conjunction with the embodiments and the attached drawings:

[0021] Embodiment 1: As shown in the attached Figure 1 ​As shown, the bromide ion recovery and treatment device in PTA production includes a filter 1, a sodium carbonate conversion tank 2, a nanofiltration membrane device 3, a weak cationic resin bed 4, a strong cationic resin bed 5, a dilute hydrobromic acid heater 6, and a hydrobromic acid tank 7. The upper inlet of the filter 1 is fixedly connected with a tail gas alkali washing liquid pipeline 12, the lower outlet of the filter 1 and the top inlet of the sodium carbonate conversion tank 2 are fixedly connected with a first alkali liquid pipeline 13, the upper inlet of the sodium carbonate conversion tank 2 is fixedly connected with a sodium hydroxide pipeline 21, and the bottom outlet of the sodium carbonate conversion tank 2 and the bottom inlet of the nanofiltration membrane device 3 are fixedly connected with a second alkali liquid The pipeline 14, the third alkali solution pipeline 15 is fixedly connected between the upper outlet of the nanofiltration membrane device 3 and the upper inlet of the weak cationic resin bed 4, the first feed pipeline 17 is fixedly connected between the lower outlet of the weak cationic resin bed 4 and the top inlet of the strong cationic resin bed 5, the second feed pipeline 18 is fixedly connected between the bottom outlet of the strong cationic resin bed 5 and the first feed inlet of the dilute hydrobromic acid heater 6, the third feed pipeline 19 is fixedly connected between the first discharge port of the dilute hydrobromic acid heater 6 and the upper inlet of the hydrobromic acid tank 7, and the lower outlet of the hydrobromic acid tank 7 is fixedly connected with a hydrobromic acid recycling pipeline 20.

[0022] As needed, the concentration of the sodium hydroxide solution introduced into the sodium carbonate conversion tank 2 is 32% to 50%, and the pH value of the solution in the sodium carbonate conversion tank 2 is adjusted to 11.0 to 12.0, so that all the sodium bicarbonate in the filtered tail gas alkaline washing liquid is converted into sodium carbonate.

[0023] The cationic resins in the weak cationic resin bed 4 and the strong cationic resin bed 5 are both hydrogen-type cationic resins. The working principle of the hydrogen-type cationic resin is the process of ion exchange resin separating the salt in the solution: the aqueous solution in the ion exchange resin working environment contains metal cations (Na + , Ca 2+ , K + Mg 2+ , Fe 3+ etc.) and cation exchange resin (containing acidic groups such as sulfonic acid group (-SO3H), carboxyl group (-COOH) or phenol group (-C6H4OH), which are easy to generate H + ) on H + Ion exchange is performed so that the cations in the solution are transferred to the resin, and the H + It is exchanged into water to react with hydroxide ions and bicarbonate ions to generate water and carbon dioxide, and the remaining hydrogen ions are electrically neutralized with bromide ions to form hydrobromic acid, which is concentrated and reused.

[0024] The bromide ion recovery and treatment device in the above-mentioned PTA production can be further optimized and / or improved according to actual needs:

[0025] Embodiment 2: It is different from Embodiment 1 in that:Figure 1 As shown, the second alkali solution pipeline 14 and the second material delivery pipeline 18 are respectively fixedly installed with an alkali solution pump 10 and a hydrobromic acid delivery pump 8 .

[0026] Embodiment 3: It differs from Embodiment 1 to Embodiment 2 in that: Figure 1 As shown, the bottom inlet of the weak cation resin bed 4 is fixedly connected to a first hydrochloric acid pipeline 16, the inlet of the first hydrochloric acid pipeline 16 is fixedly connected to a hydrochloric acid storage tank 11, a hydrochloric acid delivery pump 9 is fixedly installed on the first hydrochloric acid pipeline 16, and a second hydrochloric acid pipeline 26 is fixedly connected between the first hydrochloric acid pipeline 16 between the hydrochloric acid delivery pump 9 and the weak cation resin bed 4 and the bottom inlet of the strong cation resin bed 5.

[0027] Embodiment 4: It differs from Embodiments 1 to 3 in that: Figure 1 As shown, a first online pH detector 29 is fixedly installed on the first feed pipeline 17, a second online pH detector 33 is fixedly installed on the second alkali solution pipeline 14 between the sodium carbonate conversion tank 2 and the alkali solution pump 10, and a sodium ion online detection device 30 is fixedly installed on the second feed pipeline 18 between the dilute hydrobromic acid heater 6 and the hydrobromic acid delivery pump 8.

[0028] As needed, when the sodium ion online detection device 30 displays a value lower than 10ppm and the first online pH detector 29 displays a value lower than 7.5, it can be determined that the weak cation resin bed 4 and the strong cation resin bed 5 have failed, and the beds are backwashed and regenerated using 4% to 6% dilute hydrochloric acid.

[0029] Embodiment 5: It differs from Embodiments 1 to 4 in that: Figure 1 As shown, the top outlet of the nanofiltration membrane device 3 is fixedly connected to a sodium carbonate delivery pipeline 23, and the second alkali liquid pipeline 14 between the nanofiltration membrane device 3 and the alkali liquid pump 10 and the middle inlet of the sodium carbonate conversion tank 2 are fixedly connected to an alkali liquid reflux pipeline 22.

[0030] Embodiment 6: The difference between the embodiment 6 and the embodiments 1 to 5 is that the second feed port of the dilute hydrobromic acid heater 6 is fixedly connected to the steam pipeline 24 , and the second discharge port of the dilute hydrobromic acid heater 6 is fixedly connected to the steam condensate pipeline 25 .

[0031] Embodiment 7: It differs from Embodiments 1 to 6 in that: Figure 1As shown, a pressure regulating valve 27 is fixedly arranged on the lye reflux pipeline 22, a remote pressure gauge 28 is fixedly arranged on the second lye pipeline 14 between the lye reflux pipeline 22 and the nanofiltration membrane device 3, a steam regulating valve 31 is fixedly arranged on the steam pipeline 24, a remote thermometer 32 is fixedly arranged on the third feeding pipeline 19, and a remote flowmeter 34 and a flow regulating valve 35 are fixedly arranged on the hydrobromic acid recycling pipeline 20 in sequence according to the medium flow direction. Interlocks are respectively arranged between the pressure regulating valve 27 and the remote pressure gauge 28, between the steam regulating valve 31 and the remote thermometer 32, and between the remote flowmeter 34 and the flow regulating valve 35.

[0032] Example 8: The difference from Examples 1 to 7 is that as shown in the appendix Figure 1 As shown, it further includes a DCS controller. The hydrobromic acid delivery pump 8, hydrochloric acid delivery pump 9, lye pump 10, pressure regulating valve 27, remote pressure gauge 28, first on-line pH detector 29, sodium ion on-line detection device 30, steam regulating valve 31, remote thermometer 32, second on-line pH detector 33, remote flowmeter 34, and flow regulating valve 35 are all electrically connected to the DCS controller.

[0033] According to requirements, the model of the DCS controller can be the CS2100 controller produced by Yokogawa Corporation of Japan.

[0034] In the present utility model, unless otherwise specified, the equipment and devices used are all the existing well-known and publicly used equipment and devices in the art.

[0035] The above technical features constitute the embodiments of the present utility model, which have strong adaptability and implementation effects. Non-essential technical features can be increased or decreased according to actual needs to meet the requirements of different situations.

[0036] The usage process of the embodiment of the present utility model: First, the tail gas lye washing solution passes through the filter 1, and after filtering mechanical impurities, it enters the sodium carbonate conversion tank 2. At the same time, sodium hydroxide solution is introduced to adjust the pH value of the solution, and the sodium bicarbonate in the filtered tail gas lye washing solution is converted into sodium carbonate. Then, the converted tail gas lye washing solution containing sodium carbonate first passes through the nanofiltration membrane device 3, and then passes through the weak cation resin bed layer 4 and the strong cation resin bed layer 5 in sequence to remove the salt ions in the solution, obtaining a dilute hydrobromic acid solution. Finally, the dilute hydrobromic acid solution is heated by the dilute hydrobromic acid heater 6 and then recycled.

Claims

1. A bromide ion recovery and treatment device in PTA production, characterized in that The invention comprises a filter, a sodium carbonate conversion tank, a nanofiltration membrane device, a weak cation resin bed, a strong cation resin bed, a dilute hydrobromic acid heater and a hydrobromic acid tank. The upper inlet of the filter is fixedly connected with a tail gas alkali washing liquid pipeline, the lower outlet of the filter and the top inlet of the sodium carbonate conversion tank are fixedly connected with a first alkali liquid pipeline, the upper inlet of the sodium carbonate conversion tank is fixedly connected with a sodium hydroxide pipeline, the bottom outlet of the sodium carbonate conversion tank and the bottom inlet of the nanofiltration membrane device are fixedly connected with a second alkali liquid pipeline, the upper outlet of the nanofiltration membrane device and the upper inlet of the weak cation resin bed are fixedly connected with a third alkali liquid pipeline, the lower outlet of the weak cation resin bed and the top inlet of the strong cation resin bed are fixedly connected with a first feeding pipeline, the bottom outlet of the strong cation resin bed and the first feeding port of the dilute hydrobromic acid heater are fixedly connected with a second feeding pipeline, the first discharge port of the dilute hydrobromic acid heater and the upper inlet of the hydrobromic acid tank are fixedly connected with a third feeding pipeline, and the lower outlet of the hydrobromic acid tank is fixedly connected with a hydrobromic acid recycling pipeline.

2. The bromide ion recovery and treatment device in PTA production according to claim 1, characterized in that The second alkali solution pipeline and the second material delivery pipeline are respectively fixedly installed with an alkali solution pump and a hydrobromic acid delivery pump.

3. The bromide ion recovery and treatment device in PTA production according to claim 1 or 2, characterized in that The bottom inlet of the weak cation resin bed is fixedly connected with a first hydrochloric acid pipeline, the inlet of the first hydrochloric acid pipeline is fixedly connected with a hydrochloric acid storage tank, a hydrochloric acid delivery pump is fixedly installed on the first hydrochloric acid pipeline, and a second hydrochloric acid pipeline is fixedly connected between the first hydrochloric acid pipeline between the hydrochloric acid delivery pump and the weak cation resin bed and the bottom inlet of the strong cation resin bed.

4. The bromide ion recovery and treatment device in PTA production according to claim 3, characterized in that A first online pH detector is fixedly installed on the first feed pipeline, a second online pH detector is fixedly installed on the second alkali solution pipeline between the sodium carbonate conversion tank and the alkali solution pump, and a sodium ion online detection device is fixedly installed on the second feed pipeline between the dilute hydrobromic acid heater and the hydrobromic acid delivery pump.

5. The bromide ion recovery and treatment device in PTA production according to claim 2 or 4, characterized in that The top outlet of the nanofiltration membrane device is fixedly connected with a sodium carbonate delivery pipeline, and the second alkali liquid pipeline between the nanofiltration membrane device and the alkali liquid pump and the middle inlet of the sodium carbonate conversion tank are fixedly connected with an alkali liquid reflux pipeline.

6. The bromide ion recovery and treatment device in PTA production according to claim 3, characterized in that The top outlet of the nanofiltration membrane device is fixedly connected with a sodium carbonate delivery pipeline, and the second alkali liquid pipeline between the nanofiltration membrane device and the alkali liquid pump and the middle inlet of the sodium carbonate conversion tank are fixedly connected with an alkali liquid reflux pipeline.

7. The bromide ion recovery and treatment device in PTA production according to claim 1, 2, 4 or 6, characterized in that The second feed port of the dilute hydrobromic acid heater is fixedly connected with a steam pipeline, and the second discharge port of the dilute hydrobromic acid heater is fixedly connected with a steam condensate pipeline.

8. The bromide ion recovery and treatment device in PTA production according to claim 5, characterized in that The second feed port of the dilute hydrobromic acid heater is fixedly connected with a steam pipeline, and the second discharge port of the dilute hydrobromic acid heater is fixedly connected with a steam condensate pipeline.

9. The bromide ion recovery and treatment device in PTA production according to claim 7, characterized in that A pressure regulating valve is fixedly installed on the alkali liquid reflux pipeline, a remote pressure gauge is fixedly installed on the second alkali liquid pipeline between the alkali liquid reflux pipeline and the nanofiltration membrane device, a steam regulating valve is fixedly installed on the steam pipeline, a remote thermometer is fixedly installed on the third feed pipeline, and a remote flowmeter and a flow regulating valve are fixedly installed on the hydrobromic acid recycling pipeline in sequence according to the flow direction of the medium. Interlocks are respectively arranged between the pressure regulating valve and the remote pressure gauge, the steam regulating valve and the remote thermometer, and the remote flowmeter and the flow regulating valve.

10. A bromide ion recovery and treatment device in PTA production according to claim 9, characterized in that It also includes a DCS controller, and a hydrobromic acid delivery pump, a hydrochloric acid delivery pump, an alkali solution pump, a pressure regulating valve, a remote pressure gauge, a first online pH detector, a sodium ion online detection device, a steam regulating valve, a remote thermometer, a second online pH detector, a remote flow meter, and a flow regulating valve are all electrically connected to the DCS controller.

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