Recycling device for hydrobromic acid in PTA (pure terephthalic acid) production tail gas

Abstract

The utility model relates to the technical field of terephthalic acid production, in particular to a device for recycling hydrobromic acid in PTA (pure terephthalic acid) production tail gas, which comprises a hydrobromic acid recycling tower, a tail gas alkaline washing tower and a dilute hydrobromic acid recycling device. The device is reasonable and compact in structure and convenient to use, and has the characteristics of safety, labor saving, simplicity, convenience and high efficiency. The upper part of the hydrobromic acid recovery tower is fixedly communicated with a desalted water pipeline, bromine-containing tail gas enters the hydrobromic acid recovery tower from the lower part of the hydrobromic acid recovery tower, desalted water is circularly sprayed in the hydrobromic acid recovery tower, gas and liquid are fully contacted on a filler of the hydrobromic acid recovery tower, bromine ions are dissolved in water, and the bromine concentration in the water reaches a certain value; a hydrobromic acid solution is continuously extracted and enters a dilute hydrobromic acid recovery device, so that the consumption of fresh hydrobromic acid is reduced; and the tail gas with hydrobromic acid cleaned by desalted water enters a tail gas alkaline washing tower, is continuously washed by a sodium hydroxide solution, and is discharged after meeting the environmental protection requirement.

Description

Technical Field

[0001] The utility model relates to the technical field of purification of tail gas in terephthalic acid production, and is a device for recycling hydrobromic acid in PTA production tail gas. 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 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 tail 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 to form bromide ions in the tail gas catalytic combustion reactor and enter the expander with the tail gas to do work and then be discharged. In order to meet the environmental protection standards, the tail gas is subjected to alkali washing before discharge. The bromide ions form sodium bromide and are discharged into the sewage or sodium bromide is recovered. There is also a device that enters the combustion process for alkali washing and discharge after the expander does work. In the above devices, hydrobromic acid is not recycled. Summary of the Invention

[0004] The utility model provides a device for recycling hydrobromic acid in PTA production tail gas, which overcomes the deficiencies of the above-mentioned prior art and can effectively solve the problem that bromide ions are not recycled in the existing treatment of terephthalic acid tail gas.

[0005] The technical solution of the present utility model is achieved by the following measures: A device for recycling hydrobromic acid in the tail gas of PTA production includes a hydrobromic acid recovery tower, a tail gas caustic scrubbing tower, and a dilute hydrobromic acid recovery device. The first inlet at the upper part of the hydrobromic acid recovery tower is fixedly connected to a desalinated water pipeline, the lower inlet of the hydrobromic acid recovery tower is fixedly connected to a bromine-containing tail gas pipeline, a first conveying pipeline is fixedly connected between the bottom outlet of the hydrobromic acid recovery tower and the dilute hydrobromic acid recovery device, a second conveying pipeline is fixedly connected between the top outlet of the hydrobromic acid recovery tower and the lower inlet of the tail gas caustic scrubbing tower, the first inlet at the upper part of the tail gas caustic scrubbing tower is fixedly connected to a caustic liquid pipeline, the bottom outlet of the tail gas caustic scrubbing tower is fixedly connected to a sewage pipeline, and the top outlet of the tail gas caustic scrubbing tower is fixedly connected to a tail gas discharge pipeline.

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

[0007] A hydrobromic acid circulation pump and a caustic scrubbing circulation pump are respectively fixedly installed on the above-mentioned first conveying pipeline and sewage pipeline.

[0008] A first reflux pipeline is fixedly connected between the first conveying pipeline between the hydrobromic acid circulation pump and the dilute hydrobromic acid recovery device and the second inlet at the upper part of the hydrobromic acid recovery tower, and a second reflux pipeline is fixedly connected between the sewage pipeline at the outlet of the caustic scrubbing circulation pump and the second inlet at the upper part of the tail gas caustic scrubbing tower.

[0009] A packing layer is arranged in the above-mentioned hydrobromic acid recovery tower, and the packing layer is located between the upper inlet and the lower inlet of the hydrobromic acid recovery tower.

[0010] A liquid level regulating valve is fixedly arranged on the above-mentioned desalinated water pipeline, a remote transmission liquid level gauge is fixedly arranged on the hydrobromic acid recovery tower, and an interlock is arranged between the remote transmission liquid level gauge and the liquid level regulating valve.

[0011] A first flow meter and a first flow regulating valve are successively fixedly arranged on the first reflux pipeline according to the medium flow direction, a second flow meter and a second flow regulating valve are successively fixedly arranged on the first conveying pipeline between the first reflux pipeline and the dilute hydrobromic acid recovery device according to the medium flow direction, and interlocks are respectively arranged between the first flow meter and the first flow regulating valve, and between the second flow meter and the second flow regulating valve.

[0012] The above-mentioned device further includes a DCS controller, and the hydrobromic acid circulation pump, the caustic scrubbing circulation pump, the remote transmission liquid level gauge, the liquid level regulating valve, the first flow meter, the first flow regulating valve, the second flow meter, and the second flow regulating valve are all electrically connected to the DCS controller.

[0013] The structure of the utility model is reasonable and compact, and it is convenient to use. By utilizing the characteristic that bromide ions are easily soluble in water, the bromine-containing tail gas and desalted water are in full gas-liquid contact on the packing of the hydrobromic acid recovery tower to remove chloride ions in the tail gas. The hydrobromic acid solution is sent to the dilute hydrobromic acid recovery device to reduce the consumption of fresh hydrobromic acid, and then the tail gas is continuously washed with sodium hydroxide solution and discharged after meeting the environmental protection requirements. It has the characteristics of safety, environmental protection and high efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0015] Appendix Figure 1 The codes in are respectively: 1 is the hydrobromic acid recovery tower, 2 is the tail gas caustic scrubbing tower, 3 is the hydrobromic acid circulation pump, 4 is the caustic scrubbing circulation pump, 5 is the dilute hydrobromic acid recovery device, 6 is the bromine-containing tail gas pipeline, 7 is the first conveying pipeline, 8 is the first reflux pipeline, 9 is the second conveying pipeline, 10 is the sewage pipeline, 11 is the second reflux pipeline, 12 is the caustic liquid pipeline, 13 is the tail gas discharge pipeline, 14 is the desalted water pipeline, 15 is the remote transmission liquid level gauge, 16 is the liquid level regulating valve, 17 is the first flowmeter, 18 is the first flow regulating valve, 19 is the second flowmeter, 20 is the second flow regulating valve. DETAILED DESCRIPTION OF THE EMBODIMENTS

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

[0017] In the utility model, unless otherwise specified, the equipment and devices used are the existing well-known and commonly used equipment and devices in the art.

[0018] In the utility model, for the convenience of description, the description of the relative positional relationship of each component is carried out according to the layout mode of the attached Figure 1 drawings of the specification, such as the positional relationships of front, back, up, down, left, right, etc. are determined according to the layout direction of the attached Figure 1 drawings of the specification.

[0019] The following further describes the utility model in conjunction with the embodiments and the drawings:

[0020] Embodiment 1: As shown in the appendix Figure 1As shown in the figure, the recovery and utilization device of hydrobromic acid in the PTA production tail gas includes a hydrobromic acid recovery tower 1, a tail gas caustic scrubbing tower 2, and a dilute hydrobromic acid recovery device 5. The first inlet at the upper part of the hydrobromic acid recovery tower 1 is fixedly connected to a desalted water pipeline 14, the inlet at the lower part of the hydrobromic acid recovery tower 1 is fixedly connected to a bromine-containing tail gas pipeline 6, a first conveying pipeline 7 is fixedly connected between the bottom outlet of the hydrobromic acid recovery tower 1 and the dilute hydrobromic acid recovery device 5, a second conveying pipeline 9 is fixedly connected between the top outlet of the hydrobromic acid recovery tower 1 and the lower inlet of the tail gas caustic scrubbing tower 2, the first inlet at the upper part of the tail gas caustic scrubbing tower 2 is fixedly connected to a caustic liquid pipeline 12, the bottom outlet of the tail gas caustic scrubbing tower 2 is fixedly connected to a sewage pipeline 10, and the top outlet of the tail gas caustic scrubbing tower 2 is fixedly connected to a tail gas discharge pipeline 13.

[0021] As needed, when the bromide ion concentration in the desalted water absorption liquid in the hydrobromic acid recovery tower 1 reaches 1% to 2%, continuously extract the hydrobromic acid solution and feed it into the dilute hydrobromic acid recovery device 5, recycle it for PTA production, supplement the required accelerator, and reduce the consumption of fresh hydrobromic acid.

[0022] According to actual needs, the above-mentioned recovery and utilization device of hydrobromic acid in the PTA production tail gas can be further optimized and / or improved:

[0023] Example 2: The difference from Example 1 is that as shown in the appendix Figure 1 As shown in the figure, a hydrobromic acid circulation pump 3 and a caustic scrubbing circulation pump 4 are fixedly installed on the first conveying pipeline 7 and the sewage pipeline 10 respectively.

[0024] Example 3: The difference from Examples 1 to 2 is that as shown in the appendix Figure 1 As shown in the figure, a first reflux pipeline 8 is fixedly connected between the first conveying pipeline 7 between the hydrobromic acid circulation pump 3 and the dilute hydrobromic acid recovery device 5 and the second inlet at the upper part of the hydrobromic acid recovery tower 1, and a second reflux pipeline 11 is fixedly connected between the sewage pipeline 10 at the outlet of the caustic scrubbing circulation pump 4 and the second inlet at the upper part of the tail gas caustic scrubbing tower 2.

[0025] Example 4: The difference from Examples 1 to 3 is that as shown in the appendix Figure 1 As shown in the figure, a packing layer is arranged in the hydrobromic acid recovery tower 1, and the packing layer is located between the upper inlet and the lower inlet of the hydrobromic acid recovery tower 1.

[0026] As needed, the packing of the hydrobromic acid recovery tower 1 can be non-metallic regular packing, such as non-metallic materials like PTFE and PP; the desalted water is sprayed downward in a circulating manner from the upper part of the hydrobromic acid recovery tower 1, and on the packing of the hydrobromic acid recovery tower 1, the gas-liquid fully contacts, and bromide ions dissolve in water to form hydrobromic acid.

[0027] Example 5: The difference from Examples 1 to 4 is that as shown in the appendix Figure 1As shown, a liquid level regulating valve 16 is fixedly arranged on the desalination water pipeline 14, and a remote liquid level gauge 15 is fixedly arranged on the hydrobromic acid recovery tower 1. An interlock is arranged between the remote liquid level gauge 15 and the liquid level regulating valve 16.

[0028] Embodiment 6: The difference from Embodiments 1 to 5 is that as shown in the appendix Figure 1 As shown, a first flowmeter 17 and a first flow regulating valve 18 are fixedly arranged on the first reflux pipeline 8 in sequence according to the medium flow direction. A second flowmeter 19 and a second flow regulating valve 20 are fixedly arranged on the first conveying pipeline 7 between the first reflux pipeline 8 and the dilute hydrobromic acid recovery device 5 in sequence according to the medium flow direction. Interlocks are respectively arranged between the first flowmeter 17 and the first flow regulating valve 18, and between the second flowmeter 19 and the second flow regulating valve 20.

[0029] Embodiment 7: The difference from Embodiments 1 to 6 is that as shown in the appendix Figure 1 As shown, this device further includes a DCS controller. The hydrobromic acid circulation pump 3, the caustic washing circulation pump 4, the remote liquid level gauge 15, the liquid level regulating valve 16, the first flowmeter 17, the first flow regulating valve 18, the second flowmeter 19, and the second flow regulating valve 20 are all electrically connected to the DCS controller.

[0030] According to requirements, on each pipeline and equipment of the device for recovering and utilizing hydrobromic acid in the PTA production tail gas, conventional valves, thermometers, pressure gauges, etc. well-known and commonly used in the art can also be arranged according to production needs.

[0031] 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 added or reduced according to actual needs to meet the requirements of different situations.

[0032] The using process of the embodiment of the present utility model: First, the bromine-containing tail gas enters from the lower part of the hydrobromic acid recovery tower 1, and on the packing layer of the hydrobromic acid recovery tower 1, it makes full gas-liquid contact reaction with the desalinated water sprayed from the upper part of the hydrobromic acid recovery tower 1; then, the tail gas from which bromide ions have been removed enters the tail gas caustic washing tower 2, and chloride ions are further removed through caustic liquid washing and discharged after reaching the standard; finally, when the bromide ion concentration in the absorption liquid of the hydrobromic acid recovery tower 1 reaches the required value, the second flow regulating valve 20 is opened to send the hydrobromic acid solution into the dilute hydrobromic acid recovery device 5 for reuse.

Claims

1. A device for recycling hydrobromic acid in tail gas from PTA production, characterized in that The invention comprises a hydrobromic acid recovery tower, a tail gas alkali washing tower and a dilute hydrobromic acid recovery device. The first inlet at the top of the hydrobromic acid recovery tower is fixedly connected with a desalted water pipeline, the lower inlet at the hydrobromic acid recovery tower is fixedly connected with a bromine-containing tail gas pipeline, the bottom outlet at the hydrobromic acid recovery tower and the dilute hydrobromic acid recovery device are fixedly connected with a first conveying pipeline, the top outlet at the hydrobromic acid recovery tower and the lower inlet at the tail gas alkali washing tower are fixedly connected with a second conveying pipeline, the first inlet at the top of the tail gas alkali washing tower is fixedly connected with an alkali solution pipeline, the bottom outlet at the tail gas alkali washing tower is fixedly connected with a sewage pipeline, and the top outlet at the tail gas alkali washing tower is fixedly connected with a tail gas discharge pipeline.

2. The device for recycling hydrobromic acid in the PTA production tail gas according to claim 1, characterized in that A hydrobromic acid circulation pump and an alkali washing circulation pump are fixedly installed on the first delivery pipeline and the sewage pipeline respectively.

3. The device for recycling hydrobromic acid in the PTA production tail gas according to claim 2, characterized in that A first reflux pipeline is fixedly connected between the first delivery pipeline between the hydrobromic acid circulation pump and the dilute hydrobromic acid recovery device and the second inlet on the top of the hydrobromic acid recovery tower, and a second reflux pipeline is fixedly connected between the sewage pipeline at the outlet of the alkali washing circulation pump and the second inlet on the top of the tail gas alkali washing tower.

4. The device for recycling hydrobromic acid in the tail gas of PTA production according to claim 1, 2 or 3, characterized in that A packing layer is arranged in the hydrobromic acid recovery tower, and the packing layer is located between the upper inlet of the hydrobromic acid recovery tower and the lower inlet of the hydrobromic acid recovery tower.

5. The device for recycling hydrobromic acid in the tail gas of PTA production according to claim 1, 2 or 3, characterized in that A liquid level regulating valve is fixedly installed on the desalted water pipeline, a remote liquid level gauge is fixedly installed on the hydrobromic acid recovery tower, and an interlock is arranged between the remote liquid level gauge and the liquid level regulating valve.

6. The device for recycling hydrobromic acid in the tail gas of PTA production according to claim 4, characterized in that A liquid level regulating valve is fixedly installed on the desalted water pipeline, a remote liquid level gauge is fixedly installed on the hydrobromic acid recovery tower, and an interlock is arranged between the remote liquid level gauge and the liquid level regulating valve.

7. The device for recycling hydrobromic acid in the tail gas of PTA production according to claim 3 or 6, characterized in that A first flow meter and a first flow regulating valve are fixedly arranged on the first reflux pipeline in sequence according to the flow direction of the medium; a second flow meter and a second flow regulating valve are fixedly arranged on the first delivery pipeline between the first reflux pipeline and the dilute hydrobromic acid recovery device in sequence according to the flow direction of the medium; interlocks are respectively arranged between the first flow meter and the first flow regulating valve, and between the second flow meter and the second flow regulating valve.

8. The device for recycling hydrobromic acid in the tail gas of PTA production according to claim 4, characterized in that A first flow meter and a first flow regulating valve are fixedly arranged on the first reflux pipeline in sequence according to the flow direction of the medium; a second flow meter and a second flow regulating valve are fixedly arranged on the first delivery pipeline between the first reflux pipeline and the dilute hydrobromic acid recovery device in sequence according to the flow direction of the medium; interlocks are respectively arranged between the first flow meter and the first flow regulating valve, and between the second flow meter and the second flow regulating valve.

9. The device for recycling hydrobromic acid in the tail gas of PTA production according to claim 5, characterized in that A first flow meter and a first flow regulating valve are fixedly arranged on the first reflux pipeline in sequence according to the flow direction of the medium; a second flow meter and a second flow regulating valve are fixedly arranged on the first delivery pipeline between the first reflux pipeline and the dilute hydrobromic acid recovery device in sequence according to the flow direction of the medium; interlocks are respectively arranged between the first flow meter and the first flow regulating valve, and between the second flow meter and the second flow regulating valve.

10. The device for recycling hydrobromic acid in the tail gas of PTA production according to claim 9, characterized in that It also includes a DCS controller, and the hydrobromic acid circulation pump, the alkali washing circulation pump, the remote liquid level meter, the liquid level regulating valve, the first flow meter, the first flow regulating valve, the second flow meter, and the second flow regulating valve are all electrically connected to the DCS controller.

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