CN-224220794-U - Recovery device of p-methylbenzoic acid

Abstract

The utility model discloses a recovery device of p-methylbenzoic acid (PT acid), which comprises a mother liquor extraction tower, a mother liquor stripping tower, a condensate extraction tower, a condensate stripping tower and an extractant regeneration tower. By adopting Paraxylene (PX) as an extractant, the PTA refining mother liquor and PT acid in the refining condensate are simultaneously and efficiently recovered. The device is provided with a mother liquor heater and an extractant heater to maintain the operation temperature and prevent organic acid from crystallizing, an extractant regeneration tower realizes PX recycling, and a first energy recovery device and a second energy recovery device are arranged to recover system heat. The device ensures that the recovery rate of PT acid reaches more than 90 percent, and the raffinate condensate can be directly used as product washing water, has the characteristics of high recovery efficiency, low energy consumption, stable operation and the like, and is suitable for recycling the PT acid in the PTA production process.

Inventors

• DUAN HONGFENG
• WEN YUJUN
• YANG SHENGDONG
• WANG JIANZHEN
• YANG DONG

Assignees

• 浙江东江绿色石化技术创新中心有限公司

Dates

Publication Date

20260512

Application Date

20250416

Claims (10)

1. 1. A recovery device for p-methylbenzoic acid, comprising: a mother liquor extraction tower for refining PT acid in the mother liquor by PX extraction; a mother liquor stripping tower for removing PX carried in the process of removing PT acid from the refined mother liquor in the mother liquor extraction tower; a condensate extraction tower for refining PT acid in condensate by PX extraction; the condensate stripping tower is used for removing PX carried in the process of removing PT acid from the refined condensate in the condensate extraction tower; And (3) regenerating the PX in which the PT acid has been extracted in the mother liquor extraction tower by the extractant regeneration tower, and continuously extracting and refining condensate.
2. 2. The apparatus for recovering p-methylbenzoic acid according to claim 1, further comprising a first energy recovery means through which PX regenerated in the extractant regeneration column passes to the lower part of the condensate extraction column.
3. 3. The recovery apparatus of p-methylbenzoic acid according to claim 1, wherein the upper part and the lower part of the mother liquor extraction column are respectively provided with a first mother liquor extraction inlet and a second mother liquor extraction inlet; the first mother liquor extraction inlet is communicated with a mother liquor heater, and refined mother liquor enters a mother liquor extraction tower from the first mother liquor extraction inlet after passing through the mother liquor heater; The second mother liquor extraction inlet is communicated with the extractant heater, and the extractant passes through the extractant heater and then enters the mother liquor extraction tower from the second mother liquor extraction inlet.
4. 4. A recovery apparatus for p-methylbenzoic acid according to any one of claims 1 to 3, wherein a first mother gas inlet is provided at an upper portion of the mother gas stripper, the first mother gas inlet is communicated with a second mother gas extraction outlet at a bottom portion of the mother gas extraction column, and a mother gas stripper reboiler is provided at a lower portion of the mother gas stripper.
5. 5. A p-methylbenzoic acid recycling device according to claim 4, wherein a second mother gas inlet is arranged at the upper part of the mother gas stripping tower, a second mother gas outlet is arranged at the top part of the mother gas stripping tower, the second mother gas outlet is communicated with a decanting tank, and water phase separated by the decanting tank enters the mother gas stripping tower from the second mother gas inlet.
6. 6. A recovery apparatus for p-methylbenzoic acid according to any one of claims 1 to 3, wherein a first condensing inlet is provided at an upper portion of the condensate stripper, the first condensing inlet is communicated with a second condensing outlet at a bottom portion of the condensate extractor, and a condensate stripper reboiler is provided at a lower portion of the condensate stripper.
7. 7. The recovery device of p-methylbenzoic acid according to claim 6, wherein a second condensing inlet is arranged at the upper part of the condensate stripping tower, a second condensing outlet is arranged at the top part of the condensate stripping tower, the second condensing outlet is communicated with the decanting tank, and the water phase separated by the decanting tank enters the condensate stripping tower from the second condensing inlet.
8. 8. A recovery apparatus for p-methylbenzoic acid according to any one of claims 1 to 3, wherein a first regeneration inlet is provided in the extractant regeneration column, the first regeneration inlet is communicated with a first mother liquor extraction outlet at the top of the mother liquor extraction column, and an extractant regeneration column reboiler is provided in the lower part of the extractant regeneration column.
9. 9. The apparatus according to claim 8, wherein a second regeneration outlet is provided at the bottom of the extractant-regenerating column, and the second regeneration outlet is in communication with the oxidation reaction system.
10. 10. The recovery device of p-methylbenzoic acid according to claim 9, wherein a first condensate extraction outlet is arranged at the upper part of the condensate extraction tower, a first condensate extraction inlet is arranged at the lower part of the condensate extraction tower, and the first condensate extraction inlet is communicated with a first regeneration outlet at the top of the extractant regeneration tower.

Description

Recovery device of p-methylbenzoic acid Technical Field The utility model relates to the technical field of separation of p-methylbenzoic acid, in particular to a device for recycling p-methylbenzoic acid. Background The Purified Terephthalic Acid (PTA) is one of important basic organic chemical basic raw materials, and is mainly used for producing polyester fibers, polyester films and the like. In the production of PTA, raw material Paraxylene (PX) reacts with oxygen in acetic acid solvent to generate Crude Terephthalic Acid (CTA) with purity of about 99.7% of Terephthalic Acid (TA), and impurities mainly exist in the form of intermediate paracarboxybenzaldehyde (4-CBA). However, TA and 4-CBA are not easily separated, the quality of CTA cannot meet the downstream process requirement, and the TA needs to be purified by a refining unit. The refining unit is used for mixing CTA and process water into slurry, heating and pressurizing to form CTA aqueous solution, selectively reducing 4-CBA into p-methylbenzoic acid (PT acid) through hydrogenation, converting colored impurities into colorless soluble impurities, and purifying TA to more than 99.98% through TA crystallization and solid-liquid separation by utilizing the solubility difference of TA and PT acid in water. In the TA purification process, flash evaporation steam containing various organic acids such as PT acid, TA, benzoic Acid (BA) and the like generated in the TA crystallization section is changed into refined condensate after heat recovery, and the refined condensate is recycled as a refined circulating solvent in a refining system, so that the purification difficulty of TA is increased due to the existence of PT acid and the like. A large amount of refined mother liquor containing TA, PT acid, 4-CBA, BA and the like is generated in the solid-liquid separation process, and particularly the content of PT acid is the highest. PT acid is an intermediate product of PX oxidation process, if PT acid in refined mother liquor can be recovered, the yield of PTA can be improved, PTA mother liquor can be purified, and the difficulty of a subsequent treatment section of the mother liquor is reduced. At present, the method for recovering PT acid in a refining system mainly comprises a physicochemical method, and mainly comprises a crystallization method, a rectification method and an extraction method. The invention discloses a PT acid separation device in refined condensate, which adopts a mode of statically mixing PX and the refined condensate to extract PT acid in the refined condensate into the PX, and then the PX and the PT acid are separated from the refined condensate after decantation, so that the PX and the PT acid are returned to an oxidation reaction system. However, in order to avoid precipitation of PT acid, the device adopts a mode of static mixing of PX and PT acid for extraction, and the recovery rate of PT acid is lower due to limited contact mass transfer time. Disclosure of utility model The utility model overcomes the defects in the prior art that (1) the PTA production device is limited by the flow of raw material PX, only extracts one medium in refining mother liquor and refining condensate, and does not realize the mass recovery of PT acid in a refining system, (2) the mother liquor extraction and stripping temperature is relatively low, TA and PT acid are easy to crystallize and separate out, the safe and stable operation of the device is affected, and the recovery device of p-methylbenzoic acid is provided, which can simultaneously realize the extraction of refining mother liquor and refining condensate, thereby realizing the mass recovery of PT acid in the refining system, ensuring the stripping temperature in the extraction process, ensuring that organic acid is always in a dissolved state, and avoiding the abnormal conditions such as blockage of a mother liquor extraction system caused by crystallization and precipitation. In order to solve the technical problems, the utility model adopts the following technical scheme that the recovery device of the p-methylbenzoic acid comprises: a mother liquor extraction tower for refining PT acid in the mother liquor by PX extraction; a mother liquor stripping tower for removing PX carried in the process of removing PT acid from the refined mother liquor in the mother liquor extraction tower; a condensate extraction tower for refining PT acid in condensate by PX extraction; the condensate stripping tower is used for removing PX carried in the process of removing PT acid from the refined condensate in the condensate extraction tower; And (3) regenerating the PX in which the PT acid has been extracted in the mother liquor extraction tower by the extractant regeneration tower, and continuously extracting and refining condensate. The application realizes simultaneous extraction of refining mother liquor and refining condensate, realizes mass recovery of PT acid in a refining system, can regenerate