Method of recycling mother liquid of pure terephthalic acid (PTA) refining unit
원문보기
IPC분류정보
국가/구분
United States(US) Patent
등록
국제특허분류(IPC7판)
C07C-051/44
B01D-003/06
B01D-009/00
B01D-003/08
B01D-003/00
C07C-063/26
출원번호
16330230
(2017-05-15)
등록번호
10787411
(2020-09-29)
우선권정보
CN-2017 1 0173237 (2017-03-22)
국제출원번호
PCT/CN2017/084350
(2017-05-15)
국제공개번호
WO2018/171028
(2018-09-27)
발명자
/ 주소
Zhao, Xu
Shen, Tao
Wang, Tianbao
Zhang, Wanyao
Lu, Yuanrui
Xu, Lilong
Jia, Min
Han, Dongzhao
Xie, Xiaoling
Qiu, Yongning
출원인 / 주소
TIANHUA INSTITUTE OF CHEMICAL MACHINERY AND AUTOMATION CO., LTD
대리인 / 주소
Muncy, Geissler, Olds & Lowe, P.C.
인용정보
피인용 횟수 :
0인용 특허 :
0
초록▼
The present invention relates to a method of recycling mother liquid of a PTA refining unit. The present invention recycles waste heat and PT acids of a PTA mother liquid to effectively utilize heat in the PTA mother liquid, solves influence of crystallization of the PT acids on subsequent system, r
The present invention relates to a method of recycling mother liquid of a PTA refining unit. The present invention recycles waste heat and PT acids of a PTA mother liquid to effectively utilize heat in the PTA mother liquid, solves influence of crystallization of the PT acids on subsequent system, reduces pollution to the environment, and can produce huge economic benefits by using high efficient multistage flash distillation technology, low temperature cogeneration technology, heat pump heating and cooling technology, and low temperature crystallization technology.
대표청구항▼
1. A method of recycling mother liquid of a pure terephthalic acid (PTA) refining unit, comprising steps of: multistage flash distillation cooling step: the mother liquid of the PTA refining unit enters a multistage flash tower including at least Nth stage flash zones, and performs (N−1)th stage fla
1. A method of recycling mother liquid of a pure terephthalic acid (PTA) refining unit, comprising steps of: multistage flash distillation cooling step: the mother liquid of the PTA refining unit enters a multistage flash tower including at least Nth stage flash zones, and performs (N−1)th stage flash distillation in the multistage flash tower;the Nth stage flash zone in the multistage flash tower is a flash distillation cooling zone, where no flash distillation is performed, and the flash distillation cooling zone is between an (N−2)th stage flash zone and an (N−1)th stage flash zone;waste heat utilization step: flash distillation steam produced in a first stage flash zone to an Mth stage flash zone enters a waste heat utilization unit; andP-methylbenzoic acid (PT acid) crystallization and recycling step: the mother liquid produced in the (N−1)th stage flash zone enters a low temperature crystallization unit to crystallize and recycle the PT acid in the mother liquid of the PTA refining unit;wherein, N=4˜8, M=1˜4, N>M, and N and M are both integers. 2. The method of recycling mother liquid of a PTA refining unit according to claim 1, wherein the waste heat utilization unit comprises a first waste heat utilization unit and a second waste heat utilization unit; the first waste heat utilization unit is a heating unit and/or a cooling unit, where a first flash distillation steam produced in the first flash zone enters;the second waste heat utilization unit is a power generation unit, where flash distillation steam produced in the second stage flash zone to the Mth flash zone enters. 3. The method of recycling mother liquid of a PTA refining unit according to claim 2, wherein: the following steps are performed in the heating unit:one part of the first stage flash distillation steam from the multistage flash tower enters a generator, where lithium bromide dilute solution is heated and evaporated; a steam condensate after heat exchange enters a third stage condensate buffer tank; the steam produced by evaporation enters a condenser and is condensed under the action of circulating cooling water; working medium condensate produced by the condenser enters a heating evaporator, in which the working medium condensate is heated and evaporated by another part of the first stage flash distillation steam, and a cooling evaporator respectively through a working medium circulating pump; a first stage flash distillation steam condensate after condensation enters the third stage condensate buffer tank; the heated and evaporated working medium steam enters a heating absorber, where lithium bromide concentrated solution is in an unsaturated state, thereby absorbing the working medium steam, during the course of which a large amount of heat is released; a condensate from a fourth stage condensate delivery pump enters the heating absorber to be heated; and the heated condensate enters a second stage condensate buffer tank and performs flash distillation therein to produce medium, low pressure steam, which enters subsequent system for use. 4. The method of recycling mother liquid of a PTA refining unit according to claim 2, wherein: the following steps are performed in the cooling unit:working medium condensate entering the cooling evaporator is evaporated under the action of heating of low-temperature water; working medium steam produced by evaporation enters a cooling absorber, where lithium bromide concentrated solution is in an unsaturated state, thereby absorbing the working medium steam; a large amount of heat released during the course of the absorption is cooled by circulating cooling water, and the low-temperature water after heat exchange in the cooling evaporator is cooled down, thereby obtaining freeze water with lower temperature;one part of the freeze water produced by the cooling evaporator enters an air heat exchanger to cool air at an inlet of an air compressor; the freeze water after heat exchange enters a freeze water buffer tank, and is delivered to the cooling evaporator through a freeze water delivery pump for recycling; and another part of the freeze water enters the multistage flash tower to cool the flash distillation steam. 5. The method of recycling mother liquid of a PTA refining unit according to claim 2, wherein: the following steps are performed in the power generation unit:the second stage flash zone to the Mth flash zone connect with heat exchangers, respectively, while the respective heat exchangers are connected in series, such that the steam produced by the multistage flash tower can gasify solvent in the heat exchangers;flash distillation steam from the Mth flash zone performs indirect heat exchange with solvent from a solvent delivery pump in a first stage heat exchanger connected thereto, and a steam condensate after heat exchange is discharged into a first stage condensate buffer tank;the solvent after being heated in the previous step enters the next stage heat exchanger connected to the first stage heat exchanger in series, and a steam condensate after heat exchange is discharged into the first stage condensate buffer tank;repeating heat exchange steps of the above solvent and the heat distillation steam in the flash zones;solvent steam after gasification enters a steam turbine to push the steam turbine so as to do work and generate power; then the solvent steam after doing work enters a solvent condenser; and a solvent condensate produced by condensation enters a solvent buffer tank and is delivered to the first stage heat exchanger under the action of a solvent delivery pump, thereby completing circulation process of converting a part of waste heat in the PTA mother liquid into electric energy; andthe condensate in the first stage condensate buffer tank is delivered to subsequent system for use under the action of a first stage condensate delivery pump. 6. The method of recycling mother liquid of a PTA refining unit according to claim 1, wherein: the following steps are performed in the low temperature crystallization unit:the (N−2)th flash zone in the multistage flash tower connects to a Venturi ejector; the Nth flash zone in the multistage flash tower is a flash distillation cooling zone and connects to a second stage condensate delivery pump;the mother liquid produced in the (N−1)th flash zone enters a crystallization tank, in which a large amount of crystallized PT acids is separated out; the remaining liquid containing small amount of solid impurities after crystallization sequentially enters a plurality of series connected filters under the action of pressure of a first stage mother liquid delivery pump while solid particles are left and discharged through bottoms of the filters; the filtered mother liquid enters a mother liquid buffer tank, and enters the Venturi ejector under the action of a second stage mother liquid delivery pump to condense flash distillation steam from the (N−2)th flash zone; and the condensate after condensation is delivered to subsequent film processing system under the action of the second stage condensate delivery pump. 7. The method of recycling mother liquid of a PTA refining unit according to claim 1, wherein N is 8, and M is 4. 8. The method of recycling mother liquid of a PTA refining unit according to claim 6, wherein N is 8, and M is 4. 9. The method of recycling mother liquid of a PTA refining unit according to claim 7, wherein the mother liquid of the PTA refining unit has a temperature of 140° C. to 150° C. 10. The method of recycling mother liquid of a PTA refining unit according to claim 5, wherein a solvent of the solvent delivery pump is 1,1,1,3,3-pentafluoropropane. 11. The method of recycling mother liquid of a PTA refining unit according to claim 3, wherein the lithium bromide dilute solution has a mass concentration of 56% to 60%, and the lithium bromide concentrated solution has a mass concentration of 60% to 64%. 12. The method of recycling mother liquid of a PTA refining unit according to claim 6, wherein the plurality of series connected filters are series connection of first stage filters and second stage filters, and filter cloths are provided in the plurality of series connected filters.
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