Steam heated polyester production process
View Patent ↗Processes for making polyesters in a polyester production facility are disclosed, that include the steps of: forming a reaction medium comprising at least one monomer that includes terephthalic acid (TPA) and/or an ester derivative of TPA; subjecting at least a portion of the reaction medium to one or more chemical reactions in the polyester production facility to thereby produce the polyester; generating high-pressure steam having a pressure of at least 5 megapascals; heating one or more process fluid streams of the polyester production facility by indirect heat exchange with the high-pressure steam, wherein the process fluid streams include any stream that is formed predominately of the reaction medium and/or the at least one monomer; heating a heat transfer medium (HTM) via indirect heat exchange with the high-pressure steam to thereby form heated HTM; and heating at least a portion of the process fluid streams by indirect heat exchange with the heated HTM.
1. A process for making a polyester in a polyester production facility, the process comprising:
(a) forming a reaction medium comprising at least one of terephthalic acid (TPA) and an ester derivative of TPA, and at least one diol monomer;
(b) reacting at least a portion of the reaction medium in the polyester production facility to thereby produce the polyester;
(c) heating the reaction medium during the reacting in a first heat exchanger containing the reaction medium and a high-pressure steam;
(d) heating a heat transfer medium (HTM) in a second heat exchanger with the high-pressure steam to thereby form a heated HTM; and
(e) heating at least a portion of one or more process fluid streams comprising the reaction medium with a third heat exchanger containing the heated HTM and the reaction medium.
2. The process of claim 1 , wherein the heating of step (c) is carried out in one or more shell-and-tube heat exchangers.
3. The process of claim 1 , wherein the heating of step (d) is carried out in one or more shell-and-tube heat exchangers.
4. The process of claim 1 , wherein the total amount of energy provided by the heating of step (c) is at least 70 percent of the total amount of energy used to heat the reaction medium in the polyester production facility.
5. The process of claim 1 , wherein the high-pressure steam has a temperature of at least 290° C.
6. The process of claim 1 , wherein the reacting comprises esterification and polycondensation.
7. The process of claim 1 , wherein the reacting is carried out in a plurality of serially connected reactors that include a first reactor, a second reactor, and a third reactor.
8. The process of claim 7 , wherein each of the first, second, and third reactors has a respective first, second, and third reactor heat exchanger associated therewith.
9. The process of claim 8 , wherein each of the first, second, and third reactors has a respective first, second, and third vapor-liquid separation zone associated therewith.
10. The process of claim 9 , wherein the heat exchangers and vapor-liquid separation zones associated with each of the first, second, and third reactors are located in separate vessels.
11. The process of claim 10 , wherein the first vapor-liquid separation zone is located downstream of the first reactor heat exchanger, wherein the second vapor-liquid separation zone is located downstream of the second reactor heat exchanger, wherein the third vapor-liquid separation zone is located downstream of the third reactor heat exchanger.
12. The process of claim 8 , wherein the first, second, and third reactor heat exchangers are shell-and-tube heat exchangers with the high-pressure steam on the shell-side and the reaction medium on the tube-side.
13. The process of claim 7 , wherein esterification is carried out in the first reactor, and wherein the reaction medium has a conversion of at least 70 percent upon exiting the first reactor.
14. The process of claim 7 , wherein esterification is carried out in the second reactor, and wherein the reaction medium has a conversion of at least 93 percent upon exiting the second reactor.
15. The process of claim 7 , wherein the first reactor has a first reactor heat exchanger associated therewith, and wherein from 40 percent to 100 percent of the total energy input employed for heating the reaction medium of the polyester production facility is provided by the high-pressure steam in the first reactor heat exchanger.
16. The process of claim 7 , wherein the amount of the heating of the reaction medium provided by the high-pressure steam in the first reactor heat exchanger is from 500 joules per gram to 10,000 joules per gram of the polyester produced from the polyester production facility.
17. The process of claim 7 , wherein polycondensation is carried out downstream of the first, second, and/or third reactors.
18. The process of claim 7 , wherein the serially connected reactors include a fourth reactor and a fifth reactor, wherein polycondensation is carried out in the fourth and fifth reactors.
19. The process of claim 18 , wherein the polyester is recovered from the fifth reactor.
20. The process of claim 19 , wherein esterification is the predominate reaction in the first and second reactors and polycondensation is the predominate reaction in the fourth and fifth reactors.
21. The process of claim 1 , wherein the first heat exchanger is a shell-and-tube heat exchanger, wherein the reaction medium is on the tube side and the high-pressure steam is on the shell side during the heating and the reacting.
22. The process of claim 1 , wherein the (b) reacting and the (c) heating is carried out in a reactor.