High-pressure condensate recycle in the manufacture of purified aromatic carboxylic acids
Processes for manufacturing purified aromatic carboxylic acids include: generating high-pressure steam from boiler feed water supplied to a boiler; heating a crude aromatic carboxylic acid using the high-pressure steam, whereby the high pressure steam is condensed to form a high-pressure condensate; and purifying the crude aromatic carboxylic acid to form a purified aromatic carboxylic acid. The boiler feed water includes at least a portion of the high-pressure condensate and makeup boiler feed water from at least one additional source.
1. A process for manufacturing a purified aromatic carboxylic acid comprising:
generating high-pressure steam from boiler feed water supplied to a boiler;
heating a crude aromatic carboxylic acid in a heating zone using the high-pressure steam, whereby the high pressure steam is condensed in the heating zone to form a high-pressure condensate; and
purifying the crude aromatic carboxylic acid to form a purified aromatic carboxylic acid;
wherein the boiler feed water comprises at least a portion of the high-pressure condensate.
2. The invention of claim 1 further comprising oxidizing a substituted aromatic hydrocarbon in a reaction zone to form the crude aromatic carboxylic acid.
3. The invention of claim 1 wherein the boiler feed water further comprises makeup water from at least one additional source.
4. The invention of claim 3 , wherein the high-pressure condensate and the makeup boiler feed water are combined prior to delivery of the boiler feed water to the boiler.
5. The invention of claim 3 wherein the makeup boiler feed water is at a lower temperature than the high-pressure condensate prior to their combination.
6. The invention of claim 5 wherein the high-pressure condensate has a temperature of between about 250° C. and about 305° C. and a delivery pressure to the boiler of between about 80 bar(g) and about 120 bar(g), and wherein the makeup boiler feed water has a temperature of between about 100° C. and about 150° C. and a delivery pressure to the boiler of between about 80 bar(g) and about 120 bar(g).
7. The invention of claim 1 further comprising preheating air feed to the boiler with flue gas.
8. The invention of claim 1 preheating makeup boiler feed water with boiler flue gas.
9. The invention of claim 1 wherein the feed water to the boiler of the high-pressure condensate comprises between about 65% and about 97% of the high-pressure condensate formed in the heating zone.
10. The invention of claim 7 wherein at least one of gas/gas air preheaters comprises a polymeric luftvorwärmer (LUVO) gas/gas air preheater.
11. The invention of claim 1 further comprising transferring flue gas from a boiler stack in fluid communication with the boiler through, successively, a downstream carbon-steel gas/gas air preheater and a further downstream polymeric LUVO gas/gas air preheater.
12. The invention of claim 1 wherein the aromatic carboxylic acid comprises terephthalic acid.