Purified terephthalic acid (PTA) vent steam utilization

Patent metadata

Field	Value
Publication number	US-10414712-B2
Application number	US-201715823951-A
Country	US
Kind code	B2
Filing date	Nov 28, 2017
Priority date	Dec 29, 2016
Publication date	Sep 17, 2019
Grant date	Sep 17, 2019

Abstract

Processes for manufacturing a purified aromatic carboxylic acid include oxidizing a substituted aromatic compound in a reaction zone to form a crude aromatic carboxylic acid and a gaseous stream; heating the crude aromatic carboxylic acid in a pre-heating zone, contacting the crude aromatic carboxylic acid with hydrogen in the presence of a catalyst in a hydrogenation reactor to form a purified aromatic carboxylic acid, crystallizing the purified aromatic carboxylic acid in a crystallization zone to form a slurry stream comprising solid purified aromatic carboxylic acid and a vapor stream. At least a portion of the vapor stream is directed to the pre-heating zone and at least a portion of the vapor stream from the pre-heating zone is vented to the off-gas treatment zone in order to achieve energy savings.

First claim

The invention claimed is:

1. A process for manufacturing a purified aromatic carboxylic acid comprising:
oxidizing a substituted aromatic compound in a reaction zone to form a crude aromatic carboxylic acid and a gaseous stream;
heating the crude aromatic carboxylic acid in a pre-heating zone;
contacting the crude aromatic carboxylic acid with hydrogen in the presence of a catalyst in a hydrogenation reactor to form a purified aromatic carboxylic acid;
crystallizing the purified aromatic carboxylic acid in a crystallization zone to form a slurry stream comprising solid purified aromatic carboxylic acid and a vapor stream, wherein the vapor stream comprises steam and hydrogen;
recovering a purified carboxylic acid product from the slurry;
directing at least a portion of the vapor stream to the pre-heating zone in order to heat the crude aromatic carboxylic acid;
venting at least a portion of the vapor stream from the pre-heating zone to an off-gas treatment zone, the off-gas treatment zone configured to treat at least a portion of the gaseous stream formed by the oxidization of the substituted aromatic compound; and
recovering energy from the vapor stream in the off-gas treatment zone.

2. The process of claim 1 , wherein the off-gas treatment zone comprises at least one heat exchanger, a catalytic oxidation unit, and an expander.

3. The process of claim 2 , wherein the at least a portion of the vapor stream is vented upstream of the at least one heat exchanger.

4. The process of claim 2 , further comprising:
distilling the gaseous stream in a distillation column to form a distilled gaseous stream.

5. The process of claim 4 , wherein the at least a portion of the vapor stream is vented to a stream leading to the catalytic oxidation unit in order to heat the distilled gaseous stream.

6. The process of claim 4 , further comprising:
directing the distilled gaseous stream to the catalytic oxidation unit, wherein the distilled gaseous stream comprises methyl bromide;
burning hydrogen in the vapor stream in the catalytic oxidation unit;
oxidizing methyl bromide in the catalytic oxidation unit to form bromine;
forming a first catalytic oxidation effluent and a second catalytic oxidation effluent; and
directing the first catalytic oxidation effluent to the expander, wherein the expander recovers energy from the first catalytic oxidation effluent.

7. The process of claim 6 , further comprising:
directing the second catalytic oxidation effluent to a scrubber; and
removing bromine from the second catalytic oxidation effluent with the scrubber.

8. The process of claim 6 , wherein the temperature of the first catalytic oxidation effluent entering the expander is greater than 150 degrees Celsius.

9. The process of claim 1 , wherein the pre-heating zone comprises a heat exchanger and wherein the vapor stream enters a shell side of the heat exchanger.

10. The process of claim 1 , wherein the purified aromatic carboxylic acid comprises terephthalic acid.

Assignees

• Bp Corp North America Inc

Inventors

• Bartos Thomas
• Buckalew Kathryn

Classifications

• C07C51/265

  having alkyl side chains which are oxidised to carboxyl groups · CPC title

• C07C51/42

  Separation; Purification; Stabilisation; Use of additives · CPC title

• B01J2219/00006

  Large-scale industrial plants · CPC title

• C07C51/487

  by treatment giving rise to chemical modification (by chemisorption C07C51/47) · CPC title

• C07C51/43 Primary

  by change of the physical state, e.g. crystallisation · CPC title