Using pressurized wet gas lines to avoid fouling in purified terephthalic acid (PTA) filters and lines

Patent metadata

Field	Value
Publication number	US-10577301-B2
Application number	US-201715823988-A
Country	US
Kind code	B2
Filing date	Nov 28, 2017
Priority date	Apr 28, 2017
Publication date	Mar 3, 2020
Grant date	Mar 3, 2020

Abstract

Processes for recovering a purified aromatic carboxylic acid include contacting a 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 to form a solid/liquid mixture comprising purified aromatic carboxylic acid solids; filtering the solid/liquid mixture in a rotary pressure filter apparatus to remove a liquid filtrate, washing the solid/liquid mixture in the rotary pressure apparatus with a wash fluid to form a washed solid/liquid mixture, and drying the washed solid/liquid mixture in the rotary pressure apparatus with an inert gas to form a filter cake comprising purified aromatic carboxylic acid solids and a wet gas stream; withdrawing the wet gas stream from the rotary pressure filter apparatus while maintaining the wet gas stream at a pressure above ambient; and recovering the purified aromatic carboxylic acid solids from the filter cake.

First claim

The invention claimed is:

1. A process for recovering a purified aromatic carboxylic acid comprising:
contacting a 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 to form a solid/liquid mixture comprising purified aromatic carboxylic acid solids;
filtering the solid/liquid mixture in a filtering zone of a rotary pressure filter apparatus to form a filtered solid-liquid mixture and a liquid filtrate stream;
withdrawing the liquid filtrate stream from the filtering zone of the rotary pressure filter apparatus;
washing the filtered solid/liquid mixture in a washing zone of the rotary pressure filter apparatus with a wash fluid to form a washed solid/liquid mixture;
drying the washed solid/liquid mixture in a drying zone of the rotary pressure filter apparatus with an inert gas to form a filter cake comprising purified aromatic carboxylic acid solids and a wet gas stream;
withdrawing the wet gas stream from the drying zone of the rotary pressure filter apparatus while maintaining the wet gas stream at a pressure above ambient; and
recovering the purified aromatic carboxylic acid solids from the filter cake.

2. The process of claim 1 , further comprising flashing the wet gas stream to form a gas stream and a solid/liquid stream.

3. The process of claim 2 , further comprising recycling the solid/liquid stream to the hydrogenation reactor.

4. The process of claim 1 , wherein the wet gas stream is at a pressure above 1.5 bar.

5. The process of claim 1 , wherein the wet gas stream is at a pressure of between 2 bar and 3 bar.

6. The process of claim 1 , wherein the wet gas stream is at a pressure between 1.5 bar and 4 bar.

7. The process of claim 1 , wherein the pressure in the wet gas line is controlled with a pressure control mechanism located at an entry of a separation zone.

8. The process of claim 2 , wherein the flashing step is performed in a separation zone at atmospheric pressure.

9. The process of claim 1 , wherein the wash fluid removes impurities from the filter cake.

10. The process of claim 1 , further comprising oxidizing a substituted aromatic compound in a reaction zone to form the crude aromatic carboxylic acid.

11. The process of claim 1 , further comprising drying the filter cake in a dryer to form a purified aromatic carboxylic acid product.

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

13. The process of claim 1 , further comprising, after washing the filtered solid/liquid mixture, withdrawing at least a portion of the wash fluid from the washing zone of the rotary pressure filter apparatus.

14. The process of claim 1 , further comprising separating the wet gas stream to form a gas stream and a solid/liquid stream.

Assignees

• Bp Corp North America Inc

Inventors

• Keyes Timothy H
• Bartos Thomas

Classifications

• C07C51/47 Primary

  by solid-liquid treatment; by chemisorption · CPC title

• C07C51/42

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

• B01D33/62

  for drying · CPC title

• B01D33/06

  with rotary cylindrical filtering surfaces, e.g. hollow drums (B01D33/044 takes precedence {; rotating drums for paper-making D21B}) · CPC title

• B01D2009/0086

  Processes or apparatus therefor · CPC title