Method for increasing the capacity of an ammonia plant

Patent metadata

Field	Value
Publication number	US-10696561-B2
Application number	US-201615576068-A
Country	US
Kind code	B2
Filing date	May 4, 2016
Priority date	May 21, 2015
Publication date	Jun 30, 2020
Grant date	Jun 30, 2020

Abstract

A method for treatment of process condensate ( 1 ) in an ammonia plant, wherein the ammonia plant comprises a front-end section producing a make-up gas and a synthesis section where the make-up gas is reacted to ammonia, and said process condensate ( 1 ) is collected from one or more equipment of the ammonia plant and is an aqueous solution comprising ammonia, carbon dioxide and methanol. Said method comprises: stripping said process condensate with low-pressure steam ( 4 ), obtaining a vapour phase ( 5 ) comprising ammonia, carbon dioxide and methanol stripped from the process condensate; condensing said vapour phase, obtaining a solution ( 11 ) enriched of ammonia and methanol; re-introducing a first portion ( 12 ) of said solution to said stripping environment; recycling a second portion ( 13 ) of said solution to said ammonia plant.

First claim

The invention claimed is:

1. A method for treatment of process condensate in an ammonia plant, wherein:
the ammonia plant comprises a front-end section producing a make-up gas from reforming of a hydrocarbon source, and a synthesis section where the make-up gas is reacted to ammonia;
said process condensate is collected from one or more equipment of the ammonia plant and is an aqueous solution comprising ammonia, carbon dioxide and methanol,
the method comprising:
stripping of said process condensate in a stripping environment with low-pressure steam having a pressure of no more than 10 bar, obtaining a vapour phase comprising ammonia, carbon dioxide and methanol stripped from the process condensate;
condensing said vapour phase, obtaining a condensate solution enriched of ammonia and methanol;
re-introducing a first portion of said condensate solution to said stripping environment wherein said first portion of solution is reintroduced directly into said stripping environment;
recycling a second portion of said condensate solution to said ammonia plant, wherein said second portion is no more than 4% by volume of said condensate solution.

2. The method according to claim 1 , wherein the pressure of said stripping steam is 5 bar or less.

3. The method according to claim 1 , wherein said second portion of solution is recycled to the front-end section of the ammonia plant.

4. The method according to claim 3 , wherein said second portion of solution is recycled to a primary reformer of the front-end section of the ammonia plant, where said solution is added to the process stream subjected to reforming.

5. The method according to claim 1 , wherein said condensate solution contains 5 to 10 mol % of carbon dioxide, 3 to 8 mol % of methanol and 7 to 13 mol % of ammonia.

6. The method according to claim 1 , wherein said second portion is no more than 3% by volume of said condensate solution.

7. The method according to claim 1 , wherein said second portion is 2% by volume of said condensate solution.

8. The method according to claim 2 , wherein the pressure of said stripping steam is 3 to 5 bar.

9. The method according to claim 1 , wherein said second portion is no more than 2% by volume of said condensate solution.

Assignees

• Casale Sa

Inventors

• Panza Sergio
• Pasco Luca

Classifications

• B01D3/38 Primary

  Steam distillation · CPC title

• C01B2203/0205

  containing a reforming step · CPC title

• C01C1/047 Primary

  by condensation · CPC title

• C01B3/025

  Preparation or purification of gas mixtures for ammonia synthesis · CPC title

• Y02P20/52

  using catalysts, e.g. selective catalysts · CPC title