Process for the synthesis of ammonia

Patent metadata

Field	Value
Publication number	US-11261099-B2
Application number	US-201716469740-A
Country	US
Kind code	B2
Filing date	Sep 26, 2017
Priority date	Dec 14, 2016
Publication date	Mar 1, 2022
Grant date	Mar 1, 2022

Abstract

A dual pressure process for the synthesis of ammonia from a make-up gas, wherein the make-up gas is reacted in two steps in series, the second step operating at a greater pressure than the first step, and wherein a portion of the effluent of the first step is recycled back to the first step, said portion containing unreacted make-up gas.

First claim

What is claimed is:

1. A process for the synthesis of ammonia from a make-up gas, the process comprising a first reactive step at a first pressure and a second reactive step at a second pressure greater than the first pressure, wherein:
the first reactive step provides a product stream containing ammonia and a gaseous effluent containing unreacted make-up gas;
a first portion of said gaseous effluent is subjected to said second reactive step, and
a second portion of said gaseous effluent is recycled to said first reactive step,
the process further comprising a step of compression of the gaseous effluent of the first reactive step from said first pressure to said second pressure, wherein the second portion of said gaseous effluent is taken before said step of compression and is recycled to said first reactive step through an ejector.

2. The process according to claim 1 , wherein said make-up gas works as motive fluid inside said ejector.

3. The process according to claim 2 , wherein said make-up gas mixes with said second portion inside the ejector forming the input stream to said first reactive step.

4. The process according to claim 1 , said second reactive step providing a purge gas stream containing hydrogen and at least part of said hydrogen is separated from said purge gas stream as a hydrogen-containing stream.

5. The process according to claim 4 , wherein said hydrogen-containing stream mixes with said make-up gas.

6. A method for revamping a plant for the synthesis of ammonia from a make-up gas, the plant comprising:
a first synthesis loop operating at a first pressure, wherein said make-up gas reacts at the first pressure providing a first product stream and a gaseous effluent containing unreacted make-up gas;
a second synthesis loop operating at a second pressure greater than the first pressure, wherein a first portion of said gaseous effluent reacts at the second pressure providing a second product stream;
a compressor, wherein said gaseous effluent of the first synthesis loop is compressed from the first pressure to the second pressure,
wherein:
installation of a line for recycling a second portion of said gaseous effluent to the first synthesis loop, said line being installed at a suction-side of the compressor, and comprising the installation of an ejector at the inlet of the first synthesis loop, so that said second portion of said gaseous effluent is taken before said step of compression and is recycled to the first synthesis through said ejector.

7. The method according to claim 6 , said ejector being installed on the feeding line of the make-up gas to the first synthesis loop, so that the make-up gas is motive fluid in said ejector.

Assignees

• Casale Sa

Inventors

• Panza Sergio

Classifications

• C01C1/0476

  Purge gas treatment, e.g. for removal of inert gases or recovery of H2 · CPC title

• C01C1/0447 Primary

  Apparatus other than synthesis reactors · CPC title

• C01C1/047

  by condensation · CPC title

• C01C1/0488

  Processes integrated with preparations of other compounds, e.g. methanol, urea or with processes for power generation · CPC title