Process and apparatus for compressing hydrogen gas in a centrifugal compressor

Patent metadata

Field	Value
Publication number	US-11926906-B2
Application number	US-202117201293-A
Country	US
Kind code	B2
Filing date	Mar 15, 2021
Priority date	Mar 15, 2021
Publication date	Mar 12, 2024
Grant date	Mar 12, 2024

Abstract

A process for producing compressed hydrogen gas, said process comprising electrolysing water to produce hydrogen gas and compressing said hydrogen gas in a multistage compression system to produce compressed hydrogen gas. The multistage compression system comprises at least one centrifugal compression stage, and the hydrogen gas is fed to the centrifugal compression stage at a pre-determined feed temperature and pressure and having a pre-determined relative humidity. The process further comprises adding water and heat to the hydrogen gas upstream of the centrifugal compression stage, as required, to humidify the hydrogen gas to the pre-determined relative humidity.

First claim

The invention claimed is:

1. A process for producing compressed hydrogen gas, said process comprising:
electrolysing water to produce hydrogen gas; and
compressing said hydrogen gas in a multistage compression system to produce said compressed hydrogen gas,

wherein the multistage compression system comprises at least one centrifugal compression stage, and the hydrogen gas is fed to the centrifugal compression stage at a pre-determined feed temperature and pressure and having a pre-determined relative humidity, and
wherein the process comprises adding water and heat to the hydrogen gas upstream of the centrifugal compression stage, as required, to humidify the hydrogen gas to the pre-determined relative humidity.

2. The process according to claim 1 , wherein the pre-determined relative humidity is from 70 up to 100%.

3. The process according to claim 1 , wherein the water is added in excess to humidify the hydrogen gas, and the pre-determined relative humidity is 100%.

4. The process according to claim 1 , wherein the hydrogen gas is humidified by:
determining a mole fraction of water in the hydrogen gas upstream of the centrifugal compression stage;
injecting water into the hydrogen gas at a flowrate and temperature,

wherein the flowrate and temperature of the water being injected is controlled as required based on the mole fraction of water.

5. The process according to claim 1 , wherein the pre-determined feed temperature is from 20 to 60° C.

6. The process according to claim 1 , wherein the hydrogen gas being fed to the centrifugal compression stage has an apparent molecular weight in a range from 2.2 to about 3.5.

7. The process according to claim 1 , wherein the centrifugal compression stage is a first or initial stage in the multistage compression system.

8. The process according to claim 1 , wherein the compressed hydrogen gas is consumed in at least one downstream process, and wherein during periods when more hydrogen gas is produced by the electrolysis than is required by the downstream process(es), the process comprises feeding excess compressed hydrogen gas to storage, optionally after further compression; and
wherein during periods when more hydrogen gas is required by the downstream process(es) than is produced by the electrolysis, the process comprises withdrawing the compressed hydrogen gas from the storage and, after suitable pressure reduction, feeding a reduced pressure hydrogen gas to a stage of the multistage compression system.

9. The process according to claim 1 , wherein the centrifugal compression stage comprises an outlet end and a feed end, and the hydrogen gas being fed to the feed end contains recycled hydrogen gas taken from the outlet end after suitable pressure reduction.

10. The process according to claim 1 , wherein the hydrogen gas is fed to the centrifugal compression stage at the pre-determined feed temperature by controlling temperature and/or flow rate of the water being added.

11. The process according to claim 1 , wherein the multistage compression system comprises a first section and at least one further section downstream of the first section.

12. The process according to claim 1 , wherein all stages of the multistage compression system are centrifugal compression stages.

13. The process according to claim 1 , wherein the water and the heat are added as steam to form a combined steam/hydrogen stream.

14. The process according to claim 13 , wherein the steam is de-superheated steam.

15. The process according to claim 14 , wherein liquid water is added to superheated steam to provide the de-superheated steam.

16. The process according to claim 13 , wherein the combined steam/hydrogen stream passes through a phase separator to remove liquid water from the hydrogen gas which is then fed to the centrifugal compression stage.

17. The process according to claim 1 , wherein the water and the heat are added as liquid water to produce a two-phase combined stream.

18. The process according to claim 17 , wherein the two-phase combined stream passes through a static mixer prior to being fed to a phase separator to remove excess liquid water from the hydrogen gas which is then fed to the centrifugal compression stage.

19. The process according to claim 18 , comprising:
pumping the liquid water from the phase separator to produce pumped liquid water;
cooling compressed hydrogen gas by indirect heat exchange against the pumped liquid water in a cooler to produce cooled compressed hydrogen gas and warmed liquid water;
reducing the pressure of the warmed liquid water to produce reduced pressure recycle water; and
using said reduced pressure recycle water as at least part of the liquid water being added to the hydrogen gas to form the two-phase combined stream.

20. The process according to claim 19 comprising adding make-up water to the reduced pressure recycle water as required.

21. The process according to claim 1 , wherein the water is in the form of liquid water, said process comprising:
humidifying the hydrogen gas with the liquid water in a saturation column having a top, a bottom and at least one heat and/or mass transfer zone located therebetween;
removing humidified hydrogen gas from the top of the saturation column and feeding the humidified hydrogen gas to the centrifugal compression stage; and
removing excess liquid water from the bottom of the saturation column.

22. The process according to claim 21 , comprising:
pumping the liquid water from the saturation column to produce pumped liquid water;
cooling compressed hydrogen gas by indirect heat exchange against the pumped liquid water in a cooler to produce cooled compressed hydrogen gas and warmed liquid water;
reducing the pressure of the warmed liquid water to produce reduced pressure recycle water; and
using said reduced pressure recycle water as at least part of the liquid water being used to humidify the hydrogen gas in the saturation column.

23. The process according to claim 22 comprising adding make-up water to the hydrogen gas or reduced pressure recycle water, as required.

24. The process according to claim 1 , wherein the water is in the form of liquid water, said process comprising:
humidifying the hydrogen gas with the liquid water in a first direct contact cooler having a top, a bottom and at least one heat and/or mass transfer zone located therebetween;
removing humidified hydrogen gas from the top of the first direct contact cooler and feeding the humidified hydrogen gas to the centrifugal compression stage for compression to produce compressed hydrogen gas; and
removing excess liquid water from the bottom of the first direct contact cooler;
recycling as required a portion of the compressed hydrogen gas produced in the centrifugal compression stage to the first direct contact cooler after suitable pressure reduction and without any cooling.

25. The process according to claim 24 , wherein the centrifugal compression stage is an initial stage or an intermediate stage of the multistage compression system, said process comprising:
humidifying compressed hydrogen gas from the centrifugal compression stage with liquid water in a second direct contact cooler having a top, a bottom and at least one heat and/or mass transfer zone located therebetween;
removing humidified hydrogen gas from the top of the second direct contact cooler and feeding the humidified hydrogen gas to

Assignees

• Air Prod & Chem

Inventors

• Wehrman Joseph Gerard
• Higginbotham Paul
• White Vincent

Classifications

• C25B1/04 Primary

  by electrolysis of water · CPC title

• C25B1/50

  Processes · CPC title

• C25B9/70 Primary

  Assemblies comprising two or more cells · CPC title

• C25B15/02

  Process control or regulation · CPC title

• C25B15/083

  Separating products · CPC title