8 replies to this topic

[dylant]

Has anybody ever used Liquid H2 to cool down a reactor packed with catalyst? If you have, would you mind sharing? All comments are welcome. Thanks.

[djack77494]

I have never heard of anyone using liquid H2 for cooling except in regard to superconductors. The ultra extreme low temperatures where H2 vaporization occurs makes such an application unlikely in anything not involving space or high energy physics.

[dylant]

You are absolutely right.

What if we vaporize the liquid H2 before it is injected to the vessel? I would think this will serve pretty much the same purpose as vaporized liquid N2.

I have never heard of anyone using liquid H2 for cooling except in regard to superconductors. The ultra extreme low temperatures where H2 vaporization occurs makes such an application unlikely in anything not involving space or high energy physics.

[djack77494]

What if we vaporize the liquid H2 before it is injected to the vessel?

A variation of this is actually commonly done for hydrogenation reactors. Cool H2 is admitted at various points within the main hydrogenation reactor under temperature control. Though the H2 is a reactant, it is also much cooler than the contents of the reactor at the points where it is injected. Thus it serves to cool the contents.

[dylant]

Jack, thanks for the response.

Could you provide me with examples? Lots of people think this is a costly process and pretty dangerous and I have not found anybody who actually knows someone who really use hydrogen for cooling down reactors.

What if we vaporize the liquid H2 before it is injected to the vessel?

A variation of this is actually commonly done for hydrogenation reactors. Cool H2 is admitted at various points within the main hydrogenation reactor under temperature control. Though the H2 is a reactant, it is also much cooler than the contents of the reactor at the points where it is injected. Thus it serves to cool the contents.

[djack77494]

Could you provide me with examples?

Hydrogenation processes, used for example to desulfurize petroleum fractions such as diesel, kerosine, etc., have gaseous hydrogen added to the liquid hydrocarbon stream upstream of the hydrogenation reactor. That reactor typically consists of multiple beds. As the hydrocarbon plus H2 travel through the catalyst beds, the exothermic heat of reaction causes the temperature to rise. To limit the temperature, cool H2 is added between the beds of catalyst under temperature control. Often, multiple injection points are used.

[Qalander (Chem)]

Could you provide me with examples?

Hydrogenation processes, used for example to desulfurize petroleum fractions such as diesel, kerosine, etc., have gaseous hydrogen added to the liquid hydrocarbon stream upstream of the hydrogenation reactor. That reactor typically consists of multiple beds. As the hydrocarbon plus H2 travel through the catalyst beds, the exothermic heat of reaction causes the temperature to rise. To limit the temperature, cool H2 is added between the beds of catalyst under temperature control. Often, multiple injection points are used.

Dear Doug Hello/Good Morning, A really admirable and clear-cut explaination indeed!
Best regards
Qalander

[dylant]

Djack:

Thanks for the response. I heard about it but I have never seen the application in the real life. Is this practice not popular? Apart from the liquid H2 cost and flammability, what other considerations need to be put in mind?

Thanks.

Could you provide me with examples?

Hydrogenation processes, used for example to desulfurize petroleum fractions such as diesel, kerosine, etc., have gaseous hydrogen added to the liquid hydrocarbon stream upstream of the hydrogenation reactor. That reactor typically consists of multiple beds. As the hydrocarbon plus H2 travel through the catalyst beds, the exothermic heat of reaction causes the temperature to rise. To limit the temperature, cool H2 is added between the beds of catalyst under temperature control. Often, multiple injection points are used.

[djack77494]

Apart from the liquid H2 cost and flammability, what other considerations need to be put in mind?

dylant,
I'm afraid you have misunderstood me. Outside of rockets and superconductors, I have never heard of LIQUID hydrogen being used - for cooling or for anything else. Hydrogen doesn't condense into a liquid until it is chilled down to about 37F above absolute zero or about -423F. This is an incredibly cold temperature - much colder than say liquified air or LNG. It is very difficult and expensive to generate these low temperatures, so only the most exotic of applications could justify doing so. The applications I refer to all involve relatively cool GASEOUS hydrogen being used as a coolant. Compressed hydrogen gas is readily obtainable and can be stored or transported in compressed form.
Doug