8 replies to this topic

[tummalap.chowdary]

Dear members,

In API industry, in Hydrogenation reaction, excess amount of hydrogen gas is vented to atmosphere by mixing with Steam.

What is reason behind mixing of steam with Hydrogen.

To vary LEL or any other Reason is there

Is H2 gas absorbed in Steam?

Thanks and regards
T.P.Chowdary

Edited by tummalap.chowdary, 02 July 2012 - 01:44 AM.

[Technical Bard]

I don't know why anyone would "vent hydogen", as it is very valuable. Most plants attempt to recover hydrogen for reuse.

I have seen designs where emergency hydrogen vents were designed with steam or nitrogen injection to help prevent ignition due to static electricity at the vent tip. However, most developed world jurisdictions now require even hydrogen vents to be routed to flare.

[Art Montemayor]

T.P.Chowdary:

TechBard has correctly hit on the high points of this topic.

Hydrogen is too scarce, expensive, valuable, and very hazardous to simply vent to the atmosphere. There is technically no excess of hydrogen in industry. It can all be used.

Kindly tell us where, specifically, it is presently being done in the “API industry”. I hope it isn’t in the USA (or Texas); we waste far too much energy and chemicals to do that. If so, I certainly want to know.

Hydrogen is mixed with steam to eliminate any ignition of the gas due to friction or static electricity. this is a common procedure when discharging hydrogen from a PSV – which in not a “venting” procedure.

Hydrogen is not absorbed in the steam.

[tummalap.chowdary]

Thanks for reply,

Here H2 gas is comes in cylinders at 140 kg/cm2 pressure, this gas cylinders are connected to reactors

Reactors are operated up to 100 C temperature and 40 bar pressure

while reaction under progress Hydrogen consumed, after completion of reaction excess amount of hydrogen
is vented by mixing with steam

In Industry nitrogen is available but why steam is using instead of nitrogen,

venting Quantity is small amount compared to Petrochemical industry,

This process is Adopted by API industries of INDIA

[Mahesh@A&M]

As Mr. Art pointed out Hydrogen is expensive and rare. Here in Texas we pay $12 to $15 per MCF. Excess hydrogen after reaction is vented to a recovery tank to use in subsequent batch reactions.

Couple of reasons I can think of are;

1. Economics or do you buy Nitrogen and make steam in your plant
2. Steam pressure is higher than Nitrogen pressure at your site.

Regards,
Mahesh @A&M

[tummalap.chowdary]

They Venting H2 gas due to impurities in GAS which are Released in reaction or may be another reason

We buy nitrogen and producing steam in plant having pressure 3.5 Kg/cm2 (Absolute)

Normally nitrogen and steam are at same pressure

but Steam is adding in H2 Vent

[Tom the Hydrogen Guy]

Hydrogen, if it was of high purity, would not require mixing with steam or nitrogen, per NFPA, CGA, and ASME.
A simple flash arrestor can be used to eliminate concern for flashback down the pipe incase of unpure hydrogen is being vented.

Are you buying your cylinders of hydrogen from API too?

Are Interested in your using an advanced safer more reliable supply of hydrogen from a Hydrogen Gas Generating Appliance?

Please contact me for more information. I can help you in India. I will be there later this month.

[karguvelayyanar]

T.P. chowdary

           My thinking is nitrogen has purity may be 99.99%. But remains is oxygen. That oxygen also help to form a fuel mixer and then ignition will happens. But steam is full of inert at that pressure and temperature as well as cheaper compared with nitrogen.  

[thorium90]

karguvelayyanar

 

oxygen at 0.01% is not going to ignite in the reactor.
 

Its likely OP does not have a very optimized plant thats all. Further more OP has never replied since july last yr despite logging in 2 months ago. Probably no longer interested in the topic.

Edited by thorium90, 19 February 2013 - 02:57 PM.