3 replies to this topic

[cravindran]

Hii


We are planning a new chlor alkali project. To maintain the pressure in the hydrogen header , some quantity of low pressure hydrogen (3000 mmwc) is vented from the system through a tall stack when there is no consumption of hydrogen due to stoppage of Hcl reactor or during start up. The stack has been provided with provisions for injection of low pressure steam /nitrogen. The environmental ministry objects to release of hydrogen saying it is a fire hazard and venting of hydrogen is not allowed


Can you please suggest s suitable reply to the ministry

Thanks

C.Ravindran

[Art Montemayor]

A suitable reply to your ministry could state that you regret the process oversight of not eliminating any unsuitable atmospheric venting and that you will correct this by installing an appropriate hydrogen flare system such that all the excess hydrogen generated will be efficiently flared (burned with atmospheric air) to produce essentially pure water vapor.

[cravindran]

Hii

Thanks for the reply

Chlor alkali plants normally dont use hydrogen flare system and we do want to avoid this. Is there any other way to reduce the risks associated with venting and convince the authorities about the very low risk potential of low pressure hydrogen venting

Regards

C.Ravindran

[Whit123]

Hii

Thanks for the reply

Chlor alkali plants normally dont use hydrogen flare system and we do want to avoid this. Is there any other way to reduce the risks associated with venting and convince the authorities about the very low risk potential of low pressure hydrogen venting

Regards

C.Ravindran

The risk is not "low". Why? Because Hydrogen has something called the reverse Joule Thomson effect. It means that if you have a a high velocity venting, it will absorb heat from surroundings (absorb energy) which may lead to a fire. The second risk is that a Hydrogen fire is "colorless" , therefore invisible.