6 replies to this topic

[Sandeep01]

Amandeep

A molecular seal is used in the flare tip, and a water seal in the flare KOD. Could you clarify what do you mean by "water seal of a molecualr seal"

Regards
Sandeep

[gvdlans]

Check the following site: http://www.geocities.com/flareman_xs/
Especially for menu items: "Systems and Components" and "Purging and Low Flow"

[djack77494]

Caution.

The folks at geocities have, unfortunately, turned to the dark side and their site is loaded with unpleasant malware that they will visit upon you if you visit them.

[ichemco]

I will be thankful if anybody discuss about the basic principles and requirement of the molecular seal(and water seal of molecular seal) in flare system. What happens without a molecular seal in flare stack particularly when a base water seal is there to take care of flame back case?

Dear Amandeep,

Molecular seal and water seal drums are the accessories of a flare system that protects the stack from flame front or flash back. Moleculare seals work based on the diference between the density of the air and hydrocarbon mixture. Actually, the hydrocarbon acts like a seal and prevents the air to ingress into the flare stack and makes a flammable air/HC mixture that potentially has high tendency to explode. On the other hand a water seal drum uses the same way except that the sealing fluid is water and the drum is instaled at the flare stack base after the knock-out drum vessel, whereas moleculare seal is instaled at the top of flare stack before the tip. A molecular seal also could be very efficient in reducing the amount of purge gas required to maintain a positive pressure in the flare network piping system and the stack. The level of decreasing the purge gas flow rate is directly dependant to the moleculare seal manufacturer. Using a suitable moleculare seal can reduce the required flow velosity from 50 ft/sec down to .01 ft/sec and this would lead to a considerable savings in purge gas quantity. It should be noted that in order to have a reliable sealing device, selecting water seal drum would be the best choice, because moleculare seals require a contineous purge gas flow to prevent flame flash back into the flare system and if the purge gas flow cuts off then the device would have no reliability to protect the system. For this reason generally the engineers employ a secondary gas e.g. nitrogen as a back up for purge gas. Utilising water seal drum as a flame front protection device doesn't need to fed purge gas into the flare network piping system, but it shall be fed into the lare stack to protect it from flash back.

[gvdlans]

Good post, but...

did you notice that this thread is over three years old, and the topic starter has not been active on this forum since November 2006...?

[joerd]

And to beat a dead horse once more: since Geocities was closed (finally) by Yahoo!, Flareman's site has been moved to http://flareman.com/