×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Nitrogen Purge for Thermal Oxidizer Vent Collection Header

Nitrogen Purge for Thermal Oxidizer Vent Collection Header

Nitrogen Purge for Thermal Oxidizer Vent Collection Header

(OP)
Hello, I am working on a project to add a nitrogen purge to a vent collection header that feeds a direct-fired thermal oxidizer. This is for a batch plant so there will be times when there are no process vapors being released to the header, only the purge. I cannot find a guide that tells me what flow rate / velocity of purge gas I should design for. According to the plant the TOX was assembled from available parts so there isn't a vendor to ask. I'd appreciate any help.

RE: Nitrogen Purge for Thermal Oxidizer Vent Collection Header

What is the purpose of the nitrogen sweep? What value is it adding? Why will it be added when the system is down? With some more info about the objective of the project we could provide some insight.

RE: Nitrogen Purge for Thermal Oxidizer Vent Collection Header

(OP)
Thanks for your reply. The purpose of adding nitrogen is to reduce the oxygen concentration to below the LOC, which in this case is about 12 vol% O2. The nitrogen won't be added when the system is down but in between batches when the TOX must remain in operation. My understanding is there must be a minimum flow to the TOX at all times to assure no flammable gases are accumulating in the header.

RE: Nitrogen Purge for Thermal Oxidizer Vent Collection Header

There are values for flame propagation velocity for various fuels in Perry 7th edn pg 27-26, table 27-18. You could interpret these to be the min purge gas velocity at the burner feed nozzle.

RE: Nitrogen Purge for Thermal Oxidizer Vent Collection Header

(OP)
That is some helpful information. Thanks very much.

RE: Nitrogen Purge for Thermal Oxidizer Vent Collection Header

I recommend using the Husa method with a safety factor of 6. Just google "Husa gas purge" and you'll get all the information you need. There have been numerous discussions on eng-tips regarding this. Also you may refer to API Standard 521 Section 7.3.3.3.3.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources