×
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!

*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

Dispersion Calcs using SCREEN3

Dispersion Calcs using SCREEN3

Dispersion Calcs using SCREEN3

(OP)
I am attempting to determine the stack height for a vent required to maintain the concentration of contaminant (ammonia) below the LDHL during a release. The stack will be installed above the roof a building. The key is that maintenance will sometimes be required on a platform installed above roof level.

I am using EPA's Screen3 program, but am confused about the best approach. In one case I set up with a the roof = terrain level (~80') and a receptor (the maintenance man) = 98', then determined the required height of the stack. Is it appropriate to assign the terrain level = roof level, since the flare discharge is above the roof line?

I also ran the calculations assuming that the roof height = ground level of the flare (and no terrain change), and maintaining the same height difference between the receptor and roof. Frankly, I assumed I would see the results as in the first case - but the required stack height in the second case was much lower.

In a third trial, I assumed the roof did not exist (i.e. no terrain). The results were nearly identical to Case 2.

Anyone have experience using SCREEN3? If so, any input would be appreciated.

RE: Dispersion Calcs using SCREEN3

I've run these Gaussian dispersion calcs in my younger days, but with a Company program. From your description, it looks like the roof level is of no significance in this simulation - all you've got is the release point, the true ground level, and the x,y,z coordinates of the receptor (and of course the windspeed and wind stability class). I dont have an explanation for the differing results in Cases 1-3. You've got to have a simulation input which you believe most closely reflects the actual spatial details, from an Audit point of view also.

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! Already a Member? Login


Resources

eBook - Functional Prototyping Using Metal 3D Printing
Functional prototypes are a key step in product development – they give engineers a chance to test new ideas and designs while also revealing how the product will stand up to real-world use. And when it comes to functional prototypes, 3D printing is rewriting the rules of what’s possible. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close