×
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

Maximum Velocity of Two Phase Fluid in Air-Cooled Heat Exchanger

Maximum Velocity of Two Phase Fluid in Air-Cooled Heat Exchanger

Maximum Velocity of Two Phase Fluid in Air-Cooled Heat Exchanger

(OP)
I am presently preparing an evaluation of some bids for air-cooled heat exchangers used downstream of a natural gas compressor that is pulling gas from a salt dome.  The gas will be water saturated at the equillibrium temperature; therefore, there is a potential for two-phase flow inside the tubes as the gas cools.  The problem here is extremely high flow rates and I am concerned that we need to limit the velocity inside the tubes (3/4-inch x 0.060-inch wall SA-214 or SA-179 carbon steel tubes).

Has anyone seen recommendations on the maximum allowable velocity of two-phase natural gas inside the tubes of an air-cooled heat exchanger?

I am concerned that we will have erosional velocities near the tube outlet.  I have witnessed tubewall thinning at the tube outlet end before.  I recall seeing something in HTRI literature several years ago, but I do not recall the limiting velocity as a function of diameter.

RE: Maximum Velocity of Two Phase Fluid in Air-Cooled Heat Exchanger

Bill1959,

Most customers do not normally specify a maximum tube velocity in gas coolers.  Usually the velocity is controlled by the maximum allowable pressure drop, which is typically in the 5 psi range, but sometimes lower.

In gas compressor aftercooler applications, there are usually several cases to be considered, ranging from high pressure and low flow to lower pressure and high flow.  If all these are taken into account, and the pressure drop is limited for the very high flow cases, erosion would not be likely.

It also helps to look at the Rho-V-Square at the inlet and outlet ends, including nozzles.  Typically they should be under about 3500 to 4500 (depending on how conservative you want to be.  Rho is density (or mixed density) in #/ft^3, and V is velocity in feet/sec.

Also, most process air-coolers have tubes 1.0" OD or larger.  Where API-661 specs are required, the minimum tube wall is .083" for carbon steel tubes.  These are pretty good guidelines.

Regards,

speco (www.stoneprocess.com)

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