Tubeside Gas Velocity Range on Heat Exchanger

[Ricardo11]

Hello everyone,

I'm currently in the process of designing a heat exchanger using Aspen, where the shellside carries liquid and the tubeside carries gas. For the liquid phase, we have RhoV² limits according to TEMA, but I’m unsure if there are similar guidelines for gas velocities.
From the literature I've reviewed so far, the only typical velocity range I found for gases in tubes is between 15 m/s and 30 m/s. However, I'm not sure if this range applies to my case, because the gas is condensing—not completely, but partially.
Currently, the design uses a tubeside gas velocity of 18 m/s.
Would this be considered safe and appropriate under these conditions, or should I be concerned due to the condensation aspect?
I’d appreciate any insights or recommendations from those with experience in this area.

I'm still relatively new to this type of design work, so any insights or recommended literature would be very helpful.

Thank you!
.

 

[LittleInch]

Not sure about HX's but high velocity liquid droplets in a gas stream above about 7 to 10m/sec are going to erode whatever the first thing is that it touches. Very rapidly.

Need to talk to to some HX vendors before you go modelling something which can't be built

 

[EdStainless]

What is the tube material?
Condensing streams are tricky.
Often there will be impingement protection in the form of solid rods as the first two rows in place of tubes.
In main steam condensers they run some crazy velocities but they can spread it out a lot and provide protection.

 

[Ricardo11]

What is the tube material?
Condensing streams are tricky.
Often there will be impingement protection in the form of solid rods as the first two rows in place of tubes.
In main steam condensers they run some crazy velocities but they can spread it out a lot and provide protection.

The tube material can be either SS304L or Duplex 2205.

Just to confirm — impingement protection is typically intended only for the shell-side fluid, correct? Its main purpose is to protect the tube bundle from erosion caused by high-velocity flow or particles on the shell side.

In this case, the gas flows inside the tubes, which is where my concern lies. On the shell side, the liquid’s ρV² values are within acceptable limits.

Thank you for your support!

 

[Ricardo11]

Not sure about HX's but high velocity liquid droplets in a gas stream above about 7 to 10m/sec are going to erode whatever the first thing is that it touches. Very rapidly.

Need to talk to to some HX vendors before you go modelling something which can't be built

My main concern is the potential for erosion inside the tubes, or any specific phenomena that may arise due to the combination of high gas velocity and droplet formation from condensation. The presence of entrained droplets at high velocity could potentially lead to erosion or other effects. As I am still gaining experience in this area, I am seeking to better understand the potential risks associated with these conditions, and would appreciate any clarification or guidance.

I’ll try to check with some vendors to make sure the design is realistic and feasible to manufacture, but before that, I’d like to better understand some of the physical phenomena that might occur under these conditions.

Thank you for your support!

 

[georgeverghese]

For thermal design of and pressure drop on tubeside in partial condensors, pls refer to page 11-12 in Perry Chem Engg Handbook 7th edn. You can do a manual check of the Aspen output with these correlations.

 

[pierreick]

For your consideration:

Recommended shell and tube side velocities

Recommended shell and tube side velocities that can be used in preliminary design calculations for shell and tube heat exchangers

www.webbusterz.org

Pierre