Maximum velocity at nozzles for two phase fluid
Maximum velocity at nozzles for two phase fluid
(OP)
Good morning,
we are thinking of recovering more heat of a residue current for generating more steam.
The idea is to extend the lengths of the tubes of a shell and tube heat exchanger whils keeping the current diameter.
At the moment we basically heat a boilerfeedwater current and just produce 1% of steam but with the new heat exchanger we will be able to produce 10% of steams in the tube side. The current goes into a vapor/liquid separator.
I have seen the simulation of the new heat exchanger and noticed that the velocity in the outlet nozzle was 6.9 m/s.
Whilst hte criteria of velocity for tubes are quite clear:
*3-5 ft/s (0.9-1.5 m/s) for liquids
*50-100 ft/s (15-30 m/s) for gases
I am not sure for a two phase flow. Could anyone which velocities could be considered for a two phase case?
The performance check of the heat exchanger says ok and the pressure drop was ok as well at 0.8 kg/cm2. I was thinking of maybe erosion due to the high velocity in the liquid
Thank you for your answers.
we are thinking of recovering more heat of a residue current for generating more steam.
The idea is to extend the lengths of the tubes of a shell and tube heat exchanger whils keeping the current diameter.
At the moment we basically heat a boilerfeedwater current and just produce 1% of steam but with the new heat exchanger we will be able to produce 10% of steams in the tube side. The current goes into a vapor/liquid separator.
I have seen the simulation of the new heat exchanger and noticed that the velocity in the outlet nozzle was 6.9 m/s.
Whilst hte criteria of velocity for tubes are quite clear:
*3-5 ft/s (0.9-1.5 m/s) for liquids
*50-100 ft/s (15-30 m/s) for gases
I am not sure for a two phase flow. Could anyone which velocities could be considered for a two phase case?
The performance check of the heat exchanger says ok and the pressure drop was ok as well at 0.8 kg/cm2. I was thinking of maybe erosion due to the high velocity in the liquid
Thank you for your answers.





RE: Maximum velocity at nozzles for two phase fluid
Exchanger design and materials of construction should avoid unintended migration of residue into BFW, else BFW pressure should kept always higher than resid pressure.
RE: Maximum velocity at nozzles for two phase fluid
I don't know the details, but maybe there is a cheaper option e.g. to change the tube pitch and/or tube pattern and fit more tubes into the existing shell.
As for the flow velocity, look at the momentum limits and potential tube vibration. Software like HTRI can calculate this for you.
Dejan IVANOVIC
Process Engineer, MSChE
RE: Maximum velocity at nozzles for two phase fluid
Dejan IVANOVIC
Process Engineer, MSChE
RE: Maximum velocity at nozzles for two phase fluid
RE: Maximum velocity at nozzles for two phase fluid
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