Criteria for Impingement plate at Inlet nozzle in Heat Exchangers 1

[ak1965]

Dear All,

We are desigining 02 heat exchangers for Virgin C5+ service.

It is a duplex type of heat exchnagers (One placed over another), the lower exchnager is a kettle type & the upper one is U-tube. The shell outlet of lower one is the shell inlet to the upper one.

Shell Pressure : 9.6 kg/cm.2 (Virgin C5)
Tubes Side : 46.5 kg.cm.2 (Steam)

Inlet nozzle size : 10" (To upper heat U tube exchnager)

Standards under consideration : ASME VIII Div.1 & TEMA R

Please suggest should there be an impingement plate at the inlet nozzle of upper heat exchnager to protect the tube bundle?

What is the right criteria for this requirement?

Can we have a perforated or customized shaped impingement plate to avoid distortion of impingement plate due to hevay fluid forces coming over the plates.

 

[gr2vessels]

Impingement plate is required for ro x v^2 larger than 6000-8000. The HTRI will alert you on the need of impingement plate. The size of the impingement plate is typically 25% larger than the nozzle cross section. For gases you can use perforated plate, but for liquids and droplets carried over it should be solid plate. If impingement forces are so high that they will bend the tubes, then use suspended nozzle inserts, hanged of the nozzle, rather than attached to the tube bundle. I also have seen impingement plates welded in top of the support baffles to protect the tubes.
cheers,
gr2vessels

 

[ak1965]

gr2vessels

True.....!!

good info,,,,,!!

In the mean time, I notice somewhere that ro x v^2 value larger than 15000 for vapors and ro x v ^2 value larger than 5000 applicable for liquids and heavy fluids is the selection criteria for impingement plate.

And API 660 7.6.4.6 dictates that perforated impingment plates shall not be used. we have already ordered a perforated one.

Is this also right?

 

[gr2vessels]

I should have mention first the units, metric or imperial;- I was considering the single phase gas flow in metric units, with disregard of the TEMA recommendations.
However, for the start it would be a good review of the TEMA standard, perhaps later the Shell DEP's are more detailed and somehow more accurate. Also, in top of this page is the search box, type in the 'rho x v^2', this topic has been discussed numerous times.
Cheers,
gr2vessels