TEMA Rho*V^2 number high 2

[stewbaby]

Have an shell and tube AES heat exchanger in crude preheat that has high RHO*V^2 numbers on shell nozzles. Can someone help point me to the TEMA section / code that discusses this and its effects. I' like to replace the exchanger due to maintenance history and expected rate increase in the future and this would only give the replacement justificaton more "teeth".

 

[25362]

From very old notes of mine:

[ρ]V² = 500 TEMA R-4.61​

[ρ]V² = 1500 TEMA C-4.61​

where V is the linear velocity of the fluid in fps and [ρ] is its density in lb/ft³.

 

[Montemayor]

Stew:

25362 is essentially correct in his reference. The specific paragraph is: RCB-4.61 on page 30 of the 7th Edition and it reads as follows:

"An impingement plate, or other means to protect the tube bundle against impinging fluids, shall be provided when entrance line values of rhoV^2 exceed the following:
-non-corrosive, non-abrasive, single phase fluids, 1500;
-all other liquids, including a liquid at its boiling point, 500.

For all other gases and vapaors, including all nominally saturated vapors, and for liquid-vapor mixtures, impingement protection is required. V is the lineal fluid velocity in ft/sec and rho is fluid density in lb/ft3. A properly designed diffuser may be used to reduce line velocities at shell entrance."

I would also refer you to the next paragraph:

RCB-4.62 Shell or bundle entrance and exit areas
In no case shall the shell or bundle entrance or exit area produce a value of rhoV^2 in excess of 4,000.

I hope this helps.


Art Montemayor
Spring, TX