Velocities across Heat Exchangers

[Falcon03]

What is the minimum velocity across the heat exchangers?

We are planning to utilize one our heat exchangers (mainly out of service) to cool MHFO (Marine Heavy Fuel Oil) products since the current MHFO coolers is under size due to increase in unit throughput. So to maximize cooling we are going to slip streaming some of the hot MHFO which fed to the current coolers into the new coolers. I 'am bit worried of the velocity (min. velocity) which might cause some fouling and degrade heat efficiency.


Your help in this matter is highly appreciated. Thanks

 

[patrickraj]

Calculate what is the velocity in the existing / old exchanger.You have to maintain the same. If erosion not going to be the problem(SS-MOC),YOU CAN GO UP ON VELOCITY.

 

[Gabamco]

There are velocity criteria for tubes and they are as follows:

CS tubes: Velocity between 3 ft/sec to max 6 ft/sec
SS tubes: Max 15ft/sec (fresh water)
Cu Ni tubes: 10 ft/sec
Adm Brass: 5 ft/sec

The lower limit would be 3 ft/sec in all cases, below this velocity fouling frequency would increase, heat transfer coeff will decrease.

Good luck.

 

[25362]

One ROT recommends slurries be moved at minimum 6 fps to avoid particle settling. Thus, one could assume this limit could be used in your HFO stream.