3 replies to this topic

[Tamizh]

Hi all.........

 

In a shell and tube exchanger,tube side is my process fluid and cooling medium in the shell side......

There is a temperature transmitter in the tube out which senses the Temperature and controls the flowrate of the cooling medium by means of temperature control valve in shell out.

 

And my doubt why the TCV is in cooling medium return line?  can we place the TCV in cooling medium supply line? Which is the best engineering pratice??

 

Thanks in advance 

[breizh]

Tamizh,

On the return line , to ensure the shell side is full of liquid .

 

Hope this helps

 

Breizh

[fallah]

Tamizh,

 

The best engineering practice dictates to be in cooling medium return line, because:

 

1) In the case the TCV might be failed closed due to control loop malfunction the connectivity of exchanger shell to cooling medium would be kept causes there would be at least a static liquid medium can continue to absorb the heat from hot side...

 

2) The pressure inside the shell is higher than that of the opposite case (TCV on supply line) causes the boiling point of the cooling medium would be higher which will result in better long term performance...

[Teknas]

Hi Tamizh,

 

If the TCV is installed on inlet to the shell, then throttling TCV will lead to uneven distribution of cooling water on the shell side and also result in hot spots along the tube length.

 

If the tube side fluid temperature is higher than the boiling point of water, uneven distribution can also lead to localized vaporization of the water.

 

Moreover as Fallah and Breizh have pointed out, in the event of TCV fail close, you still have the cooling medium filled in the exchanger. If TCV is on upstream the exchanger shell will be dry and may also lead to mechanical damage of the tubes due to thermal expansion.

 

Hence, its a normal engineering practice to keep TCV on the cooling medium outlet.