STHE tube side inlet & outlets are at the same end

[patrickraj]

Dear members,

Though add no of tube passes are not unknown, most STHE have an even number so that both tube-side inlet and outlet piping connections are made at the same end.What are the advantage?

Thanks in advance.

 

[25362]

My thought only: who would like to have the floating end nozzle extending through the rear end cover in an odd (mainly one) number of tube passes ? What about leakage ?

 

[patrickraj]

DEAR 25362,

With floating end you are correct(no one will like the floating end nozzle extending through the rear end cover in an odd pass STHE).
In the case of fixed tube sheetSTHE, is there any advantage in having both tube-side inlet and outlet piping connections at the same end.

 

[speco]

Dear Patrickraj,

Here are two more ideas to consider:

1. Normally, when designing an exchanger, you try to get the tubeside fluid velocity high (within reason) to maximize the inside coefficient. Sometimes this is better with an even pass design, sometimes better with an odd pass design. The "best" design depends on a number of factors, such as temperature range, density, tube diameter, etc.

2. If the exchanger is a fixed tubesheet design, say as a TEMA Type BEM (fixed tubesheets, and removable bonnets on both ends, single-pass shell side), then it it simple for the nozzles to be configured either way, even-pass or odd-pass. There are no nozzles protruding through an end cover.

One good reason to use an even-pass design is that it is easy to configure the exchanger with U-tubes, allowing for both differential thermal expansion and and a removable (or replaceable) tube bundle.

Regards,

Speco

http://www.stoneprocess.com

 

[25362]

There is not much that can be added concerning location of nozzles of fixed tube sheet heat exchangers. Except, probably, by mentioning that one shell pass and one tube pass with the tubeside nozzles at opposite ends, allow the heat transfer (HT) between the two fluids to be close to either cocurrent or countercurrent flows. Each one of these arrangements having their HT advantages in particular cases.

BTW, when two horizontal BEM units are stacked and in series, the channel connections appear on the same side.