2 replies to this topic

[Sadananda Konchady]

Regarding Vertical Shell and Tube Heat Exchangers ---

1. Does it make a difference in performance of sensible heat transfer cases, whether the unit is horizontal or vertical?

To my knowledge, there does not seem to be a difference, except for the convenience in draining the liquid on the tube side.

2. Is it practical to have multiple tube side passes in vertical shell and tube heat exchangers?

I suspect that it would be difficult to vent gases in the top bonnet and avoid the build-up of suspended solids in the bottom bonnet.

Thank you for your feedback.

Escape

[Art Montemayor]

Escape:

Yours are very perceptive and analytical questions regarding the application of TEMA type heat exchangers. This is the type of analysis that all engineers should go through each time they contemplate a heat exchanger application. In my opinion, if they did so they wouldn't suffer at least 75% of the problems and agonies that arrive later after the wrong unit is installed.

1. Yes, you are correct. When dealing with only sensible heat transfer, the direction of the flow or the effects of gravity don't make any difference in the efficiency of the heat transferred - with pure, 100% single-phase flow in both the tube and shell side.

2. Again, you have spotted a liability (or trade-off) in a vertical unit with multiple tube passes. Not only will you have a propensity to accumulate gases or vapors at the top channel or bonnet and also deposit solids in the bottom channel or bonnet, but how do you drain all the tubes when you need to inspect or do maintenance?

The second question is a reason why designers are forced to apply a faster tube side velocity than they normally would. If you are dealing with solids in the tube side fluid, this could lead to more errosion and force the application of thicker tubes - not a cure for a problem, but a trade off in the form of additional costs and maintenance (or repairs).

Vertical units are useful for some purposes, but you have just spotted two notorious bad points in their characteristics.

(By the way, your query is well-written, fully understandable, and directly to the point. It's great to read an efficient communication and understand it immediately.)

[trilok_sontakke]

I think that pressure drop across the horizontal HE is less than vertical HE. so where there is any issue regarding operating cost we have to think the position.

moreover i think that if there is a phase transfer involved then vertical HE is preferred.