Heat Exchanger (Steam and Oil) 2

[SaCaZu]

as The tittle indicates it...

Is it logical to think that the steam shall always flow outside tubes if its purpose is to warm the oil? Does TEMA support it?

I guess that the steam flows by outside due to its high temperature and pressure.

I don't know if I'm wrong but I believe to remind that according to calculations related with Heat Transference, the flows of heat exchangers must be inverted to be highly efficient... is this type of arrangement seen in the industries or flows are always parallel? Some Code or TEMA demands it?

P.D. as you can see, some questions sound like simple and that can be answered according to TEMA but I don't have it at hand right now, by that I appeal a their wisdom

Thanks in advance

 

[rmw]

To answer your first question, bayonet type heaters that are used to heat heavy oil in storage tanks are steam inside the tubes, oil outside. Many other types of oil heaters have the oil outside the tubes and the steam inside. Unless the oil is high purity, I would design a Hx to have the oil outside the tubes. But that is just me.

To answer your second question, counter current flow produces the optimum heat transfer as a general rule, but due to physical limitations of heat transfer equipment and processes it is not always possible.

rmw

 

[davsy]

SaCaZu

You may need to give a little more info on the actual industry or duty and conditions such as temperatures, pressures, materials required etc. also do you have any pressure drop or fouling/ cleaning issues. All of these and more will help the decision making process.

Most of the continuous steam/oil heat exchangers that we use are steam on the shell side with oil in the tubes, mostly they are vertical but we do have one customer who insists that S&T heat exchangers are horizontal but still with the oil on the tube side to aid cleaning.

Depending upon material compatibility with your "oil" the decision may be affected by cost, if for example you need stainless steel wetted parts for your "oil stream" (you did not say what type of oil) then oil in the tubes could probably mean you could use a carbon steel shell in contact with the steam if the oil was on the shell side then you would need a full stainless exchanger (again if stainless is required for this application).

 

[25362]

A ChE article published July 25, 1983, titled Shell-and-tube heat exchangers by D. K. Mehra, Brown & Root, Inc. presents several arguments on fluid allocation, and other considerations of value.

 

[TXiceman]

Shell side or tube side design really depends on the application if it is a shell and tube type. One thing you need to consider is the expansion of the tubes and/or shell. Typically they will expand at different rates and the tubes can fail at the tube/tubesheet joint if it is a fixed tubesheet design.

Most use a U-bundle design to avoid the potential of a tube expansion problem. Of course you can also us a shell with an expansion join and it gets expensive. There are also packed head designs to get around the expansion problems.

Ken

Ken
KE5DFR