Manifolded Exchanger Arrangement

[sshep]

I have been assigned a project to replace a stack of 3 CEU exchangers. These exchangers steadily foul the tubes until pressure drop becomes so high the plant can't run. The concept which the plant desires would allow for individual exchangers to be taken off-line and cleaned. Space is at a premium, but is sufficient for the concept I have in mind (below). The service has a temperature cross such that 3 active CEU shells are needed at all times.

I have the following idea for replacement: A stack of 3 AFU exchangers with tangential nozzles on the shell and tube side (the long baffles will not be welded to the shells). The tube nozzles will be on the left side and connected by a manifold running parallel to the length of the exchangers, the shell nozzles will be on the right side with a similar manifold on that side. The counter-current advantage of the AFU design should allow 2 shells to perform at least as well as three CEU shells. These will be sized so that 2 exchangers are sufficient and running all 3 will be a heat recovery bonus.

We have a few plants with exchanger banks that allow bypassing and cleaning, but these are not compact piping designs- i.e. these heat exchanger banks appear to have evolved in the field rather than being the result of a well thought-out design. I am trying to do better.

Does my idea seem a reasonable design, or can anyone suggest something else to consider? I will gladly take any comments or advice.

Thanks, sshep

 

[srfish]

That type of arrangement is done sometimes. I am curious about why a welded-in long baffle is not being considered. T

 

[sshep]

Thanks for your interest and glad to know you have seen such a layout in use.

With respect to having the long baffle welded to the shell, this results that the U tube bundle cannot be pulled. The service is liquid-liquid, and sufficiently fouling and corrosive such that I feel pulling the bundle must remain an option. The technology for sealing the removable long baffle is not perfect, but I intend to size such that minor leakage will be within my design allowances. -sshep