4 tube passes in TEMA D front head 1

[mthausif123]

Hi, is it allowable to opt for 4 tube passes (U-tube) in an exchanger with TEMA D type front head (High pressure gas). The vapor fraction inlet/outlet tube side is: 100/92 percentage respectively.

 

[EdStainless]

People normally resist doing this and build two smaller utube HX instead.
With gas exchangers the properties and heat transfer can vary a lot and often the passes require different conditions.

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P.E. Metallurgy, consulting work welcomed

 

[georgeverghese]

Perry Chem Engg Handbook 7th edn, on page 11-40, does not state any limitations on no of tubeside passes for TEMA rear head type D. Type D head stated to be more economical for tube side design pressure > 900psig.

 

[Christine74]

TEMA D could refer to any number of different propriety closure devices including Screw Plugs, Breech Locks, Taper-Locks, Lummus LABLEX, Superbolts, and several others so I'm not sure if you can generalize, but I can't think of any reason why you couldn't do this for 4 tube passes.

One difficulty you might have is that a 4-pass U-tube bundle would require a Quadrant Flow arrangement, which would have a pass partition plate on the vertical centerline. This means your channel nozzles would have to be offset from the vertical centerline, which can increase costs and make fabrication difficult.

(By the way I don't agree with the Perry's Handbook claim that Type D is more economical for design pressures 900 psig. I think this would only be true if the exchanger was very large diameter).


-Christine