Floating-head exchanger

FIG. 11-36 Heat-exchanger-component nomenclature, (a) Internal-floating-head exchanger (with floating-head hacking device). Type AES. (h) Fixed-tiihe-sheet exchanger. Type BEM. (Standard of Tiihiilar Exchanger Manufacturers Association, 6th ed., 1978. )... 

Interna] Floating-Head Exchanger (Fig, 11-36a) The internal floating-head design is used extensively in petroleum-refinery service, but in recent years there has been a dechne in usage. 

Removable-Bundle, Externally Sealed, Floating-Head Exchanger... 

Removable-Bundle, Pull-Through, Floating-Head Exchangers... 

Full Circle Tube Layouts Floating Head Exchanger -in. O.D. Tubes on -in. Triangular Pitch... 

FuU Circle Tube Layouts Floating Head Exchanger, 1-in. 

In order to allow for the removal of the tube bundle and for considerable expansion of the tubes, a floating head exchanger is used, as shown in Figure 9.63. In this arrangement one tube plate is fixed as before, but the second is bolted to a floating head cover so that the tube bundle can move relative to the shell. This floating tube sheet is clamped... 

Using a split-ring floating head exchanger for efficiency and ease of cleaning. 

For a split-ring floating head exchanger the typical shell clearance from Figure 12.10 is 56 mm, so the shell inside diameter,... 

Labor cost data for mild-steel floating-head exchangers (0-500 psig) working pressure... 

Suppose the cost for a fixed-head heat exchanger constructed of 316 stainless steel operating at 300-600 psi is to be estimated. The base case is a carbon steel, floating-head exchanger operating at 100 psi of area A. For such operation (Kuri and Corripio 1984), the base cost is... 

K = factor for cost index based upon a base year Cb = base cost of a carbon-steel floating-head exchanger, 150-psig design pressure... 

Referring to Fig. 19.1, we can see how a floating-head exchanger works. The tube-side flow enters the bottom of the channel head. This assumes the cold fluid to be on the tube side. The cold fluid may be on the shell side or the tube side of an exchanger. The convention is to put the cold fluid nozzle on the bottom of the exchanger. Sometimes this is necessary. Sometimes it does not matter, but it is still the convention. 

But this is not the case with a floating-head exchanger. The tube-side fluid reverses direction in the floating head. It has to. There is no way to attach the tube-side outlet nozzle to the floating head. It is a mechanical impossibility. So we bring the tube-side fluid back to the top half of the channel head. So, half of the tubes are in countercurrent flow with the shell-side flow. And that is good. But the other half of the tubes are in concurrent flow with the shell-side flow. And that is bad. 

Use of the fixed-head type of exchanger should be limited to exchangers with short tubes or to cases in which the maximum temperature difference between shell and tubes is less than 50°F. In general, floating-head exchangers with removable bundles are recommended for most services. 

Finned-tube floating-head exchangers at 150 psi. Cost is for 1-in. OD Tu. rfin tubes. 

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