A heat exchanger is a devices used to transfer heat between mediums. A floating head heat exchanges is a type of “shell and tube” device with several components, including tubes, tube sheets, shell and shell-side nozzles, tube-side channels and nozzles, channel covers, a pass divider and baffles. Floating head designs solve problems associated with thermal stress. There are four basic kinds of floating head heat exchangers.
In the pull-through bundle type of floating head heat exchanger, one of the tube sheets is designed to be small enough so that it may by pulled through the shell. Its "gasketed" bonnet can also be pulled through in this way. This allows access to the inside of the shell so that it may be inspected, repaired and cleaned. However, this design has fewer tubes than the others, which means that it transfers heat more slowly. There are fewer tubes in order to accommodate the bonnet flange and bolt circle.
The split-ring type of floating head heat exchanger meets the challenge presented by the pull-through bundle. This design bolts the floating head bonnet onto a split backing instead of onto the tube sheet. This feature of the split-ring type allows for the inclusion of most of the tubes that are missing from the pull-through bundle. The split-ring type also has the “pull through” feature associated with the pull-through bundle type of floating head heat exchanger.
Outside-Packed Lantern Ring
The outside-packed lantern-ring type of floating head heat exchanger lacks positive sealing, and is thus much more prone to leakage than either the pull-through bundle type or the split-ring type. This makes it somewhat unreliable in situations dealing with high pressure or hazardous fluid. Furthermore, it only contains two tubes.
Outside-Packed Stuffing Box
The outside-packed stuffing box type of floating head heat exchanger also lacks positive sealing, and is thus also prone to leakage. It therefore presents the same safety concerns associated with the outside-packed lantern rings design. Unlike the outside-packed lantern ring design, the stuffing-box design includes four tubes and not two, making it faster at transferring heat from medium to medium.