Heat exchanger with floating head

#The present invention relates to heat exchangers.

#Although heat exchangers were developed many decades ago, they continue to be extremely useful in many applications requiring heat transfer. While many improvements to the basic design of heat exchangers have been made over the course of the twentieth century, there still exist tradeoffs and design problems associated with the inclusion of heat exchangers within commercial processes.

#One of the most problematic aspects associated with the use of heat exchangers is the tendency toward fouling. Fouling refers to the various deposits and coatings which form on the surfaces of heat exchangers as a result of process fluid flow and heat transfer. There are various types of fouling including corrosion, mineral deposits, polymerization, crystallization, coking, sedimentation and biological. In the case of corrosion, the surfaces of the heat exchanger can become corroded as a result of the interaction between the process fluids and the materials used in the construction of the heat exchanger. The situation is made even worse due to the fact that various fouling types can interact with each other to cause even more fouling. Fouling can and does result in additional resistance with respect to the heat transfer and thus decreased performance with respect to heat transfer. Fouling also causes an increased pressure drop in connection with the fluid flowing on the inside of the exchanger.

#FIG. 1 is a side elevation cutaway view of a heat exchanger having a removable tube bundle and a central pipe representing a first embodiment of the present invention;

#FIG. 2 is a more detailed view of the floating head area of the heat exchanger illustrated in FIG. 1;

#FIG. 3 is a side elevation cutaway view of a two-pass heat exchanger according to a second embodiment of the present invention;

#FIG. 1 illustrates a heat exchanger 100 constructed according to the present invention. In the figure, the shell portion is broken away to illustrate the tube bundle construction more clearly. While FIG. 1 shows a shell-and-tube exchanger, the present invention is equally applicable to many other forms of shell-and-tube exchangers. The heat exchanger 100 illustrated in FIG. 1 is a two-pass heat exchanger with a large central tube positioned to transport tube-side fluid during the second pass from the return head located near the end of the heat exchanger 100 near shell-side inlet nozzle 110 to the other end of the heat exchanger 100 where the tube-side fluid exits the heat exchanger 100 at tube-side outlet 130. Although the embodiment of the heat exchanger 100 is described as a two-pass heat exchanger, in reality, an overwhelmingly large percentage of overall heat transfer occurs during the first pass with only very limited heat transfer occurring during the second pass while the tube-side fluid is flowing through central pipe 145 toward tube-side outlet nozzle 130.

#The heat exchanger 100 includes a shell 150 and a tube bundle 160 contained in it. Tube bundle 160 includes tubesheets 180 and 190 located, respectively, at each end of the tube bundle 160. Tubesheet 180 is fixed in place while tubesheet 190 is movable with respect to the longitudinal axis of the exchanger part, forming part of a floating head, described in greater detail below. The tubes contained in tube bundle 160 are fastened to apertures within tubesheets 180 and 190 by known means in the art such as by welding or by expanding the tubes into the tubesheets. Tube-side inlet 140 and tube-side outlet 130 allow for introducing a first fluid into the tubes in tube bundle 160, and for expelling the first fluid from exchanger 100, respectively. Shell-side inlet 110 and shell-side outlet 120 allow for a second fluid to enter and exit the shell-side of heat exchanger 100, respectively, and thus pass over the outside of the tubes comprising tube bundle 160.

#The embodiment shown in FIG. 1 includes tube supports 170. Tube supports 170 are preferably metal coil structures disclosed in co-pending patent application entitled “Heat Exchanger Flow Through Tube Supports”, corresponding to U.S. application Ser. No. 10/209126 (Provisional No. 60/366,914) and which eliminates the need for baffles and allows for high-velocity fluid flow. By using these metal coil structures as tube supports 170, conventional baffles may be eliminated and higher fluid velocities may be employed. Alternatively, the tubes in tube bundle 160 may consist of “twisted tubes” or may be supported by conventional means such as by “rod baffles” or “egg crate” style tube supports. Segmental baffles are not preferred because they generally do not allow high-velocity fluid flow and they further create dead zones.