Abstract: A shell and tube heat exchanger (which can be a boiler) which includes a plenum chamber defined by at least one of the tube-sheets and a diaphragm plate. In this plenum chamber a system of outer and inner annuli around each of the tubes created by a system of baffle tubes that surround each fluid tube and a holes in the thick tube-sheet of the exchanger. This arrangement allows the high pressure cooling fluid in the shell to keep the high temperature low pressure fluid tube inlet, and the associated tube-sheet cool under very high hot fluid flow rates at lower cost, smaller footprint and with lower pressure loss of the low pressure hot fluid than previous art.

Abstract: A heat exchanger apparatus (which can be a boiler) includes a plurality of tanks assembled together. Each of the tanks is a separate structural member that provides opposed parallel surfaces. The surfaces carry a plurality of parallel longitudinally extending U-shaped grooves that are correspondingly placed. When the grooves are aligned, they form a first plurality of channels for holding a first fluid system. A load-carrying portion of each plate-like tank extends between the opposed surfaces. A second plurality of fluid conveying channels carries a second fluid system through the load carrying portion of the tank. Fluid inlets and outlets are provided for each fluid system. The design of the present invention provides an improved plate-like tank structure that allows the separate fluid systems to be maintained at substantial pressure differentials such as, for example, between about 1,000-3,200 p.s.i.