GB1462804A - Heat exchanger assemblies - Google Patents

Abstract

1462804 Tubular heat exchangers COAL INDUSTRY (PATENTS) Ltd 20 March 1975 [21 March 1974] 12611/74 Heading F4S A heat exchanger comprises an annular flow space containing a fluidized bed of particulate material in which bed is immersed at least some of a plurality of heat exchange tubes extending between the inner and outer walls defining the annular space, said tubes being of involute form particularly wherein the evolute of the involute is a circle. In all the forms of apparatus described the annular space is defined within an outer casing by a header, e.g. 26, 36 or 42 to which the tube ends are connected and which extends along the longitudinal axis of the casing. The header may be subdivided transversely as shown to form inlet and outlet compartments 43, 44 for the tube-side fluid with the tubes extending therefrom across the space to and from a return header provided by a jacket space, e.g. 41 around the casing. Alternatively (Fig. 5), the jacket space may be subdivided into inlet and outlet compartments with the central header (51) forming a return header for the tube-side fluid. The tubes are disposed in layers which may be separated by spacers, each tube layer being generally planar or alternatively conical (Fig. 8). In adjacent layers corresponding tubes may be aligned or relatively offset. Or, as shown in Fig. 2, the involute form of the tubes may be of opposite sense in adjacent layers. In Fig. 2 also a, b and c denote alternative arrangements for connecting the tube ends to their headers. Fig. 3 shows tubes of serpentine form extending between locations 1-1, 2-2 &c. In use, a fluid to be heated, evaporated or condensed flows through the tubes in heat exchange with a fluidizing gas in the annular space. In Fig. 4 the annular space contains a bed 46 of particles fluidized by a combustionsustaining gas (e.g. air) passed into the bed from below via a grid 45 and reacting with fuel introduced into the bed and burning therein to evaporate a liquid or heat a gas flowing in the tubes. Such combustion apparatus may if necessary be enclosed in a pressure vessel.