GB969319A - Improvements in heat exchangers - Google Patents

Abstract

969,319. Heating steam boilers by hot liquids; tube-type heat exchangers. CLARKE, CHAPMAN & CO. Ltd., and R. L. HOLMES. Sept. 12, 1960 [Sept. 17, 1959], No. 31763/59. Headings F4A and F4S. In a heat exchanger of the kind providing a plurality of co-current paths for a fluid subject to enthalpy change in one sense, by means of a number of sets of helical coils of tubing, each of the sets of helical coils comprises a plurality of coaxial coils of equal and constant pitch diameter intercoiled into a multi-pass helical structure with equal pitch lengths throughout the length of the structure and casing means enclose said coils affording passage about the coils for another fluid subject to enthalpy change in the other sense, said casing means comprising inlet and outlet chambers, a plurality of sheath tubes in parallel disposition each sheath tube opening into said inlet and outlet chambers and one of said sets of helical coils being housed in each of said sheath tubes for said other fluid to pass around the coils structure. Fig. 1 shows a nuclear reactor in which heat-exchanger coils 32, 33, 34 of a three-start helix structure are housed within each of the tubes 35 which are grouped, in honeycomb disposition, between plates 36, 37 carried respectively by upper and lower domed members 40, 41 having outlets and inlets 42, 43 for initially cool fluid, e.g. liquid sodium. Inlet and outlet pipes 44-46 and 47-49, passing respectively through the domes 40, 41, lead to headers connected to the heating medium. The tubes 35 may be enclosed by a shell 50. A core tube 53, Fig. 2, closed by a plate 54 at its upper end, prevents the passage of cooling fluid through the interior of each coil, a helical baffle-plate 55 being located in the annular space between the tubes 35, 53. In an alternative arrangement having U-shaped ducts, Fig. 3, not shown, coil structures are located within the upper vertical limb of each duct. In the steam generator, Fig. 5, liquid sodium enters a shell 76 through an opening 83 to compress nitrogen into an upper dome 82 incorporating a rupturable disc 85, the coil tubes 88 being connected respectively by pipes 90, 91 and 95, 96 between alternately spaced, horizontal, outlet and feed headers 92, 93, discharge and supply pipes 97-99 and 101-103 from which emerge from the dome 82 in two concentric rings. A water feed tube 96, Fig. 7, extends through a core tube 105 to the bottom of each coil 88 for connection with a subheader 104, equi-angularly spaced strips 106 having upper end portions turned over the upper rim of the tube 80 being associated with spacer bars welded to the coils and having portions cut out and turned inwardly to extend obliquely between two adjacent turns of the coil as deflector segments 108. The embodiment is also described having six-start reheater coil structures incorporated in it.