GB856512A - Improvements in tubulous heat exchangers - Google Patents

Abstract

856,512. Forced-flow steam boilers. SPENCER - BONECOURT - CLARKSON Ltd. March 13, 1959 [March 13, 1958], No. 8075/58. Class 123(2) A tubulous heat exchange unit for a forced-circulation steam boiler comprises a bank of similar tubes 3 of zig-zag form which extend across a rectangular metal casing 6 defining a gas-flow passage and which are connected between upright inlet and outlet headers 4, 5 located adjacent the sides of a front face 30 of the casing 6, the return bends of adjacent tubes, at the sides of the bank, being in staggered relationship so that adjacent limbs 21 of the tubes are mutually disposed in crosswise fashion. The plane containing the longitudinal axes of the limbs 21 of each tube 3 is inclined to the longitudinal axes of the distributer and collector headers 4, 5. The latter compise outer trough-shaped casings 9, 16 having base flanges 10, 17 connected respectively to rectangular tube plates 11, 18 provided with pairs of vertical rows of openings 15A, 15B and 20A 20B into which one expanded the corresponding vertically staggered ends of the tubes 3. A curved baffle 12, welded at its upper end and its edges to the inner surface of the distributer casing 9, has its lower end spaced from the corresponding end of the casing and divides the latter longitudinally into inlet and outlet spaces, slots 14 being provided in the baffle 12 opposite each pair of openings 15A, 15B. The ends of the tubes 3 extend through end plates 31, 32 secured to the casing front wall 30 the spaces above and below the plates being filled respectively with plates 37. 38. During assembly the inclination of the tubes depends upon the required spacing of the headers 4, 5, the casing 6 being dimensioned accordingly and if desired being lined internally with refraction material. A forced-flow steam generator, Fig. 3 comprises five serially connected heat exchange units two 50, 51, being accommodated in a combustion gas section 43 having an oil burner 45, a roof 61, and baffles 49, 60 and the remaining three units 68...70 being housed in an upper wasteheat section 42 which has a roof 79, baffles 77, 78, and an exhaust outlet 80. The section 43 is supplied e.g. with exhaust gases from a gas turbine through a duct 66 a corresponding opening being formed in the casing adjacent the heat exchanger 68 opposite the duct 66. A combustion gas section outlet 61A, between a side wall 47 and the roof 61 and leading to a damper controlled exhaust pass 83A also communicates, through a parallel opening 64 controlled by a damper 65, with the wasteheat section 42. A forced circulation pump 83 delivers water, from a downcomer 82 connected to an upper steam and water drum 81, to the lowest heat exchange unit 50, the uppermost unit 70 being connected to the steam space of the drum 81. When either section 42, or 43 is operated on its own the remaining heat exchange units 68...70 can be by-passed.