Patent GB-1072492-A (GB)
Title: Improvements in or relating to air heaters
IPC: F28D7/00
Filed: 1965-04-23
Abstract: 1,072,492. Tubular heat exchangers. BABCOCK & WILCOX CO. April 23, 1965 [April 23, 1964], No. 17360/65. Heading F4S. An air heater comprises tube heat exchanger units 21, arranged in two banks 20A, 20B and connected by a gas-tight hopper arrangement (19) (Fig. 2, not shown) to form an upstanding U-shaped gas flow path. The units are mounted on a rectangular supporting base 22 anchored at its centre by a centre column (31), and supported by pivot supports 30A, 30B spaced along the horizontal centrelines, and suspended by flexible means 72 at its corners so that it may thermally expand and contract in a horizontal direction about its centre. The supporting base 22 consists of girders 23 and I-beams 24, to form its outer boundaries, attached to which are I-beams 25, to divide the base into two rectangular sections 26A, 26B, and grid bars 27 which are prevented from twisting and lateral bending by spacer pipes (35) (Fig. 4, not shown). Bearing bars 29 act as spacers between the grid bars 27 and the heat exchanger units 21 which consist of a plurality of parallel straight vertical tubes 40 held at their extremities by tube plates 41 and (42). The edges of adjacent plates 41 and (42) being sealed by means of a sealing strip (43) (Fig. 4, not shown). The pivot supports 30A, 30B (Figs. 5, 6, 7, 8, not shown) consist of upper (51), intermediate (52) and lower (53) shaft portions, one end of the lower (53) and upper 51 portions being secured to a foundation base (54) and the supporting base (22) respectively, the free ends being connected to the intermediate portion (52) by means of hinge pins (56) or in the case of the lower joint in one axis by means of mating convex and concave surfaces (65). The horizontal movement of the supporting base being limited by gaps (55A) and (56A) between the respective portions. The supports 30A and 30B are protected from dirt and moisture by means of a cover tube (57). The flexible means suspending each corner of the supporting base is formed of four rods 72 at each corner, of sufficient length and strength to permit the diagonal expansion experienced at corners, fixed at one end to the supporting base 22 by means of reinforcing plates (77), rocking washers (74) and nuts (73) whilst the other end is fixed by similar means to a span girder 70 supported by corner columns 71. Vertical expansion of the heater units is accommodated by expansion joints (80) (Fig. 9, not shown) comprising of slidable walls (82) &c. and a bellows unit (85) fitted around the perimeter of the gas inlet and outlet. A casing (92), sealed at its upper edges to the expansion joints (80) and at its lower edges to the tube plates (42), is provided around the sides of the banks of heat exchanger units 21 to contain and to direct the air to be heated between an inlet (17) and an outlet (18) in two opposite easing walls. The casing (92) and the tube plates (41) and (42) are reinforced against the internal pressure of the air by means of three types of internal ties (89), ((90), (97) (Figs. 9, 13, 14, not shown) extending perpendicular to each other.