GB842828A - Improvements in or relating to tubulous vapour generating and vapour heating units and heat exchanger tube platens for such units - Google Patents

Abstract

842,828. Steam superheaters. BABCOCK & WILCOX CO. Nov. 13, 1958 [Nov. 14, 1957], No. 36523/58. Class 123(3) In a high capacity and temperature steam generating and superheating unit, the outermost tube 82 of each platen 69 in a radiation superheater 68, suspended from inlet and outlet headers 70, 72 in the upper part of a furnace chamber 21, is relatively interchanged in position with, the adjacent inner tube 83 in the plane of the platen at locations A, B, Fig. 2, in order to compensate for the increased absorption rates in the tubes bordering front and rear cavities 80, 81 in the furnace chamber. Each platen comprises a number of closely-spaced nested U-shaped, tubes 76 the upright limbs of which are interconnected at C, C<SP>1</SP>, C<SP>2</SP>, Fig. 2, by means 90 which allow a degree of relative axial movement between the limbs. The connection between each pair of limbs comprises two pairs of sleeves 91 which are rigidly connected e.g. to a tube limb 82, Figs. 7, 8, one pair on each side of the platen, and loosely embrace a pair of axially aligned intermediate sleeves 92 rigidly connected to a neighbouring tube limb 83. The sets of aligned sleeves 91, 92, on each side of the platen, are engaged by pins 93 which are welded to the top sleeve member 91 of each set. The furnace chamber 21 is lined with steam generating tubes 27, 28, 33, 35 which are supplied with water by a downcomer 49 and lead to a steam and water drum 32. An economiser 48 and first and second sections of a primary superheater 62, 64 are located in a downpass 22, the first section 73 of the secondary superheater being located in a lateral pass 22. Front wall burners 50 are housed in a casing 51 which defines a windbox 52 supplied with heated air from a duct 53. Three or more superheater tubes in a platen 64 may have parts interchanged in position.