Patent GB-883133-A (GB)
Title: Heat exchangers
IPC: F22B37/64
Filed: 1959-01-09
Abstract: 883,133. Tube walls for furnaces. SULZER FRERES S.A. Jan. 9, 1959 [Jan. 10, 1958], No. 927/59. Class 51 (1). In an upright furnace lined with vertical heat-exchange tubes, adjacent tubes form a lining panel and are connected to the tubes of a contiguous panel by return bends at their bottom ends, the panels are suspended from a framework and at least the tube of one panel which has the bottom bend of smallest radius is resiliently suspended for vertical movement relative to the tube of the contiguous panel to which it is connected. The tubes are arranged in groups, each tube of a group extending from a common header, and the tubes of all the groups running parallel in each lining panel, so that there is differential expansion between the tubes of different groups in one panel as well as between the tubes of different panels. Tube panels 50, 48, 46, 44 extending the full height of the side wall 22, Fig. 2, are supported by vertically spaced buck-stay assemblies 78, 80 connected by rods 90 to intermediate support members 72, 73, 74 and 76. Each buck-stay assembly comprises spaced T-lugs 86, Fig. 4, welded transversely of horizontal angle irons 82, 84. Sleeves 88 welded to the lugs 86 embrace the support rods 90 and rest on nuts 89. Further T-lugs 91, Fig. 5, carry sleeves 92 surrounding pins 96 passing through elongated apertures in the arms of stirrups 94 welded to plates 100. Channel members 98, outside the furnace casing, are welded to the plates 100. The tubes of panels 50, 48, 44 and some of the tubes of panel 46 indicated at A are welded to the angle irons of the lower buck-stay 80, and the remaining tubes of panel 46, some tubes of panel 50, and the tubes of a superheating panel 60 indicated at A are welded to the upper buckstay 78. T-lugs welded to the tubes and loosely engaging the angle irons of the buck-stays maintain the alignment of the tubes where they are not welded to the buck-stays in the regions B. Intermediate support members 72, 73, 74 and 76 are carried from the furnace framework 68 by hangers 70, and the hangers of members 73 and 74 co-operating with coil springs 104. The provision of two buck-stays 78, 80 allows relative movement between the tops of panels 48, 46 and between panels 44 and 60. The adjacent tubes of panels 46, 48 are allowed relative movement since these tubes of panel 46 are welded to buck-stay 78 which is connected to resiliently supported intermediate member 74, while the tubes of panel 48 are welded to buck-stay 80 which is in this region connected to resiliently supported member 73. The part of buck-stay 78 welded to the superheater panel 60 is resiliently supported direct from the furnace framework 68, so that this panel can move relative to the adjacent panel 44. A tube panel 42 below the superheater panel 60 in the wall 22 is welded to a buck-stay 106 similar to buck-stay 78, and connected to intermediate member 112 supported by a constant load spring mechanism 110 on the framework 68. Lower panels 38, 39, 40 in wall 20 are similarly supported by buck-stay 108, intermediate member 116 and constant load mechanisms 110. Since tube panel 44 is rigidly connected through buck-stay 80 and intermediate member 76 to the framework 68, the panel expands downwardly, carrying with it lower panels 42, 40, 39 and 38. Superheater panels 62 in the upper part of wall 20 and 64 are welded to a buck-stay 118 resiliently supported from the framework 68, while the part of superheater panel 60 in wall 20 is welded to a buck-stay 114 resiliently suspended from the framework 68. To maintain the furnace wall gas-tight between the superheater panels and the tube panels below them, angle irons 124, Fig. 8, on the outer side of the wall carry brackets 126 linked by a member 128 pivoted to them and a plate 130 is welded to the angle irons 124. The lower superheat tubes carry fins 134, while the upper tubes of the lower panel carry fins 136, spaced lugs 138 on the superheater tubes maintaining fins 136 and 134 in position to protect insulating material between the angle irons 124 from the furnace radiation. Sheet steel plates 142, Figs. 4 and 5, outside the tubes have flanges 146 which are welded to the angle irons of the buck-stay assemblies, and to cover-plates 148 round the buck-stays. The cover-plates 148 are also welded to the T-lugs 86 and 91. Additional buck-stay assemblies 140, Fig. 2, are connected to the tubes of different panels so as to allow for relative movement. The welded connections are indicated at A, and sliding connections at B. Since the lower part of the tube panels of the rear wall and panels 39, 40 of wall 20 incline inwardly and then run horizontally outwards to form the furnace bottom, the relative expansion between adjacent panels is accommodated.