GB936462A - Improvements in or relating to industrial furnaces with arched roofs - Google Patents

Abstract

936,462. Furnace roofs. BRITISH IRON & STEEL RESEARCH ASSOCIATION. Oct. 28, 1959 [Oct. 28, 1958], No. 34555/58. Class 51(2). Supporting means for the arched roof of an industrial furnace comprises pivot means operatively coupled with opposite ends of the arch such that, during cycling, the ash may rise and fall, the span of the arch may vary and opposite ends of the arch may rotate, and self-adjusting compression means operable automatically and continuously during cycling with varying effect between opposite ends of the arch to maintain the line of pressure of the arch at any transverse cross-section thereof within the central third of that cross-section. As shown in Fig. 7 the arch 1 is supported between skewback channels 6 and 7, skewback channel 6 at the front of the furnace being pivoted at 8 to the vertical stays 9, and skewback channel 7 at the rear of the furnace engaging the projection 19 on a lever 10 pivoted at 11 to vertical stays 12 an adjustable tension spring 15 being pivotally connected to the lever at 16 and to a cross-tie 17. It has been found that with an arch in the form of an incomplete circular annulus having an included angle 0, a weight W and a hot face temperature T with a force remaining substantially normal to the end of the arch, the magnitude of the force is substantially #/2 cosec ¢ ¢ # T . Where the force remains horizontal, the corresponding expression is #/2 cot ¢ # T . In a modification, Fig. 1, the arch 1 is suspended between a pair of spring-loaded bell-cranks 42 and 43 pivoted at 45 and 46, respectively, to the furnace framework 44 and pivotally engaging the arch skewback channels at 47 and 48, respectively. The springs may be compression springs 51 and 52 or tension springs 53 and 54. Further modifications show an arch supported at one end by a pivot and pivoted at the other end to the furnace framework by a mechanical link incorporating a spring, Figs. 3 and 9 (not shown), and also supported by cranked arms incorporating adjustable weights, Figs. 4 and 5 (not shown). A final modification, Fig. 6 (not shown), has the spring connected horizontally between the furnace framework and the arch pivot, the latter forming the top of a vertical arm riding on a lower roller running horizontally on a platform connected to the said framework.