GB523432A - Improvements relating to burners and fittings for radiant tube furnaces and the like - Google Patents

Abstract

523,432. Gas-fired heaters. SANDERSON BROS. & NEWBOULD. Ltd., and HOLMES, J. G. Jan. 6, 1939, No. 512. [Class 126] [Also in Groups XII and XXII] In gas fired radiant tube furnaces or domestic heaters the radiant tubes have an outer casing composed of a material which is resistant to scaling and maintains its mechanical strength at high temperatures, and an inner casing composed of material that is resistant to scaling at high temperatures and to attack by the products of combustion including sulphur and its compounds. The tubes b may be arranged vertically, as shown in Fig. 3, within the furnace a and supplied with gas from burners c the combustion products being exhausted into flues d<SP>2</SP> or the tubes may be arranged horizontally in the furnace. Fig. 5 shows a section of a tube having an outer casing e and inner casing f. The tubes may be formed by taking a plate of nickel chromium steel for the outer casing e containing 20 to 80 per cent. of nickel and 5 to 30 per cent. of chromium, and welding it to a plate for the inner casing f containing about 20 per cent. of chromium and little or no nickel since the nickel is attacked by the sulphur compounds in the combustion products. The plates are welded together by the process described in Specification 446,439, [Group XXII], or by centrifugally casting the outer casing from the nickel chromium steel and by centrifugally casting the inner casing from chromium steel on the inside of the outer casing. The composite tubes may also. be produced by forging or pressing the two layers together or by an extrusion process in which the inner and outer casings are extruded separately and united to form the composite tube by the method described in Specification 446,439 or the two parts may be extruded simultaneously so that they are bonded together by the extrusion process.