GB504794A - Improvements in the production of gaseous atmospheres for use in the heat treatment of steel and other metals - Google Patents

Abstract

504,794. Furnace atmospheres. BRAYSHAW FURNACES & TOOLS, Ltd., BRAYSHAW, S. N., and RUSHTON, F. Oct. 29, 1937, No. 29555. [Class 51 (ii)] In an apparatus for the production of a gaseous mixture containing carbon monoxide in excess for use as a furnace atmosphere in the heat treatment of metals, by the combustion of gas with insufficient air, the temperature of combustion is maintained by supplying additional heat to the combustion chamber either from a separate combustion chamber surrounding it, or by internally-fired combustion tubes passing through it. In the constructions shown in Fig. 1 the combustion chamber A for a correctly-proportioned mixture of gas and air supplied through the inlet pipe a, is surrounded by a combustion chamber C fired by a burner c. The offtake flue B for the atmosphere gas surrounds the inlet pipe a so that the ingoing mixture is preheated before combustion. Modifications of this apparatus are described in which (a) Fig. 2 (not shown), the waste gases from the chamber C are exhausted through a flue surrounding the flue B in order to maintain the temperature of the atmosphere gas when it is to be used immediately; (b) Fig. 3 (not shown), the ingoing mixture is not substantially preheated, but the temperature of the atmosphere gas is maintained as in (a) ; (c) Fig. 4, not shown, the ingoing mixture is preheated by the waste gases from the combustion chamber C; (d) Fig. 5 (not shown), a connection is provided by which a regulable proportion of the combustion products from the chamber C can be mixed with the atmosphere gas, and (e) Fig. 6 (not shown), gas and air are supplied to the combustion chamber A through concentric nozzles so that mixture takes place immediately before combustion, the gas preferably being supplied through the inner and cooler nozzle. In the construction shown in Fig. 9 additional heat is supplied to the combustion chamber A by means of a ring of tubes E internally fired by gas or oil burners. A baffle A<1> is placed between the gas and air inlet a<1> and the atmosphere gas outlet a<2>, and radial partitions a<8> are provided to direct the combustion products over the tubes E <1>. In other forms of apparatus the combustion chamber A is heated by a single central tube, Figs. 7 and 8 (not shown) ; and a U-shaped chamber A has tubes passing through it at right angles to the direction of flow of the combustion products, Figs. 11 and 12 (not shown). Specification 455,486 is referred to.