GB937293A - Catalytic radiation heater - Google Patents

Abstract

937,293. Radiation gas burners. CATALYTIC COMBUSTION CORPORATION. March 7, 1961, No. 8206/61. Class 75 (1). A radiation unit, Fig. 3, for a heater comprises a catalytic combustion element 21 mounted in front of a gas-permeable layer 22, a heat-reflecting metal screen 23b interposed between the layer and the catalytic element and a metallic guard net or grating 78 protecting the front of the catalytic element, the latter consisting of a wire net formed by one or more metal screens and coated with noble metal, for example palladium, platinum, osmium, ruthenium, rhodium or iridium or a mixture of these metals. The guard 78 has larger openings than the openings in the catalytic element and the reflecting screen 23b has openings which are either equal to or less than the openings in the catalytic element. The gas permeable layer 22 is made of mineral or ceramic or metallic wool and may be made in two layers, the one nearer the reflecting screen 23b being more tightly packed than the other. The rear surface of the layer 22 is covered by a screen 23. The unit comprises a frame 18 having flanges 19, 20 which retain the elements of the unit. The apparatus, Fig. 1, for heat treating an article 49 comprises two identical heaters 11, 12 slidably mounted on a base 10 and facing each other. The heater 11 comprises a rectangular housing 13 having an outer wall 14, a top wall 15, a curved bottom wall 16 and an inner wall 17 formed by a radiation unit as described. An inclined partition 24 extends from the top wall 15 to just short of the bottom wall 16 and provides an inner compartment behind the radiation unit and an outer compartment to the top of which a mixture of gas and air is supplied by a perforated tube 29. Brackets 30 secured to the housing slide in T-slots in the upper surface of the base. At starting air is supplied to the perforated tube 29, and an elongated preheating burner 28 disposed at the bottom of the housing is ignited to heat the catalytic element in the radiation unit to ignition temperature. A fuel/ air mixture is then supplied to the perforated tube 29 and burns without flame at the catalytic element. The two heaters 11, 12 may be provided with co-operative shields 44, 45 at their lower portions and with adjustable shields 46, 47 at their tops. Another heat-treating apparatus, Figs. 4, 5, 6 (not shown), comprises a housing having its bottom wall formed by a plurality of radiation units as described. Each radiation unit has a blower supplying a mixture of gas and air to a compartment behind the unit. A gas pipe leading to the blower has a shut-off valve and a proportional valve, the shut-off valve being opened by a temperature responsive element positioned near the radiation unit and the proportional valve being controlled by a second temperature responsive element positioned in the zone of heating of the radiation unit. A preheating burner for each radiation unit is located either in the gas/air inlet or outside the housing. Articles to be heated are conveyed by an endless belt supported on pulleys or rollers and passing beneath the radiation units. Specification 775,549 is referred to.