1350207 Radiant heaters TECHNICAL DEVELOPMENT CAPITAL Ltd 11 Oct 1971 [10 Oct 1970 12 May 1971] 48246/70 and 14586/71 Headings F4W and F4T A fuel burning radiant heater or space heater comprises a bed of refractory particles, to which fuel and air is fed to fluidize the bed, at least when hot, and the bed as a radiator of heat energy. In one embodiment, Figs. 3 and 4, a space heater comprises a row of tubes 45, of heat resistant material transparent at least to infra-red rays, such as silica, each containing a bed 47 of refractory particles, enclosed in the slumped state by thermally non-conductive walls 50, and supplied with a gas/air mixture at the periphery of the bottom 51, from a manifold 38. Air is supplied by a centrifugal fan 30, which has sound deadening material 31 in its inlet, through an outlet 32 to a mixer supplied with gas through a solenoid controlled valve, so that gas cannot be supplied if the fan is not operating. An igniter 53 is provided at the top of each combustion chamber. The burning gas heats the bed 47 rapidly at first because it is surrounded by walls 50, and as the temperature of the bed rises to the fuel ignition temperature, it becomes fluidized and the particles rise into the transparent tube 45. A metal mesh 44 prevents any particles passing to the flue 27. The tubes 45 may be arranged in front of a reflector, and the rear of each tube may be opaque to radiation. In another embodiment, Fig. 6 a bed 59 is fluidized to lie between inclined refractory walls 78 by burning gas and air fed through a porous block 58 by a fan 68. Gas is supplied to a ring 74 and air is drawn in through dampers controlled openings 63. This embodiment may be used in a fireplace. The particles of the refractory beds may be silica, an aluminium silicate and limestone particles may be added to reduce noise and absorb sulphur. The heaters may be ignited by supplying heated air to the bed before supplying fuel, or the fuel/ air mixture may be ignited below the bed, the rate of delivery being increased when the bed is hot so that the flame migrates through the bed. Since the slumped beds are enclosed by insulating refractory material, the temperature of the particles does not fall below the ignition temperature of the fuel when the heater is turned down. In a heater having a manually operated igniter switch, this is connected to the fuel valve so that if the temperature in the flue is not sufficiently high when the igniter switch is released, the fuel supply is cut off, and apparatus purged with air. Similar heaters may be used in cookers, furnaces or for drying.
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