Patent GB-1265081-A (GB)
IPC: F23D11/34
Filed: 1969-03-18
Abstract: 1,265,081. Spray producers. K. H. STAHL. 18 March, 1969 [20 March, 1968; 16 July, 1968], No. 14274/69. Heading B2F. [Also in Divisions F1 and F4] An oscillating gas column combustion apparatus which may be used to produce an atomised spray or a jet of flame, e.g. for disinfection, heating or weed killing, comprises a combustion chamber 10 having an exhaust pipe 12 into which is injected via valves 80 and/or 80a and nozzles 84 and/or 84a the liquid to be sprayed or fuel to produce the flame jet, the apparatus also including a starting air pump coupled to operate jointly with the ignition mechanism. The nozzles 84, 84a are supplied with fuel or spraying liquid from tanks 70, 70a which are pressurised via lines 18, 18a and non-return valve 20 from a fuel/ air mixing device 22 at the inlet to combustion chamber 10. Relief valves 76, 76a permit the pressure in the tanks to be released or the nozzles 84, 84a blown through, when required. The tanks 70, 70a may contain different liquids but can be connected by opening valves 90, 92 if they contain the same liquid. The portion 72, 72a of the liquid supply lines within the tanks are flexible and have weights 74, 74a to ensure that liquid withdrawal always takes place from the lowest point of the respective tank. The valve 80 (or 80a) comprises Fig. 2, a slide 94 disposed across liquid supply pipe 78 and biassed by spring 98 towards a position in which flow passage 96 is closed. During normal running of the combustion apparatus the slide 94 is held in the open position of passage 96 by a piston 108 having an extension 104 urged into engagement with a groove 100 in slide 94 by the exhaust pipe pressure communicated to the right side of piston 108 through line 82. If the pressure fails, spring 106 forces piston 108 to the right allowing slide 94 to move to the closed position of passage 96 to cut off the liquid supply to nozzle 84. The liquid supply can also be manually shut off by depressing pin 112. The fuel/air mixing device 22 for the combustion chamber 10 comprises a venturi tube into which project fuel and starting air nozzles 24, 26 respectively. One end of the venturi tube communicates with combustion chamber 10 adjacent an ignition plug 14 and a flame trap and mixing grid 16. The other end of the tube is funnel shaped and contains a plug 30 and a manually controllable main air valve 32 having a silencing and filtering cover 53. The apparatus is started by opening main fuel valve 52 by operation of push button 48, pressurising fuel tank 56 by bellows 64 so as to force fuel past non-return valve 50 to nozzle 24 and then operating starting air bellows 42 to force air past non-return valve 38 to nozzle 26 to mix with the fuel. Depression of bellows 42 simultaneously operates a switch 44 of a magneto or other type ignition system so as to energise plug 14 for combustion of the fuel/air mixture. The nozzles 24, 26 are shaped and disposed relative to each other to assist mixing, Fig. 5 (not shown). In a modification, Fig. 6 (not shown), fuel tank 56 is pressurised at starting by a tapping (11) from bellows 42. In a further modification, Fig. 3 (not shown), the starting mechanism comprises a motor (114) driving a disc (118) carrying two cam tracks (120, 122) which respectively actuate a make and break igniter (126) and a diaphragm type air pump (130) to ensure synchronism of the air blasts and ignition sparks produced. In a further modified apparatus, Fig. 7, a tube 150 surround the combustion chamber 10 and exhaust pipe 12 to define a chamber through which cooling air is drawn by the ejector action of gases leaving pipe 12. An exhaust silencer 160 is connected to tube 150, a drain connection 161 leading back to the liquid tanks via valve 166 and line 168. The air inlets to fuel/air mixing device 22 and to tube 150 also have silencers 170, 156 respectively the latter being adjustable at 152. An afterburner may be provided in the region of the exhaust silencer, into which further fuel is injected and burnt.