Refractory flame-gunning apparatus

A refractory flame-gunning apparatus which comprises:

• a feeder comprising a refractory powder feeding section, an inflammable gas feeding section, a combustion-assisting gas feeding section, and an inert gas feeding section;
• a controller for controlling the supply of refractory powder and the supply of inflammable gas, combustion-assisting gas and inert gas, said controller having an inflammable gas pipe means extending from said inflammable gas feeding section, a combustion-assisting gas pipe means extending from said combustion-assisting gas feeding section, a first inert gas pipe means extending from said inert gas feeding section and connected to said inflammable gas pipe means, a second inert gas pipe means extending from said inert gas feeding section and connected to said combustion-assisting gas pipe means, an inflammable gas valve in said inflammable gas pipe means between the point where said inflammable gas and first inert gas pipe means meet and said inflammable gas feeding section,
• a combustion-assisting gas valve in said combustion-assisting gas pipe means between the point where said combustion-assisting gas and second inert gas pipe means meet and said combustion-assisting gas feeding section, a first inert gas valve in said first inert gas pipe means, a second inert gas valve in said second inert gas pipe means;
• and a control unit including a temperature sensor for detecting a temperature due to backfiring, the control unit including means for outputting opening and closing signals to said inflammable gas valve, said combustion-assisting gas valve and said first and second inert gas valves on the basis of signals emitted by said temperature sensor;
• and
• a flame-gunning burner having a plurality of refractory powder and flame ejecting nozzles disposed at the tip thereof, a gas mixer having an inflammable gas passage to which said inflammable pipe means is connected, a combustion-assisting gas passage to which said combustion-assisting gas pipe means is connected, said burner having a gas mixing chamber therein to which said inflammable and combustion-assisting gas passages are connected, and a mixed gas passage extending out of said gas mixing chamber to said flame ejecting nozzles, and a combustion-assisting gas cutoff valve in said combustion-assisting gas passage normally urged toward the closed position and held out of said closed position and having means exposed to said mixed gas passage for releasing the holding of said cutoff valve to quickly close said combustion-assisting gas passage in response to a build-up of pressure in said mixed gas passage due to backfiring, said temperature sensor being positioned in said mixed gas passage, and said outputting means in said control unit outputting signals for closing said combustion-assisting gas valve and opening said second inert gas valve when a temperature indicating backfiring is sensed, and for subsequently closing said inflammable gas valve and opening said first inert gas valve.