Combustion type waste gas treatment system

A combustion type waste gas treatment system comprising:

• a waste gas treatment system body including a burner part and a combustion chamber;
• a means for forming combustion flames inside said waste gas treatment system body;
• a waste gas supply line for introducing a waste gas into said waste gas treatment system body so as to oxidatively decompose the waste gas;
• an oxygen gas supply line for supplying oxygen gas;
• a fuel gas supply line for supplying fuel gas;
• a mixer outside said burner, said mixer being connected to said oxygen gas supply line to receive oxygen gas therethrough, being connected to said fuel gas supply line to receive fuel gas therethrough, and being shaped and arranged to mix together the oxygen gas and the fuel gas to thereby form a mixed gas, said mixer comprising an ejector for using oxygen gas as a driving force to suck the fuel gas into said mixer;
• a mixed gas supply line connecting said mixer to said waste gas treatment system body so as to supply the mixed gas formed in said mixer to said waste gas treatment system body, said mixed gas supply line having a bent portion at a location downstream of an outlet of said mixer;
• a temperature sensor for detecting backfire at said bent portion;
• an oxygen gas supply valve in said oxygen gas supply line;
• a fuel gas supply valve in said fuel gas supply line;
• a non-combustible gas supply line for supplying non-combustible gas;
• and
• a purge line arranged to inject the non-combustible gas from said non-combustible gas supply line into said oxygen gas supply line downstream of said oxygen gas supply valve, and into said fuel gas supply line downstream of said fuel gas supply valve;
• wherein said oxygen gas supply valve, said fuel gas supply valve, and said purge line are arranged and operable such that, when the combustion flames in said burner are extinguished, said oxygen gas supply valve and said fuel gas supply valve are closed, and said purge line injects the non-combustible gas from said non-combustible gas supply line into said oxygen gas supply line and said fuel gas supply line in an amount equal to an amount of the oxygen gas and the fuel gas which would otherwise be supplied through said oxygen gas supply line and said fuel gas supply line.