| 摘要 |
PURPOSE:To prevent drop in gas temperature and burn harmful gas by a method wherein the position of returning exhaust gas from a preheating chamber to a combustion chamber is changed over in accordance with the production rate of harmful gas. CONSTITUTION:In case harmful gas can be reduced to almost nil by heating the gas in a preheating chamber 7, the high temperature gas in a combustion chamber 4 is dishcarged from the preheating chamber 7 through a bypass pipe 26 by opening only a change-over valve 27. When a small amount of harmful gas is produced by heating the gas in the preheating chamber 7, a change-over valve 21 is opened to introduce the exhaust gas from the preheating chamber 7 through an exhaust supply pipe 17 into the space under the combustion chamber 4 where it is burnt and emitted from a flue 10 installed under the chamber 4. In case a large amount of harmful gas is produced by heating the gas in the preheating chamber 7, the change-over valves 24 and 25 are opened to introduce the exhaust gas from the preheating chamber 7 into the space above the combustion chamber 4 together with the high temperature gas from an electric oven 1 so as to burn the harmful gas and discharge it through the flue 10. |
