| 摘要 |
PURPOSE:To prevent malfunction due to the outside air intruding from the outside of a batch type furnace, and to keep an optimum air-fuel ratio at all times by mounting a bypass piping crossing a first flow control valve to a fuel piping and totally closing the bypass piping in response to O2 concentration in exhaust gas from the furnace and when the opening of the first flow control valve is brought to a fixed value or less. CONSTITUTION:A bypass piping 6 with a second flow control valve 5 is mounted while crossing first flwo control valves 4 for a fuel piping 3. O2% by arithmetic operation and O2% (2.0%) by setting are compared by a control section 12 in detecting signals from an O2 concentration detector 11 detecting O2 concentration in exhaust as sampled from a duct 10, and a control motor 13 is operated in response to the deviation to open or close the second flow control valve 5, thus adjusting an air-fuel ratio. Signals to a control motor 9 from a temperature regulator 8 are transmitted over the control section 12, and the second flow control valve 5 is closed when the angles (the openings of the first flow control valves 4) of the control motor 9 are brought to a value such as 20% or less. |
