Method of controlling atmosphere gas in continuous annealing furnace

摘要

PROBLEM TO BE SOLVED: To provide a control method of in-furnace atmosphere gas in a continuous annealing furnace capable of reducing atmosphere gas basic unit while maintaining a state without generating quality unsuitable at low cost with no need to arrange a new facility in the continuous annealing furnace and consider problems of spatial restriction.SOLUTION: When M(°C) and M(ppm), which are measured values of dew point temperature and carbon monoxide concentration with defining lower limitation values and upper limitation values of dew point temperature and carbon monoxide concentration at any section of a continuous annealing furnace at A1 (°C), B1 (ppm), A2 (°C) and B2 (ppm) respectively as control references satisfy one of Conditional Expression (1) or Conditional Expression (2), a Nth (1 or more and n or less) diffusion valve in n diffusion valves which is targets to be controlled is opened and when they satisfy Conditional Expression (3) and Conditional Expression (4), the Nth diffusion valve is closed.SELECTED DRAWING: Figure 3