Air-fuel ratio fine control method based on flue gas online analysis

The invention relates to the technical field of air-fuel ratio control in the combustion process of a heating furnace, and discloses an air-fuel ratio fine control method based on flue gas on-line analysis, which comprises the following steps: S1, adding a laser flue gas analyzer in the heating furnace to measure O2 content and CO content in a primary heating section, a secondary heating section and a soaking section of the heating furnace to obtain actual values, s2, in the state of stable control over the gas flow and the heat value, the air excess coefficient reference value k based on the furnace type, equipment and control precision of the heating furnace is obtained by tracking the air excess coefficients under different air-fuel ratios and the temperature change condition of the heating furnace of the corresponding section, and automatic control is conducted in combination with the measured value of the L1 instrument and the L2 model process; on one hand, the combustion state of the heating furnace can