A Combustion Monitoring and Evaluation System for Large Utility Boilers

A combustion monitoring and evaluation system, with a microcomputer, for large scale boilers in thermal power plants has been developed. This system can determine indices, such as impurity concentrations of NOx and CO, temperatures of heaters and burner impellers, thermal efficiency, etc. Standard values of these twelve indices necessary for proper operation, as well as the allowed upper and lower limit values, are shown in concentric circles on a color CRT. Measured index values are superimposed on the concentric circles in the form of a polygon. By comparison between measured and standard values, operators can determine the boiler combustion condition. When values of any index exeed the allowed limit values, an alarm signal is sent to the CRT with relevant messages indicating where to check. In addition, this system provides operating guidelines for optimal recirculation-gas control, enabling the reduction of NOx concentration in exhaust gas, since the plant can be operated in accordance with instruction procedures calculated by a multiple regression method.