Spectrometer-based combustion monitoring for flame stoichiometry and temperature control

Conventional combustion control systems for multi-burner furnaces rely on simplified temperature measurement schemes away from the flame and single-point exhaust monitoring of excess O2 and, sometimes, CO. However, an overall furnace stoichiometry control does not preclude inefficient operation of individual burners due to local maldistributions of air and fuel, or malfunction of burner hardware. This, in turn, results in furnace operation at less than optimal fuel efficiency and elevated pollutant emissions. This paper reports on the application of a spectrometer-based system to provide real-time flame stoichiometry and temperature monitoring capabilities at the burner level in natural gas-fired glass furnace applications. The system consists of a special collimating lens, a dual commercially available off-the-shelf spectrometer setup and a bifurcated fiber-optic cable. This paper details full-scale experiments conducted at a 13.7 × 106 kJ/h multi-burner oxyfuel-fired fiberglass furnace and a 179.4 × 106 kJ/h multi-burner gas/air-fired flat glass furnace. The results show great promise for on-line combustion condition monitoring and control applications.