Application of quotient pyrometry to industrial pulverised coal combustion

Abstract

This paper will show the application of quotient pyrometry for the measurement of particle cloud temperatures in industrial pulverised coal combustion systems. The main objective of the work is to facilitate those measurements in industrial furnaces and to investigate the distribution of particle cloud temperatures in a full-scale furnace under full load conditions. For this application a special configuration, the combination of a three-colour quotient pyrometer with an optical fiber integrated in water-cooled probe, was developed. The probe, with a length of 8.5 m, facilitates temperature measurements up to 1600 °C and a penetration depth into the furnace of about 6 m. A water-cooled background in front of the probe excludes the background radiation of the flames and so reduces the visual range of the optical fiber. For the investigation of the temperature distribution extensive measurements were carried out in a 730 MW th bituminous coal fired utility boiler. The measurements took place in the near-burner zone and above the over fire air injection. The results show the distribution of the particle cloud temperatures in the different zones. The comparison with additionally determined flue gas temperatures, particle velocities and gas concentrations mirrors the main in-flame processes. The presentation of time-resolved temperatures shows the fluctuation of particle cloud temperatures in the furnace and therefore of the combustion process itself.