The CellaCombustion PX 47 is a special pyrometer for non-contact temperature measurement of sooty flames in coal power plants or waste incineration plants. The measurement and signal processing based on the two-colour method detects the heat radiation of the sooty particles of the flame in the near infrared region at two wavelengths. The burn-out operation can be optimized by the flame temperature, the pollutant emission can be reduced and the slagging of the walls in the combustion chamber can be minimized.