Vision-based measurement of temperature distribution in a 500-kW model furnace using the two-colour method

This paper describes the design and evaluation of a novel optical instrumentation system that has been developed for the on-line continuous measurement of temperature distribution in a furnace. The system comprises optical filters, a CCD camera, a frame-grabber and associated software. Based on the two-colour method, the average temperature of the flame field is calculated from the ratio of averaged grey levels of the two images alternatively captured at two different wavelengths. Accordingly, a pseudo-instantaneous temperature distribution is obtained from a single-wavelength image and presented by pseudo-colour. Experimental results obtained from a 500-kW model furnace show that the temperature distribution ranged from 1331 to 1606 °C for coal-fired flames and from 1156 to 1358 °C for gas-fired flames. A continuous monitoring of the temperature distribution in the furnace has also been performed over a period of 100 min. A comparison between the results measured by the system and those from a conventional pyrometer demonstrates that the system is capable of measuring the temperature distribution with a reasonable accuracy.