Abstract

Despite increasing recycling quota the removal or long time storage of the remaining municipal waste remains a difficult task. This is valid especially in densely populated countries like Germany or Japan where there is little space for waste disposal sites. Hence waste combustion is used as a effective way to reduce the waste volume and to utilize the energy stored therein. However due to the large inhomogeneities of the refuse its combustion is a very demanding task. To minimize emission of pollutants and corrosion damage and to optimize energy production simultaneously fast in-situ diagnostics and active combustion control systems, like TACCOS [1], a thermography system based on an mid-infrared scanner camera which directly measures local imbalances in the fuel bed temperature or LISA [2], a CO₂-laser based in-situ ammonia sensor used for on-line control of NO_x removal systems (SNCR or SCR), are required. A very promising tool for the development of fast in-situ sensors are tunable diode lasers. They are inexpensive, compact, rugged, and relatively simple to operate. Due to their fast tunability, high spectral resolution and spectral power density they offer the opportunity for specific, nonintrusive, chemical sensors with a fast time response making them attractive for active combustion control. Since oxygen is one of the most important molecules for all combustion processes and not accessible by alternative optical detection methods there is a strong need (e.g. to adapt the secondary air flow or distribution in incinerators or other combustors) for a fast in-situ oxygen sensor which can measure at high temperatures and close to the reaction zone. Hence in a first attempt we tried to develop a diode laser based in-situ oxygen sensor which had to be fast enough for active control purposes e.g. in incinerators.

© 1998 Optical Society of America