Multi-Channel Zirconia Oxygen Analyzer

Boilers and various industrial furnaces were not only the most commonly used terminal techniques of energy, but also the main sources of air pollution. It was proved that the optimum combustion-state with minimum heat-loss and public nuisance, maximum efficiency for conversion and utilization obtaining by accurate control of combustion process was an important measure for energy-saving and environmental protection.An important method to keep the optimum combustion-state was to control oxygen concentration in flue gas. Traditional thermomagnetic oxygen analyzer with simple structure, easy fabrication and modification have been replaced by zirconia oxygen analyzer because of its long response time, big measurement error, easy clogging of measurement chamber and severe corrosion of heat-sensitive element.High sensitivity, high reliability, fast response, simple equipment were all advantages of zirconia oxygen analyzer, and high operating-temperature (600-1400℃) was fit for high-temperature(200-1000℃)flue gas in combustion-control. At present, zirconia oxygen analyzer has been commonly used in industrial furnace and has been gradually used in most of domestic station-boiler.Because of structure complexity of boiler flue, oxygen concentration in flue gas differs in different measuring points, therefore, selecting correct measuring point will have major influence on measurement results and control effects. It was proved that one measuring point was inadequate for combustion-control of station boiler. In general, more than three measuring points were necessary for the optimizing control system of boilers, and two zirconia oxygen analyzers were symmetrically installed on each measuring point, therefore, multi-channel zirconia oxygen analyzer was developed. In this paper, two-channel zirconia oxygen analyzer withhigh-performance analog device (A/D,D/A etc.) was developed using yttrium-stabilized zirconia (YSZ) tube as sensitive element and 89C58 as microprocessor, thus measurement and control of two oxygen analyzer could be realized on one equipment. Intrinsic error of measurement was±1% of full range using standard N2/O2 mixture (Shanghai Institute of Measurement and Testing Technology) as calibration.This equipment has been used by Jinshan Petrochemical Company and the prospective effect was obtained. We will develop four-channel and eight-channel zirconia oxygen analyzers on the base of two-channel one.