A portable calibration gas generator for H2O, HCl, NH3 and Mercury
The calibration of emission measurement systems for water vapor, hydrogen chloride, ammonia and mercury is difficult and span gas is not available for every component. On the principle of the dynamic evaporation of liquids and the continuous addition of carries gas, a portable calibration gas generator was developed. Linearity, accuracy and the reproducibility is comparable with the quality of certified cylinder span gas or even better. Besides a number of advantages over existing calibration methods, the system provides a calibration gas with similar constitution as flue gas especially for water content. Mercury chloride has been investigated up to a concentration of 150 μg/m³. Besides carrier gas flow variation, also time constant and the speciation of mercury under the influence of evaporator temperature has been examined.