Quality assurance of emission measurements. Factors influencing the determination of emissions

The aim of the project was to study the means to minimise uncertainties of the emission measurement results in calculation the annual emissions and in comparing the emission data to emission limit values of a plant. The report is based on uncertainty calculations by VTT Chemical Technology, results obtained from national comparison measurements and previous studies, is completed. Experimental knowledge of Finnish emission measurement institutes has also been available for the project. Uncertainties of the results were estimated for two cases (a coal-fired power plant and a gas boiler in a pulp plant both being a subject for comparison measurements). An emission measurement procedure and a procedure to calculate annual emissions were described for the cases. Additionally, international measures for the quality control of emission measurements are presented. In the report uncertainty factors of the results of particle, NOx, SO2, and flow rate measurements as well as suggestions of methods to minimise the uncertainty are presented. Uncertainties of emission measurement results were estimated in two cases taking into account the method used and the measuring conditions. The results indicate to a lowest achievable uncertainty with a state-of-art emission measurement equipment. The report deals also the uncertainty of calculation of annual emission in two case-plants.