Assessment of opacimeter calibration on kraft pulp mills

This paper describes the methodology and specific techniques for calibrating automatic on-line industrial emission analysers, specifically equipments that measure total suspended dust installed in pulp mills within the scope of Portuguese Regulation No. 286/93 on air quality. The calibration of opacimeters is a multi-parameter relationship instead of the bidimensional calibration which is used in industrial practice. For a stationary source from a pulp mill such as the recovery boiler stack, which is subjected to significant variations, the effects of parameters such as the humidity and gas temperature, deviations of isokinetism, size range of particles and characteristic transmittance of equipment are analysed. The multivariable analysis of a considerable set of data leads to an estimate of about 98% of equipment transmittance over the other parameters with a level of significance greater than 0.99 which is a validation of the bidimensional practical calibrations.