COMPARISON OF METHODOLOGIES FOR CONTINUOUS, AUTOMATIC EMISSION DUST MONITORING

Introduction

Automatic monitoring for particulates in gaseous medias is a special challenge, as the required answer from the monitors is a signal of Concentration, however, the matter to be detected is a mixture of two phases (stack gas = gaseous phase, particulates = solid phase), and such a mixture never can be ideal. Therefore in-situ methods avoiding the extraction of sample gas for measurement have a significant advantage over extractive methods. For extractive methods (including the reference method Isokinetic Gravimetric Sampling) the position of the extraction point (= representative point) is of vital importance for the accuracy of the measurement.

For automatic monitoring various methodologies are available. In general they can be grouped into several, partially also overlapping, groups:

Qualitative and Quantitative Methods

In-situ and Extractive Methods

Electrical and Optical Methods

Optical methods can be sub-grouped into Light-Transmission and Light-Scattering Methods.