Abstract
The technique of dust sampling in flue gas emitted from stationary sources is widely used for purposes of controlling air pollution and evaluating the performance of dust collectors. In the dust sampling, the gas sample must be aspirated into the nozzle of the sampler at the same velocity as that of the stack gas to avoid inertial segregation.
For the purpose of confirming the effects of anisokinetic sampling of dust concentration and examining the equations estimating the effects, a lot of anisokinetic dust sampling were carried out over a wide range of sampling ratio. For the oil-fired flue gas 36 samples by anisokinetic sampling and 11 samples by isokinetic sampling, and for the test dust-laden gas 48 samples of coal fly ash, 24 samples of calsium carbonate and 24 samples of titanium dioxide were obtained. For larger particles in the test dust-laden gases the effects of anisokinetic sampling are considerably large, while for fine particles of approximately 0.2 pm the effects are negligible, which proves that isokinetic sampling is not necessary for oil-fired flue gases.
These results were compared with the well-known estimating equations proposed by S. Badzioch ('60), H. H. Watson ('54), C. N. Davies ('54), G. S. Mirrell ('75) and Yoshida et al.('76). It has been confirmed that the results agree fairly well with the inclination calculated from the Davies' equation and the theoretical resolution by Yoshida et al. The Dav ies' equa tion may be recommended for estimating the errors of anisokinetic sampling because it can be easily made use of.
