Stack dust sampling is often carried out using a sampling nozzle and a certain length of sampling line which is connected with a dust sensor or a dust collector.
Dust deposition was experimented using CaCO₃ powder (mmd=4μm) as test dust and 2m of sampling tube (dia.=φ6-14 mm). The test dust was deposited about 45-53% upstream of the dust collector, and especially 20-26% in the 90° bend of the sampling nozzle.
In order to prevent dust deposition the mechanical vibration was added to the sampling line using a magnetic vibrator. As a result of the experiment the prevention effect or dust re-bounce was confirmed significantly with the stronger vibration effect, which was defined as the ratio of vibration acceleration to vibration frequency. About 86% of dust deposition was reduced in the range above 1.5 G/Hz for flyash and CaCO₃ dust respectively, though vibration effect was applied up to 1.7 G/Hz in this experiment.
Vibration Reynolds number was adopted by non-dimensionizing the strength of vibration effect. It was found that the relation between vibration Re and reduction of dust deposition was expressed in a curve line for both the test dusts, and from the relation high reduction rate over 90% can be predicted to be obtained for above 700 of vibration Re.