JPS57201551A - Electrical dust precipitator - Google Patents

Abstract

PURPOSE: To make dust precipitation of high efficiency possible even with soot and dusts of about 10¹¹W10¹⁴Ωcm specific resistances in the stage of flowing currents intermittently to a device operating on a DC high voltage controlled by an electric power control element such as thyristor by specifying electric charge time widths and charge rates.

CONSTITUTION: An intermittent control circuit 1 controls the phase of a thyristor 2 and is connected to either one of an automatic circuit 4 or a manual circuit 5 by a selection switch 3. A DC high voltage of variable pulse widths of about 0.01W1sec is applied to dust precipitating electrodes by using a commercial frequency or other power sources, whereby soot and dusts are precipitated thereon. Here, the charge time width T₁ is selected at about 20ms in the case of 50Hz and at 16ms in the case of 60Hz. At the same time, the charge rate T₁/ (T₁+T₂)(T₂ is a charge stop time) is selected respectively at ≤0.3, >0.2W<0.5, ≥0.3, in the case of ultra high-, middle high- and low high resistance dusts. Although there are differences in the degree of generation of the reverse ionization phenomena of dusts in accordance with their electric resistances, the timings for charging of the dust precipitating electrodes are optimized by this and the intended purpose is achieved.

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