Experimental data are given on the best amount of dust accumulated before corona electrodes are shaken
(optimal dust capacity), which is functionally related to the resistivity of the dust layer. The ratios for the
shaking intervals are related to the degree of gas cleaning in the corona electrode fields.
Until recently, it was considered that shaking corona electrodes in electrical filters was necessary to provide a max-
imum cleanliness. To avoid the production of an insulating layer on a corona electrode, a shaking interval of 3–5 min was
suggested . However, frequent shaking leads to additional escape of dust from the filter and elevated wear on the shaking
units, so it is necessary to choose the best interval for shaking the electrodes.
The dust contents of gases at the inlet to electrical filters vary over the range 0.2–200 g/m
in various branches of
industry. If one assumes that shaking becomes necessary when there is a certain amount of dust on the electrodes, then the
lengths of the shaking intervals for the first fields in electrical filters will differ by factors of up to 10
Experiment shows  that a near-exponential law mostly applies to the amounts of dust on the electrodes in the
direction of the gas flow in the filters, and the degree of gas cleaning of 99.5% means that the amounts of dust trapped
on the electrodes (depositional and corona ones) for a four-field filter are in the ratio 54:14:3.8:1, while the relation
between the shaking intervals for the first and last fields will differ by a factor 54·10
on the basis of the range in the
input dust level, which shows that it is wrong to choose a fixed interval of 3–5 min for shaking the corona electrodes in
all electrical filters.
In each particular case, the necessary interval is controlled by the filter design, the working conditions, and the prop-
erties of the dust.
The corona in an electrical filter produces positive ions, and these give positive charge to a small part of the dust.
Some fraction of these particles is deposited on the corona electrodes (up to 1% of the amount of dust on the deposition ones).
The shaking interval for the corona electrodes is governed by the amount of dust and the electrical resistance of the
layer on the corona parts. If the dust is of low resistivity, the particles deposited on the corona parts form a conducting layer
and increase the radius of curvature, which raises the corona striking voltage, and reduces the corona current and the degree
of gas cleaning in the filter.
When the filter deposits low-resistance dust such as technical carbon, minimal shaking intervals are required for the
When high-resistance dust is deposited, a layer is formed on the corona sections that breaks down in the strong field
at the surface, so the ionizing capacity of the corona electrodes persists from some while. In the deposition for example of
high-resistance ash from Ekibastuz coal, the shaking intervals for the corona electrodes in the latter fields may be several hours.
Laboratory and industrial experiments have shown that the best amount of dust before shaking µ
capacity) is related to the resistivity ρ
of the trapped dust layer (Table 1).
Chemical and Petroleum Engineering, Vol. 41, Nos. 3–4, 2005
SHAKING OPTIMIZATION FOR ELECTRIC
FILTER CORONA ELECTRODES
Yu. I. Sanaev
Siberian Branch, NIIOGAZ OAO. Translated from Khimicheskoe i Neftegazovoe Mashinostroenie, No. 4,
pp. 36–37, April, 2005.
2005 Springer Science+Business Media, Inc.