Method of cleaning electric filter and electric filter

A method of cleaning an electric filter during filtration, said method comprising the steps of:

• feeding gas containing particles to a chamber of the electric filter by feeding means,
• feeding the gas containing particles further to gas channels in an emission system provided in the chamber, the gas channels being formed between separation electrodes in the emission system provided in the chamber and including emission electrodes,
• effecting electric charging of the particles in the gas and the attachment thereof to the separation electrode,
• removing the gas that has at least partly purified of particles from the gas channel of the emission system,
• removing the gas that has been at least partly purified of particles from the chamber of the electric filter through exhaust means,
• shaking the separation electrode with shaking means to remove the particles attached to the separation electrode therefrom,
• limiting the gas flow at least partly in such a gas channel that adjoins the separation electrode to be shaken by the shaking means when the separation electrode to be shaken by the shaking means is shaken whereby the shaking of the separator electrode with the shaking means is synchronized with the limiting of the gas flow such that the limiting of the gas flow occurs first followed thereafter by the shaking of the separation electrode, and
• in that the gas flow is limited by moving in a certain predetermined order a first perforated plate arranged in the gas channel and provided with first apertures in relation to a second perforated plate arranged in the same gas channel as the first perforated plate and provided with second apertures so that either the second perforated plate at least partly covers at least one of the first apertures provided in the first perforated plate and thus limits the gas flow through the first aperture or the first perforated plate at least partly covers at least one of the second apertures in the second perforated plate and thus limits the gas flow through the second aperture.

An electric filter comprising:

• a chamber including
• feeding means for feeding gas to be purified of particles to the chamber,
• separation electrodes forming gas channels between the separation electrodes, the gas channels being provided with emission electrodes that can be electrically charged,
• exhaust means for feeding gas purified of particles from the chamber,
• shaking means for shaking off particles from at least one separation electrode,
• closing means arranged in each gas channel for at least partly limiting the gas flow in each gas channel,
• synchronizing means arranged to co-ordinate the operation of the closing means and the shaking means such that after the closing means has at least partly limited the gas flow in the gas channel when the shaking means is activated to effect therewith the shaking of the separation electrode, and the closing means comprises in each gas channel a first perforated plate provided with first apertures and a second perforated plate provided with second apertures, the first perforated plate in each gas channel being movable in relation to the second perforated plate so that either the second perforated plate at least partly covers at least one of the first apertures provided in the first perforated plate and thus limits the gas flow through the first aperture or the first perforated plate at least partly covers at least one of the second apertures in the second perforated plate and thus limits the gas flow through the second aperture.