Filtering method of flue gas of a boiler and a filter apparatus for hot gas

A filter apparatus for hot gas comprising:

• ceramic filters incorporated in a vessel;
• a reverse cleaning means for regenerating the ceramic filters by removing dust trapped by the ceramic filters;
• a hopper provided at a lower portion of the vessel for collecting the removed dust;
• a diffuser provided in the vicinity of a gas introducing port of the vessel or at a dust laden gas introducing pipe;
• and
• one or more gas passages for communicating an inlet of the diffuser with the hopper;
• wherein the diffuser converts a dynamic pressure of the dust laden gas to a static pressure and recirculates the dust laden gas to the inlet of the diffuser from the hopper and through said one or more gas passages by utilizing said static pressure.

A filter apparatus for hot gas, comprising:

• ceramic filters incorporated in a vessel;
• reverse cleaning means for regenerating the ceramic filters by reverse cleaning;
• at least one detecting means for directly or indirectly detecting flue gas accompanied by unburnt component and a flying-over of the unburnt component to the filter apparatus;
• control means including means for opening and closing valves of a compressed gas in response to a signal transmitted from the control means when the flying-over of the unburnt component is detected to thereby start a frequent reverse cleaning in which compressed gas is blown into a space on a cleaned gas side of the filter apparatus, wherein the frequent reverse cleaning is continued until the flying-over of the unburnt component decreases to a small quantity.