To provide a dust collection structure of a combustion furnace which does not need any large installation area and any electric power for sucking, can uniformly and efficiently perform a dust collection and can prevent the dew condensation inside a stack.

The dust collection structure 10 comprises: a first smoke funnel 1 for passing exhaust gas to discharge to the outside by connecting it to the combustion furnace 9; a second smoke funnel 2 with a lower end 2B provided above the lower end of the first smoke funnel 1 and having an upper end 2A for discharging exhaust gas; a dust collection cylinder 3 provided inside the first smoke funnel 1, a dust collection vessel 8 provided at the lower end of the dust collection cylinder 3; and a plurality of duct collection cylinder windows 4 for internally introducing exhaust gas rising up through the space between the cylinder 3 and first smoke funnel 1 formed over the whole periphery of the cylinder 3. The second smoke funnel 2 is communicated with the dust collection cylinder 3 in the vertical direction.

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