Patent ID: 8404030

Claim:
A method for renewing a sheet-type filtering material exposed to a flowing gas stream inside a conduit, said method comprising: (a) loading the sheet-type filtering material in a filter assembly with a supply of unused sheet-type filter material on a first side of the filter assembly and a leading edge of the sheet-type filter material on a second side of the filter assembly, across from the first side, so that a portion of the sheet-type filtering material is in a position to filter a flowing gas stream that traverses the filter assembly, the filter assembly receiving a propeller placed to allow a flowing gas stream traversing the filter assembly to rotate the propeller and a propeller shaft connected to the propeller to convert energy from the flowing gas stream traversing the filter assembly to rotational energy on the propeller shaft; (b) placing the filter assembly loaded with sheet-type filtering material into a conduit used for conveying a flowing gas stream such that that at least some of the flowing gas stream that will be forced through the conduit will traverse the filter assembly, including traversing the portion of the sheet-type filtering material in the position to filter the flowing gas stream; and (c) converting energy from the flowing gas stream that traverses the filter assembly through use of the propeller, and using at least a portion of the converted energy to indirectly drive a gear which drags the sheet-type filtering material across the filter assembly from the first side to the second side, whereby the portion of the at sheet-type filtering material in the position to filter the flowing gas stream traversing the filter assembly changes as long as a flowing gas stream traverses the filter assembly and the supply of unused filter type material is not exhausted.