Demolition of tuyere -> professional unit to determine air dust situation -> add inspection robot -> look inside the duct, determine the cleaning solution (CD) can be made up -> in needs cleaning duct two placed two airbags and cut a small opening on one side of the circular hole (or using original outlet), and referring to the hole and the trap of suction hose connection -> again from another (or use the original outlet) into the cleaning robot walk while playing loose dust by the dust catcher and the siphon off the "Yang Chen aspiration method" (suitable for medium and small duct).