| 摘要 |
A hoarding assembly having a non-combustible innermost portion is sealed against the cladding of a hot surface, such as that of a large boiler, to create an envelope. Outside air may enter the otherwise airtight envelope through controlled inlets in the hoarding assembly. The boiler is insulated with a layer of asbestos that is to be replaced. A vertically extending first array of supply air inlets is provided in one end wall of the hoarding assembly and a vertically extending second array of suction outlets is provided in the other end wall. A fan assembly injects cool air through the first array and a negative air machine assembly withdraws air through the second array. The placement of the inlets and outlets results in a wall of air moving parallel to the boiler wall and having its centerline spaced from the cladding, typically about 1 to 3 feet from it. With the foregoing operating, the sheet metal cladding is removed from the boiler. A narrow vertical strip of the asbestos is then removed. Insulation or a ceramic fiber curtain is temporarily placed over each exposed strip of boiler wall, to contain the heat radiation. The asbestos is progressively removed in this fashion. A sealant is then sprayed on the bared cleaned wall. The system overcomes the problems inherent in removing asbestos from a potent source of radiant heat, without shutting the boiler down.
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