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AssigneeSage of America, Inc.
InventorMarcio Gerep
Estimating the term…
Boiler tube studs of composite construction, particularly for protecting waterwall tubes in pulp mill recovery boilers. The studs include an inner solid cylindrical core of a material having thermal conductivity sufficient to provide proper heat transfer to the boiler tubes during operation, and an outer cylindrical sleeve of a material resistant to destructive conditions within a boiler during operation, such as chemical attack and abrasion. The sleeve surrounds the cylindrical surface of the core, but leaves an end surface of the core exposed. The core may be made of low carbon steel, and the sleeve of stainless steel. In order to avoid melting of the stainless steel sleeves when the studs are welded to the tubes, the cylindrical sleeves do not extend all the way to the attachment end such that axial gaps are defined where the sleeves do not cover the cylindrical surfaces of the cores. Compared to standard carbon steel studs, the composite studs have a much longer life before replacement is required, and yet they wear sufficiently for wear patterns to be observed as an indicator of boiler operating conditions. The composite studs maintain a cylindrical configuration as they wear, resulting in improved anchoring of a frozen smelt layer and thus protection of the boiler tubes compared to conventional studs. The composite studs are compatible with conventional studs, in the context of either studs replacement, or replacement of tubes or groups of tubes in panels, and methods of use are disclosed.
A boiler tube stud of composite construction comprising:
A recovery boiler for burning black liquor in a pulp mill, said boiler comprising:
A method for protecting carbon steel boiler tubes in a recovery boiler, said method comprising:
Dependencies are inferred from the claim text.