Numerous fossil steam turbine utilities are experiencing performance degradation due to copper deposition. Current restoration techniques involve periodic foam cleaning or blast cleaning of the steam path (depending on degradation rate), both of which can be costly in terms of unit down time. Using data from units experiencing similar problems, the deposition distribution pattern in the steam path can be determined. Steam turbine design analysis tools are applied to create an analytical model. Changes in bucket/nozzle surface finish, profile losses and reductions in flow area are included inputs. A direct comparison of output loss between older impulse-type and advanced, modern steam paths can then be made from the analytical model developed. Some conclusions as to the deposition conditions can be inferred from comparing the thermodynamic conditions to the deposition pattern.

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