Apparatus and method of purging gas turbine exhaust trough to reduce hot flow leakage

Abstract

A purge box, which is added to an expansion joint between an exhaust diffuser and an aft diffuser, can include a cover plate and a T-fairing radially adjacent the cover plate. An inner fairing of T-fairing can be an extension of a duct of the exhaust diffuser and can be attached to a flex seal of the joint. A leg of the T-fairing extends radially outward toward a cover projection extending from a rear of the cover plate. A purge box flow path can have at least one seal therein to reduce flow while accommodating radial and/or axial movement of the duct, the cover plate, and/or the T-fairing to improve operational efficiency of the turbine and safety of those nearby.