Patent ID: 7707818

Claim:
An exhaust stack, comprising: a junction tube configured to receive exhaust gases from a heat recovery steam generator (HRSG); and a flue having a silencer portion, a converging duct portion, a tubular portion, and a diverging diffuser portion, the silencer portion fluidly communicating with the junction tube, at least a portion of the silencer portion having a first hydraulic mean cross-sectional flow path, at least a portion of the tubular portion having a second hydraulic mean cross-sectional flow path less than or equal to the first hydraulic mean cross-sectional flow path, the converging duct portion being coupled between the silencer portion and the tubular portion, the diverging diffuser portion being coupled to an end of the tubular portion opposite to the converging duct portion, such that exhaust gases flowing through the junction tube, the silencer portion, the converging duct portion, the tubular portion and the diverging diffuser portion have a reduced overall pressure drop, at least in part due to the diverging diffuser portion, and the second hydraulic mean cross-sectional flow path being less than or equal to the first hydraulic mean cross-sectional flow path.