Exhaust stacks and power generation systems for increasing gas turbine power output

A power generation system, comprising:

• a gas turbine having a compressor, a combustion region and a turbine, the compressor being configured to compress air, the combustion region being configured to receive the compressed air from the compressor and combust a mixture of the compressed air and fuel which produces exhaust gases, and the turbine being configured to receive the exhaust gases from the combustion region and rotate in response to an expansion of the exhaust gases, such that a pressure of the exhaust gases decreases as the exhaust gases expands through the turbine;
• a heat recovery steam generator configured to receive the exhaust gases and generate steam from heat of the exhaust gases;
• and
• an exhaust stack having a junction tube and a flue, the junction tube being configured to receive the exhaust gases from the heat recovery steam generator, the 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 local 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, the reduced local pressure drop increasing an overall pressure differential of the exhaust gases through the turbine and increasing an amount of power output of the gas turbine.

An exhaust stack, comprising:

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

A power generation system, comprising:

• a gas turbine having a compressor, a combustion region and a turbine, the compressor being configured to compress air, the combustion region being configured to receive the compressed air from the compressor and combust a mixture of the compressed air and fuel which produces exhaust gases, and the turbine being configured to receive the exhaust gases from the combustion region and rotate in response to an expansion of the exhaust gases, such that a pressure of the exhaust gases decreases as the exhaust gases expands through the turbine;
• a heat recovery steam generator configured to receive the exhaust gases and generate steam from heat of the exhaust gases;
• and
• an exhaust stack having a junction tube and a flue, the junction tube being configured to receive the exhaust gases from the heat recovery steam generator, the flue having a first tubular portion, a first diverging diffuser portion, a silencer portion, a converging duct portion, a second tubular portion, and a second diverging diffuser portion, the first tubular portion fluidly communicating with the junction tube, at least a portion of the first tubular portion having a first hydraulic mean cross-sectional flow path, at least a portion of the silencer portion having a second hydraulic mean cross-sectional flow path, the first hydraulic mean cross-sectional flow path being less than or equal to the first hydraulic mean cross-sectional flow path, the first diverging diffuser portion being coupled between the first tubular portion and the silencer portion, at least a portion of the second tubular portion having a third hydraulic mean cross-sectional flow path less than or equal to the second hydraulic mean cross-sectional flow path, the converging duct portion being coupled between the silencer portion and the second tubular portion, the second diverging diffuser portion being coupled to an end of the second tubular portion opposite to the converging duct portion, such that exhaust gases flowing through the junction tube, the first tubular portion, the first diverging diffuser portion, the silencer portion, the converging duct portion, the second tubular portion and the second diverging diffuser portion have a reduced overall pressure drop, at least in part due to the second diverging diffuser portion, and the third hydraulic mean cross-sectional flow path being less than or equal to the second hydraulic mean cross-sectional flow path.