Abstract: Heat recovery steam generators (HRSGs) including components and systems for reducing thermal stress experienced by manifolds within the HRSGs are disclosed. The HRSG may include a manifold receiving a working fluid of the HRSG, a plurality of piping links in fluid communication with the manifold, and an enclosure surrounding the manifold and the plurality of piping links. The HRSG may also include at least one thermal element positioned within the enclosure. The thermal element(s) may surround the manifold. Additionally, or alternatively, the HRSG may include a supplemental heating system in fluid communication with an interior of the enclosure. The supplemental heating system may include a heater for heating fluid (e.g., air), and an inlet conduit in fluid communication with and positioned downstream of the heater. The inlet conduit may be formed through the enclosure to provide the heated fluid to the interior of the enclosure.

Abstract: Heat recovery steam generators (HRSGs) including components and systems for reducing thermal stress experienced by manifolds within the HRSGs are disclosed. The HRSG may include a manifold receiving a working fluid of the HRSG, a plurality of piping links in fluid communication with the manifold, and an enclosure surrounding the manifold and the plurality of piping links. The HRSG may also include at least one thermal element positioned within the enclosure. The thermal element(s) may surround the manifold. Additionally, or alternatively, the HRSG may include a supplemental heating system in fluid communication with an interior of the enclosure. The supplemental heating system may include a heater for heating fluid (e.g., air), and an inlet conduit in fluid communication with and positioned downstream of the heater. The inlet conduit may be formed through the enclosure to provide the heated fluid to the interior of the enclosure.

Abstract: The present disclosure is directed to a method and a system employing a gas introduced into the system as a startup operation for a natural circulation vertical heat recovery steam generator (HRSG) to initiate natural circulation of a fluid within the system. More specifically, the present disclosure is directed to a method and a system employing a gas introduced into an outlet header of an evaporator, into an outlet header of an evaporator and into one or more risers near the outlet header of the evaporator, or into one or more risers near the outlet header of the evaporator, to initiate natural circulation of a fluid in a desired system direction from the evaporator directly into a steam drum.

Abstract: A system for preheating a heat recovery steam generator is provided. The system includes a tank and a heat exchanger. The tank contains a transferring medium. The heat exchanger is disposed in a flow path of a flue gas produced by a combustion chamber, and is fluidly connected to the tank such that the transferring medium flows through the heat exchanger and is heated by the flue gas. The transferring medium preheats one or more components of the heat recovery steam generator.

Abstract: A system for preheating a heat recovery steam generator is provided. The system includes a tank and a heat exchanger. The tank contains a transferring medium. The heat exchanger is disposed in a flow path of a flue gas produced by a combustion chamber, and is fluidly connected to the tank such that the transferring medium flows through the heat exchanger and is heated by the flue gas. The transferring medium preheats one or more components of the heat recovery steam generator.

Abstract: Disclosed herein is a heat recovery steam generator system comprising a vestibule comprising a base plate, a roof and side walls; where the base plate is opposedly disposed to the roof; a heat exchanger space through which an exhaust gas stream is charged; where the vestibule is disposed atop a heat exchanger space; and where the vestibule comprises at least one header in fluid communication with a tube bundle; where a portion of the tube bundle is disposed in the heat exchanger space; and a support system for the tube bundle; where the support system comprises a strap that is reversibly attached to the base plate as well as to the roof of the vestibule or to a structural member in the vestibule; and where each tube of the tube bundle contacts a collar that rests on the base plate.

Abstract: The present disclosure is directed to a method and a system employing a gas introduced into the system as a startup operation for a natural circulation vertical heat recovery steam generator (HRSG) to initiate natural circulation of a fluid within the system. More specifically, the present disclosure is directed to a method and a system employing a gas introduced into an outlet header of an evaporator, into an outlet header of an evaporator and into one or more risers near the outlet header of the evaporator, or into one or more risers near the outlet header of the evaporator, to initiate natural circulation of a fluid in a desired system direction from the evaporator directly into a steam drum.

Abstract: Disclosed herein is a heat recovery steam generator system comprising a vestibule comprising a base plate, a roof and side walls; where the base plate is opposedly disposed to the roof; a heat exchanger space through which an exhaust gas stream is charged; where the vestibule is disposed atop a heat exchanger space; and where the vestibule comprises at least one header in fluid communication with a tube bundle; where a portion of the tube bundle is disposed in the heat exchanger space; and a support system for the tube bundle; where the support system comprises a strap that is reversibly attached to the base plate as well as to the roof of the vestibule or to a structural member in the vestibule; and where each tube of the tube bundle contacts a collar that rests on the base plate.

Abstract: A gas turbine combined cycle system with a heat recovery steam generator which may include enclosed adjacent cavities may accumulate combustible gas mixtures during shut-downs. Gas detectors located in the heat transfer section of the heat recovery steam generator, in related duct work and in the adjacent cavities detect the presence of these gas mixtures and produce appropriate signals. A signal from the detectors in the cavities initiate the aspiration of the mixture from the cavity. Signals from the detectors in the heat transfer section and ducts as well as from the cavities control the gas turbine so that upon start-up, no fuel is introduced to the gas turbine so that the gas turbine forces purge air through the heat recovery steam generator. When all of the signals indicate that no combustible gas mixtures are present, the gas turbine is ignited.