Abstract: Exemplary embodiments are directed to systems and methods for controlling an outlet temperature of an evaporator having a plurality of evaporator tube bundles, in which a processor is configured to compute an outlet temperature setpoint for the evaporator based on outlet temperatures of each of the plurality of evaporator tube bundles. The processor also regulates fluid flow through at least one of the evaporator tube bundles to reduce deviation between the outlet temperature of the evaporator and the outlet temperature setpoint for the evaporator.

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 heat exchanger apparatus for receiving water from a steam drum (1) and providing steam and heated unevaporated liquid water to the steam drum includes a first evaporator (EVAP-1) and a second evaporator (EVAP-2). The first evaporator can receive water from a steam drum via a first feed conduit (9) and the second evaporator can receive water from a second feed conduit (11). Both evaporators can output heated fluid to the steam drum via a combined evaporator output conduit (13). Each first evaporator passageway (14) only makes a single pass through a gas duct (15) having a heated gas flow (7) passing therethrough while each second evaporator passageways (24) can make one or more passes through the gas duct for transferring heat from the gas to the fluid within the evaporators. A portion of the first feed conduit can also have a pre-specified volume a pre-specified height below the first inlet (10).

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: Exemplary embodiments are directed to systems and methods for controlling an outlet temperature of an evaporator having a plurality of evaporator tube bundles, in which a processor is configured to compute an outlet temperature setpoint for the evaporator based on outlet temperatures of each of the plurality of evaporator tube bundles. The processor also regulates fluid flow through at least one of the evaporator tube bundles to reduce deviation between the outlet temperature of the evaporator and the outlet temperature setpoint for the evaporator.

Abstract: A heat exchanger apparatus for receiving water from a steam drum (1) and providing steam and heated unevaporated liquid water to the steam drum includes a first evaporator (EVAP-1) and a second evaporator (EVAP-2). The first evaporator can receive water from a steam drum via a first feed conduit (9) and the second evaporator can receive water from a second feed conduit (11). Both evaporators can output heated fluid to the steam drum via a combined evaporator output conduit (13). Each first evaporator passageway (14) only makes a single pass through a gas duct (15) having a heated gas flow (7) passing therethrough while each second evaporator passageways (24) can make one or more passes through the gas duct for transferring heat from the gas to the fluid within the evaporators. A portion of the first feed conduit can also have a pre-specified volume a pre-specified height below the first inlet (10).