Heat exchanger with heat exchange tubes moveable between aligned and non-aligned positions

A combined cycle power plant (CCPP), comprising:

• a gas turbine system;
• a steam turbine system;
• and
• a heat recovery steam generator (HRSG) coupled to the gas turbine system to create steam for the steam turbine system using an exhaust of the gas turbine system, wherein the HRSG includes:
• a casing configured to direct the exhaust therethrough;
• a plurality of heat exchange tubes fluidly coupled to a water/steam header and positioned within the casing, the plurality of heat exchange tubes arranged into a first row of tubes and a second row of tubes;
• a fixed mount fixedly positioning the first row of tubes relative to the casing;
• and
• a movable mount operatively coupled to the second row of tubes, the movable mount movable between an aligned position in which heat exchange tubes in the second row of tubes are aligned with heat exchange tubes in the first row of tubes, creating a linear flow path for the exhaust through the plurality of heat exchange tubes, and a non-aligned position in which heat exchange tubes in the second row of tubes are not aligned with heat exchange tubes in the first row of tubes, creating a curvilinear flow path for the exhaust through the plurality of heat exchange tubes,
• wherein heat is exchanged between the exhaust and a water/steam flow passing through the plurality of heat exchange tubes.

A method for operating a heat recovery steam generator (HRSG) of a combined cycle power plant (CCPP), the HRSG including a plurality of heat exchange tubes arranged in rows, the HRSG being part of a system including a gas turbine (GT) system and a steam turbine (ST) system, the method comprising:

• measuring at least one operating parameter of at least one of the HRSG, the gas turbine (GT) system of the CCPP, and the steam turbine (ST) system of the CCPP;
• in response to at least one operating parameter not meeting a threshold, moving a first row of the plurality of heat exchange tubes relative to a second, fixed row of the plurality of heat exchange tubes between an aligned position in which heat exchange tubes in the second, fixed row of the plurality of heat exchange tubes are aligned with heat exchange tubes in the first row of the plurality of heat exchange tubes, creating a linear flow path for a first fluid through the plurality of heat exchange tubes, and a non-aligned position in which heat exchange tubes in the second, fixed row of the plurality of heat exchange tubes are not aligned with heat exchange tubes in the first row of the plurality of heat exchange tubes, creating a curvilinear flow path for the first fluid through the plurality of heat exchange tubes,
• wherein heat is exchanged between the first fluid and a second fluid passing through the plurality of heat exchange tubes.