Appendix E-2.c.i Energy Plan 2004-2013 Follow-up Studies and ...

Re-powering Study for the Northport and Port Jefferson Power Stations
Appendix II Northport System Descriptions
cold reheat system during turbine start-up, shutdown, and turbine trip events. The valve is controlled
through the steam turbine control system to prevent closure whenever the main steam stop/throttle valve
is open.
Each individual cold reheat line to an HRSG has a motor-operated gate valve and a branch from the main
steam bypass valve. Main steam is bypassed around the steam turbine to the cold reheat steam system
during plant start-up, shutdown, and when the turbine is out of service. The multiple combustion turbine
generators at Northport are assumed to operate at the same load over their range of operation. For this
reason, no balancing valves are provided in the cold reheat lines.
Within the HRSG scope of supply, IP superheater outlet piping connects to the cold reheat piping prior to
the reheat inlet connection.
A branch connection from the cold reheat line supplies steam to the auxiliary steam system during normal
operation. The branch has a motor operated block valve and a pressure control valve.
All portions of the cold reheat pipe, as well as the steam turbine HP casing, require overpressure
protection. For Northport Backyard Option, stop valves are located in the cold reheat leads to each
HRSG. These intervening stop valves could potentially isolate the relief path from the HP turbine outlet
connection to the HRSG reheater safety valves. Therefore, safety valves are required in the cold reheat
piping for Northport between the HP turbine outlet connection and the non-return valve.
Low point drain pots, equipped with level sensing devices, are in accordance with ASME TPD,
"Recommended Practices for the Prevention of Water Damage to Steam Turbines Used for Electric
Power Generation".
2.3 Hot Reheat
Refer to PID-03-3A and PID-03-03B in Appendix III.
The Hot Reheat Steam System directs superheated steam from the Hot Reheat outlet of each HRSG to the
IP steam turbine.
The reheater outlet temperature is controlled by an attemperator located within the HRSG boundary
between the primary and final sections. The attemperator uses IP feedwater to provide temperature
control and maintain the hot reheat outlet temperature.
The hot reheat steam line from each HRSG contains a flow nozzle, a bypass branch and a motor operated
stop-check valve. The HRSG steam leads combine into a common header en route to the steam turbine.
At the steam turbine, the header splits into two branches, one to each combined reheat valve.
Hot reheat bypass valves provide means to bypass hot reheat steam to the condenser during startup,
normal shutdown, steam turbine trips, or when the steam turbine is removed from service while the
combustion turbines continue to operate. The hot reheat lead from each HRSG is equipped with a steam
conditioning valve (bypass valve) to reduce the hot reheat pressure and temperature to acceptable
condenser design levels. Attemperating water for the bypass valves is from the condensate system
through temperature control valves.
Low point drains are in accordance with ASME TPD, “Recommended Practices for the Prevention of
Water Damage to Steam Turbines Used for Electric Power Generation”.
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