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
A constant differential pressure is maintained across the HP drum level control valves by varying the
speed of the feedwater pump.
A motor operated on-off tight shutoff valve is provided downstream of the HP drum level control valve to
prevent water leakage into the drum during startup.
2.8.2 Intermediate Pressure Feedwater
Each feedwater pump has an interstage bleed connection for IP feedwater supply to the HRSG IP
economizer inlet. The connection is piped to a line containing a pressure gage, a check valve, and a gate
valve. A branch line from the condensate system connects to the line to provide water to fill the IP drum.
A branch from the line provides water for the HRSG reheater attemperator. This line has a gate valve and
a flow element and transmitter for DCS indication.
Downstream of the branch connections there is a pressure transmitter. The IP feedwater line connects to
the HRSG IP feedwater inlet connection. Downstream of the inlet connection, within the HRSG's
vendors scope, there is a check valve, a manual gate valve, the IP economizer, a flow element with a flow
transmitter, a temperature element, a drum level control valve with manual block and bypass valves, and
an air operated on-off tight shutoff valve. The flow signal, along with the drum level and steam flow
signals, is used to position the drum level control valve.
A branch line immediately downstream of the economizer and upstream of the drum level control valve
provides the heating medium for the fuel gas heater.
2.9 Fuel Gas
Refer to PID-8-7A through 7D in Appendix III.
The fuel gas delivered to Northport is AGA pipeline quality gas. No gas compressors are required.
The fuel gas system (FGS) is designed to meet the requirements of the CTs including flow, pressure,
temperature, moisture content, and cleanliness. To provide these requirements the FGS will include a
pressure-reducing station, metering, filtration, gas heating, flow control, and scrubber with vent stack and
CH4 monitors to detect gas leakage.
The FGS piping begins at the outlet of the gas suppliers metering station. A single line is routed from the
metering station, through a knockout drum and filter/separator to meet the CT cleanliness requirements.
Liquids separated from the gas stream are automatically drained into a fuel gas drains tank. A
containment area is provided under the drain for capturing spills. A knockout drum, designed to remove
any liquids from the pipeline gas, will be installed at the interface with the gas supplier upstream of the
filter/separator.
For The Backyard Option at Northport, a 100% capacity shell and tube fuel gas heat exchanger is
provided for each gas turbine to raise the fuel temperature to the gas turbine manufacturer’s requirements.
The source of heat for these is cycle steam. The fuel gas supply lines leaving the heaters are routed to
their respective CT enclosures. The CT enclosures include the gas shutoff, vent, and control valves that
control the flow of gas to the CTs.
2.10 Aqueous Ammonia
Refer to PID-08-17A in Appendix III.
March 30, 2009 163