b.
Boiler Feedwater Automatic Recirculation System: (Option to
Automatic Valve). Provide to protect feedwater pumps at low flow
conditions. System shall be capable of recirculating the minimum
flow recommended by the pump manufacturer. System shall be an
engineered system consisting of various functional components
specified or shall be a self-contained and self-powered mechanical
system. Components of the engineered system shall include a flow
transmitter with orifice in feedwater line, bypass flow controller
with bypass flow control valve, and a bypass pressure reducing
orifice.
(1) System Bypass Flow Controller: Include detection of low flow
and modulation of a control valve in a bypass line returning to a
low pressure sink. Incorporate a pressure let-down feature or
device to reduce pressure from boiler feedwater pump discharge
pressure to that of the low pressure sink.
(2) System Bypass Control Valve: Modulate to provide minimum
flow recommended by the pump manufacturer and to provide shutoff
or recirculation flow when feedwater flow to boilers exceeds
minimum flow required for pump protection.
2.14.3.5
Feedwater Stop and Check Valves
Provide a Class 300, flanged, cast steel feedwater stop gate valve and
check valve on the feedwater outlet of each pump. Provide piping from
valves to economizer inlet, and from economizer to flanged connection on
boiler drum. Provide connection on pipe at economizer outlet for remote
recording thermometer.
2.14.4
Condensate Pumps
**************************************************************************
NOTE: Use this paragraph for centrifugal condensate
pumps. If regenerative type turbines are required
for the smaller capacities, they must be specified.
Use Style 1, horizontal split case pumps in all
sizes where available. Pump service requirements
shall include pump capacity of a minimum of 135
percent of boiler requirements at maximum load for
modulating service to the deaerator and 200 percent
for on-off service. Discharge head must include all
change in elevation and friction loses through pipe,
valves and fittings.
**************************************************************************
FS A-A-50562, Type I (general service), Style [1 (horizontally split case)]
[2 (end suction)], Class 1 (single stage) unless modified below.
2.14.4.1
Pump Service Requirements
a.
Capacity:
[_____] L/s gpm
b.
Pumping temperature range:
[_____ to _____] degrees C F
c.
Liquid pH:
[_____]
d.
Discharge head:
[_____] meters feet
SECTION 15501N
Page 128
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