2.11.8
Fluidizing System
Provide on the silo floor to ensure a constant and uniform feed of ash
through the silo discharge outlet. System shall consist of a series of
diffuser modules, a conical diffuser hood, designed to support the total
weight of ash when the silo is full, and compressed air piping. Each
diffuser module shall be mounted on the silo floor using sloped concrete
pads. System shall operate from the plant air system. Provide pressure
reducing valves, safety valves, and controls for a complete system.
2.11.9
Control Panel and Controls
Provide a semi-automatic control system for the ash handling system [as
indicated]. Provide a centrally controlled operation, with auxiliary local
operation, and a monitoring control system with graphic display for the ash
conveying system. Provide local control stop-start pushbuttons and
indication stations for chain drag conveyor, screw conveyors, bucket
elevator, and rotary ash conditioner. Ash handling system manufacturer
shall provide measuring devices, status switches, solenoid valves, and
auxiliary parts necessary to safely control and operate the system.
Provide related electrical work required to operate the ash handling
system. [Ash handling system manufacturer shall provide detailed control
logic diagrams to the manufacturer of the digital process control and data
acquisition system specified under VAMS Section 15901N CONTROLS AND
INSTRUMENTATION BOILER PLANT.]
2.11.9.1
Control Panel
Provide a [separate control panel] [subpanel mounted in the main plant
control panel] of NEMA 12 construction, centrally located in the main plant
control room. Panel front shall include a system graphic display as
indicated. Display shall be approximately to scale and painted with an
industrial acrylic enamel. Outline items with 3 mm 1/8 inch wide black
lines. Lettering shall be on engraved plastic screwed to the front of the
panel, with white letters on a black background. Provide controls for
operation on [_____] volt, [_____] phase, 60 Hz a.c. Panel shall be
complete with an annunciator and interlocks, relays, switches, running and
safety lights, and auxiliary parts necessary to safely control and operate
the system. Items located in the door shall be dusttight and oil tight
with push-to-test indicating lights being of the transformer type. Control
relays shall be 10 amp, 600 volt class with convertible contacts. Provide
and mark terminals for connections with the exception of the neutral.
Panel shall contain [_____] percent spare terminals. Wiring shall be No.
14 AWG Type THHN stranded. Neutral wire shall be white and other wiring of
120 volts or less shall be color coded and labeled. Provide a plastic wire
duct of sufficient size to provide [_____] percent cross sectional spare.
Wiring shall be in accordance with the requirements of NFPA 70.
2.11.9.2
Control Panel Devices
a.
Control panel shall include the following indicating lights (color
in parentheses):
(1)
Power - ON
(red)
(2) System Run (3 required)
Chain drag conveyor to elevator
(green)
Screw conveyors to drag conveyor
(green)
Bucket elevator to silo
(green)
SECTION 15502N
Page 128
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