[across-the-line] [reduced voltage start]] type with [general-purpose]
[weather-resistant] [water-tight] [dust-tight] [explosion-proof] enclosure.]
a.
Drag chain conveyor shall be of a single strand of wide, heat
treated, high alloy, drop forged, rivetless drag chain with a
[_____] mm inch pitch, [_____] mm inch overall width, and [_____]
kg pounds working strength, and shall have a hardness of 460-510
Brinell. The upper strand of the chain shall convey the ash in a
trough constructed of 9.5 mm 3/8 inch cast-iron extending from
[_____] mm inches in front of the foot shaft to [_____] mm inches
behind the head shaft and set flush with the floor. The return
strand of chain shall be carried in angle runways set flush with
the trench floor. The drag chain conveyor shall be driven by a
[_____] mm inch pitch roller chain and [_____] mm inch pitch
diameter, [_____] tooth sprocket on the drive shaft, and a [_____]
mm inch pitch diameter, [_____] tooth sprocket on the elevator
foot shaft.
b.
The casing shall be constructed of 2.656 mm 12-gauge thick steel,
minimum, with 9.5 mm 3/8 inch thick boot plates. The head-end
drive shall include a gear motor and steel roller chain complete
with drive brackets, guards, and backstop. The elevator shall be
equipped with head-end platform and ladder.
2.30.2
Ash Handling Controls
The ash handling system control panel shall contain all necessary
instrumentation, including selector switches, annunciators, push buttons,
and ammeters required for monitoring and operation of the ash handling
system. The panel shall graphically display the system. In addition, the
panel shall contain all necessary timers, relays, and terminal blocks that
are required for the control system. Control and monitoring of the ash
removal system shall be from a single panel. This panel shall have push
buttons to start automatic operation of each system and also push buttons
for individual control of each component. The panel shall have sufficient
instrumentation to observe the removal operations and controls to permit
effective emergency control. Local control stations at each ash removal
point for local manual operation shall also be provided. Local selector
switches shall be provided so that equipment may be operated manually for
test and maintenance purposes. The operation of the bottom ash system
shall be controlled by a microprocessor-based control system, a solid-state
programmable controller or an electromechanical system. All controls and
instrumentation for location indoors shall have NEMA 12 rating in
accordance with NEMA ICS 1. All outdoor components shall have NEMA 4
rating, in accordance with NEMA ICS 1. All major equipment components,
including control panels and devices, shall be factory-mounted, prewired,
tubed, and tested to the maximum practical extent. The system shall
include controls for fully automatic and sequential operation of the ash
handling system. These controls shall be designed so that manual steps,
such as continuous monitoring and regulation, will not be required.
Suitable safety interlocks shall be incorporated to assure that proper
permissive conditions have been met prior to changing the operating status
of major system components. Shutdown of the ash handling system, or
portion thereof, shall be automatically initiated, with alarms, should
unsafe conditions arise during operation of the system. Facilities for
monitoring and control of the ash handling system shall be provided for the
following functions:
a.
Manual start of the automatic control operations.
SECTION 15559A
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