a.
Drag Chain Conveyor: 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.
Elevator Conveyor: Elevator conveyor shall be a single strand
chain positive discharge type with head and takeup. The casing
shall be constructed of 2.657 mm (12 gauge) 12 gauge 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.
2.24.2
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
pushbuttons to start automatic operation of each system and also
pushbuttons 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 electro-mechanical system.
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. 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 15555A
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