b.
Selection of operating components.
c.
Override of the automatic control sequences, both at the ash
handling control panel and locally.
d.
Manual operation, either remotely from the control center or
locally.
e.
Emergency shutdown on a unit or system basis.
f.
Status monitoring at the ash handling control panel of the
operation of the ash handling system and its components.
The automatic controls for bottom ash collection transport shall operate as
specified. When a start command has been manually initiated, the automatic
ash collection and transport sequences for the unit shall progress through
their complete cycles, and after completion of the cycles, the system shall
automatically shut down. The system shall include an annunciator system,
complete with audio and visual alarms, as part of the ash handling control
panel. The annunciator system shall receive inputs from devices and system
logic which shall indicate any out of specification or trip condition.
Recorders shall be furnished to provide a permanent record of selected
variables that relate to the ash handling system's performance and
operation. Control stations supplied with analog control loops shall
provide bumpless transfer between the manual and automatic modes of
operation. The manual mode of operation shall provide direct control of
the end device with no intervening analog control components unless those
components are powered by the same source as the end device.
2.30.3
Submerged Drag Chain Conveyor (SDCC)
Submerged drag chain conveyor shall be designed to extract ash at normal
capacity [_____] metric tons/hour TPH and maximum capacity [_____] metric
tons/hour TPH, based on a dry ash density of approximately [_____] kg/cubic
meter pcf. The maximum chain speed shall be 76 mm/second 15 fpm. The SDCC
shall be designed for continuous operation and shall have a storage
capacity of [_____] cubic meter cu ft accumulation. The SDCC shall have an
upper compartment filled with water and a dry lower compartment. The
equipment shall be provided to maintain water temperature at approximately
60 degrees C 140 degrees F. The dewatering slope shall be at an angle of
[_____] degrees with the horizontal. The top trough shall be not less than
9.5 mm 3/8 inch thick carbon steel plate, welded construction, lined with
renewable abrasion resistant steel wear plates, with a minimum thickness of
13 mm 1/2 inch and 300 BHN. All welds shall be ground smooth. The
necessary track guide angles, hold-down angles, and carbon steel chain
protectors shall be provided. The minimum depth of water in the upper
trough shall be [_____] m feet. The return chain bottom trough shall be
dry, constructed of 9.5 mm 3/8 inch thick steel plate, stiffened and braced
with structural shapes and shall be water-tight. Chain track angles shall
be provided with a minimum 13 mm 1/2 inch thick steel replaceable wear
flats with a minimum 300 BHN. Wear strips shall be also provided under the
return flights, minimum 13 mm 1/2 inch thick and 50 mm 2 inch wide. The
conveyor chain shall be a double strand round-link or ship-type chain, case
hardened, corrosion and abrasion resistant, chrome-nickle-alloy, annealed
and carburized with surface hardness between 500-600 BHN. Design strength
and pitch shall be based on operating conditions. The conveyor flights
shall be [_____] mm inches deep by [_____] mm inches thick T-1 steel plates
attached on both ends to the chain. The flight shall be provided with top
SECTION 15559A
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