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.
2.24.3
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/sec 15 fpm. The SDCC
shall be designed for continuous operation and shall have a storage
capacity of [_____] cubic meters cubic feet 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 380 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 [_____] meters 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 inches 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 500-630 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 wear pads and bottom wear
SECTION 15555A
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