wear pads and bottom wear strips of abrasion resistant steel plate of 300
BHN minimum. A chain tensioner shall be provided at the tail end of SDCC
for maintaining proper tension in both strands of the chain. The assembly
shall include cast-iron idler wheel, bearings, shaft, guide block and
bearing housing. Idler assemblies for both troughs shall include heavy
duty spherical roller type bearings with external lubrication fittings.
The chain drive assembly shall include cast-iron wheels with removable,
surface hardened, toothed segments, drive shaft, bearings. The conveyor
shall be driven by a hydrostatic drive unit coupled with a low speed, high
torque hydraulic motor, built-in torque limiting valves for preventing
damage to load train or electric motor. Speed regulation,
self-lubrication, internal cooling, and dynamic braking shall be provided
with this drive. Inching capability shall be provided. Hinged inspection
doors, windows, and removable panels shall be provided along the conveyor
to permit access and observation at critical points. All inspection doors,
windows, and removable panels in mild steel shall be provided with
stainless steel hardware and must be made completely water-tight. Water
cooling and drainage connections shall be provided through flanged
connections to the conveyor trough. Provision shall be made for continuous
water flow into the top trough of the conveyor including two overflow
connections, one for normal level and one high level; including high level
alarm and an overflow weir box to prevent drain clogging. Chain cleaning
spray shall also be provided.
2.30.4
Dense Phase Ash Handling
The ash conveying system shall be pneumatic dense phase type, complete with
transfer vessels, solenoid valves, air receiver tank, air producer, and ash
conveying piping. The ash handling system shall be designed to handle
[_____] metric tons/hour tons/hour of ash weighing approximately [_____]
kg/cubic meter pcf. Each transport vessel shall be bolted to the hopper
discharge flange where ash shall flow into the vessel by gravity until a
level indicator indicates the vessel is full. The transport vessel inlet
valve then closes, and transport air between 175 to 350 kPa 25 to 50 psi
enters the vessel through a fluidizing unit located at the bottom of the
vessel. When the vessel has been brought to transport air pressure, the
transport line valve opens and a "slug" of fly ash is transported to the
storage silo. The transporting pipe shall be Schedule 40 standard black
iron pipe [_____] mm inches diameter. The material velocities in the
transportation pipe shall be [_____] meters/second fpm. The system shall
be provided with 210 to 410 kPa 30 to 60 psi compressed air to fluidize and
transmit ash. The conveying velocity shall not exceed 5.1 meters/second
1000 fpm.
2.30.5
Fly Ash Collectors
Fly ash collectors shall be as specified in Section 11500 AIR POLLUTION
CONTROL. Fly ash collectors shall be sized to handle total flue gas at
maximum boiler load and stack temperature, and shall be provided along with
induced draft equipment. Fly ash collector requirements shall be
coordinated with boiler draft and control requirements.
PART 3
EXECUTION
3.1
EQUIPMENT ERECTION
Boiler and auxiliary equipment shall be installed as indicated and in
accordance with manufacturers' instructions.
SECTION 15559A
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