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. 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 sprays shall also be provided.
2.24.4
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 vessel by gravity until a level
indicator indicates the vessel is full. The transport vessel inlet valve
then closes, and transport air between 170 to 345 kPa25 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/sec fpm. The system shall be provided with
210 to 415 kPa 30 to 60 psi compressed air to fluidize the transmit ash.
The conveying velocity shall not exceed 5 meters/sec1000 fpm.
2.24.5
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
ERECTION OF BOILER AND AUXILIARY EQUIPMENT
Boiler and auxiliary equipment shall be installed as indicated and in
accordance with manufacturers' instructions.
SECTION 15555A
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