pneumatically opened, spring closed, totally enclosed disc valve of cast
iron construction with wearing surfaces of Brinell hardness not less than
350. Provide valve complete with flanged inlet hopper, handhole with
gasketed cover and clamp and couplings. Side intake valve shall feed ash
to conveyor line on an angle, thus permitting air to mingle with ash in the
proper proportion to eliminate clogging. Valves shall provide positive and
automatic air tight shutoff and dust tight pickup. Valve shall close on
failure of operating air and before discharge cycle of intermittent
conveyor operation. A full load regulating switch shall control each valve
to prevent overloading of conveyor system.
[2.11.8.2
Manual Valve Intakes for Bottom Ash
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NOTE: Choose this subparagraph or the subparagraph
below, entitled "Rotary Valve Intake for Bottom Ash."
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Provide in front of stoker ash pit doors, a 610 by 610 mm 24 by 24 inch
cast iron grid and hopper complete with a self-feeding bottom ash intake,
seal plug and pull-out rod that may be lifted to permit ash to enter system.
][2.11.8.3
Rotary Valve Intakes for Bottom Ash
Provide a rotary valve, designed for regulating bottom ash to the a
conveyor pipeline, under each crusher. Valve shall provide intake
isolation and prevent overfilling or plugging of the conveyor line.
Construction of valve shall be of cast iron with wearing surfaces of
Brinell hardness not less than 350. Valve shall be pneumatically operated.
]2.11.8.4
Air Intake
Provide spring loaded, swing disc, check valve type air intake, designed
for air induction, at the end of each conveyor branch. When intake is
located exposed to weather, provide a rain hood.
2.11.8.5
Isolating Valves (Line Valves)
Provide an air operated, totally enclosed rotary slide gate isolating valve
at each branch pipe line connection to prevent air flow through an unused
branch line. Construct valve of abrasion resistant metal, machined and
fitted to ensure a vacuum tight fit and guard against leakage and excessive
maintenance. Provide purge air connection and a solenoid valve in the
valve housing or cavity for purging the gate cavity of ash.
2.11.8.6
Silo Discharge Valve
Provide a rotary feeder for discharging bottom ash and fly ash from the ash
silo. Feeders shall be of ductile iron or cast steel and shall be complete
with motor, motor support, chain drive, and necessary guards. Chain shall
be driven through a torque limiting clutch on the driven sprocket equipped
with electric cutout switch and alarm. [Feeder shall have spring-loaded
hinged bypass plate to permit passage of clinkers.] Inlet and outlet
flanges shall be standard drilled pipe flange. Rotor blades and sealing
arrangement shall be the manufacturer's standard for the intended service.
When rotors are equipped with adjustable tips, provide a service door in
the valve body for tip adjustment. Provide packing gland type shaft seals
with suitable packing materials. Shaft bearings shall be outboard sealed
ball bearings. Periphery seals shall be such that a complete seal is
SECTION 15501N
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