inch diameter flanged flyash outlet connection on each hopper.
2.5.1
Poke Hole
Provide each hopper with a 100 mm 4 inch diameter poke hole extending a
minimum of 150 mm 6 inches beyond the stiffeners and the hopper side, to
clear insulation and lagging. Include a screwed cap. Locate the poke hole
near the hopper outlet flange, orient to be accessible from the platform,
and position to permit downward thrusts into hopper throat.
2.5.2
Vibrators
Provide each hopper with both mechanical and manual vibrators. Mechanical
vibrators shall consist of two automatically controlled vibrators, with
manual override control, set at mid height and on opposite sides of the
hopper. Interface vibrator controls with the ash evacuation system so that
vibrators operate at the inception of and during an ash evacuation cycle.
Enclose controls in cases to prevent accidental energizing of system. Place
a warning over the vibrator manual override control, "WARNING; VIBRATOR
CONTROL. DO NOT ACTIVATE UNLESS HOPPER EVACUATION SYSTEM IS OPERATING."
Manual vibrators shall consist of two uninsulated reinforced strike plates
set at mid height and on opposite sides of the hopper. Provide strike
plates, 300 by 300 by 25 mm 12 by 12 by one inchASTM A 36/A 36M steel,
within hinged insulated panels. Provide space around strike plate to swing
a small sledge hammer. Provide a work platform with stairs for strike
plates greater than 1.50 meters 5 feet above ground.
2.5.3
Flyash Level Alarm System
Provide each hopper with a flyash level alarm system consisting of a
nuclear flyash level detector and alarm relays to indicate the 50 percent
hopper capacity level and the empty level. The nuclear detector shall be
an explosion proof, Cesium 137 single point gamma source detector having a
lockable shutter mechanism operated by an external handle. Reproducibility
shall be within one inch. Design to withstand vibration and temperatures
up to 427 degrees C 800 degrees F. Interlock with hopper access doors to
prevent entry into the hopper when the source is activated. Provide one
access key per hopper door. The alarm relays shall be rated at 10 A, 120
VAC, or 125 VDC continuous duty. House flyash level detector controls in a
[explosion proof] [dustproof] enclosure and mount in an easily accessible
location. System shall be operational at outdoor temperatures between minus
40 and 93 degrees C 40 F and 200 degrees F.
2.5.4
Hopper Heater System
Provide each hopper with an automatically controlled hopper and hopper
throat heater system able to withstand 454 degrees C 850 degrees F, the
maximum expected mechanical (normal operation) vibrations, and manual
(strike plate use) vibrations. Design using a minimum 1.1 heating safety
factor and a minimum 1.12 wind loss. Hopper and hopper throat heaters with
insulation in place, at minimum ambient temperature of [_____] degrees C F,
shall maintain an internal skin temperature of 121 degrees C 250 degrees F
while offline and during startup, and shall maintain an internal skin
temperature of 177 degrees C 350 degrees F or acid dew point temperature
while online.
2.5.4.1
Hopper Heaters
Hopper heaters shall cover not less than 33 percent of the total hopper
SECTION 15863N
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