Provide two, V-belt drive, positive displacement blowers with electric
motors and accessories with each capable of producing a vacuum of at least
41 kPa 12 inches of mercury and with the air flow necessary for handling
ashes through the system. One blower (exhauster) shall be used as a prime
mover and the other as a standby unit.
2.12.13.1
Isolation Gates
Each exhauster shall include a manual bolt-up type gate for isolation and
crossover. Gates shall include limit switches for status indication.
2.12.13.2
Accessories
Exhauster shall be complete with belt guard, air inlet silencer, air
discharge snubber, support stand, expansion joint on inlet and outlet, belt
and shaft guards, high temperature safety switch and vacuum relief valve.
2.12.13.3
Electric Motor
Totally enclosed, fan cooled, [_____] volt, three phase, 60 Hz, as
specified under paragraph entitled "Motors and Drives" in this section.
2.12.13.4
Noise Level
Noise level shall not exceed 85 dBA sound pressure level at 1.50 meters 5
feet above the floor and 1.50 meters 5 feet from the blower in any
direction.
2.12.14
Bag Filter
Provide a pulse jet self-cleaning bag filter assembly to provide a tertiary
means of removing fine ash particles from the conveying air system.
Installation of this assembly shall be on the silo roof, downstream of the
two-stage cyclone type mechanical separator so as to permit a combined
minimum separating efficiency of 99.5 percent (by weight), with a
guaranteed outlet emission less than 0.005 grains particulate per dry
standard cubic foot of exhaust air. The filter assembly shall include a
main housing, bag assemblies, bag cleaning mechanism, discharge gate and
control panel. This equipment shall be integrated with cyclone type
separators, vacuum breakers, vacuum switches and conveying system controls
as specified elsewhere. Bag filter shall be capable of operating at 25
percent above the system design vacuum. Filter housing shall be capable of
withstanding a vacuum of 96 kPa 28.5 inches of mercury.
2.12.14.1
Cloth Area
Size filter on the basis of not greater than 25.40 L/s 5 acfm of air per
square meter foot of cloth area. Calculate acfm on the maximum system air
flow.
2.12.14.2
Filter Construction
Welded construction housing or body of, ASTM A 36/A 36M plate with an upper
clean gas plenum, bag compartment, hopper bottom, internal access platform
and support structure. Plate thickness shall be a minimum of 6 mm 1/4 inch
with exception of the plenum tube sheet, which shall be a minimum of 13 mm
1/2 inch thick. Housing shall be cylindrical, having a minimum diameter of
[_____] meter feet [_____] mm inches.
SECTION 15502N
Page 135
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