material.
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NOTE: Specify air pressure available for pneumatic
operators or electrical characteristics available
for electric operators.
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The baghouse assembly shall be of modular construction. The inner housing
casing and tube sheet of each module shall be fabricated from carbon-steel
plate of 6 mm 1/4 inch minimum thickness, conforming to ASTM A 36/A 36M.
The inner casing shall be of all-welded construction, gastight and
watertight designed for a transient condition (80 percent of yield
strength) at internal pressures of at least plus 498 and minus 7470 Pa 20
and minus 30 inches WC. Joints shall be sealed by continuous fillet or
continuous complete penetration groove welds as applicable. Tube sheets
shall be continuous fillet or complete penetration groove welded gastight
so that flue gas must exit through the thimbles. Thimbles shall be
fabricated of carbon-steel plate with a minimum thickness of 12 gage and
minimum length of one nominal bag diameter and shall be spaced on not less
than 241 mm 9 1/2 inch centers for 200 mm 8 inch diameter bags and not less
than 356 mm 14 inch centers for 300 mm 12 inch diameter bags. Thimbles
shall be inline and not staggered. Tubesheet/baghanger alignment shall be
within 3 mm 1/8 inch for plumb and centering hanger adjustment shall be
provided to allow maintenance of bag alignment. Internal walkways with
kickplates shall be provided to access both upper and lower bag supports.
Upper access walkways shall be at least 457 mm 18 inches wide. Lower
access walkways shall be at least 610 mm 24 inches wide. If the upper
walkways are located between upper support frames, upper walkways shall be
one meter 3 feet below the upper support frame and a crawl space at least
1.22 meters 4 feet high shall be provided above the support frames. Each
reverse gas fabric filter baghouse shall be provided with a bag cleaning
system including two 100 percent capacity reverse gas fans, connecting
ductwork, dampers, and automatic controls. Each fan shall be provided with
automatic operated inlet louver dampers for control and shutoff.
Automatic-operated dampers shall also be provided to isolate the "standby"
fan and the modules not being cleaned. The reverse gas-cleaning system
shall provide for gradual reinflation of the bags after cleaning. The
reverse gas for cleaning shall be taken from the outlet plenum. Reverse
gas fans shall be specified in paragraph entitled "Ductwork and Draft
Equipment." Motor drives shall be as specified in entitled "Pumps, Valves,
Motors." Louver dampers for reverse gas fans shall be as specified in
paragraph entitled "Ductwork and Draft Equipment." The collector
manufacturer shall furnish valves necessary for each module to cause
effective reverse air cleaning of each module. The clean gas outlet valve
and the reverse air inlet valve for each module shall be of the [air
cylinder] [electric motor] operated, poppet-type arranged for manual
lockout capability with position indicating switches at both ends of the
travel. The clean gas outlet valves shall be the adjustable slow opening
type arranged for manual lockout capability with position indicating
switches at both ends of the travel. The clean gas outlet valve shall be
arranged to fail-safe in the closed position. The dirty gas inlet valve
for each module shall be of the manually operated, poppet-type or
butterfly-type suitable for isolating each module for maintenance. The
manual operator shall be of a type that is readily accessible. Bags shall
be suitable for continuous exposure to the flue gas temperature conditions
at the economizer outlet. Bags shall be provided with coatings, as
necessary, to minimize abrasion and to resist acid and alkali attack. Bags
SECTION 15864N
Page 47
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