each fabric filter baghouse shall be piped back to a single point within
the battery limits of the collector(s) as indicated for connection with the
steam plant piping system to be provided by the Contractor. Contractor's
piping shall include shut off valves, pressure gages, pressure regulating
stations, filters, surge tanks, and other equipment required for complete
operation of the cleaning system. For off-line cleaning modules shall be
sequentially isolated by closing the outlet valve. Manufacturer to
recommend off-line times. When the module is off-line, each row of bags
shall be individually pulsed with 483 to 690 kPa (gage) 70 to 100 psig
compressed air through a solenoid-piloted, heavy duty diaphragm valve.
Each bag support cage shall be fitted with a diffuser element. After bags
are cleaned, the module shall be held off-line for a period of time
sufficient to allow the dust to settle into the hopper. The bags to be
furnished shall be of a fabric type, weight, finish, and construction
suitable for the intended service. Bags shall be suitable for continuous
exposure to the flue gas temperature conditions at the economizer outlet.
Bags and cages shall be provided with coatings as necessary to minimize
abrasion and to resist acid or alkali attack. Bags shall not be more than
150 mm 6 inches in diameter and not more than 4 1/2 meters 15 feet in
length. Bag cage design and construction shall be suitable for the
intended service. Bags shall be clamped at top between cage and tube sheet
in such a manner that bags will not sway, but can be readily removed
without special tools. The manufacturer's standard cage design will be
considered, provided that it has a proven record of reliable services with
the bag material proposed. The method of attachment of bags and cages to
the tube sheet shall provide proper air seal, bag tension, and cage
alignment. If venturis are provided, they shall be the manufacturer's
standard type for this application. Special care shall be taken to assure
there are no rough spots on cages to cause bag abrasion. Provide equipment
and materials necessary for bag leak detection. Leak detection system
provided shall utilize a fluorescent powder for detection with ultraviolet
light. Furnish portable light and sufficient powder for one year of normal
inspections. Furnish sufficient bag capping devices for 5 percent of the
total installed number of bags. The Contractor shall precoat the bags for
initial start-up on oil.
2.8.1.1
Spare Equipment
Ten percent extra bags and two percent extra cages shall be furnished.
2.8.2
Reverse Gas Cleaning System
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NOTE: Factors involved in selecting fabric filter
bag materials include:
1.
Duration of cleaning.
2.
Type of cleaning arrangements.
3.
System temperature level.
4.
Coal type.
5.
Sulfur dioxide removal efficiency.
NEEDLED felts are most commonly specified for
pulse-jet units. Precoat bags with fly ash prior to
operation. Fabric specifications are dependent upon
SECTION 15864N
Page 46
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