S DOCUMENTThis specification covers reverse pulse jet baghouses, with induced draft fan, installed on packaged boilers fired by coal, coal and gas, coal and oil, or a combination of coal, oil and gas.

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OO-B-2925

shall be ranged from 4.5 to 6.0-inches (114.3 to 152.4 mm) in diameter. Bag length shall be ranged from 12 to 16 feet (3.65 to 4.88 m). The spacing between bags shall be not less than

2.0-inches (50.8 mm). The bag cleaning system shall only use pulsed air and venturi tubes or diffusers. The bag cleaning system shall not include traveling rings or sonic horns.

3.9.8 Fan. Each fan shall be a heavy duty radial tip, straight radial, or backward inclined blade design. The fan shall be operated from a direct drive coupled electric motor with a speed not greater than 1200 revolutions per minute. The rotor shall be overhung on two bearings. The inlet and outlet shall be flanged. Access doors shall be provided on the inlet box and outlet. Access doors shall be accessible through insulation by either having the doors raised above the fan

housing surface or by having easily removed insulation covers. Additional fan requirements are specified in 3.9.8.1 through 3.9.8.3.

3.9.8.1 Fan housing. The fan housing shall be of welded steel construction and furnished with lifting lugs. The damper shall be furnished with a damper operator as specified in 3.10.4. The housing shall be split to allow for removal of the rotating assembly without removal of ductwork. Threaded plug drain connections shall be provided on the inlet and outlet side housing low points of not less than 1.0-inch (25.4 mm) in size.

3.9.8.2 Fan rotor, bearings, and coupling. Rotor blade thickness shall be not less than 0.25-inch (6.4 mm) with an additional 0.25-inch (6.4 mm) of wear pad. The rotor shall be statically and dynamically balanced before shipment and shall be of all welded construction. Shaft critical speed shall be not less than 125 percent of motor speed. Bearings shall be roller antifriction style with grease lubrication. The coupling shall be furnished with an OSHA approved coupling guard.

3.9.8.3 Damper. The fan shall be furnished with a multi-louver parallel blade inlet box damper. The damper shall be furnished with a damper operator.

3.9.9 Explosion vents. Each module shall be furnished with explosion vents to provide rapid relief of internal pressure. The vents shall be hinged and may be side or roof mounted. The area of the vent in square feet shall be not less than 10 percent of the volume of the module in cubic feet.

3.10 Controls. The baghouse controls shall consist of the reverse pulse bag cleaning, safety hopper dump, and boiler draft control system specified below. A programmable controller shall be used to coordinate the operation of the systems. The control panel shall display the sequences as specified in 3.10.1 through 3.10.5.

3.10.1 Reverse pulse bag cleaning system. The bag cleaning system shall be capable of operating automatically on either a differential pressure switch or a timed cycle. Both control systems shall be provided with manually adjustable setpoints. A common inlet and individual module outlet manometers shall indicate the differential pressure across each module. During cleaning operations, the control panel display shall simultaneously indicate the module being cleaned and the status of the cleaning cycle. Only one module shall be capable of being cleaned at one time.

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