expansion joint; minimum of 3 mm 1/8 inch thick to prevent fly ash erosion
and buildup in web of joint and not restrict the movement of the joint, and
nuts and bolts required to attach the fabric to the flanges and the
expansion joints to the ductwork. Bolt holes on maximum of 100 mm 4 inch
centers. Belt materials shall be minimum 6 mm 1/4 inch thick, two-ply,
aramid-or fiberglass-reinforced, solid fluoroelastomer polymer specially
compounded for the intended service. Material shall be factory spliced to
form endless belt without sewn joints. Bolt holes shall be factory punched.
2.11.3
Dampers
Dampers shall be designed for a Zone [_____] seismic risk area and a wind
loading and additional loads as specified. The dampers shall be designed
to be operated without manual assistance under temperatures and pressures
specified and with normal accumulations of flue products. Dampers shall
have provision for periodic lubrication with appropriate grease, if not
permanently lubricated and sealed. Dampers shall be supplied with limit
switches which shall give positive indication of the damper position
(open/close). Dampers except guillotine dampers shall have pneumatic
operators. Guillotine dampers shall be provided with the manufacturer's
standard motor operators as required for the service intended. Dampers
shall fail in failsafe position upon loss of power or air. Fabric filter
baghouse bypass dampers shall be a double tight seal damper to provide for
essentially zero leakage at maximum fabric filter baghouse design
differential pressure. Bypass dampers shall be provided with an air
reservoir of sufficient capacity as to activate damper upon loss of plant
air. Inlet and outlet dampers shall be a minimum of 99 percent gas tight.
Fabric filter baghouse module inlet and outlet damper operators shall be
located outside of the gas stream and shall be accessible for maintenance
with the unit in operation. Induced draft fan inlet control dampers shall
be louver dampers in accordance with induced draft fan manufacturer's
recommendations. Guillotine isolation dampers at stack inlet breeching
shall be provided with control interlocks to prevent dampers from closing
when the associated induced draft fan is operating. Provide positive means
of preventing accidental closure of guillotine dampers. These dampers will
be used to isolate the equipment upstream for maintenance. They shall be
equipped with an external, locally-mounted audible alarm to signal loss of
seal air for personnel safety. Each damper frame shall be of a rigid
structural design to eliminate distortion or warpage which may interfere
with the damper operation. Frames shall be flanged for bolting to
connecting ductwork. Frames shall be designed to support a fly ash load of
1464 kg/sq m 300 lbs/sq ft on the bottom of the frame. Design frames to
support a 908 kg 2,000 pound concentrated load due to uneven fly ash
distribution, at a point that causes maximum deflection of the frame.
Frames shall be designed to support the seal air fan system, related
controls, motors, and drive mechanisms, and the entire damper unit with
only one flange bolted to the ductwork. Include lifting lugs to ensure
proper handling of the damper during transportation and erection. Frames
on louver dampers shall be of a length greater by one inch than the width
of the louver blades. Control drive units shall be as specified and shall
provide a direct position readout at the damper by means of a mechanical
position indicator showing percent of damper opening on flow control
dampers. Control drives other than poppet damper actuators shall be
equipped with a permanently mounted handwheel that is disengaged under
conditions of pneumatic or motor operation.
2.11.3.1
Seal Air Systems
Each guillotine damper shall be provided with a seal air system.
Each seal
SECTION 15864N
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