2.5.9
Air Distribution System
The air distribution system shall provide uniform air distribution to the
fluid bed under any mode of operation. The system must also meet the
mechanical and structural requirements of the boiler such as bed material
dead load support, effective seal with the enclosure wall, and nonsifting
air nozzles.
2.5.10
Mechanical Collector and Solids Recycle System for AFB Boilers
A mechanical cyclone dust collector at the outlet of the boiler shall be
provided. The mechanical dust collector shall be of the high efficiency
multicyclone type designed for maximum operating temperatures encountered
under all operating conditions. The collectors shall be designed to resist
erosion and minimize plugging, shall be gas-tight, and shall have a
collection efficiency of 85 to 95 percent on particles greater than 20
microns aerodynamic diameter, depending upon the recycle rate selected by
the manufacturer. No refractory lining will be acceptable in the
mechanical dust collector. The collection hopper shall have a valley angle
of at least 60 degrees below the horizontal. The line carrying recycle
solids back to the bed shall be fabricated of carbon steel with an
allowance for wear and be installed at an angle of no less than 60 degrees
below the horizontal. The solids collection hopper and dipleg shall be
provided with pressure differential measurement to indicate pluggage. The
design shall include provisions for sampling of recycle solids hopper
contents. The hopper shall be fabricated of material capable of enduring
the conditions imposed by a flue gas atmosphere. Provision for continuous
disposal of ash from the recycle hoppers shall be provided.
2.6
IGNITION OIL SYSTEM
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NOTE: Wherever light oil is required as a support
and/or ignition fuel, a complete ignition oil system
must be provided. The system should include two
full-size rail/truck unloading pumps, capable of
unloading a rail shipment in one 8 hour shift or a
truck shipment in 1 hour; one ignition oil storage
tank capable of storing either 88 hours continuous
plant ignition fuel demand or one rail shipment,
whichever is larger; two full size ignition oil
supply pumps per boiler unit, each capable of
supplying the maximum ignition oil demand for each
boiler unit; and one ignition oil day tank per
boiler unit capable of storing 8 hours of continuous
boiler ignition oil demand. Both the ignition oil
transfer and boiler ignition supply pumps should be
centrifugal type, where allowed by suction
conditions and discharge flow/pressure requirements;
otherwise, positive displacement pumps shall be used.
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2.6.1
Ignition Oil Pumps
Ignition oil pumps shall be furnished as duplez types assuring 100 percent
standby. Pumps shall be provided complete with coupling, coupling guard,
and electric motor shop-mounted and aligned on a common skid.
SECTION 15559A
Page 44
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