thickness of the fuel bed.
b.
Coal Hopper: Provide a coal hopper of 6 mm 1/4 inch thick Type
304 or 316 stainless steel plate at the front of each stoker. The
capacity of the hoppers shall not be less than [_____] cubic meters
feet.
c.
Stoker Front Enclosure: Provide stoker fronts with dust tight
enclosures of not less than 10 gage plate to eliminate dust from
the boiler room and prevent air infiltration to the grate. Fit
these fronts with access doors.
d.
Air Plenum (Siftings Hopper) and Ducts: Provide an undergrate air
plenum and air ducts for the stoker which will receive air from
the forced draft fan. Plenum and air ducts shall be not less than
10 gage steel plate. Provide concrete ducts or airways along the
sides of the setting when adaptable to use by the stoker
submitted. Provide ducts in accordance with drawings and
requirements furnished by the stoker manufacturer. Provide unit
with necessary observation doors or ports of the self-closing
glass-covered type for side walls, including a minimum of four for
observing the underside of the grate.
e.
Stoker Air Zones: The stokers shall have not less than [_____]
air zones with individual control to each zone in order to provide
optimum control of combustion conditions for loads within the
specified range and shall be so arranged that a positive air seal
will be formed between each zone. Design the zones to provide
removal of siftings. To ensure proper air distribution to each
zone, provide an air control valve or damper for each zone.
Control valves or dampers shall be hand controlled and shall be
accessible for instant adjustment by the operator from the side of
the stoker. Provide each zone with a pipe opening for a draft
gage connection and provide connection in the overfire air duct
for the same purpose.
f.
Stoker Grate: Mount the traveling grate stoker grate keys (clips)
on carrier bars supported from an endless heat treated type steel
chain. Provide wearing shoes on the carrier bars to carry the
grate weight on skid rails extending the length of the furnace.
The chain links shall mesh with the shaft sprockets transmitting
the driving force to the endless chain. Grate keys (clips) shall
be chrome alloyed cast iron to resist growth. Links shall be
uniform. Grates shall be made of the best quality, heavy duty,
heat resisting, cast iron or cast alloy carefully cast to minimize
initial strain. The sifting hoppers and removal system shall be
so arranged that siftings may be removed from zones.
g.
Grate Thermocouples: Provide two grate temperature sensing
thermocouple arrangements on each grate to indicate and record
grate temperatures on the operator's [interface console] [control
panel].
h.
Tension Adjustment: Provide a conveniently located adjustment
accessible from outside of the boiler or through access plates in
the stoker front cover for regulating the tension of the grate.
Provide adequate adjustment for the chain length.
i.
Stoker Seals:
Provide the stoker with seals between the bottom of
SECTION 15502N
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