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[2.4.1
Traveling Grate Coal Stoker
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NOTE: Designer shall select type of stoker most
suited for each project. Stoker Selection Criteria
is shown in NAVFAC Design Manual DM-3.6, Table 12.
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NOTE: When the boiler is not part of this project
insert Coal Analysis at end of this paragraph.
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Stoker shall be of the bar and key traveling grate type arranged for rear
ash discharge. Stoker shall be capable of continuous operation at such
rate as required for the continuous output of not less than that specified
for the boiler and shall satisfactorily provide for automatic operation, by
means of combustion control system, within the range given when burning the
specified coal and operated in accordance with instructions supplied by the
manufacturer. Obtain satisfactory operating conditions throughout the full
operating range of the stoker. The stoker shall be considered as an
integral part of the steam generator and shall be subject to applicable
provisions of the boiler design and service conditions together with
requirements of tests, performance guarantees and other warranties
specified for the boiler. Coal analysis shall be as specified in the Coal
Analysis Schedule for the boiler. The gate moving mechanism shall be
positive, up and down, and equipped with suitable operating mechanism for
manual control. Provide an indicator to show the vertical position of the
gate and the thickness of the fuel bed.
2.4.1.1
Stoker Grate Heat Release Rate
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NOTE: Normally the stoker grate heat release will be
1417 kW per square meter 450,000 Btu per square
foot per hour when coal meeting the criteria set out
in the Stoker Selection Criteria shown in NAVFAC
Design Manual DM-3.6, Table 12 is used. When coal
is specified which does not meet this criteria then
the grate heat release will have to be lowered
accordingly.
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Not greater than [_____] kW per square meter Btu per square foot per hour
at the specified maximum continuous rating for the boiler. The square meter
feet of projected grate area shall be the product of the length measured
between the inside of the coal gate and the centerline of the rear shaft or
return bend and the width of the grate.
2.4.1.2
Construction
a.
Fuel Feed Control: Control fuel feed to the stoker by the stoker
speed and the vertical position of the coal regulating gate. Coal
gate to vary the thickness of the fuel bed shall be of heavy cast
iron with refractory facing to protect it from the furnace heat.
The gate moving mechanism shall be positive, up and down, and
equipped with suitable operating position of the gate and the
SECTION 15502N
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