2.7.2
Blowoff Tank
A concrete blowoff tank shall be provided as indicated. The tank shall be
provided with bolted manhole cover, cover plate with disappearing lifts,
inlet blowoff connection equipped with mixing nozzle, vent, overflow and
drain connection.
2.8
WASTE HEAT RECOVERY EQUIPMENT
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NOTE: For the efficiencies specified, waste heat
recovery will be required. Designer must consult
with HTW generator manufacturers to select the most
appropriate unit for the size of HTW generator being
designed.
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Each boiler shall be equipped with [an economizer] [an air preheater].
Units may be separate from or integral with the boiler and shall be
complete with insulation and jackets, casings, supports, and access doors,
and shall have provisions for tube or tube bundle removal and for cleaning.
Soot blowers shall be provided as specified.
2.8.1
Economizers
Economizers shall be of a type normally provided by the boiler manufacturer
and shall include [finned tubes] [bare tubes] baffles and headers, and
shall have provisions for cleaning and tube bundle removal. Materials
shall be capable of withstanding the maximum boiler exit gas temperature
plus 28 degrees C 50 degrees F. The tubes shall conform to ASME BPVC SEC I.
The overall design and installation shall be such as to preclude cold-end
corrosion under any load condition. Economizer tube metal temperature
shall be above the maximum flue gas dewpoint for the fuel being fired under
all load conditions.
2.8.2
Air Preheaters
Air preheaters shall be a type normally provided by the boiler manufacturer
and shall be the recuperative tube plate or regenerative type constructed
of materials adequate to withstand the corrosion effects of the flue gases.
The overall installation shall preclude cold-end corrosion of the air
preheater under any load condition. Temperatures of all metals in contact
with flue gas shall be above the flue gas maximum dewpoint temperature for
the fuel being fired under all load conditions. Control shall be by
air-preheat or by automatic bypass and shall be integrated with the
combustion control system.
2.9
DRAFT FANS
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NOTE: Induced draft fan outlet dampers may not be
required in single fan/single boiler installations,
except to eliminate the stack effect during outages.
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Centrifugal fans conforming to AMCA 801 [Type I] [Type II] shall be
furnished as an integral part of boiler design. Fans shall be centrifugal
with [backward curved blades] [radial tip blades] or axial flow type. Each
SECTION 15555A
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