with ASME BPVC SEC I.
2.3.1.6
Over-Fire Turbulence and Cinder and Dust Reinjection System
Spreader stokers shall be provided with over-fire turbulence and
cinder-and-dust reinjection systems. Either air or steam may be used as
the transport medium. Air systems shall be provided with operating air by
a single, low volume, high-pressure fan, driven by a splashproof electric
motor. The reinjection system ejectors shall be properly designed,
located, and sized for maximum fly ash pickup from all points. Nozzles for
each system shall be equipped with manometer connections and heavy-duty
adjustable dampers fitted with locking devices and position indicators.
Nozzles shall provide maximum combustion efficiency and furnace turbulence.
A manometer connection and a permanent manometer shall be provided
immediately downstream from the main reinjection air supply damper. A
portable manometer shall be provided.
2.3.2
Underfeed Stokers
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NOTE: Any paragraphs describing stoker equipment
not necessary for the system specified will be
deleted.
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2.3.2.1
Single Retort, Heavy-Duty Ram-Type Stokers
Single retort, heavy-duty ram-type stokers shall be equipped with
stationary or moving grates and side dump plates, and shall be provided
with [steam] [electric motor] drive and all necessary auxiliary equipment.
Dumping power cylinders shall be compressed air actuated. Coal shall be
fed from the hopper into the retort by means of a ram and shall be evenly
distributed along the full length of the retort with auxiliary pusher
blocks on a pusher rod located at the bottom of the retort and actuated by
the coal ram. Dampers shall be provided between ash pits and main air
chamber under stoker to permit control of air distribution to the grate
surface. Dampers shall be arranged for operation from the front plate of
the boiler. Air distribution shall be such that the air pressure is
greatest where the fuel bed is the thickest. Air quantity shall vary in
direct proportion with coal feed rate and shall be controlled automatically.
a.
Grate surface shall include the underfeed retort area, air
admitting tuyeres, side combustion grates, and the side dumping
plates. Retorts shall be sectional construction of large capacity
and proper shape to distribute coal uniformly over the entire
grate surface with a minimum of moving parts within the furnace.
Stokers having total grate width of more than 2.1 m 7 feet shall
have movable grates providing positive lateral feeding of the coal
from the retort toward the dump plates. Retort and grate sections
shall be constructed of heavy-duty, heat-resisting cast iron,
shall be cored for proper air distribution, and shall be designed
for easy replacement of individual sections. Ash dump plates
shall be provided with necessary levers and linkage for hand
operation from the front of the boiler.
b.
Ram feed shall be mechanical [steam] [pneumatic or hydraulic]
[driven by an electric motor connected through an efficient gear
reduction unit, crankshaft, and connecting rod]. [Motors shall be
totally enclosed fan-cooled type [for installation in a Class II,
SECTION 15559A
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