by expanding into bored tube seats. Boilers shall have water-cooled
furnace walls of a design suitable for the application. Lower header of
sidewalls shall be round design with tubes welded to header stubs. Each
waterwall header shall have enough supply and riser tubes to ensure that no
portion of the waterwalls will become water starved at maximum capacity.
2.2.2.3
Baffles
Baffles shall be
arranged to bring the products of combustion into contact
with the heating
surfaces without excessive loss of draft. Baffles shall
be gas-tight and
shall be either a refractory material or metal suitable
for temperatures
encountered.
2.2.2.4
Access Doors
Access doors in sufficient number, of adequate size, and properly located
shall be provided for cleaning, inspection, and repair of all areas in the
complete assembly. Doors shall be gas-tight and interior surfaces exposed
to direct radiation and high temperatures shall be lined with approved
refractory material to prevent excessive heat losses and warping of doors.
Doors too large or bulky for hand removal shall be hinged. At least one
observation port with cast-iron cover shall be provided on the front and
rear wall of the furnace.
2.2.2.5
Miscellaneous Pipe Connections
Miscellaneous pipe connections shall be provided for steam outlet, safety
valves, feedwater, feedwater regulator, water column, blowoff, steam supply
to soot blowers, steam gauge and vent, continuous blowdown, continuous
chemical feed, and instrument connections. Boilers shall be provided with
necessary jets for furnace turbulence, the number and arrangement of which
shall be as recommended by the boiler manufacturer. Soot blowers shall be
provided, if required by the manufacturer. A suitable smoke outlet with
steel frame, damper, and damper shaft shall be provided. Damper shall have
external high temperature roller or ball bearings at both ends of the
shaft, and shall have a suitable operating arm and rod.
2.2.2.6
Superheater Design
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NOTE: Delete if the boiler does not include a
superheater.
**************************************************************************
The design of the superheater shall be such that at any given load, and to
the extent feasible, all elements have the same outlet temperature. The
superheater tube and support materials shall be chosen so that with any
reasonably expectable excess air and the worst expected unbalance in air,
steam, and fuel distribution, there is an ample and conservative margin of
safety to prevent damage by overheating or corrosion to the components.
Pad-type permanent thermocouples shall be installed on superheater tubes in
sufficient number and so located as to indicate the variation in, and
maximum value of, the tube temperature across the furnace width. The
thermocouples shall be located outside of the gas stream. The superheater
outlet header shall be capable of absorbing the reactions from the main
steam piping. The superheater terminals shall be extended sufficiently
clear of the boiler walls to facilitate connecting thereto. Any
superheater piping must be extended beyond the boiler front wall line, 900
mm 3 feet beyond casing. Header penetrations through the casing shall be
SECTION 15559A
Page 22
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