By these
dimensions each chimney has a fair surplus capacity, and it is
calculated that, with economizers in the path of the furnace gases,
there will be sufficient draft to meet a demand slightly above the
normal rating of the boilers. To provide for overload capacity, as may
be demanded by future conditions, a forced draft system will be
supplied, as described later.
As previously stated, the chimneys are all supported upon the steel
structure of the building at an elevation of 76 feet above the
basement floor and 63 feet above the grates. The supporting platforms
are, in each case, carried on six of the building columns (the three
front columns of two groups of boilers on opposite sides of the center
aisle of the boiler room), and each platform is composed of single-web
plate girders, well braced and surmounted by a grillage of 20-inch
I-beams. The grillage is filled solidly with concrete and flushed
smooth on top to receive the brickwork of the chimney.
Each chimney is 162 feet in total height of brickwork above the top of
the supporting platform, and each chimney is 23 feet square in the
outside dimension at the base, changing to an octagonal form at a
point 14 feet 3 inches above the base. This octagonal form is carried
to a height of 32 feet 6 inches above the base, at which point the
circular section of radial brick begins.
The octagonal base of the chimney is of hard-burned red brick three
feet in thickness between the side of the octagon and the interior
circular section.
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