Improvements in and relating to Fire-bridges for Steam-boiler and other Furnaces.
Year: 1899

page_text: Date of Application, 6th Mar., 1899-Accepted, 15th Apr., 1899
COMPLETE SPECIFICATION.
Improvements in and relating to Fire-bridges for Steam-boiler and
other Furnaces.
I, JOHN ALVES, of No. 131, William Street, Melbourne, in the Colony of
Victoria, Engineer, do hereby declare the nature of this invention and in what
manner the same is to be performed to be particularly described and ascertained
in and by the following statement:-
My object in devising this invention has been partly to provide a fire-bridge
which will be more durable than the hollow fire-bridges at present in use and
that will not be liable to become choked up and thus rendered inoperative, and
partly to provide means for supplying steam to the furnace in such a way as to
convert the furnace into a Bunsen burner thus generating an intense heat with
a minimum combustion of fuel and absence of smoke.
I will describe my invention by reference to the accompanying drawings
wherein,
Figure 1 is a front elevation of part of a furnace fitted with a fire-bridge
constructed according to this invention.
Figure 2 is a vertical transverse section thereof on line 2-2 Figure 1,
Figure 3 is a horizontal section on line 3-3 Figure 2.
The same letters of reference indicate the same parts in all the figures.
A represents a casting which is made long enough to extend across the back
of the furnace and which can either be rounded off at the top and front edge
as indicated at a in Figure 2, or can be made square across the top according to
whether the flames are intended to return to the front or be carried to the back
of the boiler.
This casting is moreover provided with a number of elongated vertical apertures
or slots B extending through the casting from front to back and practically
from top to bottom thereof.
These slots are made to gradually decrease in width toward their upper end,
so as to reduce the volume of air supplied to the flames above the line of fuel
or passing over the bridge and said slots are made wider at the back than at the
front as shown in Figure 3 so that any ashes and clinkers passing into them
will fall clear through to the back and thence down into the ash pit below. For
this purpose also the bottom of the casting is inclined towards the back and the
bottom of each slot is similarly inclined as indicated at 6 in Figure 2.
The back of the bridge may be closed in with fire brick as illustrated at C
and be provided with a door or damper D whereby the supply of air may be
regulated.
E represents a steam supply pipe which is arranged behind the bridge and is
provided with jets or orifices opposite some or all of the slots B thereby creating
a forced draught and converting the furnace into a forced Bunsen burner.
F represents a fire-brick arch projecting over the back part of the fire grate
as is usual in Babcock and Wilcox boilers.
With the construction above described a thorough combustion of the fuel will

page_text: be ensured and the bridge will not be liable to become choked up neither will
it be so liable to be destroyed by the intense heat.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:-
The herein described fire-bridge for furnaces consisting essentially of a cast-
ing extending across the furnace and having vertical elongated apertures or slots
of greater width at the back than the front and of decreasing width towards the
top and inclined rearwardly at the bottom, in combination with a steam supply
pipe arranged behind said bridge and having jets or orifices opposite some or all
of the slots in said bridge the whole being constructed and arranged substan-
tially as and for the purposes herein described and explained and as illustrated
in the accompanying drawings.
Dated this Twenty-seventh day of January, One thousand eight hundred and