Year: 1899

page_text: We, WILLIAM WHITE and ALFRED THOMAS GREGORY, both of 154, Markhouse
Road, Walthamstow, County of Essex, Furnace Builders, do hereby declare the
nature of this invention to be as follows:-
This invention has for object, the construction of furnace bridges in fire clay
moulded with a clear entry for large volumes of air from the ash pit and reduced
outlets at the upper part where the highly heated air issues in fine streams to
commingle with the products of combustion from the fire as they pass over tho
bridge, the mixture then striking against a depending baffle to more fully
establish or ensure a perfect mixture of the gaseous agents and a complete com-
bustion before entering into or between the tubes of the boiler, if tubes be fitted
as in tubular Cornish or tubular Lancashire boilers for which the invention is
particularly adapted.
Our furnace bridge is preferably moulded in one piece and the air entry may
have narrow partitions or struts as supports from its base segment, the upper
rear part being narrowed and provided with openings between V shaped cross
bars of the same or other material which may if desired be dropped in place.
The front upper part of the bridge has a step or shelf on which ordinary fire
bricks can be laid to take the first impact of the fire in passing over the edge
these being renewable at will without interfering with the bridge proper.
We, WILLIAM WHITE and ALFRED THOMAS GREGORY, both of 154, Markhouse
Road, Walthamstow, County of Essex, Furnace Builders, 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:-
This invention has for object, the construction of furnace bridges in fire clay

page_text: moulded with a clear entry for large volumes of air from the ash pit and reduced
outlets at the upper part where the highly heated air issues in fine streams to
commingle with the products of combustion from the fire as they pass over the
bridge, the mixture then striking against a depending baffle to more fully
establish or ensure a perfect mixture of the gaseous agents and a complete com-
bustion before entering into or between the tubes of the boiler, if tubes be fitted
as in tubular Cornish, or tubular Lancashire boilers for which the invention is
particularly adapted.
Our furnace bridge is preferably moulded in one piece and the air entry may
have narrow partitions or struts as supports from its base segment the upper
rear part being narrowed and provided with openings between V shaped cross
bars of the same or other material which may if desired be dropped in place.
The front upper part of the bridge has a step or shelf on which ordinary fire
bricks can be laid to take the first impact of the fire in passing over the edge
these being renewable at will without interfering with the bridge proper.
Our invention is clearly shown on the annexed drawings as applied to a plain
flued Lancashire boiler at Figure 1 in section. Figure 2 represents the bridge
detached the outlet having an angularly slotted plate to form the air exit.
Figure 3 perspective elevation of fire bridge with single partition or strut to
give rigidity to the front portion where it is stepped for the reception of fire
brick the outlet having separately fitted filling in blocks with the spaces between
to form the air outlet slits.
Figure 4 perspective elevation of a fire bridge with three struts or partitions
in the front part the air outlet slits or openings being formed as part of the
bridge.
The fire bridge consists of front A, step B, back C with hollow top D, the space
being a continuation and very much contracted of the larger entry E. F, F,
partitions or struts in the front opening as supports where needed for the step B
on which fire bricks, such as at G Figure 1, can be built to facilitate renewal
from time to time at the part most liable to destruction from the intensity of
heat and the action of the flame of fuel on the furnace bars H.
I, I, Figure 3 moulded or filling in blocks fitted separately in the outlet D
and up between which the incoming air from the ashpit J can issue in fine streams
to meet and commingle with the flame and products of combustion passing over
the bridge, a further breaking up and mixing taking place by means of the
baffle K to ensure combustion of the gases in the furnace flue, or in the tube if the
boiler flue be provided with them.
The narrow spaces of the upper back or outlet either from the moulding I¹ in
one piece as at Figure 2 or as attachments or shaped blocks I dropped in as at
Figure 3 or formed in a piece I with the bridge as at Figure 4 are preferably of
A shape to form slits, so that thin fine streams of air highly heated may escape
with a certain amount of force to impinge against and break up, enter into, and
commingle with the smoke and gases froin the fire for utilisation of their
heat giving properties in the flue which constitutes a gas developing chamber
before the fumes or vapour can pass to the uptake or chimney to escape.
In the drawing, I have shown in connection with the description, the bridge as
of moulded fire clay or its equivalent, but it may be of metal wrought or cast, the
principle feature being a furnace fire bridge with large air entry at lower part
from ashpit, contracted neck or outlet in upper rear part, the front being stepped
or provided with a shelf for ordinary fire bricks or fire slabs, as hereinbefore
described.
Having now particularly described and ascertained the nature of our said in-
vention and in what manner the same is to be performed we declare that what we
claim is:-
-
A: furnace fire bridge A with bottom air entry T of lanmo
11

page_text: from and forming back of ash pit J, with shelf B and a contracted space at rear
with uprising back C provided with slits for issue of heated air in fine streams,
as and for the purposes described, the construction or arrangement being sub-
stantially that shown on the annexed drawings, whether said fire bridge A be
used with baflle K, or alone.