IMPROVEMENTS IN FIREBRIDGES FOR BOILER FURNACES
Year: 1885

page_text: 7
I ANDREW MACKIE of 42 Cambridge Street Pimlico London in the County of
Middlesex Civil Engineer do hereby declare the nature of my invention for
IMPROVEMENTS IN FIREBRIDGES FOR BOILER FURNACES to be as follows:-
The object of this invention is to highly heat a body of air passing through and
up the back of the firebridge for the purpose of combining with and aiding the
combustion of the unconsumed gases or smoke passing over the ridge of the
firebridge.
The firebridge can be made partly of fireclay or other refractory material and
metal, or it can be made of metal alone.
Preferably the fireclay is made with a series of deep longitudinal vertical plates
placed a short distance apart transversely and cast with, or attached to a horizontal
cross plate and to two or more vertical cross plates at the back of the bridge in
such a manner that the front portions of the longitudinal vertical plates project
into or through the firebrick work forming the front or face of the bridge; the
back portions of the longitudinal vertical plates uniting with the vertical cross
plates in such a manner as to form a series of vertical channels open at top and
bottom. The front edge of the horizontal plate is about level with the back end
of the firegrate and is carried back until it unites with the first vertical cross
plate.
The front vertical cross plate is carried down from the ridge of the fire bridge
to the horizontal plate.
The back vertical cross plate is carried down by itself or is provided with a
door so as to close the back end of the ash pit. If more than two vertical cross
plates are used the intermediate ones are cast or connected to the longitudinal
vertical plates only; the top and bottom edges being left free. By means of the
horizontal vertical plates projecting into the firebrick work, part of the heat of
the furnace is transmitted to the metal passages at the back; these become highly
heated and heat the air passing through them.
The plates can be varied in shape and can be made hollow or solid as desired for
the purpose of increasing the area of the absorbing and radiating surfaces and the
direction and shape of the channels or air passages can be modified.
It is preferred to cast the whole of the metal portion of the bridge in one piece.

page_text: Improvements in Firebridges for Boiler Furnaces.
I, ANDREW MACKIE of 42 Cambridge Street Pimlico London in the County of
Middlesex, Civil Engineer do hereby declare the nature of my invention for
„IMPROVEMENTS IN FIREBRIDGES FOR BOILER FURNACES and in what manner-the
same is to be performed, to be particularly described and ascertained in and by
the following statement :-
The object of the invention is to highly heat a body of air passing through the
firebridge for the purpose of combining with and aiding the combustion of the
'unconsumed gases or smoke passing over the ridge of the firebridge.
"
The firebridge is made with a series of deep longitudinal vertical plates "a
and "d" placed a short distance apart transversely and cast with or attached to a
horizontal cross plate "g" and to two or more vertical cross plates "e" at the
back of the bridge in such a manner that the front portions of the longitudinal
vertical plates "a project into or through the firebrickwork "b" forming the
front or face of the bridge; the back portions of the longitudinal vertical plates "d"
uniting with the vertical cross plates "e" in such a manner as to form a series of
vertical channels "f" open at the top and bottom.
"
The front edge of the horizontal plate is about level with the back end of the
firegrate and is carried back until it unites with the first vertical cross plate "e."
The front vertical cross plate is carried down from the ridge of the firebridge to
the horizontal plate "g" the back vertical cross plate "e" is carried down by itself
'or is provided with a door so as to close the back end of the ash pit. If more
than two vertical cross plates are used the intermediate ones are cast or connected
to the longitudinal vertical plates "d" only, the top and bottom edges being left
free By means of the vertical plates "a" projecting into the firebrickwork, part
of the heat of the furnace is quickly transmitted to the metal forming the passages
at the back, these passages become highly heated and heat the air passing through
them.
"c" is a perforated plate used to split up the air into jets when required but the
bridge can be used without it.
The plates can be varied in shape and be made hollow or solid as desired for the
purpose of increasing the area of the absorbing and radiating surfaces and the
direction and shape of the air passages or channels can be modified. The firebridge
can be made partly of fireclay or other refractory material and of metal combined
or it can be made of either of these materials alone.
D
References
Fig. 1. is a Longitudinal section thro' B. B.
2 Plan looking down on bridge.
" "
" "
3
"
4
"
""
Front elevation (from grate).
Sectional plan on line A, A, looking de

page_text: Having now particularly described and ascertained the nature of my Inven-
tion and in what manner the same is to be performed I declare that what
I claim is
1. The use of longitudinal vertical plates as described for transmitting heat from
the furnace to the air channels or chambers at back of bridge.
2. The use of the hanging radiating plates.
3. The firebridge constructed substantially as described.