Improvements in or in connection with Fire Bridges.
Year: 1892

page_text: Date of Application, 24th June, 1892
Complete Specification Left, 24th Mar., 1893-Accepted, 13th May, 1893
PROVISIONAL SPECIFICATION.
Improvements in or in connection with Fire Bridges.
I, HERMANN BOTTGER, of Werderstrasse No. 7 Dresden, Kingdom of Saxony,
German Empire, Engineer, do hereby declare the nature of this invention to be as
follows:-
Many devices have heretofore been proposed for admitting air to the hot gases
and products of incomplete combustion escaping from the hearth of fire grates for
The main requirements
the purpose of effecting complete combustion thereof.
of such a device arc,
(1) That the air can be heated to a high temperature and introduced as directly
as possible into the unburnt gases:
(2) That the device can be easily and quickly placed in the required position
tliat is to say on or near the fire bridge;
(3) That the parts of the device shall be durable and can be easily repaired or
renewed when needed.
This invention has for object to construct a fire bridge fulfilling all these
requirements.
A fire bridge according to this invention comprises a number of hollow
perforated bricks or blocks of refractory material such as fire clay carried by an
iron frame and in front of which is arranged other brickwork.
The iron frame is formed with a number of cells or compartments that are
alternately perforated and unperforated at the bottom. The perforated are
intended to receive the hollow refractory bricks or blocks, the channels in which
are arranged to correspond with the apertures in that part of the plate above
which the bricks or blocks are placed, the arrangement being such that air coming
from the ash pit and entering the aperture in the iron frame will flow through the
channels in the bricks or blocks wherein it will become heated and will escape at
the top end into the space located above the fire bridge and through which the
unburnt gases flow.
Within the unperforated cells or compartiments are placed solid bricks or blocks
of refractory material of less height than the hollow ones so that spaces are formed
between the upper portions of the hollow bricks through which the hot gases and
products of combustion will pass on their way from the fire grate, but so as to come
in contact with such bricks in order to raise them to a high temperature, for the
purpose of heating the air passing through them.
:
Each of the hollow bricks or blocks may be formed with one channel only but
I consider it advantageous to provide several separate channels by means of
partitions, as by this means a larger heating surface will be provided and the bricks
or blocks will be rendered more rigid and durable. The upper ends of the bricks
or blocks are preferably made slanting so that the exits of the channels will be at
different levels; and the heated air will be caused to be distributed as uniformly as
possible into the unburnt gases.
Further-
A fire bridge thus constructed can be easily mounted; is durable, and can be
easily repaired or renewed either entirely or in parts when necessary.
more air flowing therethrough is heated to a high temperature and caused to flow
directly into the unburnt gases.
According to a modified construction the refractory bricks or blocks instead of
being arranged vertically as in the. arrangement just described are arranged
horizontally and the channels within them are arranged at an angle or partly in
a vertical direction and partly in a horizontal direction in order to conduct the air

page_text: In
In
flowing through them horizontally into the unburnt gases flowing past their outer
ends. In order to support the horizontal portions of the said bricks or blocks
I provide the iron frame with extensions on which the bricks or blocks rest.
order to protect such extensions against the direct action of flame, I form the lower
side of the bricks or blocks with rims or projecting parts so arranged as to cover
the sides of those parts of the extensions upon which the bricks or blocks rest.
order that with this horizontal arrangement of the bricks or blocks the highly
heated air shall become effectually mixed with the unburnt gases passing from the
grate, I have found it advantageous to provide a wall in rear of and at a higher
level than the fire bridge. The flame will mainly flow through the intermediate
spaces between the bricks or blocks while the unburnt gases will pass in front of
the said bricks or blocks where it will become mixed with the highly heated air
escaping therefrom.
According to a further modified construction the bricks or blocks are vertical
but their upper ends as well as the channels therein are inclined in the direction in
which the hot gases and products of combustion flow.
According to another construction the bricks or blocks are arranged in the form
of a hollow arch.
The iron frame is formed with two apertures and above these perforated parts
the hollow fireclay bricks or blocks are built up in such a manner that their inner
channels form a continuation of the apertures and so that they form an arch located
above the fire bridge. Through the lower or inner side of such arch a number of
apertures are formed through which air heated within the arch will escape into the
unburnt gases flowing past them. The bricks or blocks forming the arch may be
formed with one or more channels. I prefer to construct the bricks or blocks with
several channels inasmuch as the arch will then prove to be more solid and durable,
the partitions between the channels forming additional transmitters of heat to the
air flowing through them.
The arch or vault may, where circumstances will permit, be formed or con-
structed in one piece, instead of in several pieces.
Dated this 24th day of June 1892.
H. BÖTTGER,
By L. W., per F. B.
COMPLETE SPECIFICATION.
Improvements in or in connection with Fire Bridges.
I, HERMANN BÖTTGER, of Werderstrasse No. 7 Dresden, Kingdom of Saxony,
German Empire, 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 :-
".
Many devices have heretofore been proposed for admitting air to the hot gases
and products of incomplete combustion escaping from steam boiler furnaces for the
purpose of effecting complete combustion thereof. The main requirements of such
a device are,
(1) That the air can be heated to a high temperature and introduced as directly
as possible into the unburnt gases;
(2) That the device can be easily and quickly placed in the required position;
(3) That the parts of the device shall be durable and can be easily repaired or
renewed when needed.
This invention has reference to improvements in or in connection with fire bridges
whereby all these requirements are fulfilled the arrangement moreover being such
as to protect the boiler at that point at which it is mostly exposed to the destructive
action of the pointed flame (Stichflamme).
The invention is applicable to boilers of various kinds.

page_text: A fire bridge according to this invention is provided with hollow perforated brick
work of refractory material such as fire clay carried by an iron frame and arranged
in the form of a hollow arch as hereinafter more particularly described.
Referring to the accompanying drawings,
Fig. 1 is a vertical longitudinal section through part of a boiler furnace and
shewing the fire bridge with my invention applied thereto.
Fig. 2 is a vertical cross section through the fire bridge, and
Figs. 3 and 4 are vertical longitudinal sections similar to Fig. 1 but showing
slight modifications.
The iron frame a and the brickwork bresting thereon form together the fire
bridge proper within the furnace flue .. The frame a is provided at each of its
two sides with an aperture c and above these perforated parts the hollow fireclay
bricks or blocks e are built up in such a manner that their inner channel or
channels forins or form a continuation of the apertures ce and so that they form
an arch located above the fire bridge and following the curvature of the upper part
of the furnace flue. Through the lower or inner side of such arch a number of
apertures o are formed through which air heated within the arch will escape into
the unburnt gases flowing past them. With a fire bridge so constructed it will be
seen that the inner surface of the arch faces the fire bridge proper (b) and through
the apertures o air will issue which will have entered the channel or channels of
the arch, from the ash-pit in its passage having cooled down the arch to a
certain extent and itself become heated, so adding to the more complete combustion
of the gases. d is part of the grate. In Fig. 4 only the sides of the channels
abut against the interior of the furnace flue so that one side of each channel is
formed by the furnace flue. The bricks or blocks forming the arch may be formed
with one channel as shewn in Figs. 1 and 2 or with several channels as shewn in
Figs. 3 and 4. I prefer to construct the bricks or blocks with several channels
inasmuch as the arch will then prove to be more solid and durable, the partitions
between the channels forming additional transmitters of heat to the air flowing
through them.
The arch or vault may, where circumstances will permit be formed or constructed
in one piece, instead of in several pieces.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. The herein described improvements in or in connection with fire bridges
consisting in arranging in conjunction with the fire bridge proper an arch formed
with a channel or channels into which air from the ash pit can enter, said channel
or channels having openings on the underside thereof through which heated air can
pass and mix with the hot gases and products of incomplete combustion escaping
from the hearth substantially as described.
2. A fire bridge provided with a hollow perforated circular arch adapted to have
ts interior placed in communication with the ash pit of a steam boiler furnace and
being constructed and arranged substantially as herein before described with
eference to and shewn in Figs. 1 and 2 or modified according to Fig. 3 or to
Fig. 4 of the annexed drawings.
Dated this 24th day of March 1893.
H. BÖTTGER,
By L. W., per F. B.