Improvements in Bridges for Furnaces.
Year: 1891

page_text: Date of Application, 30th June, 1891-Accepted, 1st Aug., 1891
COMPLETE SPECIFICATION.
Improvements in Bridges for Furnaces.
I, ALEXANDER MELVILLE CLARK, of the firm of A. M. and Wm. Clark, of
53, Chancery Lane, in the County of Middlesex, Fellow of the Institute of Patent
Agents, do hereby declare the nature of this invention (a communication to me from
abroad by Edwin Warren Tucker, of 609, Haight Street, San Francisco, California,
United States of America, Mechanical Engineer, and Leopold Katzenstein, of
223, West 133rd Street, New York, United States of America, Mechanical
Engineer), and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement:-
This invention relates to improvements in hot air bridges for furnaces, and
consists in the arrangement of parts and details of construction hereinafter fully
set forth.
the
The invention relates more particularly to certain improvements upon
invention for which former Letters Patent were granted dated the 26th day of
July 1887, No. 10,393 which consists of a hollow bridge for the admission of air
into the combustion chamber.
The invention consists more particularly in providing a hollow bridge which
may be so regulated as to utilize either a forced or natural draught of air in order to
meet the requirements of the furnace, of such construction as is necessary to its
complete and perfect adjustment and adaptation to boiler furnaces so that the
required strength and durability may be produced conjointly with economy in
making repairs, thereby permitting of ready handling.
The invention also consists in constructing a bridge which shall be simpler, less
expensive, and more effectual in its operation, than any device of a similar nature
heretofore known.
The invention also consists in providing for the removal of the dirt and
accumulated substances upon the interior of the bridge, so that at any time when it
is found that the effectiveness of the operation of the device is impaired, all dirt or
sediment may be removed with but the slightest difficulty; also in providing a
construction whereby the liability of the lower section to bulge or break out, by
reason of the intense heat, is to a great extent obviated.
Furthermore, the invention consists in constructing the upper casting of several
separate sections whereby the same may be readily handled and the difficulty which
has hitherto existed in this respect, overcome.
Reference is to be had to the accompanying drawings, forming part of this
Specification, wherein
Figure 1 is a perspective view of the upper casting ;
Figure 2 is a transverse section of the two castings, constituting the bridge;
Figure 3 is a plan view of the upper casting;
Figure 4 is a front view of the entire device;
Figure 5 is an inverted plan of the lower casting.
Similar letters of reference indicate corresponding parts in all the views.
The letter B indicates the bottom or base casting which is provided with the
inclined side and rear walls U. To said casting is secured the front plate T which,
if so desired, may be cast integral therewith. To the front plate is secured the
damper D which is controlled or regulated by means of the rotating rod which
was fully described in the Letters Patent above referred to. The damper D is
used merely to control the inflow of the natural draught to the bridge.
The bridge consists of the upper and lower sections or castings, the upper one of
which is rontacented by the letter P The ton of said casting is provided with a

page_text: series of pyramidal apertures M. in order to create a more perfect supply or draught
of the air to the furnace or combustion chamber and has bolted to the sides thereof,
the dovetail strips or lugs N between which the bricks O are secured, to fully
protect the face of the casting from damage. It will be seen from the drawing
that the upper casting is made in several sections, so that the casting may be
readily secured in place and be as expeditiously removed from the lower casting, as is
often found necessary for the purposes of repairs or otherwise. Heretofore, owing
to the fact that the upper casting has been constructed in one piece, great difficulty
has been experienced in removing and replacing the same, owing to its great weight.
The lower or base section 13 is of such height as to fall below the plane of the
grate bars which-rest thereon. Each of said sections is provided with lugs at back
which are bolted together. The sections are further secured together by the
lugs J, which fit beneath an inwardly-extending lug G of the base B. The lugs J
are located within the section P and may either be cast or bolted to ribs R. They
are of the peculiar shape shewn in Figure 2 of the drawing, and differ in their
inode of attachment from the lugs described in the aforesaid former Patent in being
cast with, or bolted to, the ribs R which latter are provided with a bolt hole and
are cast integral with the casting. This is considered a great improvement,
inasmuch as in practice it is found that the foot or extremity of the lugs, which
fit beneath the inwardly extending lug G, are very liable to be broken or damaged.
When this occurs, the rib R remains intact and another lug J is then merely
attached to it by running a bolt through the hole of its rib and through the hole of
the remaining rib R, thus enabling a new lug to be readily substituted, whenever
an old one is broken, without dismantling the machine.
The bridge is secured within the furnace by means of the lateral lugs H at the
upper part of the base B which engage with fixed studs, in order to prevent the
Bridge being forced backward and by cars I which slip over bolts or studs provided
with nuts which serve to draw the bridge down and hold it firmly in position..
This will be found a convenient arrangement in determining the proper position for
the fixed studs in the furnace wall, inasmuch as after the bottom section has been
placed in position, the proper position for the fixed studs in relation to lugs H can
be readily marked off in tlie furnace wall.
The bottom of the bottom section is provided with openings C which permit of
the escape of dirt therethrough and also with a hole A into which air inlet pipe A¹
fits, for the introduction of air under pressure, in order to create a forced draught.
While the air has been described as entering under pressure through the bottom
of the base section, it is obvious that the same may be admitted at any point
deemed most advisable for the admission of the forced draught. The forced air
enters chamber B' of section B and has its exit through the converging openings
formed in the top of section P. However, in order to obviate the liability of the
inflowing air escaping through the bottom openings, the ordinary Tompkin plate E
is provided; thus obtaining a more perfect commingling with, and combustion of,
the gases; creating a thorough consumption of the coal; giving greater heat; and
causing a saving in the burning of the coal. The bottom opening in connection
with the device is considered of great importance, inasmuch as by simply removing
the plate E all sediment or dirt may be removed while when said plate is in proper
position the air which enters either by the forced draught, or by the natural
draught, channels is prevented from escaping downwards. By forming the bridge
in sectionis, united as set forth; the same may be more readily taken apart, in case
of breakage or damage ensuing thereto. It will be observed that the several
features or parts may be readily cast or formed integral if so desired.
In practice it will be found that the lower casting is materially weakened by the
bottom opening and the front damper-controlled opening and consequently there is
a danger of said section breaking or bulging out by reason of the intense heat. To
guard against this; an interior strengthening rib S is provided, running from the
top of the lower casting to the bottom thereof,

page_text: 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. In a hot air bridge for furnaces, the combination of a lower casting provided
with a series of rearwardly-extending lugs, an upper casting consisting of several
sections each provided with rearwardly-extending lugs registering with the lugs of
the lower casting, and bolts passing through the registering lugs K, substantially
as set forth.
2. In a hot air bridge for furnaces, the combination of the upper and lower
castings, the front wall or plate of the lower casting being provided with suitable
openings, a damper for regulating said openings, and an air inlet for creating a
forced draught, said inlet entering the lower casting, substantially as set forth.
3. In a hot air bridge for furnaces, a casting provided with an opening C for the
escape of dirt, damper-controlled openings in its front plate, and also formed or
provided with a central strengthening strip or rib S running from the top to the
bottom thereof, substantially as set forth.
4. In a hollow bridge for furnaces, the combination of the upper and lower
castings the latter having an opening in its bottom for the escape of dirt and also
damper-controlled openings in its front plate, a sliding plate for closing said dirt
openings, and a forced air pipe leading into the lower casting, substantially as set
forth.
5. In a hollow hot air bridge for furnaces, the combination of the upper and
lower sections, of the lug J within the upper section, and of the inward projection G
on the lower section, the said lug heing adapted to engage with the projection G
in order to unite said sections, substantially as set forth.
6. In a hollow hot air bridge for furnaces consisting of a base casting B and a
top casting P provided with pyramidal apertures in its top, said top being
constructed in two or more sections, ribs R cast or bolted to said section or top,
lugs J secured thereto, and of the inward projection G, substantially as set forth.
7. In a hollow hot air bridge for furnaces consisting of an upper and lower
casting suitably secured together, forced air inlet leading into said casting for the
purpose of permitting a forced air draught, and of the lugs E, I, for securing the
b.idge within the furnace, substantially as set forth.
Dated this 30th day of June 1891
A.
MELVILLE CLARK.
By A. M. & Wm. Clark,
53, Chancery Lane, London, Patent Agents.
A.
MELVILLE CLARK.
By A. M. & Wm. Clark,
53, Chancery Lane, London, Patent Agents.