AN IMPROVED CONSTRUCTION OF FURNACE FIRE-BAR
Year: 1872

page_text: LETTERS PATENT to William Henry Dilnutt, of Mawbey Road, Old
Kent Road, in the County of Surrey, Engineer, for the Invention
of "AN IMPROVED CONSTRUCTION OF FURNACE FIRE-BAR.”
PROVISIONAL SPECIFICATION left by the said William Henry Dilnutt
at the Office of the Commissioners of Patents, with his Petition,
on the 30th July 1872.
I, WILLIAM HENRY DILNUTT, of Mawbey Road, Old Kent Road, in
the County of Surrey, Engineer, do hereby declare the nature of the
said Invention for "AN IMPROVED CONSTRUCTION OF FURNACE FIRE-BAR," to be
as follows:-
-:
The object of this Invention is to provide a comparatively light, cheap,
and efficient fire-bar for steam boiler and other furnaces, the use of
which will ensure considerable windage and yet allow of the burning:
thereon of fine coal or slack. To this end I form the fire-bar with a thin
deep web and with a series of teeth projecting laterally therefrom at
both sides of the web and on a level with. the face thereof. The length
of these teeth will be about double the width of the web, and they will

page_text: be so spaced out as to allow of corresponding teeth in the next adjacent
bars entering the spaces and leaving a narrow windage between the teeth
of the adjacent bars. The sides of the teeth I make parallel with each
other and finish the teeth with square ends, or I may for facility of
casting round off the angles at the extremities of the teeth, and in that
case the angles at the root of the teeth will be rounded off to correspond
thereto. Thus a narrow zig-zag windage will be formed between every
two bars, making in all a large windage area in the fire-grate, which will
however afford no sufficient opening for slack or fine coal to fall through
into the ash-pit.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said William Henry Dilnutt in the Great Seal Patent
Office on the 30th January 1873.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
HENRY DILNUTT, of Mawbey Road, Old Kent Road, in the County of
Surrey, Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Thirtieth day of July, in the year of
our Lord One thousand eight hundred and seventy-two, in the thirty-
sixth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said William Henry, Dilnutt, Her special
licence that I, the said William Henry Dilnutt, my executors, admi-.
nistrators, and assigns, or such others as I, the said William Henry
Dilnutt, my executors, administrators, and assigns, should at any time
agree with, and no others, from time to time and at all times thereafter
during the term therein expressed should and lawfully might make, use,
exercise, and vend, within the United Kingdom of Great Britain and
Ireland, the Channel Islands, and Isle of Man, an Invention for "AN
IMPROVED CONSTRUCTION OF FURNACE FIRE-BAR," upon the condition (amongst
others) that I, the said William Henry Dilnutt, my executors or admini-
strators, by an instrument in writing under my, or their, or one of their
hands and seals, should particularly describe and ascertain the nature of
the said Invention, and in what manner the same was to be performed,
and cause the same to be filed in the Great Scal Patent Office within
six calendar months next and immediately after the date of the said
Letters Patent.

page_text: NOW KNOW YE, that I, the said William Henry Dilnutt, do hereby
declare the nature of my said Invention, and in what manner the
same is to be performed, to be particularly described and ascertained
in and by the following statement, reference being had to the Drawing
hereunto annexed, and to the letters and figures marked thereon (that
is to say)
The object of this Invention is to provide a comparatively light, cheap,
and efficient fire-bar for steam boiler and other furnaces, the use of
which will ensure considerable windage and yet allow of the burning
thereon of fine coal or slack. To this end I form the fire-bar with a thin
deep web and with a series of teeth projecting laterally therefrom at both
sides of the web and on a level with the face thereof. The teeth will be
so spaced out as to allow of a set of similar bars when placed in a
furnace interlocking by the teeth of one bar entering the spaces in the
next adjacent bar and leaving a narrow windage between the teeth of
the adjacent bars. The sides of the teeth I make parallel with each
other and finish the teeth with square ends, or I may for facility of
casting round off the angles at the extremities of the teeth, and in that
case the angles at the root of the teeth will be rounded off to correspond
thereto. Thus a narrow zig-zag windage will be formed between every·
two bars making in all a large windage area in the fire-grate which will
however afford no sufficient opening for slack or fine coal to fall through
into the ash-pit.
..
In the accompanying Drawing Fig. 1 shews in side elevation my
improved fire-bar; Fig. 2 is an end view of the same; and Fig. 3 is a
section taken in the line 1, 2, of Fig. 1.
Fig. 4 represents in plan three fire-bars, illustrating the manner in
which they will be ordinarily arranged in the furnace to form a fire-
grate.
a is the web of the fire-bar; b, b, are teeth projecting from opposite
sides of the bar and so disposed that the teeth on one side range with the
spaces on the opposite side of the web. A tolerably uniform thickness
of metal is thus ensured to all parts of the bar that are exposed to the
direct action of the fire, and thus the liability of the bar to warp and
twist is removed: In setting the bars in the furnace their ends c, c, are
caused to rest on transverse bearers and to lie in contact one with the
other. I prefer so to proportion the bars that when thus laid together,

page_text: as shewn at Fig. 4, there will be a zig-zag windage between the adjacent
bars and through the whole length of the grate of about three-eighths of
an inch in width. On a grate thus arranged I find that I am enabled
to burn small coal with great advantage as there will be ample draft
through the grate without the liability of the coal falling through into
the ash-pit. It will be understood that the two end bars of the grate
will be furnished with teeth on one side only of the web.
When burning clinking coal I may find it desirable to increase the
windage. This may be readily effected without making any change in
the form or proportions of the fire-bars. Fig. 5 illustrates the mode of
effecting this change. In laying the grate I throw out of use, say, one
bar of the set and so arrange the remaining bars that they shall cover
the whole area of the fire-place. This I do by simply inserting filling
pieces d, Fig. 5, between the ends of adjacent bars. I thus increase
the width of the zig-zag windage laterally to an extent equal to the
width of the filling pieces d, while at the same time the surface support
of the grate for the fuel is not materially detracted from.
Having now set forth the nature of my Invention of "An Improved
Construction of Furnace Fire-bar," and explained the manner of carrying
the same into effect, I wish it to be understood that under the above in
part recited Letters Patent I do not claim interlocking fire-bars however
constructed; but what I claim is, the manufacture and use of inter-
locking fire-bars, as described, whereby I am enabled to remove the
liability of the bars to warp and twist and to obtain a well distributed
windage which admits of variation at pleasure, as shewn in the accom-
panying Drawing.
In witness whereof, I, the said William Henry Dilnutt, have here-
unto set my hand and seal, the Twenty-fifth day of January,
in the year of our Lord One thousand eight hundred and seventy-