IMPROVEMENTS IN AND CON- NECTED WITH FURNACE BARS
Year: 1878

page_text: LETTERS PATENT to David Davidson, of Glasgow, in the County of Lanark,
North Britain, Boilermaker, for the Invention of "IMPROVEMENTS IN AND CON-
NECTED WITH FURNACE BARS."
Scaled the 18th February 1879, and dated the 22nd August 1878.
PROVISIONAL SPECIFICATION left by the said David Davidson at the Office
of the Commissioners of Patents on the 22nd August 1878.
DAVID DAVIDSON, of Glasgow, in the County of Lanark, North Britain, Boiler-
maker. "IMPROVEMENTS IN AND CONNECTED WITH FURNACE BARS."
This Invention has for its objects to economise fuel, to prevent smoke, and to
render furnace bars more durable than as hitherto made; and it consists mainly in
proventing the overheating of the bars, to which the defective action and want of
durability of ordinary bars are attributable, by certain improved constructions and
arrangements, herein-after described, and which are applicable to all classes of
furnaces in which grate bars are used.
In carrying out the Invention, according to one modification, the furnace bars are
made hollow or tubular, the section of the hole through each bar being similar to
that of the bar itself, whilst the section of the bar may be of any suitable form.
Across the front or outer ends of the bars there is fixed a pipe supplied with steam
from the boiler of the same furnace or from another boiler, and from this steam pipe
jets of steam are directed into or through the several bars, either by orifices in the
steain pipe opposite the ends of the bars, or by nozzles or small pipes which may
enter the hollow bars to a greater or less extent. These steam jets induce air to
pass along with them through the bars, and thereby prevent the overheating of the
Prine Adı

page_text: bars. The inner ends of the bars communicate with a hollow bridge, and the
mixed steam and air pass through the bars into this bridge, and issuing from per-
forations in it, cause the complete ignition and combustion of the gases or smoke
from the fuel.
In a second modification air forced by a blower is employed instead of steam, and
is introduced into the hollow bars in jets or otherwise.
In other modifications jets of steam or of compressed air are applied at the inner
ends of the hollow bars, or at any suitable part of the hollow bridge, so as to produce
a partial vacuum, and thereby induce currents of air to pass through the bars.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said David Davidson in the Great Seal Patent Office on the 21st February
1879.
DAVID DAVIDSON, of Glasgow, in the County of Lanark, North Britain, Boiler-
maker. "IMPROVEMENTS IN AND CONNECTED WITH FURNACE BARS."
My said Invention has for its objects to economise fuel, to prevent smoke, and to
render furnace bars more durable than as hitherto made; and it consists mainly in
preventing the overheating of the bars, to which the defective action and want of
durability of ordinary bars are attributable, by certain improved constructions and
arrangements, herein-after described, and which are applicable to all classes of
furnaces in which grate bars are used.
In carrying out my Invention I have the furnace bars made hollow or tubular,
and in one modification there is fixed across their front ends a pipe supplied with
steam from the boiler of the same furnace or from another boiler, and from this
steam pipe jets of steam are directed into or through the several bars, either by
orifices in the steam pipe opposite the ends of the bars, or by nozzles or small pipes
which may enter the hollow bars to a greater or less extent. These steam jets
induce air to pass along with then through the bars, and thereby prevent the over-
heating of the bars. The inner ends of the bars communicate with a hollow bridge,
and the mixed steam and air pass through the bars into this bridge, and issuing
from an opening or openings in it, cause the complete ignition and combustion of
the gases or smoke from the fuel.
In a second modification air forced by a blower is employed instead of steam, and
is introduced into the hollow bars in jets, as in the case of steam, or otherwise.
In other modifications jets of steam or of compressed air are applied at the
inner ends of the hollow bars, or at any suitable part of the hollow bridge, so
as to produce a partial vacuum, and thereby induce currents of air to pass through
the bars.
And in order that my said Invention and the manner of performing the same
may be properly understood, I hereunto append a Sheet of explanatory Drawings,
to be herein-after referred to, and representing two modifications of my improved
arrangements. In these Drawings the same reference numerals are used to mark
the same or like parts wherever they ere repeated.
Figure 1 on the accompanying Sheet of Drawings is a longitudinal vertical sec-
tion showing my improved bars and parts connected therewith as applied to the
furnace of a horizontal cylindrical steam boiler.
Figure 2 is a plan of the furnace grate.
And Figures 3, 4, and 5 are enlarged views of one of the bars with a part of the
steam jet pipe.
The furnace bars 7 may be of any suitable section, and they may be of either
cast iron, or wrought iron, or steel, but I believe that cast-iron bars of the form or
section shown in the Drawings, and which resembles a common form of solid bar,
will in most cases be found sufficiently satisfactory and convenient. These furnace
bars 7 are made hollow or tubular from end to end, and the section of the hole
through each bar is similar to that of the bar itself. At a short distance outwards
from the front ends of the hollow bars 7 there is fixed a transverse pipe 8, which is
supplied with steam from any convenient boiler, and which has fixed in it a series
of small jet pipes or nozzles 9. One of these jet pipes 9 enters into each hollow
bar 7, and the action of the steam jet causes air to be drawn into the outer ends of
the bars, and carried along through the bars to their inner ends. The air and steam
thus passing through the hollow bars 7 enter a hollow bridge 10, and issue by pre-
ference from the inner side thereof, so as to minglo with the fire gases passing over
the bridge, and insure the complete ignition of those gases.

page_text: The bridge 10 may be partly of cast iron and partly of brick work, as shown, or
wholly of cast iron.
Figure 6 is a longitudinal vertical section showing a modification in which the
steam pipe 8 is fitted at the bridge 10, the jet pipes 9 fixed to it being directed into
the hollow air passage in the bridge, so as to induce currents of air to pass through
the hollow bars 7 and through the hollow bridge 10.
Compressed air instead of steam may be supplied to the pipe 8 and jet pipes 9 in
either modification.
Having thus particularly described my said Invention, and the manner of per-
forming the same, I have to state that I do not restrict myself to the precise details
herein described or delineated, but that what I believe to be novel and original and
claim as the Invention secured to me by and in terms of the herein-before in part
recited Letters Patent is,
1. The combination of hollow or tubular fire-bars with pipes for applying jets of
steain or of compressed air to induce currents of air through such bars, substantially
as and for the purposes herein-before described.
.
2. The combination of the hollow bridge, having openings for the issue of air or
air and steam into the flue, with the hollow or tubular fire-bars and jot apparatus,
arranged and operating substantially as herein-before described.
In witness whoreof, I, the said David Davidson, have hereunto set my hand
and seal, this Twentieth day of February, in the year of our Lord One
thousand cight hundred and seventy-nine.
Witness,
EDMUND HUNT,
Patent Agent,
Glasgow.
DAVID DAVIDSON. (L.S.)