IMPROVEMENTS IN AND CONNECTED WITH FIRE BARS AND FURNACES
Year: 1881

page_text: LETTERS PATENT to Edward Griffith Brewer, of 33, Chancery Lane, in the
County of Middlesex, for an Invention of "IMPROVEMENTS IN AND CONNECTED
WITH FIRE BARS AND FURNACES." A communication from abroad by Jobn
Alves, of Dunedin, Colony of New Zealand, Engineer.
PROVISIONAL SPECIFICATION left by the said Edward Griffith Brewer
at the Office of the Commissioners of Patents on the 26th January 1881.
EDWARD GRIFFITH BREWER, of 33, Chancery Lane, in the County of Middlesex.
"IMPROVEMENTS IN AND CONNECTED WITH FIRE BARS AND FURNACES." A com-
munication from abroad by John Alves, of Dunedin, Colony of New Zealand,
Engineer.
This Invention has for its object improvements in and connected with fire bars
and furnaces, and refers first to fire bars, second to fire bridges in furnaces, and
third to rakes for use with these fire.bars.
According to this Invention the fire bars are made with a longitudinal knife
edge or ridge instead of a flat surface; the sides of each bar are made taper from
one end to the other, and they are so set in position as to admit of the space
between them gradually widening from one end to the other (by reason of the
tapering sides of the bars), and also set in such a position as to leave a narrow
space between them and the fire box on all sides. The spaces between the bars
gradually widen from the front to the back. The bars are provided with dividing
pieces, and are carried by bearers in any convenient manner.
The width of the spaces between them is regulated to suit the description or
quality of fuel used, and their depth according to the strength required. They
may all be of the same depth, or some of one depth and some of another. The
dividing pieces are made to fit the spaces required, and are kept below the bevilled
part of the bars to allow the rake to pass without obstruction, and also to allow
the air free play upon the coal, which the dividing pieces in the ordinary way do
not, as the fuel rests on the dead flat surface of the bar without air space. The
bars and the dividing pieces may be constructed separately, or two or more may be
[Price II

page_text: joined together to suit the length and breadth of the furnace or fire box, but so as
to leave a space on either side of the fire box, and at the back for the purpose of
causing the flame and heated air to keep to the sides of the fire box.
In some cases the bars are put across the furnace, or cross bars are put between
two longitudinal bars, according to the description of the furnace and the draught,
but the tops are bevilled to a knife edge or ridge.
The object of this part of the Invention is to expose to the fullest extent the
underneath surface of the fuel to the action of the atmosphere. By it the air is in
contact at once with the fuel throughout the whole area of the grating, inasmuch
as in going through the air spaces the air spreads on either side and fills the grooves
caused by the bevil of the bars, and as only the sharp edges of the bars touch the
fuel, there is no obstruction to the admission of air to every part of the fuel.
In the ordinary furnace bars, a little more than about one fourth is air space, the
bars occupying the remainder of the grating area.
The bevilled edge bars create a better draught. The sharp edges of the bars also
prevent the fuel from clinkering to a great extent, as on forming on the edge of
the bar the clinker turns down the slope and the action of the air makes it brittle,
the sharp edge breaks it, and it falls through between the bars in small pieces,
insteed of forming a cake or sheet of slag on the top of the bars. The air having
a free passage, the bars are less liable to be overheated or burnt, and consequently
a saving in wear and tear is effected.
The firing needs but little attention as the bars keep clean, thereby the
frequent admission of cold air into the fire box by opening the furnace door is
prevented.
The spaces at the back of the furnace being only required to free the ashes at
that part (less the portion which is carried towards the tube plate by the blast) are
made to taper narrow towards the back, and by graduating the spaces wider
towards the front of the furnace, the ashes which are made at that part (as well
as the portion carried from the back) are enabled to pass through, and the air
being admitted to a greater extent, the combustion is more perfect and the
accumulation of ashes and clinkers at the front of the furnace is materially
lessened.
When more than one length of bar is used, and two ends abut against each other,
the space pieces are kept a proper distance from the ends to prevent obstruction to
the air passing to the fuel.
These fire bars may be made without any taper if preferred, and with a uniform
width of space between them.
i
They may be also set on a level or on an incline, and may be used without
the fire bridge, and they are applicable to ranges, grates, or stoves of every
description.
The cast metal substructure, which is termed the fire bridge, has apertures or air
spaces or passages through same, and rests on space or distance pieces so as to
leave draught spaces or apertures underneath, and the back is continued down in
such a manner as to protect the tube plate from the injurious effects of the cold
air.
There is some masonry or brickwork above and resting on the fire bridge. This
brickwork superstructure has horns or projections at each side, and is braced or
otherwise secured to the substructure by tie rods or bolts.
The slots or air spaces in front of the cast iron part of the fire bridge are to
create a back current of air into the fuel next to it and to cause better combustion,
so that the air from below the bars may freely get through the fuel. At the back
and ends of the bridge, a safety plate for the protection of the tube plate and sides
of fire box is fixed, the top of the bridge resting on the top edge of the safety plate
and there secured in position by slots or dovetails, a space allowing for the rivet
heads being left between the tube plate and the safety plate for fire clay packing,
and the bottom edge of the safety plate being provided with a fillet to hold such
packing.

page_text: The safety plate may be separate or cast as part of the bridge, or if desired the
bridge may be used without the safety plate. Instead of the cast iron portion
of the bridge being protected by fire bricks bolted to it, as before described, a
hollow vessel similar in form and mode of boiler plate or other suitable material
attached to or forming part of the boiler, so as to be supplied with water, may be
substituted.
The object of this part of the Invention is to obtain a blast at the front of the
furnace, thereby creating a better draught, and preventing any accumulation of
fuel at the front of the fire box.
The whole of the fire space doing its full amount of work at the same time, and
the heat being more intense at the front of the furnace, will consume a certain
percentage of the smoke which passes over it.
.
The horns are for the purpose of causing the flames to rise towards the upper
tubes, thereby distributing the flames and heated air more evenly through the
tubes. The combustion by means of these improvements is rendered more complete,
there is no deposit of ashes either in the boiler tubes or smoke box, and the flames
being more evenly distributed through the tubes there is less destruction thereto
as well as the tube plate, and so a great saving both in labor and wear and tear is
effected.
Owing to the better draught, there is a more complete combustion of the fuel,
and a better diffusion of heat throughout the furnace.
The fire bridge can be extended round the furnace if required.
The rakes for cleaning the fire bars are provided with teeth or projections to fit
into the spaces between and to clean the bars, the number of projections on the
rake depending on the construction of fire bars employed.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Edward Griffith Brewer, in the Great Seal Patent Office on
the 26th July 1881.
EDWARD GRIFFITH BREWER, of 33, Chancery Lane, in the County of Middlesex..
"IMPROVEMENTS IN AND CONNECTED WITH FIRE BARS AND FURNACES." (A com-
munication from abroad by John Alves, of Dunedin, Colony of New Zealand,
Engineer.)
This Invention relates, first, to fire bars; second, to fire bridges in furnaces; and,
third, to rakes for use with such fire bars.
As to Fire Bars. The improvements consist, first, in making their faces with a
longitudinal knife edge or ridge instead of a flat surface; second, in making the
sides of each bar to taper from one end to the other; and, third; in so setting them
in position as to admit of the space between them gradually widening from one
end to the other (produced by the tapering sides) and also so as to leave a narrow
space between them and the fire box on all sides.
As to Fire Bridges. The improvements consist, first, in making their base or
lower part of cast iron with slots or air spaces to admit the air from the front end
of the fire bars into the body of the front of the furnace; and, second, in building
a brick superstructure on said iron base, said brick superstructure having projecting
horns at each side to throw the flames higher than they otherwise would go and
with an iron plate at the top of the brick-work to admit of its being braced together
by iron tie rods proceeding from the top to the bottom of the bridge.
As to Rakes. The improvement consists in making them with teeth which will
fit into the spaces formed by the fire bars.
Referring now to the Drawings. Figure 1 shews longitudinal section of a fire box
of a tubular boiler, whilst Figures 2 and 3 shew respectively transverse section and
plan of same. a are the fire bars resting on bearers k; d are the dividing pieces
between the bars, and u the space at either end and on either side of them; \ are
the spaces between the bars which it will be seen gradually widen from the back
of the fire box to the front; L is the furnace door; A is the cast iron substructure
or base of the fire bridge which rests on space or distance pieces c so as to leave
draught spaces c¹ underneath it. The upright part of this cast iron part marked f
is to protect the tube plate p from the injurious effects of the cold air; m are the
slotted air spaces in the face of this part of the bridge; B is the brick work thereon,
and C the horns of such brickwork; o, o, are iron plates, and n tie rods for bracing
the brick superstructure to the iron substructure of the fire bridge, the space r, and
if necessary, space 1 being packed with fire clay; t are the tubes. When the
bridge is dispensed with the bars are made longer at the front to prevent fuel
falling through.
Figures 4 and 5 shew respectively plan and longitudinal section of another mode
of using the fire bars. Here are two longitudinal bars a, a, joined together at the
ends and with my fire bars e placed across from one to the other at an angle,
although of course they may be set straight across if so desired.
Figure 6 shews at A cross section of bars in Figure 4 with alternate broad and
narrow bars; at B, cross section shewing side bars and cross bars and dividing
pieces; at C, section of three bars together, the centre one deeper than the others,
a being the longitudinal bars and e the cross bars.
Figure 7 shews rake with teeth or edge suitable for cleaning the fire bars, as
shewn in Figure 6, whilst Figure 8 shews rake suitable for cleaning the fire bars
as shewn in Figure 2.

page_text: As to the Fire Bars. The width of the spaces between them is regulated to suit
the description or quality of fuel used, and their depth according to the strength
required. They may all be of the same depth, or some of one depth and some of
another. The dividing pieces are made to fit the spaces required and are kept
below the bevelled part of the bars to allow the rake to pass without obstruction,
and also to allow the air free play upon the coal which the dividing pieces in the
ordinary way do not, as the fuel rests on the dead flat surface of the bar without
air space. The bars and the dividing pieces may be constructed separately or two
or more may be joined together to suit the length and breadth of the furnace or
fire box, but so as to leave a space on either side of the fire box and at the back for
the purpose of causing the flame and heated air to keep to the sides of the fire box.
In some cases the bars are put across the furnace, or cross bars are put between two
longitudinal bars, according to the description of the furnace and the draught, but
the tops are bevelled to a knife edge or ridge, as shewn. The object of this part of
the Invention is to expose to the fullest extent the underneath surface of the fuel
to the action of the atmosphere. By it the air is in contact at once with the fuel
throughout the whole area of the grating, inasmuch as in going through the air
spaces the air spreads on either side and fills the grooves caused by the bevil of the
bars, and as only the sharp edges of the bars touch the fuel there is no obstruction
to the admission of air to every part of the fuel. In the ordinary furnace bars
a. little more than about one fourth is air space, the bars occupying the
remainder of the grating area. The bevelled edge bars create a better draught.
The sharp edges of the bars also prevent the fuel from clinkering to a great
extent, as on forming on the edge of the bar the clinker turns down the slope
of the bar, the action of the air makes it brittle, the sharp edge breaks it, and it
falls through between the bars in small pieces instead of forming a cake or
sheet of slag on the top of the bars. The air having a free passage the bars are
less liable to be overheated or burnt, and consequently a saving in wear and tear
is effected. Less attention to the firing is necessary as the bars keep clean, and
the frequent admission of cold air into the fire box by opening the furnace door is
prevented. The spaces at the back of the furnace being required only to free the
ashes at that part, less the portion which is carried towards the tube plate by the
blast, are made to taper narrow towards the back, and by graduating the spaces
wider towards the front of the furnace, the ashes which are made at that part, as
well as the portion carried from the back, are enabled to pass through, and the air
being admitted to a greater extent, the combustion is more perfect, and the
accumulation of ashes and clinkers at the front of the furnace is materially
lessened. Where more than one length of bar is used, and two ends abut against
each other, the space pieces are kept a proper distance from the ends, to prevent
obstruction to the air passing to the fuel. If preferred, the fire bars may be made
without any taper, and with a uniform width of space between them. They may
also be set on a level or on an incline, and may be used without the fire bridge, and
for ranges, grates, and stoves of every description.
The slots or air spaces in front of the cast iron part of the fire bridge are to
create a back current of air into the fuel next to it, and to cause better combustion
of the fuel, so that the air from below the bars may freely get through the fuel.
At the back and ends of the bridge a safety plate for the protection of the tube
plate and sides of fire box is fixed, the top of the bridge resting on the top edge
of the safety plate, and there secured in position by slots or dovetails, a space
allowing for the rivet heads being left between the tube plate and safety plate for
fire clay packing, and the bottom edge of the safety plate being provided with a
fillett to hold such packing. This safety plate may be separate as above described,
or cast as part of the bridge, or if desired the bridge may be used without the
safety plate. Instead of the cast iron portion of the bridge being protected by fire
bricks bolted to it, as before described, a hollow vessel similar in form, and made of
boiler plate or other suitable material attached to or forming part of the boiler, so
as to be supplied with water, might be substituted. The object of this part of the

page_text: Invention is to obtain a blast at the front of the furnace, thereby creating a better
draught, and preventing any accumulation of fuel at the front of the fire box,
the whole of the fire space doing its full amount of work at the same time, and
the heat being more intense at the front of the furnace, will consume a certain
percentage of the smoke which passes over it. The horns are designed for the
purpose of causing the flames to rise towards the upper tubes, thereby distributing
the flame and heated air more evenly through the tubes. The combustion by
means of these improvements is rendered more complete, there is no deposit of
ashes either in the boiler tubes or smoke box, and the flames being more evenly
distributed through the tubes, there is less destruction to the tubes and tube plate,
and so a saving both in labor and in wear and tear is effected. Owing to the.
better draught there is a more complete combustion of the fuel, and a- better
diffusion of the heat throughout the furnace; steam is more quickly generated, and
a less quantity of fuel required. The fire bridge can be extended round the furnace
if required.
Having thus described the nature of this Invention, and the manner of performing
I claim as the aforesaid improvements,―
same,
First. Making.fire bars with a longitudinal knife edge or ridge for the upper
face and tapering sides, substantially as and for the purposes set forth.
Second. Making fire bridges with a cast iron substructure, having air spaces n to
admit the air from the back end of the fire bars, and air flues c and m directed to
the front, in combination with the superstructure B, C, or water chamber thereon
braced or bolted together, substantially as herein described and explained.
In witness whereof, I, the said Edward Griffith Brewer, have hereunto set
my hand and seal, this Twenty fifth day of July, in the year of our Lord
One thousand eight hundred and eighty one.