IMPROVEMENTS IN STEAM BOILER AND OTHER FURNACES
Year: 1875

page_text: LETTERS PATENT to David Annan, of the Vulcan Ironworks, Bow,
in the County of Middlesex, for the Invention of "IMPROVEMENTS
IN STEAM BOILER AND OTHER FURNACES"
Scaled the 23rd April 1875, and dated the 4th March 1875.
PROVISIONAL SPECIFICATION left by the said David Annan at
the Office of the Commissioners of Patents, with his Petition, on
the 4th March 1875.
I, DAVID ANNAN, of the Vulcan Ironworks, Bow, in the County of
Middlesex, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN STEAM BOILER AND OTHER FURNACES," to be as
follows:-
This Invention has for its object improvements in steam boiler and
other furnaces.
I employ fire-bars which are taper on the face, and I arrange them
alternately with the taper in opposite directions; they are so carried
that the alternate bars are movable longitudinally, whilst the others

page_text: remain stationary. By shifting the movable bars the air spaces between
the bars can be made wider or narrower at pleasure. To give freer
admission to the air the bars are grooved on their sides from top to
bottom, but not vertically, the grooves being made to take approximately
the course of the incoming current of air; I only groove the thicker ends
of the bars, leaving the thinner half or end of the bar plain on the sides.
I usually cast all the bars from the same pattern, or rather, as I prefer,
I cast them in the same chills, and I then groove the two sides of the
bar in opposite directions; there are also studs on the sides of the bars
where they come into contact. At one end of each fire-bar on its under 1
side is a notch to receive the rounded edge of a cross bar on which it
rests; the other end of each fire-bar rests on a similar cross bar, and
here a flat surface is formed on the bar. One of the two cross bars can
be caused to rock to and fro whilst the other remains stationary, and
thus the alternate bars receive the longitudinal motion of which I have 1
already spoken. This arrangement not only provides for the width of
the air spaces being readily adjusted, but also for the rapid cleaning of
the fire, the bars for this purpose being moved repeatedly to and fro.
Where the furnace is long I employ two sets of bars, each of half the
length, and I can couple the movable cross bars of the two sets so that 2
they may be moved simultaneously.
In some cases I arrange both the cross bars so as to be able to rock;
by means of one of them I adjust the width of the air spaces, and I
employ the other to give motion to the bars for cleaning the fire.
Sometimes I mount the cross supporting bars in a pivoting and 2
balanced frame, so that the fire bars may be lowered at their front ends,
either for the purpose of cleaning or discharging the fire or for admitting
air above the bars.
Sometimes I support the bars at both ends independently of the
rocking cross bar by which they are moved to adjust the width of the a
air spaces. In this case I cast each alternate bar only with a notch on
its under side to receive the edge of the rocking cross bar.
Sometimes I employ only a fixed cross bar and adjust the air spaces
by band before starting the furnace. Each bar in this case is formed
with several notches on its under side, and after the bars have all been
laid close together cach alternate bar is shifted endwise the distance of
one notch or more.

page_text: Sometimes I employ endless flat linked chains as fire-bars; I drive
them at different speeds and so keep the fire open. When the chain
becomes worn on one side it is turned; the fire-doors I employ are
openwork frames receiving gratings. In front of the grating a frame
covered with wire gauze is slidden in through a slit in the top of the door
frame, and in front of this again is a flap or valve hung upon pivots at its
upper edge to regulate the entrance of air into the furnace through the
door. Upon the lower edge of the valve is a jointed finger which when
the door is shut comes against the door frame, and causes the valve to
be pushed back admitting air to the fire. The valve is closed or
partially closed by the stops when required, the finger being moved out
of the way and the valve placed as required. A small ratchet retains it
where it may be placed.
In place of a fixed grating a vertically ribbed plate hung on pivots by
its upper edge may be employed; this plate can be inclined at pleasure
to regulate the quantity of air and the direction in which it enters tho
furnace; I admit steam over the fire-door by means of an L shaped nozzlo
bolted to the door frame; it is protected by a shield plate immediately
beneath it.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said David Annan in the Great Scal Patent Office on
the 4th September 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, DAVID
ANNAN, of the Vulcan Ironworks, Bow, in the County of Middlesex,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Fourth day of March, in the year
of our Lord One thousand eight hundred and seventy-five, in the
thirty-eighth year of Her reign, did, for Herself, Her heirs and suc-
cessors, give and grant unto me, the said David Annan, Her special
license that I, the said David Annan, my executors, administrators,
and assigns, or such others as I, the said David Annan, 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

page_text: vend, within the United Kingdom of Great Britain and Ireland, the
Ohannel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN
STEAM BOILER AND OTHER FURNACES," upon the condition (amongst others)
that I, the said David Annan, my executors or administrators, 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.
NOW KNOW YE, that I, the said David Annan, do hereby declare
the nature of the said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the
following statement thereof, that is to say:
This Invention has for its object improvements in steam boiler and
other furnaces.
I employ fire-bars which are taper on the face, as is shown at Figures 1
and 1ª, which are plans of the bars; I arrange them alternately with tho
taper in opposite directions; they are so carried that the alternate bars
are moveable longitudinally, whilst the others remain stationary. By
shifting the moveable bars the air spaces between the bars can be made
wider or narrower at pleasure. To give freer admission to the air the bars
are grooved on their sides from top to bottom, but not vertically, the
grooves being made to take approximately the course of the incoming
current of air; I only groove the thicker ends of the bars, leaving the
thinner half or end of the bar plain on the sides to avoid unduly
weakening it, or one side only of the bar may be left plain, as is shown
at Figure 1; Figure 1° is a transverse section of one of the fire-bars.
I usually cast all the bars from the same pattern, or rather, as I prefer, I
cast them in the same chills, and I then groove the two sides of the bar
in opposite directions; there are also studs on the sides of the bars where
they come into contact. At one end of each fire-bar on its under side is
a notch to receive the rounded edge of a cross bar on which it rests;
the other end of each fire-bar rests on a similar cross bar, and here a flat
surface is formed on the bar. One of the two cross bars can be caused
to rock to and fro whilst the other remains stationary, and thus the
alternate bars receive the longitudinal motion of which I have already

page_text: spoken. This arrangement not only provides for the width of the air
spaces being readily adjusted, but also for the rapid cleaning of the fire,
the bars for this purpose being moved repeatedly to and fro.
Where the furnace is long I employ two sets of bars, each of half the
length, and I can couple the moveable cross bars of the two sets, so that
they may be moved simultaneously.
Figure 2 is a longitudinal section of a furnace thus constructed.
a, a, are the fire-bars; b, b, are fixed cross bars on which the fire-bars
rest at one end; c, c, are moveable cross bars on which the fire-bars rest
at the other end. Each fire-bar has at one end on its under side a notch
and the bars in each set are arranged alternately, so that the notch
beneath one bar embraces one of the fixed cross bars b, and the
notch beneath the next fire-bar embraces one of the moveable cross
bars c, and so on throughout each of tho two sets which the Figure
represents.
In some cases I employ three sets if the furnace be a long one, or if
desired the number of sets might be even further increased. In other
cases I employ one set only. The moveable cross bars c, c, are carried at
their ends in V formed supports on which they are able to rock freely,
and they are coupled together by the arms c¹ and connecting rod c³.
The cross bar c at the front of the furnace also has upon it a short arm c³
which receives a lever handle d by means of which the cross bars e can
be rocked for the purpose of moving the alternate bars a to clean the
fire and the cross bars c, and the fire-bars moved by them can be left in
any position desired so as to admit to the fire more or less air as may be
considered necessary.
In some cases I arrange both the cross bars so as be able to rock;
by means of one of them I adjust the width of the air spaces, and I
employ the other to give motion to the bars for cleaning the fire.
In Figure 3 but one set of fire-bars are shown; both the cross bars aro
moveable; the front cross bar is rocked by means of a lever handle, as
already described, to clean the fire, whilst the back cross bar is moved
whenever it is desired to alter the amount of air admitted to the fire;
it has an arm upon it to which the notched rod e is connected, and
according to the amount of air desired one or other of these notches is
made to catch upon a fixed pin at e¹.

page_text: a are the
Sometimes I mount the cross supporting bars in a pivotting and
balanced frame, so that the fire-bars may be lowered at the front ends,
either for the purpose of cleaning or discharging the fire or for admitting
air above the bars. This arrangement is shown in Figure 4.
fire-bars; b, the fixed cross bar, and c the moveable cross bar; d is the
lever handle for moving the cross bar c. The bars and c are mounted
on a frame e which can pivot or turn so as to assume the position
indicated by the dotted lines; the frame e is counterbalanced, as is shown.
This
arrangement is very convenient for dyers' coppers and in other
cases where the work requires the fire to be rapidly withdrawn or
damped..
Sometimes I support the bars at both ends independently of the
rocking cross bar by which they are moved to adjust the width of the
air spaces.
In this case I cast cach alternate bar only with a notch on
its under side to receive the edge of the rocking cross bar. This
arrangement is shown at Figure 5; a, a, are the fire-bars; b, a fixed
cross bar as before; * is a lip projecting downwards from the dead plate
to support the bars at their front ends; c is the moveable cross bar
having an arm to which the notched rod e is connected, as in Figure 3.
In this case fire-bars of two patterns are employed alternately, one 2
pattern having notches to receive the edge of the fixed bar b, and tho
other to receive the edge of the moving bar c.
Sometimes I employ only a fixed cross bar and adjust the air spaces
by hand before starting the furnace. Each bar in this case is formed
with several notches on its under side, and after the bars have all been
laid close together each alternate bar is shifted endwise the distance of
one notch or more. Figure 6 shows this arrangement; it is similar to
Figure 5, except that the moving bar c is omitted, and the fire-bars are
all alike with several notches on their under sides.
Sometimes I employ endless flat linked chains as fire-bars; I drive a
them at different speeds and so keep the fire open. When the chain
becomes worn on one side it is turned. Figure 7 shows a longitudinal
section, and Figure 8 a transverse section of this arrangement. The
mechanism is mounted by preference on a carriage a so that it can be
withdrawn when desired from beneath the boiler b; c is an axis on the
carriage which is caused slowly to rotate; it has chain pinions c* of
different sizes upon it; d are endless chains passing around these

page_text: pinions, and also around carrying pulleys c, c, at the further end of the
carriage. On the upper side where the chains servo as fire-bars they are
supported at f, f, so as to keep them horizontal, or nearly so. On the
under side adjustable or weighted guide pulleys may be provided to take
up the slack of the chains; the fire-doors I employ are openwork frames
receiving gratings. In front of the grating a frame covered with wire
gauze is slidden in through a slit in the top of the door frame, and in
front of this again is a flap or valve hung upon pivots at its upper edge.
to regulate the entrance of air into the furnace through the door. Upon
the lower edge of the valve is a jointed finger, which when the door is
shut comes against the door frame and causes the valve to be pushed
back admitting air to the fire. The valve is closed or partially closed by
the stoker when required, the finger being moved out of the way and
the valve placed as required a small ratchet retains it where it may be
placed.
In Figure 3, a fire-door, thus constructed is represented in section.
is the doorway frame, and i the door frame, hinged to it at one side in
the usual way; is a grating fixed into the door frame; the front of the
grating is shown at Figure 9. Immediately in front of the grating a
light frame covered with wire gauze is dropped in through a slot in the
top of the door frame, so that the frame can instantly be withdrawn
and another substituted should the gauze become choked or worn out;
m is a valve hung in the door frame by pivots at its upper edge; it is
furnished with the jointed finger m¹ which is thrown up by a weight m²,
so that as the door is closed it comes into contact with the doorway
frame and causes the valve to be opened; n is a notched or ratchet lever
which holds the valve in any position in which it may be placed when
the finger m' has been tripped by lifting the weight m³.
In place of a fixed grating a vertically ribbed plate hung on pivots by
its upper edge may be employed; this plate can be inclined at pleasure
to regulate the quantity of air and the direction in which it enters the
furnace; I admit steam over the fire-door by means of an L shaped
nozzle bolted to the door frame; it is protected by a shield plate
immediately beneath it. This arrangement is seen at Figure 5; o is tho
ribbed plate; it is shown in section at Figure 10; it has a notched arc o'
jointed to it which serves as a handle and to hold it in any position in
which it may be placed. Figure 11 is a front elevation of the fire-
door; p shows the steam pipe and spreader by which I cause steam to be

page_text: introduced above the fire-door; Figures 12 show details of theso
parts.
Having thus described the nature of my said Invention and the
manner of performing the same, I would have it understood that I claim
as my improvements in steam boiler and other furnaces,―
First. Forming the fire-bars taper and mounting them so that the
alternate bars may be moved longitudinally, substantially as described.
Second. Forming the fire-bars substantially as described.
Third. The arrangement of fire-bars and parts connected therewith,
substantially as described and shown in the annexed Drawings.
Fourth. The arrangement of fire-doors and parts connected therewith,
substantially as described in respect to Figures 3, 5, 9, 10.
In witness whereof, I, the said David Annan, have hereunto
set my hand and seal, this Fourth day of September, in the
year of our Lord One thousand eight hundred and seventy.
five.