IMPROVEMENTS IN BURNING POWDERED FUEL. AND IN FURNACES AND APPARATUS FOR BURNING POWDERED FOEL, ALSO IN ADAPTING SUCH FURNACES FOR THE MELTING AND WORKING OF GLASS, IRON, STEEL, AND OTHER MATERIAL, AND TO HEATING STEAM BOILERS
Year: 1869

page_text: LETTERS PATENT to Thomas Russell Crampton, of Great George
Street, Westminster, in the County of Middlesex, for the Invention
of "IMPROVEMENTS IN BURNING POWDERED FUEL. AND IN FURNACES AND
APPARATUS FOR BURNING POWDERED FOEL, ALSO IN ADAPTING SUCH FURNACES
FOR THE MELTING AND WORKING OF GLASS, IRON, STEEL, AND OTHER MATERIAL,
AND TO HEATING STEAM BOILERS."
Sealed the 17th May 1870, and dated the 3rd December 1869.
PROVISIONAL SPECIFICATION left by the said Thomas Russell
Crampton at the Office of the Commissioners of Patents, with his
Petition, on the 3rd December 1869.
I, THOMAS RUSSELL CRAMPTON, of Great George Street, Westminster,
in the County of Middlesex, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN BURNING POWDERED. FUEL, AND IN FURNACES
AND APPARATUS FOR BURNING POWDERED FUEL. ALSO, IN ADAPTING SUCH FURNACES
FOR THE MELTING AND WORKING OF GLASS, IRON, STEEL, AND OTHER MATERIAL,
AND TO HEATING STEAM BOILERS," to be as follows:-

page_text: burning a mixture of powdered fuel and air with combustion chambers,
into which a stream or streams of powdered fuel and air were supplied,
and were caused to pass through the combustion chamber in a circuitous
course by forming the combustion chamber with a zig-zag flue or by
building up brickwork within it.
The object of my present Invention is to employ a plain combustion
chamber without any division or brickwork therein, and for this purpose
I cause the stream or streams of air and fuel to be introduced into
the combustion chamber in a manner to cause them to move in a
circuitous course therein to prevent their separating from one another,
and also to cause the several currents diverging from the incoming stream
or streams of air and coal to mingle and unite with one another before
they pass into the body of the furnace where the heat is to be utilized,
thus ensuring that the coal and air shall again be brought into contact
with one another even though they shall have partially separated in the
combustion chamber; and I also cause the streams of gases as they
leave the combustion chamber to sweep past or impinge against the
incoming stream or streams of coal and air to cause them to carry in
with them to the combustion chamber the finer particles of the
powdered fuel and the more volatile matter contained in it, both of
which require less time for their combustion than the larger and heavier
particles, which will pass into the combustion chamber and he burned
therein. To effect this I form the exit from the combustion chamber at
one of its ends, and near to this outlet I project a stream or streams of
air and coal into the chamber, by preference causing the stream or
streams to somewhat incline away from the outlet from the chamber.
As the stream or streams thus introduced into the combustion chamber
ignite branch currents pass off from them, and these currents as they
pass towards the exit orifice from the combustion chamber mingle with
one another, and thus perfect combustion is effected. The currents so
mingling together also as they escape from the orifice move past the
stream or streams of air and coal which are entering the combustion
chamber and carry off with them any flames coming from these streams
direct into the body of the furnace where the heat is to be utilized.
thus introducing the stream or streams of air and coal into the com-
bustion chamber close to where the heated gases are to pass from the
combustion chamber into the part of the furnace where their heat is to
be utilized the heat is generated close up to the point. In some cases
By

page_text: the chamber where the heat is to be utilized can also be used as
the combustion chamber, and in this case I similarly inject the stream
or streams of air and coal into the furnace from its back end, and in a
direction away from the chimney or outlet which passes from this end of
the furnace. By this means the larger particles in the stream of air and
coal and which are not consumed at or near the chimney end pass
through the furnace to its opposite extremity, and as they are consumed
the products of combustion split up into various currents and return
through the chamber, and thus are all consumed before they reach the
chimney. In some cases also a close chamber may be formed at the end
of the furnace opposite to that at which the stream or streams of air and
fuel are blown in, and the stream or streams of air and fuel will be blown
towards and into this close chamber, and will thus afford longer time for
the combustion of the larger particles of fuel. In order also to effect
perfect combustion of a stream or streams of air and fuel blown into a
furnace or into a combustion chamber I inject such stream or streams
into the furnace or chamber at such a velocity that the stream or streams
shall not strike or but slightly strike against the opposite side of the
furnace to that at which the stream or streams are injected. If the stream
or streams are allowed to impinge with considerable velocity against a
side of the furnace or chamber this side is very rapidly worn away.
In those cases where the larger particles of coal are projected against
a deposit of slag which accumulated at the bottom of the furnace or
combustion chamber the coal will do less injury, and a greater velocity
may be given to the coal, but I prefer even in this instance that high
velocity should be avoided. To afford an even and continuous supply
of powdered fuel to the stream of air that is forced into a furnace I
place the powdered fuel into a hopper constructed with vertical sides, and
having stirrers so arranged at the bottom that the whole area of the fuel
contained in the hopper is disturbed by their action, the working of these
stirrers forcing the fuel from the hopper through an opening at its side
to and between the rollers placed one above the other, thus keeping a
regular and continuous supply of fuel to them. The quantity of fuel to
be fed is regulated by the distance at which the rollers are placed apart,
or by driving them at a greater speed. The feed may also be regulated
by making the distance between the rollers a fixed one, and by slides
diminishing the length of it. If coned hoppers are used stirrers are to
be placed at different heights in them to ensure the fuel falling. The
rollers may be close to the side of the hopper or projecting a small

page_text: distance into it or outside of it. In some cases the rollers may be
without a hopper, and have powdered fuel supplied to them by worms or
other means, so that they be fed with more fuel than is required, the
surplus passing away from them. A screen is to be placed at or near
the top of the hopper to be shaken or otherwise. In connection with the
feeding apparatus a fan may be attached into which the fuel is fed, and
an engine is also attached for driving both. To adapt furnaces for
burning powdered fuel and air to heat steam boilers 1 arrange the com-
bustion chamber or chambers of metal surrounded by water, and lined
with fire-brick or other refractory material. One end is closed, and near
the other or at which the air and fuel are ejected is an opening or
openings into a subsidiary chamber or chambers, or more properly flues,
forming part of the boiler. The air and fuel are directed towards the
closed end of the chamber, and the current of the larger, particles,
which require a longer time for their consumption, passes to the end, and
on returning carries along with it into the subsidiary chambers the
products of the volatile and smaller portions, which are consumed soon
after their entrance and without reaching the farther end of the furnace.
Holes may be made between the two chambers at various distances in
place of employing a single opening. The dimensions of the combustion
chamber must be proportioned in accordance with the quantity of air
and fuel used, and the pressure with which they are injected. The
second chamber or flues may be wholly or partially lined with refractory
material. Three chambers may conveniently be thus used in con-
junction with one another, streams of air and powdered fuel being injected
into two of them, whilst the products of combustion from both pass into
the third chamber. In those boilers when it is not convenient to place
combustion chambers within them lined of brickwork separate chambers
may be provided, but these should be considerably larger, unless some
special arrangement is made for keeping the bricks cool on the outside.
Another part of my Invention consists in causing the heated gases
escaping from a reverberatory or other furnace heated by the combustion
of an admixture of air and powdered fuel to pass into a second furnace,
where fresh air and fuel or the products of combustion of the same are
added to it, thereby increasing its temperature, so that similar work may
be effected in the second furnace as in the first; similarly the products of
combustion passing from the second furnace may be caused to enter a
third, and so on. In conducting by pressure a mixture of air and pow

page_text: dered fuel along conduits or pipes to a chamber or chambers to be
burned the fuel if its direct course is impeded by bends in the pipes or
other obstructions sometimes becomes partially separated from the air.
Where such obstructions occur and the proximity of the furnace does not
admit of a sufficient length of straight pipe to allow of the air and fuel
again becoming mixed before entering the furnace I fix in the pipe pro-
jections in an angular or screw form, so as to impart to the air and fuel
a rotating motion and thus again mix them together. When a mixture
of powdered fuel and air has to be conveyed from a round pipe or pipe
of large capacity through a long thin slit into the furnace the change
from the round to the long narrow form should be very gradual in order
to insure the mixture being maintained at the entrance to the furnace,
and care should be taken that in the event of any tendency of the fuel
to collect in one side of the main pipe it should be on that side nearest
the flattened portion of the tapered pipe in order that the fuel may strike
in the centre and be more evenly distributed. In arranging furnaces
heated by powdered fuel and heated air the latter produced by the waste
heats of the furnace itself by means of regenerators, I so construct them
that the fuel in being injected with a small quantity of air of less tem-
perature than the great mass of the air heated by the regenerators shall
enter such mass of hot air between this regenerator and the working
chamber, and so arranged that the combustion is practically effected
before entering the working chamber, or in some cases before leaving it.
The waste heats in passing to a regenerator at the other extremity of the
furnace can be supplied with the required quantity of air so as to con-
sume any particles of fuel or gases that may have escaped complete
combustion before entering this regenerator. Also where heated air is
produced by passing it through pipes heated on the outside by the waste
heats of the furnace, such waste heats should pass through sufficient
space between the working chamber and pipes, so that should it be
necessary air may be admitted to insure the combustion of any uncon-
sumed particles of fuel or gases which may have passed the working
chamber, and thereby obtain a clean heat in the pipe, chamber, or stove.
In constructing cupola furnaces for melting iron I form at one side of
or all around the bottom of the furnace a combustion chamber; into this
chamber the iron descends, the fuel and air being injected into the same
melts the iron, and the products of combustion pass up through the iron
not yet melted, the metal as it fuses being retained in the combustion

page_text: chamber and tapped as required. A small quantity of coke or other fuel
may be mixed with the cast iron in the cupola. To adapt the ordinary
furnace for melting iron where the iron is placed on an inclined bed
for the flames from a fire to play over it, and where the iron as it is
melted runs down into a receptacle at the back of the bridge, I make a
combustion chamber of the existing fire-place by removing the fire-bars
and closing the same, and inject the air and fuel into it, the products
passing through the furnace melt the iron on the inclined bed. The
furnace may also be constructed so as to inject the fuel and air into a
chamber at the bottom of an incline, upon which incline metal is placed,
the flame passing between and over it, and the metal as it is melted may
be caused to run to the combustion chamber, from which it can be tapped.
Or it may be so formed that the air and fuel can be injected into the
furnace at or near the top of the incline, a portion being caused to pass
over the iron to the bottom, when it returns up the incline to the
chimney. This incline may be extended to any desirable length, so
that the iron may be prepared by the waste heat, and pushed forward
on the incline to be melted.
In melting steel or other metal in pots where the pots are lifted out
from the top a chamber is constructed of a size to contain the pot with
sufficient space round or near it to form a combustion chamber, into
which the air and fuel is injected, and when several pots are to be heated
in one furnace it is to be made of the length required for containing
them in a row or rows, the air and fuel being injected at several points of
the chamber suitably arranged, several outlets or only one outlet to the
chimney being used as may be desired. When the chamber is not of too
great a length it may be so constructed that the air and fuel be injected
from the chimney end of the pot chamber on one or both sides of the
pots, the larger particles of fuel passing to the extremity of the chamber,
the products returning to the same chamber to the chimney. In some
cases when burning powdered fuel I employ a large per-centage of volatile
combustible fuel with anthracite coke, Welsh dry coal, or similar fuel,
and introduce the mixture into a current of air to be burnt. The
mixture of the two kinds of fuel may take place either before or after
being ground.
In the ordinary glass melting furnaces the air and coal can be injected
into a compartment or compartments suitably arranged in the existing
fire-places and ash-pit, the fire-bars being displaced so that the products

page_text: of combustion ascend freely over the receptacles containing the glass,
and that the whole is practically consumed on or before entering the
chimney. When the glass is melted in a bath the fuel and air may be
consumed in one or more combustion chambers at the ends of the
furnace, or the stream or streams of air and fuel may be blown into the
furnaces above the bath containing the glass. Pot glass furnaces may
also be similarly heated. By thus constructing glass furnaces, whether
to melt in pots or in a bath, so that they shall be heated by the pro-
ducts of the combustion of a mixture of air and powdered fuel injected
into the furnace at a pressure above the atmosphere, the products of
combustion escaping from the furnace at one or more parts of the
furnace, and escaping up one or several chimneys or outlets, the com-
bustion of the fuel may be arranged to depend chiefly upon the pressure
and not upon the chimney draft.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Thomas Russell Crampton in the Great Seal
Patent Office on the 3rd June 1870.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
RUSSELL CRAMPTON, of Great George Street, Westminster, in the
County of Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria by Her
Letters l'atent, bearing date the Third day of December, in the year
of our Lord One thousand eight hundred and sixty-nine, in the thirty-
third year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Thomas Russell Crampton, Her special
licence, that I, the said Thomas Russell Crampton, my executors, admi-
nistrators, and assigns, or such others as I, the said Thomas Russell
Crampton, 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 "IMPROVEMENTS IN BURNING POWDERED FUEL, AND IN FURNACES AND APPA.
NATUS FOR BURNING POWDERED FUEL, ALSO IN ADAPTING BUCH FURNACES FOR THE
MELTING AND WORKING OF GLASS, IRON, STEEL, AND OTHER MATERIAL, AND TO

page_text: HEATING STEAM BOILERS," upon the condition (amongst others) that I, the
said Thomas Russell Crampton, 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 Seal Patent Office, within six
calendar months next and immediately after the date of the said Letters
Patent.
NOW KNOW YE, that I, the said Thomas Russell Crampton, 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:-
In the Specification of a former Patent granted to me for a previous
Invention on the 13th day of August 1868 (No. 2539) was described
the constructing furnaces for burning a mixture of powdered fuel and
air with combustion chambers into which a stream or streams of
powdered fuel and air were supplied, and were caused to pass through the
combustion chamber in a circuitous course by forming the combustion
chamber with a zig-zag flue or by building up brickwork within it.
Upon my said previous Invention I have now made further improve-
ments in order to avoid the inconvenience arising from the destructive
action of the streams of fuel and air when allowed to impinge upon
zig-zag flues or brickwork within the furnace, as described in the
Specification of my said former Patent, and to insure that the air and
powdered fuel which tend to separate from one another shall re-admix in
the combustion chamber.
In carrying out my present Invention I employ, as herein-after
described, a plain combustion chamber, that is to say, without any
division or brickwork therein, and for this purpose I cause a stream or
streams of mixed air and fuel to be introduced into the combustion
chamber in the manner herein-after described so as to cause them to
move in a circuitous or other equivalent course therein, thereby pre-
venting the fuel and air from separating too much from one another, and
also to cause the several currents diverging from the incoming stream or
streams of air and fuel to mingle and unite with one another before they
pass into the body of the furnace where the heat is to be utilized, thereby
ensuring that the fuel and air shall again be properly mixed with one
another even though they shall have been partially separated. I also in

page_text: some cases cause the streams of gases and partially consumed fuel as
they leave the combustion chamber to sweep past or impinge against the
incoming stream or streams of coal and air, thereby causing them to
carry with them into the utilizing or working chamber some of the finer
particles of the powdered fuel and the more volatile matter contained in
it, both of which require less time for their combustion than the larger
and heavier, particles which will pass into the combustion chamber and
be burned therein.
In
In the application of my system of heating furnaces by introducing
streams of air charged with properly powdered fuel, such streams being
so regulated, directed, and controlled as to ensure a proper commingling
of air and fuel in the requisite proportions to effect the desired com-
bustion, I have ascertained that rapid wear and waste of the refractory
material composing this chamber or furnace are caused by the impinging
streams of fuel and air, which are far more destructive than would have
been anticipated without practically testing their operation. The expense
attending the repairs that would be constantly needed in furnaces would
in practice to some extent nullify the advantages of the system unless
an efficient remedy could be provided for the difficulty to which I refer.
This difficulty has I believe been one among the many causes which
have hitherto invariably led to the failure of the various attempts which
I am aware have been attempted to burn powdered fuel mixed with
streams of air in combustion chambers connected with furnaces.
some cases the fuel employed has not been reduced to a sufficiently fine
powder, whereas as I will point out that the size of grains ought not
under given conditions to exceed a given size. In other cases when
streams of air and fuel have been introduced into furnaces or com-
bustion chambers no efficient means have been provided for regulating,
directing, and controlling the said streams so as to retain the proper
mixture of air and fuel, whereas without such provision the streams of
air charged with fuel would be found to be only partially and inefficiently
consumed in the combustion chamber where such a chamber is used in
connection with a utilizing or working chamber. In no case as far as
I am aware have efficient means been provided to counteract the
tendency of the fuel particles to separate from the air when streams of
mixed air and powdered fuel are put in motion, especially when the
direction of motion is other than straight, a tendency which is due to
the air and powdered fuel being of different specific gravities. Unless

page_text: provision be made to prevent the separation of fuel and air good results
cannot be obtained, as in practice the powdered fuel would to a large
extent become separated from the air and be deposited unconsumed
or partially consumed in the combustion chamber or in the working
chamber, or be driven forward into the chimney of the furnace. In
some cases the combustion chamber has not only not been properly
constructed with reference to the means of introducing streams of air,
charged with powdered fuel, but also has not been properly constructed
with reference to its connection with the utilizing or working chambers,
whereas it is necessary to so construct the combustion chamber that, as
above stated, the air and fuel may be kept mingled together therein
until the particles of fuel are sufficiently consumed; and the access to
the working chamber should be so arranged that the gases and nearly
consumed particles of fuel, if any, be carried into it, may freely and
without meeting undue obstacles or resistance be carried forward in a
state of perfect admixture into the working chamber and be consumed
therein, and he made to do the required work of heating its contents
without any waste fuel being carried unconsumed through the working
chamber or being injuriously deposited therein.
My present improvements have enabled me to overcome successfully
the difficulties above referred to, and by employing the plain combustion
chamber provided with the means of introducing, regulating, directing,
and controlling the streams of air charged with properly powdered fuel
arranged and worked in the manner herein-after described, I have
succeeded in effecting that which has never been effected before, viz.,
the employment of streams of powdered fuel and air not only with great
regularity and efficiency, but also with the requisite economy for the
heating of furnaces of any ordinary construction.
The main feature of these my further improvements consists in so
introducing into a plain combustion chamber regulated streams of air
and powdered fuel that a re-mixing of air and powdered fuel shall take
place as to ensure that those volumes of air that may be surcharged with
particles of fuel may be mixed with other volumes that are less charged,
so as to maintain the reqiured equilibrium of fuel charge, or where the
equilibrium is temporarily disturbed from any cause to ensure that it is
properly restored. This object, as will be seen by referring to the various
modifications of furnaces herein-after described, may be effected by
various arrangements of the streams of fuel charged air, but in all these

page_text: I employ the same system of compensating for any undue aggregation
of fuel particles in certain volumes of air by insuring their admixture
with other volumes so as to restore throughout a proper average or
equilibrium of fuel charge. When streams of air charged with powdered
fuel are made to impinge upon one another the momentum of one
stream may be met and absorbed or counteracted by that of another
stream, and the relative directions of the streams should be so regulated
that the proper commingling of the air and powdered fuel is effected,
the general equilibrium of the fuel charge held in suspension in the air
is maintained, and all tendency to undue separation of air and fuel into
separate streams or to deposit of inefliciently consumed fuel is avoided.
It will be seen that in some of the arrangements herein-after described
I make use of tubes or tuyeres that are noveable and can be set in any
required direction so as to guide the fuel charged streams of air in the
required relative directions and so control tlieir relative action.
In some cases the streams of air and fuel may be made to impinge
downwards upon the bottom of the plain combustion chamber, and the
bottom should in such cases always be protected by a bed or stratum of
fire-resisting materials, such as a bed of sand, or any of the materials
ordinarily used for protecting the bottoms of furnaces exposed to great
heats may be employed, or a layer of the naturally formed slag may be
allowed to accumulate, such protecting material being capable of being
removed when melted and renewed when necessary. It may be generally
stated that in all cases where streams of air charged with fuel are
injected into the combustion chamber at high velocities care should be
taken either to absorb the momentum of one stream by counteracting its
effect by another stream, or to prevent it by some protecting bed or
coating from being allowed to impinge upon the sides or any part of the
chamber or furnace that is unprotected.
In some cases the powdered fuel held in suspension in the volumes of
air introduced into the combustion chamber may be advantageously
introduced and maintained in the required equilibrium, that is, equally
diffused in proper relative quantities by injecting the fuel charged air in
parallel lines through a row of pipes or tuyeres placed side by side.
Care must be taken that the intervals between the pipes are such that
the injected volumes which expand rapidly from the action of the heat
in the chamber shall as it were overlap, circulate, and mingle together,
so that if there there shall be (as practically is found to be the case) a

page_text: surcharge of fuel in one part of the injected air it may mix with another
part not sufficiently charged, and so restore and maintain the equilibrium.
In using powdered fuel for heating purposes careful attention must
be given to the size of the particles employed, regard being had to the
nature of the fuel and the purpose for which it is to be used. When
ordinary bituminous coals or peat, or other similar fuels that are more
easily volatilized than anthracite and similar fuels, are employed for
ordinary heating purposes the coal may be conveniently ground between
ordinary millstones, such as are used for grinding flour, and be reduced
to a size of grain that will readily sift through the meshes of an ordinary
sieve having 30 divisions each way to the square inch. For heating or
melting operations where a small deposit of carbon will not be injurious
to the materials under treatment in the furnaces herein-after described
coarser grains of fuel may be used, such, for instance, as will pass
through meshes of the size of 10 each way the square inch. When
anthracite or other similar fuel is employed it may be conveniently
mixed with powdered bituminous coal in equal proportions, but if
greater proportions of anthracite or coke or other similar fuels are
employed, or if anthracite or coke alone are used they should be ground
finer than when the bituminous coals are used, in that case I recommend
it should be ground so fine as to pass through meshes of the size of from
40 to 80 divisions to the inch, or even finer, each way, and be injected
into the combustion chamber in such a way that a longer time is
afforded for combustion than is needed in the case of biluminous coals,
and a longer combustion chamber may be employed for this purpose.
The combustion chambers in the first instance should be sufficiently
heated by burning ordinary fuel placed on fire-bars temporarily
inserted in the combustion chamber, and on the chamber becoming
sufficiently heated to effect the combustion of powdered anthracite, coke,
or charcoal the fire bars should be withdrawn and the fuel and air
should be injected. When bituminous fuel is used the chamber can be
heated by burning wood in it, and when well alight the air and fuel may
be gradually fed until the furnace is hot.
I have herein-after described the apparatus which I prefer to use for
the supply of powdered fuel.
As will be seen my present improvements may be readily applied with
very little trouble and expense to existing furnaces of the ordinary
construction. By covering the ordinary fire-bars, of a common rever-

page_text: beratory furnace with a layer of bricks, and protecting the bottom so
formed with a layer of suitable fire-resisting material a plain combustion
chamber is at once provided, into which the streams of air and fuel may
be introduced and burned, as herein-after described, or the fire-bars may
be displaced and a bottom made at any convenient height between the
bottom of the ash-pit and the top of the bridge, also any projections
built on the bridge to deflect the flame to one side may be displaced,
leaving a perfectly free outlet the whole length of the bridge between
the combustion and working chambers, as well as retain the whole
height between the bridge and the roof of the furnace, any desired
deflection of the heat to either side being readily effected by placing
the jets in the direction required. Where it is proposed to erect new.
furnaces they may be advantageously constructed in the same manner.
In order that the manner in which I propose to apply my system of
heating furnaces may be fully understood I will now describe, reference
being had to the Drawings annexed, various modifications of furnaces,
in which a plain combustion chamber is arranged, applied, and worked
on my improved system.
Figures 1, 2, 3, 4, show a reverberatory furnace of the ordinary type.
In order to convert the fire-place into a plain combustion chamber so
that it may be used, according to my Invention, I first cover the fire-
bars A with a suitable refractory material, so as to form a closed bottom,
or the bars may be removed, and a bottom may be placed at any con-
venient distance between the top of the bridge B and the bottom of the
ash-pit C, the under side being by preference exposed to the outer
atmosphere, but I prefer the bottom being nearly level with the bridge,
or within a few inches of it. The pipes E, E, through which the mixture
of air and powdered fuel are injected are by preference placed at an
angle into each side of combustion chamber F near the bridge, the
streams striking each other in the body of the combustion chamber,
causing great circulation of the particles where they mix, returning
in this chamber in a mixed state, and carrying with them into the
working chamber G some of the lighter particles of fuel and products
which leave the streams before they have entered very far into the
chamber, or before mixing with the air and fuel proceeding from the
opposite side.
The air and fuel issuing from each jet are not as a rule
properly mixed, particularly where curves or bends are made in the
introducing pipes near the furnace. In such cases it will be found that

page_text: the particles of fuel carried in suspension in the streams of air gather
on the outside of the bend, as shown by the shaded parts of the pipes
E, E, Figure 3. By placing the bends of the pipes in opposite directions,
as shown in Figure 3 by E, E, the surcharged part of stream S is made
to impinge upon the less charged part of the stream S', therefore a
compensating mingling of the volumes of air takes place and the
equilibrium of the fuel charge suspended in the air is restored and
maintained. Streams of air charged with proper proportions of suitably
powdered fuel introduced, as shown in Figure 3, will produce good
circulation or mixture.
for.
Figure 4 is an illustration of a case where, for obvious reasons
deducible from what is said above, the contrary result would be obtained,
and any attempt to employ powdered fuel in a simple chamber in the
manner indicated in Figure 4 would be unsuccessful, because the essential
condition of surrounding the fuel particles held in suspension with the
requisite quantity of air to provide for proper combustion is not provided
The jets, as shown in Figures 3 and 4, are directed horizontally
into the body of the chamber, but they may be directed upwards to the
roof or downwards on the bottom, or they may be directed downwards
through the roof on to the bottom, or one or more upwards and the
others downwards, or at any other convenient place, but I prefer
directing them from the bridge against the current to the chimney, as
shown, so as to give the most time to mix in the body of the combustion
chamber, particularly when with a given size simple combustion
chamber the maximum combustion of the particles of fuel is required
to be consumed in it. At the same time it is not absolutely necessary
in all cases to inject in a direction away from the bridge, as good
practical circulation or re-admixing of the air and fuel are obtained by
injecting the streams from the opposite direction, as shown at A, 'A,
and B, B, Figure 6, or direct across the furnace into each other, as
shown at C, C, Figures 5 and 6, but great care should be observed in
fixing the pipes, so that the mixture issuing from each jet is made as
perfect as possible, or the streams of air and fuel may be introduced
through jets inserted in the top and directed downwards, or one directed
upwards whilst the other is downwards, see E, E, Figure 5.
The above descriptions more particularly apply to those furnaces
where the heat travels horizontally, but it must be understood that the
principle of action previously described may be carried out in those

page_text: furnaces where the flame traverses upwards, as in some zinc furnaces,
This
or downwards, or other direction from the combustion chamber.
system of blowing in the mixture of air and powdered fuel in the
direction of the working chamber acts perfectly well in ordinary cases
of heating products when fuel containing volatile matter, such as the
ordinary smoky or bituminous coal or peat, is used, and in those cases
where a little less or more solid carbon may enter or pass unconsumed
through the working chamber without injury to the material under
treatment the streams of mixed air and fuel may be directed to join
together at any required point before reaching the bridge, or even. in
the working chamber itself, as may be desired. When the object to be
obtained, viz., the maintenance of a proper equilibrium of the fuel
charged carried in suspension in the air is borne in mind no practical
difficulty will be encountered by persons accustomed to the working of
furnaces in so directing and controlling the streams of fuel charged air
as to effect that object with certainty.
The
In order to be able readily to set the pipes at the angle desired so
that the streams may impinge into each other the pipes may be placed
in the walls or roof of the furnace by any ordinary means, so as to be
easily shifted to the required angle. This may be accomplished by
joints being placed in the pipes, but I prefer to do it by simply placing
the ends of the pipes in holes in the furnace larger than the pipes.
pipes when put in the required position are luted with clay.
the pipe or pipes are again required to be shifted the clay is removed,
the pipe or pipes shifted, and then luted again. By this simple means
the junction of streams may be effected nearer or further from the
bridge, as required. Water tuyeres may be used if desired.
When
If one jet or stream of air and powdered fuel he employed to heat a
simple combustion chamber great care in the arrangements are required
to produce an effective combustion of the whole of the fuel.
If, for example, a jet oblong or any other form A be placed over the
bridge B of an ordinary reverberatory furnace, as shown, Figures 8, 9,
and 10, and be supplied with air and fuel passing through a bend in the
pipe, as shown in Figure 9, the air and fuel will be partially separated
on entering the chamber, as described in Figures 4 and 5, and as is also
shown by the shadowed lines in Figure 10, and the air and fuel will
enter the combustion chamber C, descend it, and return over the
bridge B into the working chamber D unmixed, the results would be

page_text: imperfect combustion and waste of fuel, and supposing wrought iron
was being heated in chamber D one side would be oxidized whilst the
other would be covered to a certain extent with carbon dust; this will
be the effect notwithstanding the partial or one-sided circuitous action
produced by its striking upon the bottom, therefore in using single jets
great care is required that the mixture is perfect on leaving the pipe
and entering the combustion chamber, and this to a certain extent can
be accomplished by placing thin projections E (Figure 9) in the pipe A
between the last bend and the furnace of an angular or spiral form, so
as to whirl together the air and fuel in its passage before entering the
furnace; the forced stream by this means will circulate and pass the
chamber in a comparatively good mixed condition, avoiding to a certain
extent the inconvenient separation referred to. When a mixture of air
and powdered fuel has to be conveyed from a round pipe or pipes
through a long thin slit into the furnace the change from the round to
the long narrow form should be very gradual, in order to facilitate the
most easy and regular spreading out of the mixture from the larger
portion of the pipe to a long thin exit where it enters the furnace, and
care should be taken in the event of any tendency of the fuel to collect
on one side of the main pipe it should be directed on that side nearest
the centre of the flattened portion of the tapered pipe, in order that the
fuel may strike in the centre of the flattened portion and be distributed
on each side of it. When the length of slit is required to be nearly the
whole width of the side of the furnace into which it enters, I cause a
proper mixture of air and powdered fuel to issue from a long thin slit
into the furnace in the manner shewn in Figures 8, 9. B, B, B, are
the pipes; C, a receptacle forming a long narrow slit or nozzle, into
which the pipes are fixed. The several jets of air and fuel entering at
'different points produce an even mixture throughout the entire length of
the nozzle, this long nozzle entering or being placed on or against a hole
constructed in the furnace. The long nozzle may be protected when in
connection with the furnace by the ordinary water tuyere arrangements.
The pipes A, A, A, (Figures S, 9,) are shown over the bridge; they may
be placed flatter or more vertical than shewn, or they may be placed
completely opposite in the direction of the dotted lines F, Figure 8. In
all cases where it is convenient to apply two or more streams acting as
described I prefer their use to the single streams.
Another method of causing the required circulation of several streams
of air and fuel to maintain the required equilibrium of the fuel and air

page_text: when injected into a plain combustion chamber as shown in Figures 11
and 12. At the end of the combustion chamber B several small
jets A, A, A, of the mixture placed a few inches apart are injected at
any convenient angle on to the bottom, formed as before described, and
made level with the bridge C, or at any convenient distance below it, by
preference 3 or 4 inches, so that the air and fuel from these jets on
striking the bottom D are deflected and mixed, the unconsumed particles
of fuel passing over the bridge C in a perfectly mixed state with the air,
and entering freely and evenly into the utilizing chamber, where those
particles not burned in the combustion chamber will be sufficiently
consumed for all practical purposes before reaching the chimney. When
a series of jets or. a thin stream is used, directing them vertically on to
the bottom should, as a rule, be avoided, since, if the air and fuel
entered the furnace after passing a bend in the pipe most of the fuel
would be deflected, see Figure 11, A', by striking the bottom to the
one side, and most of the air to the other, and sometimes fuel will
accumulate on the bottom, but if (see A) the unmixed steam is projected
at a sufficient angle then the air will run into the fuel on striking the
bottom and produce the re-admixture. Good circulation and mixture of
the particles of air and fuel can also be obtained in the simple com-
bustion chamber by placing small jets, say, about 2 inches diameter, and
about 3 or 6 inches apart in the end of the chamber in a direct line
with the furnace, the rapid expansion of the mixture on entering the
intensely hot chamber causing them to spread into each other, producing
the desired circulation and mixture of the particles of air and fuel, even
if the air and fuel issue from the pipes in an unmixed state into the
combustion chamber. The distance between the jets may be more or
less according to circumstances, such as length of combustion chamber,
velocity of streams, or other reasons. If the distance between each jet
be too great the expansion would not effect the object. For instance, if
two streams 42 inches diameter of powdered fuel and air in an unmixed
state, as before alluded to, were placed 3 feet apart in the end of a com-
bustion chamber 4 feet wide, the streams being injected at a pressure
of inch of water, and directed in parallel lines to each other straight
through the combustion chamber over the bridge into the working
chamber, the expansion of such stream in the combustion chamber
would not produce the circulation and mixture necessary for perfect
combustion. When a row of parallel jets are thus directed straight

page_text: through a combustion chamber, and if almost complete combustion of
all the particles of fuel is desired to take place in this combustion
chamber it should by preference be made somewhat longer than if
the jets were made to travel in a more indirect course therein.
The mode of injecting or working of furnaces with many jets will be
understood by reference to Figures 13 and 14, Figure 13 being a plan
through A, B, in elevation, Figure 14 being a section through C, D, in
Figure 13.
E is the feeding apparatus, that shown is the same as
described in this Specification, the fuel leaving the rollers in regulated
quantities falls equally divided into a number of pipes corresponding to
the number of jets to be used; F is a box or chamber into which the
forced streams of air passing the regulating valve G placed in the pipe H
enters in the quantity required, and passes out of it through the
nozzles I, I, I, I, I, taking with it the fuel and some induced air, which
descends the pipes J into the pipes K, K, K, K, K, through which the
air and fuel are conducted in the regulated proportions into the furnace
or combustion chamber, or it might be into a small chamber opening
into and practically forming part of such combustion chamber. These
pipes are shown level and parallel to each other near where they enter
the furnace, placed about 5 inches apart. At that distance asunder
sufficient intermingling of one jet with another will be given by the
expansion previously referred to, and ensure a good circulation and
mixture of powdered fuel and air. The fuel feeder may be placed in
any convenient position, and the connections or pipes carrying the fuel
or air to the furnace may be arranged in any suitable manner so long as
the essential conditions of supplying each jet with its proportion of air
and fuel is adhered to, whether the fuel is fed into the inlet of a fan,
and projected with air through a pipe or pipes to the furnace by feeding
the fuel into the end of a pipe and projected by a current of air or steam
into the furnace through various branch pipes to the furnace, or other-
wise. The pipes may be arranged in pairs, each pair being so directed
that the streams impinge into each other at any angle required, or all
the pipes may be directed to one common centre within the furnace or
combustion chamber, or in any other convenient manner, or the ends
of each pipe may be flattened into a thin slit, the ends of each pipe
touching or nearly so each other when they enter the furnace, pro-
ducing in effect one long thin jet, and this is a good practical mode for
producing a long thin admission of the mixture in the furnace.

page_text: In Figures 15 and 16 another mode is shown of injecting the mixture
of air and powdered fuel so that the combustion takes place in the
working chamber, which in this case is used as the equivalent of the
plain combustion chamber employed in the modifications previously.
described. B, B, B, are pipes placed near the neck of the furnace,
directed so that the streams pass near the upper surface of the furnace,
being mixed by causing them to impinge into each other on their route
to the end C; the products will return mixed between the incoming
stream and the material D under treatment. Care should be taken that
the incoming stream should proceed through the centre of the chamber
or nearly so, as if the stream were directed on one side by a single jet,
particularly if unmixed on entering the chamber at A, Figure 18, and
traversing the circumference of the furnace, as shown in dotted lines,
the air and fuel would not keep on their route sufficiently mixed to
produce the best results, and carbon dust would be in most cases
deposited in the chamber and on the material under treatment, if such
material, such as welding scrap iron, or other material not protected by
pots or otherwise, it would cause considerable inconvenience. A series
of jets placed parallel or at an angle to each other as before alluded to
at the chimney end near B, Figure 16, and the streams directed parallel
to the top of the furnace, or nearly so, the currents will return in the
chamber between the work and the incoming streams. A thin long
stream of the mixture may be used instead of the jets.
that the velocity of the incoming streams should not have a higher,
velocity on striking the material composing the chamber than con-
venient. The greater the velocity the more excessive the wear of the
furnace, and which should be avoided; care must however be taken
when furnaces are working with a partial vacuum in them that there
is sufficient force in the injected mixture of air and fuel to enter the
chamber freely when the vacuum of the furnaces is reduced by the door
being opened or otherwise, so as to prevent the fuel being retained in
the pipes conducting the air and fuel, particularly where the pipes are
of some length and containing many bends, also to prevent the fuel
blowing back in the event of the fuel being fed into pipes close to the
furnace or otherwise. I have found that in an ordinary heating furnace
worked with an ordinary vacuum in the chimney equal to about of an
inch of water, the inlet pipes being 4½ inches diameter, that when the
air alone without coal is injected at 2 inch pressure into a cold furnace,
the pressure is sufficient to carry in the fuel when the doors are open
It is desirable

page_text: during the ordinary working when at full heat, therefore in proportioning
the pipes for supplying the air and fuel they should have reference to
the pressure indicated. The importance of this point will be readily
understood by those acquainted with working furnaces. If the furnaces
are to be worked under a pressure of a few inches of water or just on a
balance with the outer atmosphere the pressure of the jets must be
increased or diminished according to the pressure used in the furnace.
Figure 19 shews an arrangement of furnace heated by powdered fuel
and heated air, the latter produced by the waste heats of the furnace
itself by means of regenerators.
In applying my improvements I so construct the furnaces and arrange
the supply pipes that they may inject powdered fuel carried in with a
small quantity of air of less temperature than the great mass of the
air heated by the regenerators, which shall enter such mass of hot air
between this regenerator and the working chamber, and so arranged that
the combustion is practically effected before entering the working
chamber, or in some cases before leaving it. The waste heats in passing
to a regenerator at the other extremity of the furnace can be supplied
by pressure or otherwise, according to circumstances, with the required
quantity of air so as to consume any particles of fuel or gases which
may have escaped complete combustion before entering this regenerator.
Figure 19 shows an arrangement sufficiently clear to effect this object.
The particular form of construction of regenerators or their action by
the necessary valves or otherwise is not described, as that is well known,
neither is the means of ejecting the air and powdered fuel described, for
the same reason.
A is a regenerator of Siemens' construction, up which and in the
direction of the arrow the mass of hot air required for combustion
passes, meeting in the space B or combustion chamber a stream of
powdered fuel injected by a small quantity of cold air or moderately
heated air (not sufficiently hot to injure the pipes, say 600°) admitted
through a pipe E (the air in the pipe E' being shut off), in which space
the circulation or mixture takes place, the products passing through the
working chamber F, and thence through the space or second combustion
chamber G, into which if required a stream or streams of cold air is
injected into such products, and consuming them and the burnt products
then passing down the second regenerator I, and thence to the chimney.
Any excess of air required for cooling the products may be allowed to

page_text: enter the pipe H¹. On reversing the action of the regenerator the air
through His shut off, as well as the air and fuel entering at E, the
air and powdered fuel entering the chamber through the pipe H,
the products passing through F meeting in the chamber B, a stream
of air entering at E', and thence down the generator A to the
chimney, the number of jets, direction, and other conditions for pro-
ducing good mixtures previously described to be observed in carrying
out this arrangement of furnace. Also where heated air is produced by,
passing it through pipes heated on the outside by the waste heats of the
furnace, such waste heats should pass through suflicient space between
the working chamber and pipes or stove, so that should it be necessary,
air may be admitted in this space to ensure the combustion of any
unconsumed particles of fuel or gases which may have passed the work-
ing chamber, and thereby obtain a clean heat in the pipe chamber or
stove, nothing but incombustible dust passing the regenerator or stove.
Should it be required to reduce the tenperature of the waste heats
before entering the stove or regenerator any desired quantity of the
external air may be injected into it at the same point for that purpose.
The general remarks respecting the construction of regenerators and
injecting the air and powdered fuel made in the previous description of
Figure 19 equally apply in the case when a pipe stove is used.
Figure 20, A is a stove containing a coil or other suitable arrangement
of pipes, through which chamber or stove the waste heat from the
working chamber B passing to the chimney Cheating the air required
for combustion, which is forced through the stove pipes entering at D
and passing into the combustion chamber E at the point E in an
intensely heated state, meeting the powdered fuel injected through the
pipe F.
At G a pipe having a suitable regulator in it is placed, through
which cold air is forced as required into the space H formed sufficiently
long between the chamber B and the stove A to effect the perfect com-
bustion of all the unconsumed products passing the space. More air
than required for combustion may be allowed to enter the chamber for
cooling the waste heats before entering the stove.
In constructing cupola furnaces for melting iron, &c. I form at
one side of or all round the bottom of the furnace a combustion
chamber. Into this chamber the iron descends, the fuel and air being
injected into the same melts the iron and the products of combustion
pass up through the iron not yet melted, the metal as it fuses being

page_text: A small
retained in the combustion chamber and tapped off as required.
quantity of fuel ordinarily used may be mixed with the cast iron in the
cupola.
One form of furnace for melting cast iron is as follows:-
Figures 21 and 22 shew a vertical section of a chamber of the ordinary
cupola form (A, see Figures 21 and 22) into which cast iron is put. At
the bottom of this cupola a combustion chamber B is placed on one
side, as shown, or more than one may be used, or it may continue all
round the cupola. Into this combustion chamber the air and powdered
fuel are injected through the pipes C, C, (Figure 22) and c (Figure 21),
or by any of the methods described for placing the injecting pipes
suitable to this form of furnace may be used, the heat produced melting
the iron, which falls or runs into the combustion chamber, which iron is
soon covered with slag, the slag protecting the molten iron from the air
and powdered fuel. The height of the cupola may be that ordinarily used.
Should it be desired to use a smaller portion of fuel than is generally
employed with the iron when melting in the ordinary way it may be
done, but in that case sufficient air must be injected not only to con-
sume the powdered fuel, but also the ordinary fuel interspersed with the
iron in the cupola. The iron will be charged into the cupola in the
ordinary manner. D is a tap hole of the usual kind for drawing off
the molten iron when desired; F is a door to be used for putting in
the fuel for heating the furnace. I prefer to have the bottom of the
cupola inclined as shewn at E (Figure 21). Care should be taken that
the mixture of the air and powdered fuel is not caused to enter the
chamber B in such a manner as to impinge in a mass directly on to the
unmelted iron. To adapt the ordinary furnace for melting iron where
the iron is placed on an inclined bed for the flames of a fire to play
over it, and where the iron as it is melted runs down into a receptacle
at the back of the bridge, I make a combustion chamber of the existing
fire-place by removing the fire-bars and closing the same and inject air
and fuel into it, the products passing through the furnace melt the iron
on the inclined bed.
At
Figure 23 is a vertical section of an ordinary melting furnace.
any convenient position in the fire-box, by preference near the bridge, a
closed bottom B of suitable refractory material is formed; into this
chamber the air and powdered fuel are injected at the end through the
pipes B', B", or by any of the means described in this Specification

page_text: applicable, or this particular form of furnace may be adopted, the products
passing the bridge C over the melted metal in the well D and over and
between the metal placed on the incline E, and thence to the chimney; or
the
space C may be bricked up as shown by the dotted lines and the
air and fuel injected into the chamber at the sides or at the top (see F)
or other suitable position. The furnace may also be constructed so as to
inject the fuel and air into a chamber at the bottom of an incline, upon
which incline metal is placed, the flame passing between and over it,
and the metal as it is melted may be caused to run to the combustion
chamber, from which it can be tapped. The slag formed floating on the
top of the molten iron protects the metal from the air and fuel which
pass over or on it.
Or it may be so formed that the air and fuel can
be injected into the furnace at or near the top of the incline, a portion
being caused to pass over the iron to the bottom when it returns up
the incline to the chimney. This incline may be extended to any
desirable length so that the iron or other material may be prepared by
the waste heat and pushed forward on the incline to be melted.
Figure 24 is a vertical section through a melting furnace constructed
in accordance with the foregoing description. The bed of the bath E,
Figure 24, to be constructed of good sand or other refractory material
in the usual manner; the mixture of air and powdered fuel is injected
at A, A, or at B, or in any other convenient manner as described in the
Specification. The metal to be melted is placed on the incline C and is
melted by the heat passing over and between it on its way to the
chimney D, the molten metal running into the bath E, the slag pro-
duced resting on the molten metal to protect it from any injurious action
of the products of combustion passing over it. The incline C may be
extended to any desired length. When the metal under treatment
would be injured by unconsumed particles coming in contact with it
before it is melted the form of the chamber, the direction of the stream
of air and powdered fuel, and those conditions set forth as necessary for
consuming the largest portion of the fuel should be attended to. Jn
simply melting cast iron on the bank a little unconsumed carbon and free
oxygen would do less injury to it than it would to wrought iron, when it is
being melted in molten cast iron for making steel. Many other metals
on being melted require, as perfect a combustion as practicable. In
melting steel or other metal in pots where the pots are lifted out from
the top a chamber is constructed of a size to contain with sufficient space

page_text: round or near it to form a combustion chamber, into which the air and
fuel are injected, and when several pots are to be heated in one furnace
it is to be made of a length to contain them in a row or rows, the air
and fuel being injected at several points of the chamber suitably arranged,
several outlets or only one outlet to the chimney being used as may be
desired. The injection may be on the bottom and the outlet in or
near the bottom so as to keep the heat low. When the chamber is not
.of too great a length it may be so constructed that the air and fuel may
be injected from the chimney end of the pot chamber on one or both
sides of the pots, the larger particles of the fuel passing to the extre-
mity of the chamber, the products returning in the same chamber to the
chimney.
Figures 25 and 26 shew a furnace to contain one pot for melting steel
or other metal. D is a square chamber, but it may be round, oblong, or
other convenient form, built of refractory material, and in the centre of
which a raised portion E a few inches high is made on which the pot F
stands; the slag formed in the chamber accumulates all round this
raised portion and is drawn off through the hole G placed in any suitable
position as it accumulates. The air and powdered fuel are shewn
injected through the pipes H, H, on one side so as not to impinge
directly on the pot, sufficient space being left so that the flame or
products of combustion shall play round the pot and escape through
the flue I, by preference being placed below the top of the pot. The air
and fuel may be injected in many places in the manners previously
described, but especial care must be observed that they do not directly
strike the pot. The pot is inserted into the chamber through an opening
in the top J having a moveable cover. The door may be made in the side
of the furnace if preferred for the placing of the pot in its position.
When several pots are to be heated in a furnace an arrangement is
shewn in Figures 27, 28, 29. Figure 27 is a sectional elevation of a
furnace constructed of refractory material. The pots A, A, are inserted
into the chamber B through holes C, having moveable covers and placed
on a raised bottom D, D, raised a few inches above the centre portion E.
The distance between the pots, as seen in Figure 27, being considerably
more than that between the pots and the sides of the furnace F, F, the
air and fuel being injected through pipes G, G, G, G, into the centre
of the space between the pots, the products of combustion traversing
the furnace passing over and between the pots and then out of any

page_text: convenient openings or flues H, H, placed by preference below the top
of the pots, and thence to the chimney. The slag formed in the chamber
runs into the lower part E, and is tapped out when required through a
tap hole I placed in any convenient position. The position of the
injection pipes may be varied to suit circumstances so long as the
conditions for obtaining proper mixture of the air and powdered fuel
be maintained as previously set forth in this Specification, but it is better
to keep the injection of air and fuel as low as possible in the furnace.
If the fuel is injected between the pots at various places the pots should
be kept sufficiently far asunder to prevent the direct impinging action
of the air and fuel upon them. The plan, Figure 28, shews the pots
within few inches of the ends of the furnace j, j, but the furnace may
be extended a few feet longer at each end than shewn, leaving a large
space between the pots and the end walls, thus forming a species of
interior combustion chamber at each extremity. The fuel may be
injected from one end only and be made to traverse the chamber as
previously described. It should be observed that the doors may in some
case be placed at the sides of the furnace for removing the pots instead
of at the top.
This arrangement of furnaces for melting steel and
other metals in pots enables the whole of the furnace to be built above
the surface of the ground if desired. In ordinary glass melting furnaces
the air and fuel are injected into a compartment or compartments
suitably arranged in the existing fire-places and ash-pit, the fire-bars
being displaced so that the products of combustion ascend freely over
and between the receptacle containing the glass and so that the whole
is practically consumed on or before entering the chimney. When the
glass is melted in a bath the fuel and air may be injected and consumed
or partly consumed in one or more combustion chambers at the end of
the furnace, or the stream or streams of air and fuel may be blown into
the furnace above the bath containing the glass. Pot glass furnaces
may also be similarly heated. By thus constructing glass furnaces
whether to melt in pots or in a bath so that they shall be heated by
the products of the combustion of a mixture of air and powdered
fuel injected into the furnace at a pressure above the atmosphere, the
products of combustion escaping from the furnace at one or more parts
of the furnace and escaping up one or several chimneys or outlets, the
combustion of the fuel may be arranged to depend chiefly upon the
pressure or forcing in of the air and fuel and not upon the chimney draft.

page_text: Figures 30, 31 and 32, give a general idea of the form of an ordinary
glass furnace, the pots resting on beds B, B, Figure 31, above the level
of the fire-bars, the fire-bars C, C, Figures 30 and 32, being within
the chamber and between the pots. In applying my Invention to these
furnaces I close the bottom with suitable refractory material to any
convenient height in the fire-place or ash-pit (taking out the ordinary
fire-bars) by preference to within a few inches of the top of the
sieges D, Figure 31, forms a channel for the slag made in the furnace to
run into from which it may be tapped from tap holes E, E, Figure 30
placed in any convenient position. The air and powdered fuel may be
injected into the furnace through pipes F, F, F, by preference placed
below the level of the top of the pots directed into the chamber between
the pots, so as not to impinge directly upon them. The flame circulates
in the furnace passing between and over the pots out of the outlets
G, G, G, G, into the chimney or cone. It is desirable to keep the heat
as low down as possible in the furnace, therefore in constructing new
furnaces, or even in altering old ones, I prefer to inject the mixture so
that it travels low, and make the outlets to the chimney also as low as
convenient. It will be seen that as I can use a pressure in the furnace
by the forced current of air the large cone ordinarily used may in some
cases be dispensed with, and each outlet may have a short chimney
attached to it, or all the outlets may be joined together by a flue, the
waste products of combustion being conveyed to an ordinary chimney,
working holes being made at suitable positions. The dotted lines H, H,
H, H, Figures 30 and 32, shew the position of fire-places in some
ordinary furances outside the pot chamber, in these cases the bottoms
are closed as previously described, thus joining combustion chambers,
and air and fuel being injected into them by any of the means herein-
described, so that the air and fuel are not caused to impinge directly on
to the pots.
This system of arranging glass furnaces permits of their
being constructed without ash-pits, caves, or large cones.
furnaces for burning powdered fuel and air to heat steam boilers I
arrange the combustion chamber or chambers of metal surrounded by
water and lined with fire-brick or other refractory material. One end.
is closed, and near the other or that at which the air and fuel are
injected is an opening or openings into a subsidiary chamber or chambers
or more properly flues forming part of the boiler. The air and fuel are
directed towards the closed end of the chamber, and the current of the
To adapt

page_text: large particles which require a longer time for their combustion pass
to the end, and then returning carry along with them into the subsidiary.
chambers the products of the volatile and smaller portions of the fuel
which are consumed soon after their entrance, and without reaching the
further end of the furnace. Holes may be made between the two
chambers at various distances in place' of employing a single opening.
The dimensions of the combustion chamber may be proportioned in accord-
ance with the quantity of air and fuel used and the pressure' with which
they are injected, the second chamber or flue may be wholly or partially,
lined with refractory material. Three chambers may conveniently be
used in conjunction with one another, streams of air and powdered fuel
being injected into two of them, whilst the products of combustion from
into the third chamber. In those boilers where it is not con-
pass
venient to place combustion chambers within them lined with brick-
work separate chambers may be provided, but these should be consider-
ably larger unless some special arrangement is made for keeping the
bricks cool on the outside.
both
One method of arranging boilers is as follows, see Figures 33 and 34;
A is a section of the ordinary single flue type of boiler; the flue B is
lined with fire-brick C or other suitable refractory material to such a
distance along it that all or nearly all the solid particles of fuel are
consumed before passing the brickwork. The end D is also closed
with fire-brick having an opening E in it for putting in fuel for heating
up the furnace or other purposes, which is generally closed; F is a hole
for drawing out slag or other material which may collect in the
chamber B; G is a tube or tubes placed in any convenient position
between the outside of the boiler and the tube directed inwards, through
which the measured quantity of air and powdered fuel are injected into
the tube, some of it passing to the end at D and returning through the
same tube, and be practically consumed before leaving the lined portion,
and thence to the flue H, where the products traverse the boiler, giving
out their heat in the usual manner, care being taken that the mixture
of air and fuel effects combustion as set forth in this Specification.
prefer the connecting pipe or pipes for the admixture of air and fuel to
pass through the boiler in a straight diagonal line.
I
Figures 36 and 37 shew an arrangement of boilers of the return flue
type often used for marine purposes having three tubes for fire-places
A, A, A; these tubes are closed at the end and are lined with fire-brick,

page_text: I described in the last description of boiler. A tube is placed in the water
space at B, connecting the inside of the fire tube to the outside of the
boiler at any convenient angle; a pipe C conducting the air and powdered
fuel is inserted into this, which pipe may be brought and be conducted
under or through the boiler to the front at D, or in any convenient
position; the air and fuel entering at E in a straight or inclined direction
passes to the end E, returning to the same flue into the uptake F through
the tubes G to the chimney H. More than one pipe may be used, and
any of the arrangements described suitable for providing a good mixture
of air and fuel in this form of furnace may be employed.
Figures 38, 39, and 40 shew another arrangement.
The flues are
lined with fire-brick as before described, but the ends A, B, of the two
chambers C, D, Figure 40, are closed.
The fuel and air are injected
into the combustion chambers C, D, through pipes E, E, the currents
passing to the ends A, B, returning through the same chamber, and
passing into the centre chamber or flue F through one or more
holes G, G, G, G, the products leaving F passing up at H, and then
through the tubes to the chimney. This description is sufficient to make
clear the Invention, but the detail may be varied to suit circumstances.
Separate combustion chambers composed of fire-brick surrounded with
water may be placed clear of the boilers themselves with proper con-
nections between them, so that the main features described to effect the
objects are maintained. To afford an even and continuous supply of
powdered fuel to the stream of air that is forced into a furnace I place
the powdered fuel into a hopper constructed with vertical sides, and
having stirrers so arranged at the bottom that the whole area or nearly
so of the fuel contained in the hopper is disturbed by their action. The
working of these stirrers forcing the fuel from the hopper through an
opening at its side to and between rollers placed one above the other,"
thus keeping a regular and continuous supply of fuel to them.
quantity of fuel to be fed is regulated by the distance at which the
rollers are placed apart, or by driving them at a greater or less speed;
the feed may also be regulated by making the distance between the
rollers a fixed one, and by moveable slides diminishing the length of the
opening between the rollers. If coned hoppers are used stirrers are to
be placed at different heights in them to ensure the fuel falling. The
rollers may be close to the sides of the hopper, or projecting a small
distance into it or outside of it. In some cases the rollers may be
The

page_text: without a hopper, and have powdered fuel supplied to them by worms or
other means, so that they may be fed with more fuel than is required,
the surplus passing away from them. A screen may be placed at or near
the top of the hopper to be shaken or otherwise.
Figure 41 shews the feeder worked by a belt on a drum which
communicates motion to the stirrers and rollers by suitable gearing.
of
A is a hopper with vertical sides: B, a strainer for the purpose
preventing large particles of matter entering the hopper; C, D, are
stirrers disturbing nearly the whole lower area of the fuel, and revolving
in direction of the arrow, thereby forcing the powdered fuel through the
opening E, regulated by the sliding door F, the top of the opening E
being kept below the top of the box G, so that the fuel entering at E is
not forced over the edge of the box. Should the box become full of fuel
by reason of the rollers not taking it away as quickly as it is supplied to
the box, the stirrers not having sufficient force to increase the height of
the fuel in the box, the stirrers will continue to revolve and agitate the
fuel until the rollers have reduced the quantity in the box. The
rollers H, I, are for the purpose of feeding the fuel into the shoot K,
conducting the fuel to an injector, the inlet of a fan or other position
required, the quantity of fuel being regulated by varying the distance
between the rollers H, I, by means of a regulating screw L acting upon
the lever M, thence on the lever N, to which are attached the bearings
of the roller H. One of the rollers H, I, should be a roller of small
diameter, by preference 4 or 5 inches diameter. As the rollers take away
the fuel from the box G it is continuously replenished by that forced into
it by the stirrers D, the effect being that the fuel in the box and in
contact with the rollers is kept in a comparatively loose state and at a
comparatively uniform pressure whatever the height of the fuel in the
hopper A may he; besides the position of the rollers one above the other
enables the entire action to be in view, whereby any irregularity in the
feed passing over the scraper O can be immediately detected and the
cause ascertained, a most important consideration, as any irregularity of
the fuel passing to the furnace causes a variation in the heat and pro-
duces bad effects. The roller H may be placed at the side of the
roller C, having a shallow box over both of them, into which the stirrers
force the fuel, but in this case the fuel will fall underneath and be more
hidden from view than when the rollers are one above the other, and
although they will act I prefer the rollers one above the other and kept

page_text: fed by a very small head of fuel.
This small and constant head of fuel
between or on the rollers can be maintained in various ways without a
hopper being attached to each pair of rollers, and also many feed rollers
at distances apart from each other can be supplied by an ordinary screw
as used for conveying flour or other suitable means.
Figure 42 shews several sets of rollers A, A, A, for feeding various
furnaces, above which is a long open trough B, B, fitted inside with a
screw or worm, at each end are fixed the hoppers C, C, containing the
powdered fuel which are to be used alternately as required. Take, for
example, the hopper C; the fuel is forced in excess of that required for
the feeders A, A, A, by means of the stirrers D, D, through an outlet E,
regulated by the slide F, into the trough B, the worm conveying it along
such trough up to and beyond the openings G, G, G, through which
falls the quantity required for the respective feeders into a shallow
box H, H, H, abutting on the rollers A, A, A, from which box the
rollers supply themselves as previously mentioned, the surplus fuel
passing out at the end I into the receptacle K, from which it may be
reconveyed to the hopper C in any ordinary manner, or it may be lifted
by means of an elevator or otherwise into the hopper C', and by reversing
the worm opening the outlet E' and closing E reconveyed through the
trough to the feeder, the surplus passing into the receptacle K'. The
worm rollers and other movements are actuated by an ordinary well
known means not necessary here to describe, as it will depend upon the
position of the whole apparatus.
Having thus described the nature of my said Invention, and the
manner of performing the same, I would have it understood that,
First. I claim the use of furnaces for the combustion of powdered fuel
mixed with air provided with means so arranged that the surcharged
and undercharged portions of the air and fuel are properly intermixed in
the manner and for the purposes substantially as herein-before described.
Second. I claim the use of furnaces when altered by converting the
fire-place into a plain combustion chamber, or when constructed with a
plain combustion chamber, and provided in either case with means for
introducing, regulating, and controlling the streams of air charged with
powdered fuel, so arranged that the surcharged and undercharged
portions of air and powdered fuel are properly intermixed in the manner
and for the purposes substantially as herein-before described.

page_text: Third. I claim the use of regenerators and of pipe stoves in com-
bination with furnaces heated by the combustion of powdered fuel and
air introduced as herein described, such furnaces having spaces between
the working chamber and the regenerator or stove for permitting a
further supply of air to be mixed with the products of combustion before
they enter the regenerator or stove for the purposes substantially as
herein-before described.
Fourth. I claim the use of furnaces for melting metal constructed and
employed for burning a mixture of powdered fuel and air in the manner
and for the purposes substantially as herein-before described.
Fifth. I claim the use of furnaces for melting steel and other metal
in pots constructed and employed for burning a mixture of powdered
fuel and air in the manner and for the purposes substantially as herein-
before described.
Sixth. I claim the use of furnaces for melting glass constructed and
employed for burning a mixture of powdered fuel and air in the manner
and for the purposes substantially as herein-before described.
Seventh. I claim the use of boiler furnaces constructed and employed
for burning a mixture of powdered fuel and air in the manner and for
the purposes substantially as herein-before described.
Eighth. I claim the use of feeding apparatus for supplying powdered
fuel to furnaces constructed in the manner and for the purposes
substantially as herein-before described.
In witness whereof, I, the said Thomas Russell Crampton, have
hereunto set my hand and seal, this Third day of June, in the
year of Our Lord One thousand eight hundred and seventy.
T. R. CRAMPTON. (L.S.)