Improvements in Means for Feeding Furnaces and Stoves with Coal Dust and the like.
Year: 1895

page_text: Date of Application, 10th Sept.. 1895
Complete Specification Left, 10th Jun, 1396-Accepted, 18th July, 1896
PROVISIONAL SPECIFICATION.
Improvements in Means for Feeding Furnaces and Stoves with Coal
Dust and the like.
I HANS WILD, of 2ª Rheinziegelstrasse Strassburg, Alsace, Germany, Merchant
do hereby declare the nature of this invention to be as follows:-
This invention has for its object to provide means for feeding furnaces and
stoves with coal dust and the like which shall be entirely automatic and not require
any outside motor apparatus, which shall supply the coal dust free from lumps in a
regular manner and also ensure a sufficient supply of air to support combustion
intimately mixed with the coal dust and consists essentially in causing a current of
air induced by a fan operated by the draught of the furnace or stove to carry the
coal dust from the feed hopper to a second chamber where it is acted on by a fan
or the like also operated by the draught of the furnace or stove to intimately mix
the coal dust and air, and is then drawn through a number of pipes into the furnace
where it is burnt without the production of smoke.
In one arrangement as applied to a steam boiler or other furnace, the apparatus
consists of two chambers, one containing the coal dust forming a feed hopper
communicating through a horizontal opening near the bottom and extending nearly
its whole length with the other which is free from the coal dust. The size of the
said horizontal opening is regulated by a flap forming the bottom of the feed
hopper which is raised or lowered at one end to diminish or increase the size of the
horizontal opening, and thereby the rate of supply of the coal dust. The raising
or lowering of the flap may be effected by a roller upon which it rests and which
on rotating a screwed rod or the like connected to the frame in which the roller is
pivoted, is caused to advance or recede thus raising or lowering the flap. Any
other suitable means may be adopted.
The roller may be made corrugated or serrated so as to give a vibrating movement
to the flap and thus loosen any coal dust that may be lumped together.
In the second chamber which is free from the coal dust, a fan is arranged to
draw air in through an opening in the top of the chamber and direct a current
of air into a number of tubes leading into the feed hopper at the above described
horizontal opening so that the current of air carries a quantity of coal dust
with it into the bottom of the said second chamber where the mixture of coal
dust and air is acted on by another fan to cause the coal dust and air to be
intimately mixed. Any lumps and coarse dust particles carried through from
the feed hopper, fall on to a grating and into a chamber arranged underneath.
Any dust falling therewith is caught up again by the current of coal dust and
air. The coal dust and air then pass through a number of tubes, each provided
with a throttle or other suitable valve to regulate the supply into the furnace
where it is burnt without the production of smoke.
The action of the apparatus is as follows: The furnace is first lit in the
ordinary manner and when it becomes sufficiently heated a draught is induced
of sufficient strength to cause the two fans above described one to supply air
and the other to intimately mix the coal dust and air to rotate and to draw the
coal dust and air through the feed tubes into the furnace. The supply then goes
on continuously and regularly and without the aid of any outside motor apparatus.
The supply of air to the fan for supplying air may be regulated by a "hit and

page_text: "
miss or other suitable valve. The action is sufficient to carry not only dry but
relatively very damp dust into the furnace.
In previous apparatii for feeding furnaces with coal dust one feed tube from the
mixing chamber to the furnace has been used but by using a number of smaller
tubes an extra pressure is induced therein; and consequently not only the speed of
the air current but also its carrying capacity is greatly increased. The feeding
apparatus may for the same reason be placed outside the boiler room or at a
distance from the furnare.
When applied to a heating stove for house use the feeding apparatus which is
practically the same as described above with reference to a furnace, is placed in
the upper part of the stove and covered by a removable dome having inlets for air.
The conducting or feed tubes lead downwards on one side of the stove to the place
of combustion and are fitted with regulating and stopping discs.
The fire space is completely lined with fire brick and has a fire brick arch which
acts as a fire bridge. Above this is a second firebridge which reduces the speed of
the heated gases and thus effects a better utilization of the heat. A chimney and
also an inspection opening covered with mica or other transparent and fire resisting
material are provided.
For cooking stoves the feeding apparatus is arranged on
one side and the
conducting or feed tubes are led horizontally into the fire space. The latter forms
a firebrick retort above which either laying closely thereon or at some distance is
the oven plate.
Dated this 10th day of September 1895
WHEATLEY & MACKENZIE,
40 Chancery Lane, London, W.C., Agents.
Improvements in Means for Feeding Furnaces and Stoves with Coal
Dust and the like.
I HANS WILD, Merchant of 24 Rhein ziegelstrasse Strassburg Alsace, Germany,
do hereby declare the nature of this invention and in what manner the same is to
be performed to be particularly described and ascertained in and by the following
statement :-
This invention has for its object to provide means for feeding furnaces and
stoves with coal dust and the like which shall be entirely automatic and not
require any outside motor apparatus, which shall supply the coal dust free from
lumps in a regular manner and also ensure a sufficient supply of air to support
combustion intimately mixed with the coal dust, and consists essentially of
apparatus so arranged that the natural draught of the chimney amply suffices for
the maintenance of an adjustable and thoroughly automatic continuation of the
feed. Any special driving power is therefore dispensed with, such as vibrating or
rotating sieves, roller brushes, feeding blades and the like, which are in previous
systems necessary for feeding in the dust. The present arrangement also has the
advantage that the container for the coal dust and the blower connected therewith
may be erected outside the boiler room and communicate solely with the boiler
furnace by means of leed tubes of any desired length. Space and freedom of
movement is thereby gained in the boiler room, any distribution of dust in this
room is avoided and in particular waste of material is prevented, such as is
unavoidable by the shovelling in from time to time of fresh coal dust to the feed
hoppers of the old systems, erected almost in front of the boilers. This further-
more enables a whole battery of boilers to be supplied from one commo centre.
In addition to these advantages, this system of coal dust firing possesses the
further advantage of permitting the use of very damp dust. This in practical

page_text: operation is of tbe greatest importance as it is almost impossible to always obtain
dry coal dust or to prevent it from absorbing atmospheric moisture and thus
become moist again. The above mentioned properties of the new system of coal
dust firing make it suitable not only for use in ordinary stationary steam boilers
but also for marine and locomotive boilers and for house fires, in apartment
furnaces and cooking stoves.
In the accompanying sheet of illustrative drawings:-
Fig. 1 is a vertical section, and Fig. 2 a horizontal section of a coal dust firing
apparatus for a steam boiler constructed according to this invention.
The storage container A for the coal dust, is of sufficient capacity to hold dust
fuel for 10 to 12 hours working so that in the whole of this time a further filling
of the container is not necessary. This storage container contracts underneath in
the shape of a funnel, leaving only a small opening A2 which opens into a
chamber A³.
The bottom of this chamber A³ is formed by a plate B hanging movably on
hinges B2 and resting on any suitable regulating apparatus E. The plate B moves
in the slot C cut the whole width of the side D of the chamber A³ nearest the
steam boiler. By raising or lowering the plate B by means of the apparatus E
the slot C is closed or opened to the extent required. The plate B is provided
with a surface piece of flint glass in order to prevent as much as possible the
retention of damp dust. The side pieces of the plate B are formed of sail cloth up
to the height of F and this is fastened by the rod F. The part of the plate B
working in the slot C is also provided with a sail cloth apron.
Close to the chamber A³ there is a blower G, for instance a fan with air box G²
in front. Also attached to the chamber A³, and underneath the blower G¹ is the
mixing chamber H in which are fitted two easily running air vanes J. From the
air box G two tubes K lead into the mixing chainber H, arranged in such manner
that each of the outlets of the tubes plays upon the wings of an air vane.
Furthermore, one or more tubes L lead from the air box G² to the chamber A³ in
such manner that the outlet comes over the upper part of the plate B, blowing the
coal dust on to the latter in the direction of the slot C. The dust falling out of
the container A, through the opening A2, on to the plate B will spread itself out
thereon in the shape of a cone so that the air issuing from the tube L has space
for play to the right and left. Underneath the mixing chamber H there is a
chamber R with a perforated cover to receive any coarse particles of dust.
From the mixing chamber H a number of tubes U lead to the furnace M of the
boiler and these can be regulated by closing discs O fitted close to their exit from
the mixing chamber H and also close before their entrance into the furnace. The
tubes U can be completely adapted to the conditions existing on the spot, and can
enter the furnace horizontally or inclined upwards or downwards. The furnace is
carefully lined with the best fire bricks and between these and the iron parts a
non-conducting lagging is inserted (asbestos), in order to reduce as much as
possible loss of heat by radiation.
The air vanes J are connected with the ventilator G so that one drives the
other.
When commencing stoking the fan G is set in motion by a driving cord
with weights.
On the furnace front a register shutter P is provided the object of which is to
allow the entry when necessary of more air for combustion into the furnace.
Tare inspection holes for the observation of the process of combustion, and S is
the furnace door to permit the removal by means of a rake, of the refuse of the
firing (slag).
The process of the firing is as follows:-
As is known firebricks retain their heat for a long time so that a coal dust
furnace which has remained in operation up to Saturday evening can be started
again on Monday morning without wood, simply by one or two pieces of lighted
waste or a few sheets of paper. Thereupon, or quite simultaneously, the stopper
disc O of one or more tubes U is opened and there takes place at once a Fuction

page_text: of air through the tubes U from the mixing chamber H, resulting from which the
wind vanes J rotate, assisted by the blower G which is set in motion, whirl up
the coal dust contained in the chamber R and effect the transfer thereof into the
furnace by its carriage with the air passing through the tubes U. At commencing,
the movement of air is slow and the carrying power of the stream of air is slight,
in consequence of which only the finest dust is carried into the furnace. This is,
for an economical combustion, not without importance, since coarse grained dust
volatilises very easily instead of burning if the furnace is not quite white hot.
By the fan G which has been set in motion air is simultaneously driven through
the tube L in order to blow the dust down from the plate B into the mixing
space H. This action is helped by the sharp inclination of the plate B, and by
the air vanes J which by means of their rapid movement draw the dust down from
the plate B through the slot C. In the majority of cases (and especially with
steam ships) the natural chimney draught assisted by the suction power of the
high temperature furnace suffices to maintain in motion the air vanes J and thereby
the blower G so that the latter to a certain extent only acts as a fly wheel:
Where this is not the case a small power machine of about 25 H.P. is arranged
for driving the fan. The quantity of dust which is to be burnt is under perfect
control, not only because by raising or lowering the plate B, the slot C can be
closed or opened to the required extent, but also on account of the regulation of
the tubes U. The old systems have all only one conducting tube into the furnace,
so that with furnaces of large proportions (for example, under firing) two
apparatuses with two conducting tubes had always to be fitted, and yet the effects
were behind the results with fire tube boilers because it was not possible to produce
an even distribution over the fire brick surfaces of the coal dust blown in. (Quite
apart from the enormously increased cost necessitated by erecting two apparatuses.)
With the present system this equal distribution is easily obtained since the tubes U
can pass into the furnace in any manner considered suitable.
The presence of several feed tubes offers the following advantages
:―
a. Interruptions in working are completely obviated since reserve tubes can
be fitted.
b. By fitting reserve tubes the fuel supply and steam production may be
increased at times to an extreme limit such as could not be thought of with
any other system; and,
c. The consumption even with a changable and forced working is always almost
or quite smokeless because the proportionate mixture of air for combustion
and fuel remains constant.
The boiler surroundings may be kept quite clean as the container A may be
erected in any desired position, and a means of firing is thus obtained which in
respect to cleanliness can only be compared to gas firing.
It is also indifferent whether the dust is dry or moist. After the dust reaches
the plate B it is drawn downwards separated by the movement of the arms of the
wind vane J, mixed with the air and carried through the tubes U into the
furnace M. In combustion the dampness of the dust does not have much effect;
the difficulty in the old systems was essentially to get the damp dust into the
furnace. As already mentioned the necessity attaching to all previous systems of
filling the feed hopper several times per hour is completely removed.
The storage
container A holds sufficient dust to last for 10 or 12 working hours.
In cases where the coal dust mill can be erected above the container A, the
filling of the latter is avoided since the produce from the grinding is allowed to
fall directly into the container A.
Like all systems of coal dust firing the present system is not only suitable for
steam boilers, but also for all other heating smelting and burning processes.
This
system may be used in marine work with advantage since it requires no mechanical
feed for the hoppers, as in the old systems; this method of aid has the dis-
advantage that any defect in the mechanical feed lowers the fires and puts the ship
in danger.

page_text: The present system finally enables several steam boilers to be fed from one
centre.
A further form of constructing the arrangement would be that the ventilator G
be quite removed, and the air vanes J cach separately be independently rotated.
In this case the pipes K and L would not be required but in place thereof a
register shutter would be fitted in the front side of the chamber as allowing the
entry of the quantity of air necessary for the transport of the coal dust and
combustion thereof. In case of necessity a special fan could be arranged in front
of the register shutter to drive the air through the holes in the shutter.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what I
claim is:
1. A system of coal dust firing in which the fuel is solely, by means of a number
of adjustable conducting tubes Ù and by the natural chimney draught in combina-
tion with the natural suction power of the glowing furnace drawn from the storage
container A³ into the mixing space H and from the latter into the furnace M,
whereby, except the conducting tubes U₁, all parts of the transport apparatus may
be erected outside the boiler or furnace room.
2. A transporting apparatus for the coal dust firing system described under
Claim 1 characterised by a storage container A³ with regulating outlet slot C for
the dust material, through which atmospheric air is driven either by means of a
fan or by the natural draught of the furnace, in such manner that this air carries
with it even moist coal dust into the adjacent mixing chamber H and is therein
mixed with the dust by the action of the air vanes J whereupon the mixture is
carried into the furnace M by the natural draught.
3. The improved means for feeding furnaces and stoves with coal dust fuel and
the like, the whole arranged constructed and operating, substantially as described.
in the foregoing specification and illustrated in the drawings hereunto annexed.
Dated this 10th day of June 1896.
WHEATLEY & MACKENZIE,
40 Chancery Lane, London, W.C., Agents.