Improvements in or connected with Apparatus for Supplying Pulverulent Fuel to Furnaces.
Year: 1893

page_text: Date of Application, 3rd Nov., 1893-Accepted, 31st Mar., 1894
COMPLETE SPECIFICATIVA.
Improvements in or connected with Apparatus for Supplying
Pulverulent Fuel to Furnaces.
I, AUGUST RIEDINGER of 23 Eisenhammerstrasse, Augsburg, in the German
Empire, Gentleman, 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 relates to apparatus for supplying pulverulent fuel to furnaces,
in such a manner as to secure practically perfect combustion and consequently a
high efficiency, the supply of the fuel in exact proportion to the temporary
requirements, the prevention of smoke, and so also as to enable fuel of low quality
to be used which would otherwise be wasted.
I will describe my improvements with reference to the accompanying drawings.
It is well understood that in order to secure perfect and economical combustion
of fuel it is necessary that the air and fuel should be constantly supplied in known
relative proportions. In order to secure this condition the fuel must be supplied in
a finely divided state mingled with the air, but experience has shewu that if such
a mingled current of air and fuel dust be supplied to a furnace unconditionally,
explosive ignitions may take place instead of a constant combustion. Thus, if the
flame in a furnace be at some distance from the point of delivery of the mingled air
and fuel, irregular inflammation and probably explosive combustion may occur.
Figure 1 illustrates diagrammatically the manner in which I may supply the
mixed air and fuel to a furnace or combustion chamber C, in which one or more
gas or oil flames c are constantly burning near the inlet E, through which the air
and fuel pass into C. The igniting flames c may with advantage be in a ring form
surrounding the inlet E.
In the modification diagrammatically illustrated by Figure 2, the inlet E opens
into a wide tube A. In issuing from the comparatively narrow inlet into A, the
combined air and fuel have a whirling or eddying motion imparted to them and if
the mixture be ignited the space A will contain a whirling mass of flame which will
continuously ignite the fuel entering through the inlet.
A modification of the arrangement illustrated by Figure 2 is shewn by Figure 3.
In this arrangement the inlet tube is curved backward within the wide tube A so
as to deliver the incoming mixed air and fuel against the closed back of the tube.
As in the former case, the fuel having once been ignited will continue to burn in
the tube A and the flame will be continuously fed by the incoming fuel.
Figure 4 shews a further modification of the arrangement. In this case the inlet
tube E enters the combustion chamber near the top and is bent so as to deliver the
mixed current perpendicularly downwards or thereabouts. The mixture being
once ignited will continue to burn near the orifice of E because the flame being
lighter than the surrounding gases will always tend to rise.
The number of inlets may be multiplied as shewn for example by Figure 5 where
there are four such inlets of which the upper one corresponds with that shewn in
Figure 4. The mixture being once ignited will as before described remain in
steady combustion so long as the mixed air and fuel enter the combustion
chamber C. There may of course be two or more of the vertical rows of inlet
tubes and a corresponding number of downward bent upper inlets.
In the diagram Figure 6, M is a mixing chamber to which the pulverulent fuel
is supplied intermittently or continuously by suitable means and through an opening
not shewn. At the bottom of this chamber there are inlets d for blast or com-
pressed air. The in-rushing air will disturb the pulverulent fuel and blow it

page_text: through the pipe a and inlet E into the combustion chamber. There may be more
than one of the pipes a and inlets E, and the pipes may be of different lengths as
shewn by Figure 7.
Figures 8 and 9 illustrate diagrammatically by what means I may ensure the
delivery of the correct amount of fuel under varying conditions. The apparatus
indicated by Figure 8 is shewn in cross section to the right of that figure. In the
underside of a tube or trough B there is a slot D below which is a rotating
cylinder F, one half of which has longitudinal or spiral grooves formed upon its
periphery. This cylinder is fixed upon the axle f and is driven at a uniform speed.
The pulverulent fuel is conveyed along the trough or tube B by means of the
endless screw G as will hereinafter be described. If the cylinder F be in such a
position that its grooved part is under the slot D, the grooves will be continuously
filled with the fuel and will deliver it into any suitable receptacle below at the full
capacity of the apparatus. If however the smooth part of the cylinder be brought
below the slot D, it will close the slot and no fuel will be delivered. It will be
evident therefore that by moving the cylinder F to the right or left, any desired
rate of supply of the fuel may be obtained within the limits of the capacity of the
apparatus. Means for effecting the longitudinal motion of the cylinder are
hereinafter described.
Figure 9 represents an apparatus similar to that shewn by Figure 8, but the
cylinder F instead of moving longitudinally to vary the supply of fuel, is grooved
over its whole periphery and is driven at a variable speed through the friction
bowl and constantly driven disc H. The cylinder F instead of being fixed upon
the spindle fis mounted thereon and caused to rotate therewith by a feather or
fast key so that whilst the cylinder does not move laterally its spindle may be
moved longitudinally by suitable means, such as that hereinafter described. When
the friction bowl is moved nearer to the centre of the disc H, the cylinder
will rotate more slowly and deliver less fuel, and the contrary when the bowl
is moved towards the circumference of the disc. Instead of the cylinder F, a
worm may be employed.
Figure 10 is a diagrammatic illustration of a device for controlling the rate of
delivery of the fuel or air. I is a chamber closed at its top by the concentrically
corrugated steel disc i, and internally in communication with the steam space of the
boiler. Above the spring disc i there is a lever L fulcrumed at J and weighted
at K. The centre of the spring disc i bears by a suitable connection on the
under side of the lever which will consequently be moved upwards or downwards
by variations in the steam pressure. The lever L is connected by suitable means
with the herein before described fuel feeding devices in such a manner that when.
it rises with an increase of pressure, the rate of fuel supply is diminished and the
contrary. A spring k may be connected with a suitable fixing and with the lever,
to cause the apparatus to work with greater certainty, and this or another spring
may be employed in substitution for the weight K.
In the modification indicated by Figure 11 an equivalent arrangement is shewn.
The cylinder I and piston i replace the chamber and spring in Figure 10. This
figure also illustrates a connection between the lever L and the supply system.
Figures 12 to 15 inclusive illustrate diagrammatically the means which I may
employ for the control of the air supply, in proportion to the fuel supply.
The amount of air supplied to a furnace varies with its density as well as with
its velocity and the area of the passage through which it issues. If either of these
conditions vary the supply of air will vary. Assuming the velocity v and the
area a to be constant, it follows that any variation in the difference of pressure d
on either side of the outlet E, will cause a variation in the total supply of air.
The apparatus illustrated by Figure 12 is designed to compensate for any
variations in the difference of pressure d.
Ou one end of a lever I counterweighted at 1, there is suspended the bell
holder m the lower edge of which dips into a fluid m¹ as in the case of a gas holder.
The interior of the holder is in communication through the pipe m² with the

page_text: interior of the furnace. Hence any variation in the difference of pressure between
the gases in the furnace and the external atmosphere will produce a corresponding
variation in the position of the lever L. For example, if the horizontal area of the
holder be 1 square meter, and there be a difference in pressure d, of 1 ", the pull
or push exerted upon the lever will be 1 kilogram, and this force exerted through
the lever may be employed to open and close partially a damper fixed in the air
channel so as to regulate the air supply.
Figure 13 illustrates an apparatus which may be employed to automatically
regulate the proportions and rate of supply of the air and fuel. The fuel is fed by
the cylinder F, already described with reference to Figures 8 and 9, and the air
supply is measured by the fan N. If the area of the inlets E be denoted by a and
the velocity of the current issuing therethrough by r, then the volume of the air
delivered will be a v. This volume must regulate the speed of the cylinder F.
The spindle of the fan N has a worm fixed upon it which drives the worm wheel O,
on the spindle of which there is a second worm driving the second worm wheel o
upon the spindle of which is fixed the friction disc H, also shewn in Figure 9. The
motion of N may be transmitted to H by other equivalent means so that their speeds
are always proportionate, in the same degree to each other and to the volume of air
passing the fan.
As it would be generally undesirable to employ the fan N to drive the feed drum
directly through the gearing Oo Hh, it is desirable to employ some other contrivance
which will make the number of revolutions of the cylinder F in a given time always
proportionate to the number of revolutions of/1, which it will have been seen varies
with the product of av.
On the spindle is fixed a bevel wheel R and upon a separate co-axial spindle a
similar bevel wheel R', which is driven by suitable means at a regular speed.
Within a wheel S are mounted the bevel pinions r³ respectively gearing both
with R and R', the whole forming a well known differential gear. If rotation of
the wheel S be by any means prevented, the bevel wheel R will be caused to rotate
whilst if S be set at liberty, the wheel R will remain stationary whilst S will turn
at half the speed of R'. It is therefore only necessary to exert a certain brake
power upon S to give to R and therefore to F, the desired rate of revolution. This
brake action can be obtained by reversible gearing in which the cylinder F and
spindle are included. The pulley T is fixed upon the spindle f, and from this a
cord runs over the pulley T¹ thence round t to the pulley and back to T. If for
example T and t are equal, T¹ and t¹ will remain stationary if the number of
revolutions made by fare the same, and T¹ t' will commence to move as soon as the
revolution speeds of fand f' vary from each other. This permits of one of the
pulleys being employed to cause the action of the brake upon the wheel S, and thus
to equalise the speeds off and f¹.
Figure 14 illustrates an arrangement by the use of which, in case the natural
draft should be insufficient, it may be increased when used in combination with the
apparatus illustrated by Figures 6 and 7, and in combination with which the apparatus
illustrated by Figure 13 may also be employed.
t
The apparatus consists of a steam jet controlled by the steam pressure for the
purpose of inducing a current of air for combustion. U is a closed chamber having
the transverse concentrically corrugated steel diaphragm U' contained in it. The
back of the diaphragm is in a chamber to which steam from the boiler has free
access. In the front of the diaphragm there is connected to it a spindle u surrounded
by a re-acting spiral spring, and carrying at its front end a taper plug u entering
within the corresponding taper nozzle u² which also is in communication with the steam
space of the boiler and acts as a steam jet. This jet is controlled by the motion of
the diaphragm under variations of boiler pressure. Thus when the boiler pressure
rises, the diaphragm will be forced forward, and the plug moving with it will.
tend to close the nozzle and consequently reduce the steam jet and the current of
air induced by it.
When the air is supplied to the furnace by a fan the apparatus illustrated by

page_text: Figure 15 may be employed. To obtain the proper proportion of air and of fuel
supply, the fuel feed cylinder F, Figures 8 and 9, is connected with the fan V in
such a manner that the relative speeds of each apparatus shall at all times be
proportional. Either of the steam pressure regulators Figures 10 or 11 may be
employed to control the speed of the fan V. For this purpose the differential
cones W W are driven at X by a suitable motor. The cones are geared by the
endless band a and drive the fan V. The position of the belt is controlled by the
steam pressure regulator Figure 10 or Figure 11, through the rod Y which is freely
connected with the lower end of the vertical screwed spindle Z which carries on a
nut thereon a fork engaging with the strap .c. Below the screwed spindle Z there
is a horizontal axis on which the two opposed discs are fixed, and between them
is fixed on the lower end of Z a friction bowl y' which can by the motion of the
rod Y be moved into contact and so as to be driven by either of the discs 21. If in
contact with one of these discs the screwed spindle will be driven in one direction,
and in the opposite direction when the bowl is moved into contact with the other
disc. When the spindle is driven one way, the band r will travel upward on the
cones and the ventilating fan V will be driven more slowly and when it is driven the
other way, the opposite will occur, and the speed of the fan V will consequently vary
with the boiler pressure.
Figure 16 is a diagram illustrating the connection between the steam pressure
regulator and the screwed spindle Z.
Figures 17 and 18 shew in elevation and plan respectively, a fuel circulating
apparatus for the fuel feed illustrated by Figures 8 and 9. From the main
receptacle Q, the dust fuel is conveyed by an endless screw through the pipe or
trough B, below which is the slot and cylinder F, of which there may be more
.than one.
From B the fuel passes into the secondary receptacle Q1, whence it is
re-conveyed by another endless screw through the trough or pipe B¹ to the main
receptacle Q.
In order to ensure a constant and regular supply of the fuel dust to the
cylinders F, it is necessary to keep it in continual motion above the cylinders.
This motion also tends to prevent the fuel from balling or becoming choked or
clogged on its way to the feed cylinders.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is
1. In apparatus for supplying pulverulent fuel to furnaces, one or more inlets
for mixed air and fuel having arranged close to it or to them one or more permanent
flames preferably in the ring form, substantially as hereinbefore described with
reference to Figure 1 of the accompanying drawings.
2. In apparatus for supplying pulverulent fuel to furnaces, the combination and
arrangement with one or more inlets for the mixed air and fuel, of a short tube of
comparatively wide bore, substantially as and for the purpose hereinbefore
described with reference to Figure 2 of the accompanying drawings.
3. In apparatus for supplying pulverulent fuel to furnaces, the combination and
arrangement with a recurved inlet pipe for the combined air and fuel, of a short
tube of comparatively wide bore, substantially as and for the purpose hereinbefore
described and as illustrated by Figure 3 of the accompanying drawings.
4. In apparatus for supplying pulverulent fuel to furnaces, an inlet for the
combined air and fuel, recurved downwards, substantially as and for the purpose
herein before described and as illustrated by Figure 4 of the accompanying
⚫ drawings.
5. In apparatus for supplying pulverulent fuel to furnaces, the combination and
arrangement of several inlet tubes for the combined air and fuel, of which the
upper tube or upper tubes have their inlet orifices inclined downwards, substan-
tially as herein before described and as illustrated by Figure 5 of the accompanying
drawings.

page_text: 6. In apparatus for supplying pulverulent fuel to furnaces, a device for mixing
the fuel and the air, consisting of a chamber having an inlet for the fuel, an inlet
or inlets for blast or compressed air, and an outlet or outlets for the mixed air and
fuel, constructed arranged and operated substantially as hereinbefore described and
as illustrated by Figures 6 and 7 of the accompanying drawings.
7. In apparatus for supplying fuel in a pulverulent form to furnaces, a fuel.
feeding device consisting of a grooved cylinder arranged under a slot in and below
a pipe or trough through which the pulverulent fuel is conveyed, and operated to
deliver the fuel from the slot at such speeds as may from time to time be required,
substantially as hereinbefore described and as illustrated by Figures 8 and 9 of the
accompanying drawings.
8. In apparatus for supplying pulverulent fuel to furnaces, a steam pressure
regulator consisting of a concentrically corrugated spring or of a piston acted on
by the steam pressure, and a lever actuated by the spring or piston and actuating the
air and fuel supply devices, substantially as hereinbefore described and as illustrated
by Figures 10 and 11 of the accompanying drawings.
9. In apparatus for supplying pulverulent fuel to furnaces, a bell-holder
suspended from a lever and internally in communication with the furnace or com-
bustion chamber, the lever being arranged to operate or control the supply of the
fuel and air, all constructed and arranged substantially as hereinbefore described
and as illustrated by the accompanying drawings.
10. In apparatus for supplying pulverulent fuel to furnaces, the combination and
arrangement with the feeding cylinder, of differential gearing, a system of cord
and pulleys, a fan or anemometer driven by the current of air passing to the
furnace, and gearing for transmitting the motion of the fan to one of the pulleys,
substantially as and for the purpose hereinbefore described and as illustrated by the
Figure 13 of the accompanying drawings.
11. In apparatus for supplying fuel in a pulverulent form to furnaces, a
differential device for driving the supply fan, consisting of two conical rollers one
of which is driven and drives the other by an endless belt, a screwed spindle
carrying on a nut thereon a strap fork for shifting the endless belt, a friction bowl
on the end of the screwed spindle arranged between two opposed rotating discs,.
and a rod operated by a controlling device to put the friction bowl into contact
with one or other of the opposed discs, substantially as herein before described and
as illustrated by Figure 15 of the accompanying drawings.
12. In apparatus for supplying pulverulent fuel to furnaces, the combination and
arrangement of a principal and secondary receptacle for the fuel, with two tubes
connecting the receptacles, endless screws in the tubes, a slot or slots below one or
each of the tubes, and feeding devices for removing the fuel from the slots at.
determined rates, substantially as hereinbefore described and as illustrated by
Figures 17 and 18 of the accompanying drawings.
Dated this 2nd day of November A.D. 1893.
WILLIAM E. HEYS,
Agent for the Applicant..