Improvements in Pulverizers..
Year: 1899

page_text: Date of Application, 17th Oct., 1899 -Accepted, 27th Jan., 1900
Improvements in Pulverizers..
I, CLAUDE KENNEDY MILLS, of 23, Southampton Buildings, in the County of
London, Patent Agent, do hereby declare the nature of this invention (a com-
munication to me from The British Aero-Pulverizer Company, a Corporation
organized under the laws of the State of New Jersey, U.S.A., and having its
principal place of business at the corner of Grand and Green Streets, Jersey
City, County of Hudson, said State,) and in what manner the same is to be per-
formed, to be particularly described and ascertained, in and by the following
statement:-
The invention relates to various new and useful improvements in pulverizers
adapted especially for the purpose of reducing to an impalpable powder a com-
bustible material, such as coal or coke, and for forcing the pulverized material,
with the proper proportion of air as to result in perfect combustion, to the
point of use, as for instance the fire-box of a boiler; and the invention also
relates to improvements in feeding mechanism for feeding a regulable supply
of the material to the pulverizer. The improvements are not limited to use
for the pulverization. of combustible material, and may be employed with other
pulverizable substances.
The class of pulverizers to which the invention preferably relates is that
employing a series of concentric chambers of gradually increasing diameters from
the feed end to the discharge end of the device. A horizontal shaft is mounted
centrally within these chambers and carries a series of spider-arms, to the ends
of which paddles are secured, said paddles working in the concentric chambers.
Separating the respective chambers are diaphragms, hetween which and the
shaft, openings are formed for the passage of pulverized material successively
through the apparatus. At the discharge end of the device, a fan is carried in
a fan-chamber, concentric with the pulverizing chambers and on the same shaft,
for producing a flow of air through the apparatus, by reason of which the material
in course of pulverization will pass successively through the chambers and in a
fine condition will be ejected from the apparatus, intermixed with air, to the
point of use.
As a result of experiment, it has been found that when a sufficient amount of
air is caused to be drawn through the apparatus as to result in a mixture which
will give perfect combustion, the movement of the material during pulveriza-
tion through the apparatus will be relatively rapid, and the material in conse-
quence will not be reduced to its ultimate condition of fineness, as is desirable.
On the other hand, if the material is allowed to pass through the apparatus with
sufficient slowness as to be reduced to the desired condition of fineness, the air
which will be necessarily mixed therewith will be insufficient to cause perfect
combustion. With the present apparatus, the material will be allowed to pass
through the apparatus at the proper rate of speed to result in its being reduced
to an impalpable powder of the desired fineness, and at the same time the material
so pulverized will be mixed with exactly the correct proportion of air to result

page_text: in absolutely perfect combustion. When the invention is used in connection
with non-combustible material, the increased quantity of air which will be ex-
pelled with the products of pulverization may be effectively utilized for any
desired purpose, as, for example, the grading or sorting of the products by
gravity. The essential object of the invention, therefore, is to produce a pulveri
zing apparatus of this kind, wherein the material will be reduced to the finest
possible condition and will be forced to the place of use intimately intermixed
with an increased quantity of air, which in the case of combustible material will
be in the correct proportion as to result in absolutely perfect combustion.
A secondary object of the invention is to provide a feeding device for such pul-
verizers which will be simple in construction and effective in operation, and
wherein any desired proportion of material and air may be admitted to the
apparatus.
In order that the invention may be better understood, attention is directed
to the accompanying drawings, forming a part of this specification, and in which
Figure 1 is a vertical sectional view through a pulverizing apparatus of the
type referred to, illustrating the application thereto of the present improvements,
including the feeding device;
.
Figure 2, an end view thereof;
Figure 3, a vertical section through the tuyere;
Figure 4, a diagrammatic view:
Figure 5, a plan view of the feeding device detached;
Figure 6, a vertical sectional view on the line 6-6 of Figure 5:
Figure 7 a side elevation of the feeding device;
Figure 8, a top view of the shear; and
Figure 9, a side view thereof.
In all of the above views, corresponding parts are represented by the same
numerals of reference.
1 is a base, upon which is securely bolted the pulverizing device 2.
This pulverizing device, in the present instance, comprises three con-
centric pulverizing chambers 3, 4 and 5, of successively increasing diam-
eters, as shown. These pulverizing chambers are arranged concentrically
with respect to each other. The chambers 3 and 4 are divided by a
partition 6, the chambers 4 and 5 are divided by a partition 7, and
at the end of the pulverizing chamber 5, considered as an entity, is a partition S.
Mounted centrally in the apparatus is a driving shaft 9, driven in any suitable
way, as for example by a band-wheel 10. The shaft may be mounted in separate
bearings 11, 11, or in bearings formed at the ends of the pulverizing apparatus
itself: The openings in the partitions or diaphragms 6 and 7 and surrounding
the shaft 9 are preferably of the same diameter, while the opening in the dia-
phragm is preferably considerably smaller, as shown. Preferably a fan-
chamber 12 is mounted at the side of the pulverizing chamber 5. and into which
the pulverized material may pass through the opening in the diaphragm or par-
tition S. The fan-chamber 12 has a discharge opening 13 therein, arranged
tangentially with respect to the same, and this discharge opening 13 connects
with a discharge pipe 14 leading to the fire-box or elsewhere. Keyed on the
shaft 9 within each of the pulverizing chambers 3, 4 and 5, is a sleeve 15 carry-
ing spider-arms 16. On the end of each of said spiders is a paddle or pulver-
izer 1. The spider-arms in the pulverizing chambers are of correspondingly
increasing lengths, so that the paddles or pulverizers 17 in each chamber will
be located a correspondingly increased distance from the shaft 9. Hence in
operation the paddles or pulverizers in the pulverizing chamber 4 will partake
of a higher velocity than those in the pulverizing chamber 3, and the paddles
in the pulverizing chamber 5 will be operated at a higher velocity than those in
the chamber 4. By reason of this construction, the material passing through
the apparatus will be successively reduced in fineness, as is well known, Keyed

page_text: to the shaft 9 within the fan-chamber 12 is a sleeve 18, carrying fan-blades 19
in the usual way.
The pulverizing chamber 5 is preferably of a greater width than the other
pulverizing chambers. When the improved pulverizing apparatus is used for
the pulverization of non-combustible material such as cement, the paddles or
pulverizers 17 in said chamber will preferably occupy almost the entire internal
width, as shown in dotted lines, since with such material such a supply of air
only is necessary as will result in effecting a sufficiently slow movement to result
in the proper pulverization.. When, however, it is desired that a greater quantity
of air should be added to the material than is required for effecting the movement
thereof through the pulverizing chambers, a supplemental diaphragm or par-
tition 20 is secured within the pulverizing chamber, bolted or riveted firmly
in place and having an opening at its center concentric with the shaft 9, which
opening is preferably somewhat larger than the opening in the partition or
diaphragm 8 but smaller than the openings in the partitions 6 and 7. Between
the diaphragm S and the supplemental diaphragm 20, an air-chamber 21 will be
formed. The air-chamber 21 is continued at its upper portion to form a neck 22,
through which the air supply enters. If a hot blast is desired, a pipe 23 (dotted
lines Figure 2) may be connected to the mouth of the neck and with any desired
source of supply. In order to regulate the quantity of air entering the air-
chamber 21, any suitable form of valve may be employed, such as the damper 24
mounted on a shaft 25 and operated by a thumb-piece 26 or any other desired
handle. A lock-nut 27 may be carried on one end of the shaft to maintain the
damper in any desired position. Preferably the supplemental diaphragm is
provided with a cast flange 27 partially surrounding the opening therein, as
shown, said flange being of its greatest width at its top and gradually tapering
therefrom. By means of this flange, the air supply will be more evenly dis-
tributed around the shaft, instead of passing directly from the air inlet through
the upper portion of the opening in the diaphragm S.
Usually the feeding device is provided with a slide by means of which the air
entering with the material into the pulverizer may be suitably regulated. It is
desirable in some instances that the main air supply may be simultaneously
varied with the supplemental air supply, so that both supplies will always bear
the proper relation to each other, while the quantity of admitted air will be
varied to suit the exigencies of use. To effect this result, the slide 37 (Figure 4)
of the feed device may be connected to the damper 24 by suitable levers and con-
necting rods, as shown in said figure, whereby the two regulating devices con-
trolling the main and supplemental air supplies may be simultaneously moved
by a single manually or automatically operated mechanism.
The exit pipe from the fan-chamber is made generally rectangular in cross-sec-
tion as shown in Figure 1, and the supply pipe leading therefrom is generally circu-
lar in cross-section. When the apparatus is employed for the feeding of pulverized
combustible material to a fire-box, it is desirable that the stream of material and
air entering the fire-box should be as thin as possible in its vertical dimension.
By forcing into the fire-box a very thin, flat sheet of pulverized material and air,
a very perfect combustion is effected. Preferably, an exit pipe is employed, the
hore of which is very short in a vertical direction but of a considerable horizontal
width. If an exit pipe were used having a bore rectangular in cross-section, the
material passing through the exit pipe would tend to be concentrated at the
central part thereof, and would not be distributed evenly throughout the entire
surface. In order to overcome this, an exit pipe is used having a cross-sectional
area substantially like that illustrated in Figure 3, the top and bottom walls
being concaved. This offers a retardation at the center to the flow, and causes an
accurate distribution from the entire mouth of the exit pipe into the fire-box.
The construction of the feeding device is shown more particularly in Figures 1.
5, 6, 7, 8 and 9. The body of the device is formed essentially of two cast-
ings 28 and 29, bolted together as shown. The upper section 28 is formed with

page_text: an integral, interior cylindrical neck 30. 31 is a hopper mounted above said
neck, in which the material is placed and to which the material is constantly
supplied. The lower section 29 of the body is formed at its lower end with an in-
clined chute 32 having an opening 33. at the bottom through which the material
may pass and through which also air may be drawn by suction. Located beneath
the opening 33 and in front thereof is a casing 34 having an inclined bottom 35
and an opening 36 therein, which opening 36 is arranged in alignment with
the entrance opening to the pulverizer, as shown. The opening 33, it will be
noted, extends above the upper horizontal wall of the casing 34, whereby air
may be drawn into the opening 33 above said upper wall, and thence pass into
the interior thereof. 37 is a slide adapted to close more or less the opening 33
above the casing 34 to regulate the supply of air. This slide is mounted in suit-
able guides, and is operated in any suitable way, preferably by means of a
lever 38 mounted centrally in the device and having an out-turned arm 39 at its
end. Connecting the end of the arm 39 and the slide 37, is a link 40. The
lever 38 is pivoted at 41 to the web 42 cast below section 29 of the body, and is
provided at its outer end with a handle 43 by which said lever may be moved
The lever 38 works adjacent to a rack 44, with which a latch 45 may engage
to lock the lever at any desired position. The latch 45 is operated by a handle 46
extending parallel with the handle 43 in the usual way.
The section 29 of the body is formed on its interior with a bearing 47, in which
is mounted a vertical shaft 48. The shaft 48 is splined to a worm-gear 49 so
as to be movable vertically with respect to said worm-gear. The worm-gear 49
is carried in a casing, the upper portion 50 of which is cast integrally with the
section 29 of the body, the lower section 51 of said casing being bolted in place
and carrying an elongated bearing 52 at its lower end for the reception of the
shaft 48. The casing of the worm-gear 49 is formed with a bearing 53 at one
side, in which is mounted a shaft 54 carrying a worm 55 in mesh with the worm-
gear 49. The shaft 54 is operated from the main shaft 9 of the pulverizer, or
from any other moving element of the pulverizer. For the operation of the
shaft 54, the grooved pulleys 56 of different diameters keyed to the shaft 9 are
illustrated, and corresponding grooved pulleys 57 keyed to the shaft 54. A
belt 58 connects said grooved pulleys so as to transmit motion from the shaft 9
to the shaft 54. By changing the said belt on the different pulleys, the speed of
the shaft 54 relatively to that of the shaft 9 will be varied, as will be understood.
Keyed to the shaft 48 within the body of the device and below the neck 30
is a flat circular table 59 preferably having its upper surface suitably roughened.
as by cross-cuts or in any other suitable way. This table fits closely within the in-
terior of the feed chamber formed within the body of the device, and is vertically
movable within said feed chamber for the purpose to be explained. The table 59
is formed at its center with a deflecting cone 60, the purpose of which is to cause
the material to be forced by its weight upon the portions of the table adjacent
to the periphery thereof, instead of allowing the material to accumulate at the
center, as would otherwise be the case. Carried upon this deflecting cone 60
is a shear 61 sustained always in close engagement with the upper surface of
the table, but so mounted as to allow the table to move vertically therewith.
To this end the shear 61 is carried on a bracket 62, illustrated particularly in
Figures 8 and 9. This bracket is formed with two rings 63 and 64, the former
bearing upon the lower portion of the deflecting cone 60, and the latter being
mounted above said cone on the shaft 48, as shown in Figure 6. These rings 63
and 64 are connected together by a rib 65 extending parallel with the exterior
of the deflecting cone 60. Cast integrally with the rings 63 and 64 is a short
arm 66, having cast therewith a vertical arm 67 to which the end of the shear 61
is riveted or otherwise secured. The shear 61 carried by the arm 67 is located
entirely outside of the neck 30, and always projects to the same extent over a
portion of the table 59 to sweep off from said table a quantity of material of a

page_text: constant horizontal width but of a varying vertical thickness, as will be ex-
plained, according to the amount of feed desired.
Keyed to the shaft 48 immediately above the ring 64 is an agitating device 68
comprising a collar having cast radial arms 69 working within the neck 30 and
serving to agitate the material in said neck to prevent the accumulation of
material in the form of aggregates or clots, as may occur, particularly if the
material is in a wet condition.
In order to adjust the table vertically in the feed chamber so as to approach
or recede from the lower end of the neck 30, the shaft 48 is vertically adjusted
by means of the lever 38. For this purpose the said lever is provided with a cast
ring portion 70 surrounding the shaft, as shown. Mounted on the shaft 48 is a
collar 71 carried between fixed collars 72, 72. The collar 71 is provided with
trunnions 73 mounted in slots 74 in the ring 70, whereby by elevating the
handle 43 of the lever 38, the shaft 48 will be moved upwards, causing the
table 59 to approach the lower end of the neck 30. The shear 61, as shown in
dotted lines in Figure 5, is preferably curved, and at its free end works against
a cast rib 75. Leading into the feed chamber preferably adjacent to the shear 61
is a passage 76 through which the arm of the operator may be extended for the
purpose of cleaning out the feed chamber in case it becomes clogged.
The operation of the device is as follows:-Material is supplied to the hop-
per 31 in any suitable way. The pulverizer is started, rotating the shaft 9, from
which motion is communicated to the shaft 54 and to the worm 55, worm-
wheel 49 and shaft 48, rotating the table 59 below the neck 30 and with respect
to the shear 61, which is maintained stationary. The material which descends
through the neck 30 into the feed chamber is agitated by the arms 69, whereby
it is prevented from accumulating in said neck, and falls upon the rotating
table 59. By means of this table the material is carried around thereon until
it meets the shear 61, by which it will be swept off and will fall through the
opening 33 into the casing 34 thence entering the pulverizer through the
entrance opening therein. At the same time air by the operation of the pulver-
izer will be drawn by suction beneath the slide 37, and will pass with the
material through the opening 33 into the pulverizer, as shown by the arrow in
Figure 6. When it is desired to diminish the supply of material fed to the pul-
verizer, the handle 43 will be elevated to the desired extent. This moves the
shaft 48 upwards, carrying the table 59 and the shear 61 with it. The approach
of the table towards the lower end of the neck 30 results in the accumulation
upon the table of a layer of material of diminished thickness, and in consequence
the quantity of material removed from the table 59 by the action of the shear 61
will be relatively decreased. By the operation of the lever 38 to thus diminish
the supply of material, the link 40 will depress the slide 37 to correspondingly
reduce the supply of air, whereby the relative proportions of air and material
entering the pulverizer will remain constant. The fan-blades 19 produce a suc-
tion through the apparatus from the entrance to the discharge end thereof. The
material entering the pulverizing chamber 3 will be pulverized by the paddles 17
therein. As this material is reduced in fineness, it is carried by the air currents
through the opening in the partition or diaphragm 6 and enters the pulverizing
chamber 4. Here, owing to the increased speed of the pulverizing paddles, the
material is further reduced, and thence passes through the opening in the dia-
phragm to the pulverizing chamber 5, where, owing to the increased speed of
the pulverizing paddles therein, it is reduced to its ultimate condition of fineness.
Froin the pulverizing chamber 5, the material is drawn by the air currents
through the opening in the supplemental partition or diaphragm 20, thence
through the opening in the diaphragm 8 into the fan-chamber, from which it is
expelled through the opening 13 into the exit pipe 14. The operation of the
fan will obviously create a partial vacuum in the air-chamber 21, and the proper
additional quantity of air will enter said chamber through the neck 22. This
additional supply of air will be intimately admixed with the mixture of air and

page_text: material passing from the opening in the supplemental diaphragm 20 to the
opening in the diaphragm S, the mixture being completed by the movements of
the fan-blades in the fan-chamber. By making the opening in the diaphragm 8
smaller than the opening in the supplemental diaphragm 20, the material in
passing through the last mentioned opening will strike the diaphragm 8 and a
baffle effect will be thus secured, the mixture being interrupted in its move-
ments and an opportunity being offered for an intimate admixture between it and
the supplemental supply.
Having now particularly described and ascertained the nature of the said
invention, and in what manner the same is to be performed, I declare that what
I claim is:-
1. A pulverizer adapted for the pulverization of material by drawing the
material with a supply of air into contact with a series of rotating pulverizing
arms or blades, the pulverizer being provided with an additional air supply
between the pulverizer and the suction device, so that an increased quantity of
air may be intermixed with the pulverized material before it is forced to the
point of use.
2. A pulverizer comprising a casing formed of concentric sections of a gradu-
ally increasing diameter from the inlet to the discharge ends, a series of pulver-
izing blades or paddles rotating at a high speed in each of said sections, a fan
or other suction device for drawing air through the concentric sections along
with the material in course of pulverization, and an additional air supply opening
located between the largest section and the fan for supplying an added quantity
of air to the pulverized material before it is forced to the point of use.
3. The employment, in a pulverizing device, of an exit pipe of the general
shape described and shown.
4. The employment, in a pulverizer of the type described, of a supplementary
diaphragm or partition in the largest pulverizing chamber forming a separate
air chamber therein, through which an additional supply of air will be allowed
to mix with the pulverized material.
5. A feeding device for a pulverizer, employing a flat, horizontal table, which
is adjustable vertically so as to regulate the supply of material, and a stationary
shear working over the top of the table to scrape off a definite quantity of
material at each rotation of the table.
6. The employment, with a feeding device of the character last defined, of a
series of agitating arms for keeping the material in movement.
7. The general construction and arrangement of a feeding device as described
and shown particularly in Figures 5 to 9.
11
HARRIS & MILLS,
Agents for the Applicant, 23, Southampton Buildings, London.