Improvements in Separating Grain and Dust or Stive from Air laden therewith.
Year: 1891

page_text: Date of Application, 17th Apr., 1891
Complete Specification Left, 18th Jan., 1892-Accepted, 20th Feb., 1892
PROVISIONAL SPECIFICATION.
Improvements in Separating Grain and Dust or Stive from Air
laden therewith.
I, FREDERIC ELIOT DUCKHAM of Millwall Docks, London, Engineer, do
hereby declare the nature of this invention to be as follows:-
-
My invention relates principally to the separation of grain and dust from the
current of air by which it is conveyed in the pneumatic system of unloading grain
cargoes or transferring grain in warehouses and other places; and it has for its
object to enable the grain to be deposited and the conveying current of air to
disengage itself therefrom without carrying off along with it any of the dust
which may be mingled with the grain and which it is not desirable to separate
therefrom.
The invention is also applicable for dust-catching-i.e. separating the stive or
dust from the air coming from grain-milling machinery.
The invention is based on the difference of inertia of the solid and gaseous
particles, and consists in projecting the current of air laden with grain and dust or
with stive, as the case may be, into a closed receiver in such manner that, whilst
the solid particles will, by virtue of their acquired momentum, continue to move in
the direction in which they are projected and be caused to penetrate the
atmosphere of said receiver and become deposited therein, the gaseous particles
will be arrested and conducted away in another direction without carrying off any
of the dust.
For this purpose, the grain and dust or stive laden current of air is projected
downwards in the form of a jet from a nozzle, through a receiving cone into the
closed receiver with which it is connected. The smaller end of the receiving cone
is presented towards the jet nozzle and a short space intervenes between the nozzle
and cone across which the jet is projected, the velocity of the jet, the form and
proportions of the cone, and the length of the intervening space, being suitably
proportioned to each other.
The nozzle and cone are enclosed in a casing or chamber connected with the
exhauster by a pipe leading out of it from the end at which, and in the direction
opposite to that in which, the jet nozzle enters, baffles being provided within the
chamber to cause any stray particles which might perchance be carried off with the
air to be thrown down within the casing.
The momentum of the grain and particles of dust carries them across the
interval between the nozzle and cone and causes them to be deposited in the closed
receiver, while the air escaping laterally becomes disentangled from the stream of
solid particles and is then carried off in the direction of the exhauster. The
condition of the atmosphere within the receiver tends to prevent injury to the grain
by a too sudden arrest of its motion.
In applying this invention to the pneumatic system of grain discharging or
conveying described in the Specification of a previous application for Letters
Patent dated the 21st day of November 1890, No. 18,884, the closed receiver
hereinbefore referred to would be the reservoir feeding the oscillating two-chamber
receiver or other device therein described for allowing the grain to be discharged
without destroying the partial vaouum in the closed receiver.
Doted this 17th day of Anil 1801

page_text: Improvements in Separating Grain and Dust or Stive from Air
laden therewith.
I, FREDERIC ELIOT DUCKHAM of Millwall Docks, London, England, Engineer,
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 :-
My invention relates essentially to the separation of dust or stive from air laden
therewith.
The invention is applicable in flour mills for separating the dust or stive from
the air coming from grain-milling machinery. It is also applicable to the air
current used in the pneumatic system of transferring grain (from ships or in ware-
houses and other places hereafter referred to) either with the object of enabling
the grain and the dust mingled therewith to be deposited together, or with the
object of separating the dust (and any grain that may be carried off along with it)
from the air current which has been used for the pneumatic conveyance of the grain,
the purpose in either case being to enable the current of air to disengage itself
without carrying off any of the dust.
The invention is based on the difference of inertia of the solid and gaseous
particles, and consists essentially in causing the current of air laden with dust or
"stive," or with grain and dust, as the case may be, to be projected into a closed
receiver in such manner that whilst the solid particles will, by virtue of their
acquired momentum, continue to move in the direction in which they are projected
and be caused to penetrate the somewhat denser atmosphere of said receiver and
become deposited therein, the gaseous particles will be cushioned or arrested and
conducted away in another direction without carrying off the dust.
In order that the action of gravity may assist the momentum of the solid particles
in effecting their separation from the air, it is preferable, but not indispensable, that
the current should be projected in a downward direction.
The invention will be described with reference to the accompanying drawing
which illustrates in Figure 1 a central, vertical, sectional elevation of the preferred
form of the apparatus. Figure 2 is a similar section of the apparatus arranged
horizontally and applied to the pneumatic system of conveying grain.
In carrying the invention into effect, the stive-laden, or grain and dust Inden,
current of air is introduced through a pipe and projected downwards in the form of
a continuous jet from a nozzle A into a receiving cone B leading into a chamber
or receiver C which is closed, or which leads only into another closed receiver.
The smaller end of the receiving cone is presented towards the jet nozzle and n
short space intervenes between the nozzle and cone, across which the jet is
projected, the velocity of the jet, the form and proportions of the cone, and the
length of the intervening space being suitably proportioned to each other.
It may be mentioned that in separating the dust from the air which has been
used for the pneumatic transmission of grain, the nozzle velocity of the air jet, in
an apparatus proportioned as shown in the drawing, has been from 20 to 30 feet per
second, and this has given good results. As, however, this velocity resulted from
the conditions under which the air had been used for the pneumatic conveyance of
grain, that is to say, as this velocity was not intentionally adopted for the purpose
of separating the dust, it is probable that when this method is applied for
separating stive from air coming from flour mills, a considerably lower velocity
will suffice.
It is important that the area of the smaller end of the receiving cone 13 hould
only exceed that of the jet so far as may be necessary to ensure the whole of the
stream of solid particles being received in the cone B, and that in proportion as
the area of the cone is increased will be the penetration of the air jet into the cone

page_text: and the liability of eddies being formed therein and the carrying away with the
air of some of the dust.
The nozzle A and cone B are contained in a casing D enclosing an annular
space around the jet nozzle and connected by a pipe E with the exhauster if one
be used.
The momentum imparted by the air to the solid particles carries them across the
interval between the jet nozzle and cone and causes them to pass on through the
cone B, as indicated by the dotted arrows, and be deposited in the closed receiver C,
while the air escaping laterally becomes disentangled from the stream of solid
particles, and is then carried off to the exhauster.
This separation of the solid and gaseous particles is probably due to their
difference of inertia and to the slight plemm or dense atmosphere produced within
the closed receiver (by the injected current of air which is sufficient to resist the
momentum of the gaseous particles, but is penetrable by the solid particles of matter
contained in the jet.
It will be understood that the exhauster is used to impart the desired pressure
and velocity to the air current, and that the invention is equally applicable if the
air pressure to produce the jet be obtained by air compressing apparatus, in which
case no exhauster need be used, the casing D discharging into the air, or it might
be omitted entirely.
In applying this invention to the pneumatic system of grain conveying and
discharging described in the Specification of a previous application for Letters
Patent dated the 29th day of July 1890, No. 11,884, the closed receiver C shewn
in Figure 1, might be the hopper which feeds the oscillating two-chamber receiver
whereby the grain is discharged from time to time without destroying the partial
vacuum in the closed receiver C, or the nozzle and receiving cone would be inserted
in the pipe leading to the exhauster as shewn in Figure 2. The dust collected in
chamber C may be withdrawn from time to time without interfering with the stive
separating action, by means of an oscillating receiver such as described in my other
Patent above referred to.
The jet nozzle and receiving cone might however, be placed horizontally, as shown
in Figure 2, the cone being connected to a downwardly curved pipe leading into the
top of the receiver.
Having now particularly described and ascertained the nature of the said inven-
tion and in what mauner the same is to be performed, I declare that what I
claim is
The herein described method or process of separating dust or stive, or grain and
dust, from air by the difference of inertia of the solid and gaseous particles, which
method or process consists in causing the laden current of air to be projected in
the form of a jet across a short laterally open space or interval into or towards
the inlet mouth of a closed receiver, in the manner and by means of apparatus,
substantially such as herein specified.
F. E. DUCKHAM,
By A. M. & Wm. Clark,
53, Chancery Lane, London, Chartered Patent Agents.