Apparatus for Cleansing Filtering Media.
Year: 1888

page_text: COMPLETE SPECIFICATION.
Apparatus for Cleansing Filtering Media.
I, HERBERT JOHN ALLISON, of 52 Chancery Lane, London, in the County of
Middlesex, Patent Agent, do hereby declare the nature of this invention (which has
been communicated to me from abroad by The Casamajor Filter Company (Incor-
porated), of 5 Beekman Street, Temple Court, in the City of New York, United States
of America) 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 to the filtering of saccharine or other solutions, or of any
liquids holding solid matters in suspension, by means of sawdust or finely comminuted
woody fibre.
The present invention has particular and special reference to apparatus by means of
which the sawdust or finely divided woody fibre used for filtering is subsequently freed
from the foreign substances and matters which have become attached to or deposited
upon its surface during the operation of filtering or during the time it was allowed to
remain in contact with the solution or solutions to be filtered.
The object of my present invention is, further, to enable such sawdust or like filtering
substance to be cleaned and rendered fit to be used again in filtering. Where large
quantities of solutions are to be filtered, it is very desirable that the same filtering
substance should be capable of serving for as great a quantity of the solution as possible.
By means of my invention the sawdust used in the above mentioned process of filtering
can be washed and cleaned easily and quickly at a slight expense and without much
waste; so that the same sawdust can be used over and over again almost
indefinitely.
In carrying out my invention the sawdust with the substances and foreign matters
abstracted by it from the solutions filtered, is first transferred from the filter to
suitable vessel where it is agitated and stirred with considerable violence in the presence
of water. By this operation the particles of foreign matter are loosened and separated
from the particles of sawdust. The next step is to pass the sawdust through a mechanism
of an apparatus actuated by power, by means of which the sawdust is first strained of
the dirty water and then rinsed with clean water. This operation of straining and
The sawdust
rinsing is repeated as many times as is deemed necessary or desirable.
.:

page_text: is then transferred to another vessel where it is again strained. It is now ready to
be used again for filtering purposes and is found to be as efficient as freshly prepared
sawdust.
Having thus briefly set forth the nature and purposes of my invention I will.now
proceed to describe the same more in detail in connection with the accompanying
drawings forming a part of this specification, in order that its construction, operations
and functions may be more perfectly understood, and to enable persons skilled in the
art to which my invention pertains to practice, apply or work the same.
In the accompanying drawings:
:-
Fig. 1, is a side elevation of the complete apparatus showing the relation of the
various parts to each other.
Fig. 2, is a vertical central section of the agitating vat.
Fig. 3, shows a modification of the same.
Fig. 4, is a side elevation of the rotating sieve broken away in parts to show the
interior construction.
Fig 5, is a vertical cross section of the same.
Fig. 6, shows the vat for drawing off the water from the cleaned sawdust.
The sawdust to be cleaned is transferred to the agitating vat V, V, (Fig's. 2, 3)
preferably by means of a centrifugal pump discharging it with some water through a
pipe as shown at P. The sawdust may also in some cases be conveyed to this vat in a
trough or gutter. The agitating vat V, V, is provided with means for stirring or
agitating the water and sawdust. A simple means of accomplishing this object and
one which I generally employ consists of a vertical shaft S, mounted on bearings E,
above and F, below, and receiving a rotary movement in some convenient manner such
as by means of a bevel gear wheel W, secured to its upper end and engaging with
another gear wheel 2, which receives its motion from a suitable source of power.
The shaft S, carries a spider G, on the radiating arms of which are attached the
vanes H, H, H. These vanes are fastened in a slanting or oblique direction and their
lower ends come close to the bottom of the vat V. The motion is always such that
the lower edge of the vane moves in advance of the upper edge, and therefore the
vanes in rotating produce a disturbance in the water very similar to that produced
by the screw propeller of a steamship. In this manner the sawdust is stirred with and
in the water, and the agitation of the entire mass is effectively accomplished whereby
each particle of sawdust is loosened and separated from the foreign substances adhering
to its surface.
In Fig. 3, I have shown. another device for effecting the agitation of the sawdust
and water. In this case a current of compressed air, or in some cases of steam, is
forced into the mixture of water and sawdust through the pipe Z. which connects at
the bottom of the vat with a ramification of pipes p, p, p², etc., (Fig. 3.) through the
perforations y, y, y, of which the air or steam is allowed to come in contact with the
contents of the vat. The jets of air or steam is issuing from these orifices produce
upward currents in the liquid by which the entire mass is thoroughly agitated. In
practice I make use of both of these forms of agitating devices in one installation, as
will be seen in Fig. 1, where the form just described (Fig. 3,) is shown at X, being
placed so as to receive the sawdust and agitate it again after it has once been strained
or rinsed.
The length of time during which the agitation is continued depends upon the quantity
and the condition of the sawdust to be cleaned and is to be determined by experience
in each case.
After the sawdust has been properly and sufficiently agitated with water, it is found
that the foreign substances are all or nearly all separated from the particles of sawdust
and they are suspended in the water as impurities. The valve Q, Figs. 2 and 3, is
now opened and the impure water with the sawdust floating in it passes out through
a pipe as T, into the rotating sieve.
Figs. 4 and 5, show the construction of this portion of the apparatus.
zontal shaft J, resting in suitable bearings, (not shown in the drawings) is
metal spider L, shown in dotted lines Fig. 4, and in section in Fig. 5.
On a hori
mounted a
Secured to

page_text: this spider by means of screws or bolts is a flat disc D, preferably of polygonal outline
made up of flat pieces of wood joined together.
I find the octagonal form shown in Fig. 4, to be very convenient of construction and
satisfactory in working, although I do not wish to be understood as limiting myself to
this form.
The apparatus could also perform its functions more or less perfectly if made
square pentagonal or hexagonal, or with any number of sides, or with the outline of
a circle.
3
At the corners of the periphery of the disc and projecting laterally from each corner
so as to resemble somewhat the paddles of a steamship side wheel, are wooden
buckets e, e¹, e², e³, e², c³, eº, e², e, covered with sheet iron. The buckets are walled in.
at their overhanging or free ends by a flat polygonal disc D2, built up of wood of the
same outline as D, but having its interior cut out in the form of a circle as shown in
Fig. 5, so as to leave the inside space accessible from this side. In Fig. 4, a portion
of this flat ring is removed so as to expose the ends of the buckets e; e². A small iron
bolt n, passing from one side of the apparatus through the centre of the bucket to the
other side serves to make the structure firm and secure. The buckets are walled in
from the outside by a strip of fine wire cloth k, which extends from the edges of one
disc to those of the other so as to cover the spaces between the buckets. The wire
cloth which I use for this purpose is of sufficiently fine texture to prevent the sawdust
from passing through, but not too fine to prevent the finely divided impurities from
passing through with the water. I find that wire cloth having about fifty or sixty
meshes to the inch is well adapted to this purpose.
At a short distance above the rotary sieve is placed a perforated pipe or sprinkler S,
through the openings in which s, 8, 8, 8, 8, 8, etc., water can be distributed over the
wire cloth of each segment of the apparatus as it revolves past the pipe. The water
which quickly drops down through the interstices in the wire cloth is not allowed to
fall down to the opposite side below but is caught by a trough H, H, made of sheet
metal and ending in a gutter H2, made in one piece with it.
To catch the drip water from the rotating sieve I find it convenient to enclose it in a
sheet metal case such as shown at Y, and provided with an opening y. through which
the water escapes to a drain pipe or suitable receivers. When it is in operation the
rotating sieve is made to turn slowly or at a speed ranging from ten to twenty revolu-
tions per minute.
The mixture of sawdust and impure water when drawn out from the agitating vat
Fig. 2, is emptied into the rotating sieve at its lower part through the pipe T, as shown
in Figs. 4 and 5. The mixture falling on the wire cloth bottom of the cavity is quickly
strained the dirty water passing through the wire cloth and being drained away
through the opening y, in the sheet metal casing Y, surrounding the rotating sieve.
Owing to the rotation of the shaft which takes place in the direction of the arrow,
Fig. 4, it will be readily seen that the buckets lift up the sawdust just as it is being
strained. The buckets as they pass over the trough E, become almost or entirely
inverted in relative position and allow the sawdust to fall into the trough. At the same
time the water falling in jets from the pipe S, serves to wash away the sawdust from
the buckets and, from the inner surface of the wire cloth. This water moreover
mingles in the trough H, with the sawdust and serves to rinse it and at the same time
agitate it and in this way to cleanse it again of such dirt or impurities as still remain
adhering to the particles of sawdust. The mixture of water and sawdust passes out
and runs down the gutter. This gutter may be arranged so as to empty the mixture
into a second rotating sieve similar to that just described and wherein the water will
be again strained off leaving the sawdust to be carried up by the buckets so as to be
again rinsed with clean water. This process may be repeated any desired number of
times. In some cases it will be found that the sawdust is cleaned sufficiently by
passing through two such rotating sieves while in other cases as many as six sieves
may be found necessary.
From the last rotating sieve the sawdust and water is sent into the drying or draining
vat shown in central vertical section in Fig. 6. At a slight distance above the bottom

page_text: of the vat A, A, is a partition or false bottom D, having a very large number of small
perforations f. ff. This partition is covered by one or more layers of felt, burlap or
'similar fabric sufficiently pervious to the water but of close enough texture to prevent
the sawdust from passing through. The water quickly passes through the fabric into
the intermediate space C, C, below the false bottom whence it can be drained by a pipe.
'controlled by a valve.
In some cases to quicken the operation of removing the excess of water, I take
advantage of the pressure which can be produced by the use of steam injectors, steam
syphons, and like devices. I connect this injector or syphon to the drain pipe Q, or
else connect it with a separate pipe opening into the bottom B, of the vat H. In
Fig. 6, 1 have shown at R, the pipe connecting the injector with the drain pipe Q.
The injector or syphon may be of any suitable form and is not shown in the drawing.
Having now described in detail the various devices used in my invention I will now
proceed to show more clearly how these devices are co-ordinated or disposed with
respect to each other in the practical working of my said invention.
In Fig. 1 I have shown my process as applied in a chemical works or in a
in a refinery
when using four rotating sieves a', a², a³, a, arranged in "cascade" or in series.
The sawdust to be cleaned is first placed into the agitating vat V as already explained.
From this vat the sawdust and impure water are emptied through the pipe T, into the
first rotating sieve where it is first drained of the impure water and then rinsed with
clean water in the manner already explained in detail. From the first sieve the sawdust
is emptied by the gutter H2, into a second agitating vat H. This vat is of the kind
shown in Fig. 3, in which agitation is effected by the pressure of compressed air or of
steam which is allowed to escape into the contents of the vat. The water is preferably
kept at a somewhat warm temperature in order to facilitate the cleaning process. From
this vat the sawdust mixed with water is discharged through a pipe I, into the second
sieve a². From the gutter of this sieve the rinsed sawdust is in turn discharged into
the third sieve in a manner clearly shown in the figure. From this sieve it is again
passed into the fourth sieve where it receives the final rinsing and from which it is
conveyed through the gutter K, into the drying vat where it is rid of its superfluous
moisture in the manner already described in detail.
It will be seen by reference to Fig. 1, that the sawdust is raised from one floor to
the next floor above in its passage from one sieve to the next. This feature is a
great advantage particularly where the process in connection with which the sawdust
is used involves steps which are carried out on different floors. It will be apparent
that by increasing the diameter of the rotating sieves or else by increasing the number,
the sawdust can be lifted to a still higher distance.
It will be seen from the foregoing description that my invention can be carried into
effect in various ways and can be modified in details considerably without departing
from its spirit.
My said invention moreover is not applicable only to the cleansing and treatment of
sawdust but of all finely divided filtering substances of a fibrous or cellular nature
such as finely divided wood-shavings, wood pulp, browncoal, etc. 1 do not confine
myself therefore to the exact forms or applications herein before mentioned and set
forth.
Having now particularly described and ascertained the nature of my inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
:--
1. The combination of an agitating vat for agitating a filtering substance in the
presence of water, with a series of straining devices located on different levels and
provided with means for passing the filtering substance upward through the series of
straining devices.
2. The combination of an agitating vat, a series of straining devices located on
different levels, and provided with means for passing the strained material upwards
through the series of straining devices, and sprinkling devices interposed between each
pair. of straining devices.

page_text: 3. The combination with an agitating vat, of a vertically rotating sieve provided
with a circumferential straining network or mesh, elevating buckets, an elevated trough
within said sieve, and sprinkling devices located above said sieve and adapted to wash
the material from said buckets into said troughs.
4. In combination, an agitating vat, a vertically rotating sieve having a circum->
ferential network, a conveying trough between the vat and sieve, elevating buckets
within the sieve and an elevated trough, said buckets serving to convey the material
from the bottom of said sieve to said trough, as described.
5. An organised apparatus for cleansing and straining filtering substances, comprising
an agitating vat having a pipe connecting with a rotary sieve, a vertically rotating
sieve provided with interior circumferential elevators or buckets, a second agitating
vat, provided with a pipe leading to a second sieve, a second rotating sieve provided
with interior elevators, troughs leading from the sieves, and sprinkling devices above
each sieve, all arranged to operate as described.
6. In an apparatus for cleansing filtering substances, an agitating vat, connections
from the same to a rotating sieve provided with means for elevating the strained
material to a higher level within the sieve, and a casing for the drip water disconnected
from the agitating vat.
1000