Improved Filtering Process and Apparatus.
Year: 1895

page_text: PROVISIONAL SPECIFICATION.
Improved Filtering Process and Apparatus.
I, FRANCISCUS HENDRICUS EYDMAN of 161 Rotterdamsche Weg, Delft,
Holland, Chemical Engineer do hereby declare the nature of this invention to be
as follows:-
The object of my invention is to improve the ordinary method of filtration.
For this purpose I pass the liquid to be filtered at a comparatively high speed
through a filtering tube or tubes or passages the active inner cross sectional area
of which is made to diminish gradually, or stepwise in the same ratio or nearly so
that the volume of the liquid is diminished by the abstraction of the thin fluid
portion of same which is being forced out through the walls of the filtering
passages or tubes. The filtering material, the form of the filtering surfaces and
the arrangement and combination of the same and of the parts belonging thereto
may be greatly varied, all according to circumstances purposes and requirements.
The effect of the high speed and the decreasing area of the passages is to
prevent clogging of the pores of the filtering surfaces, to secure constancy in the
efficiency of the surfaces, and to obviate the necessity for frequent washing or
cleaning of the surfaces as compared with apparatus as ordinarily constructed
where the efficiency is constantly decreasing till at last a thorough cleaning
becomes necessary.
The filtering surface may itself be variously formed and constructed. It may
consist of cloth, paper, asbestos cloth, asbestos board, infusorial earth, plastic
carbon, felt, and other suitable porous materials in some cases the porous material
may in itself form the filtering tube, when the latter is for instance made of porous
earthenware and the like.
For many purposes I use iron tubes formed or provided with shallow inner
ridges, ribs or other projections arranged helically or otherwise. I line the tube
with wire cloth or other suitable open worked or perforated material and this
again I line with the filtering material. The tube is provided with perforations
at suitable distances or intervals for the escape of the filtered liquid. The size
of the tubes or passages is by preference kept the same throughout an apparatus,
thus also maintaining the same area of filtering surface per unit of length, but I
diminish the cross area for the liquid to flow through it gradually or stepwise in
some cases by providing in the interior of the tube a body the size of which latter
is gradually or stepwise increased, and that in or about the ratio of the
diminishing volume of the liquid passing through it. This inner body may be a
solid or hollow cylinder and provided with outer helical or other web or webs or
projections for maintaining its central position and in some cases aiding the
turning over of the liquid. The wire netting and filtering cloth are fixed at each
end of a filtering tube.
In one form I combine a number of filtering tubes in tiers or rows, each row
consisting of several tubes which by elbow pipes are connected at the ends, the
several rows being similarly connected and all being held in a frame at each end.
In another form I construct a filter frame by uniting two end boxes of the
frame, which boxes are divided in channels, by means of partitions cast in the end

page_text: boxes. The two open sides of the frame are covered by plates or covers provided
with filtering medium on both sides and forming joints with the edges of the
partitions. Inlet and outlet openings are provided in the end boxes, and the
liquid flows backwards and forwards between the partitions, which are arranged
so as to present decreasing cross areas for the liquid; and that either by decreasing
the horizoutal or the vertical width of the channels. These frames are combined to
form a filter press, having through holes for connecting the channels in two
adjoining frames. The division plates have passages in the interior for taking off
the filtered liquid, and collecting passages or cocks for the outlet of the filtered
liquid.
In another form I arrange the passages in the frame in a spiral; the two end
frames may be formed with one such, and the intermediate frames with one such
or with two side by side in which latter case the two passages are or may be
separated by a diaphragm wall with inlet and outlet, one at the middle, and the
other near the circumference. The width of these passages should be decreasing
in or about the same degree as the filtering fluid is diminished in volume. The
same arrangement of diaphragm wall with passages on each side may be used with
rectangular filter press frames.
Upon the felt or other filtering medium I may in some cases place thin wire
cloth in the meshes of which a certain amount of the filtrate formed in the
beginning of the process is beneficially retained, the wire preventing its being
washed off by the rapid flow of the liquid over it.
The thickness of the wire of the wire cloth should be determined by the nature
and thickness of the deposit which is to be formed in the meshes.
Dated this 7th day of February 1895
JENSEN & SON,
77 Chancery Lane, London, W.C., Patent Agents.
TT
I, FRANCISCUS HENDRICUS EYDMAN of 161 Rotterdamsche Weg, Delft,
d, Chemical 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:-
The object of my invention is to improve the ordinary method of filtration.
For this purpose I pass the liquid to be filtered at a comparatively high speed
through a filtering tube or tubes or,passages the active inner sectional area of which
is made to diminish stepwise or gradually in the same ratio or nearly so that
the volume of the liquid is diminished by the abstraction of the thin fluid portion
of same which is being forced out through the walls of the filtering passages
or tubes, while the speed of the liquid is maintained about constant. It thus
constitutes filtration during motion.
The effect of the high speed and the decreasing area of the passages is to prevent
clogging of the pores of the filtering surfaces, to secure constancy in the efficiency
of the surfaces, and to obviate the necessity for frequent washing or cleaning of the
surfaces as compared with apparatus as ordinarily constructed where the efficiency
is constantly decreasing till at last a thorough cleaning becomes necessary.
The filtering material, the form of the filtering surfaces, and the arrangement
and combination of the same and of the parts belonging thereto may be greatly
varied according to circumstances purposes and requirements.
The filtering surface itself may be variously formed and constructed. It may

page_text: consist of cloth, paper, asbestos cloth, asbestos board, infusorial earth, plastic
carbon, felt and other suitable porous materials; in some cases the porous material
may in itself form the filtering tube when the latter is for instance made of porous
earthenware or the like.
Fig. 1 of the accompanying drawings is a part sectional elevation and Fig. 2 a
side view of a filter constructed according to my invention.
In this form I use tubes or elements I to X or any other required number formed
or provided with shallow inner ridges ribs or other projections T arranged helically
or otherwise. I line the tube with wire cloth B or other suitable openworked or
perforated material which rests on the ribs T and this material again I line with
the filtering material C. The tube is provided with perforations U at suitable
distances or intervals for the escape of the filtered liquid. The size of the tubes or
passages is kept the same throughout an apparatus, thus also maintaining the same
area of filtering surface per unit of length, but I diminish the cross area, for the
liquid to flow through it, gradually or stepwise, by providing in the interior of the
tube a body the size of which latter is gradually or stepwise increased and that in
or about the ratio of the diminishing volume of the liquid passing through it.
This inner body V may be solid or hollow and may be provided with outer helical
or other web or webs or projections (not shown) for maintaining its central position
and in some cases aiding the turning over of the liquid. The wire netting B and
filtering cloth C are fixed at each end W of a filtering tube. In the form shown
I combine a number of filtering tubes in tiers or rows, each row consisting of
several tubes which by elbow pipes X are connected at the ends; the several rows
being similarly connected and all being held in a frame Y at each end.
Fig. 3 is a sectional plan of a filter constructed and working according to my
invention and
Fig. 4 a vertical section through one of the boxes or frames of the filter.
The end covers or boxes H and H' and the intermediate boxes 1 to 8 are
divided into channels by the ribs or partitions H*. The frames or elements I to IX
have similar partitions L and the two open sides of each are covered by plates or
covers provided with filtering medium on both sides and forming joint with the
edges of the partitions L in the example shown. B is a layer of strong metallic
cloth upon which is spread the filtering medium C, for instance, of cloth, paper,
wool or asbestos; D is a sheet of metallic cloth, of variable thickness as required,
in cases where it is necessary to retain on the felt or other filtering medium
a certain amount of the filtrate deposited in the beginning of the process, or
of matter purposely admixed with the liquid to be filtered before the beginning of
the process. E is a thin wire cloth which is placed upon the thicker wire cloth D
to prevent the washing off of the said filtrate deposit or of the aforesaid deposited
matter. The cloth D may be provided or not, according to the work required.
A is the inlet and F the outlet opening provided in the end boxes H and H'.
The liquid flows backwards and forwards between the partitions L through the
openings L. The sectional area for the flow of the liquid is most conveniently
reduced by gradually reducing the horizontal width of the channels or passages I to
IX as shown in Fig. 3.
The frames are as shewn combined to form a filter having through holes at M
and M for connecting the channels in two adjoining frames. The division plates
or boxes 1 to 8 between the filtering frames I to IX have passages in the interior
corresponding to those in the interior of the frames for taking off the filtered liquid
and collecting passages or cocks for the outlet of the filtered liquid.
The diminution of sectional area goes on in the frames I to VIII by diminishing
the width, but in frame IX this is no longer possible because the thickness of its
walls cannot be made less; therefore here I begin to diminish the area by a gradual
reduction of the height of the passages. As frame VIII has only nine divisions L
while frame IX has fourteen divisions, it would not be convenient to make a box
corresponding on one side with nine and on the other with fourteen divisions.
I therefore fill the box 8 with network of wire strong enough to provide for

page_text: tightness of the partitions. Such network may als if desired be used in the
boxes 1 to 7 and in the heads H and H' instead of the partitions H*.
As an extension or completion of the aforesaid filtration during motion or as an
alternative of a further filtration I employ the same principle of motion to the
subsequent washing out of the matters Hoating in the liquid to be filtered.
In Fig. 5 is shown a horizontal diagrammatical section of a filter of the same
construction as in Figs. 1 and 2 with the addition of means for washing out and
recovering any juice or other valuable liquid that may yet remain in the residual
filtrate and so complete the work of the filter. The application of such an addition
will depend upon the commercial question as to whether the amount of such
recoverable liquid is commensurate with the cost of the appliance and the cost of
working it. In some cases it may also be a question of washing the precipitate, for
instance in the manufacture of colour and other chemical industries; where it is
required not only to separate the liquid from the matters floating therein but to
recover the latter in as pure a condition as possible, and the liquid in as undiluted
form as possible. I provide a series of frames O having the filtering surfaces like
those of 1 to IX and provided with passages of the same sectional area as the last
assage in the last frame which in this case is IX, but the number of the frames may
of course vary according to requirements. Between the frames O there are boxes Q
with corresponding passages. The water or other rinsing liquid enters at N and
penetrates horizontally in the direction of the arrow R through the frames and
boxes Q. The speed of flow of the muddy liquid to be washed out is the same in the
passages of the frames O, as through the frames I to IX because the cross area
of the passages in the frames O are the same as the last passage in the frame IX
so that clogging of the filtering surfaces is rendered impossible. The passages of
the frames being but very small it becomes possible to provide a relatively
long course for the muddy liqu'd and hence an efficient washing out within a few
frames. The only way out for the product of this washing out process is on the
inside of the box 9. The frames P have no filtering surfaces. The arrow S
indicates the direction of the flow of the residuum. In some cases the boxes Q may
he omitted. The washing water only goes as far as the frames O because neither
the latter nor the boxes Q have an outlet for the filtrate. The only outlet is the
inside of the box 9: the latter may therefore have a cock but this is practically
needless, because there is a way out for the washing out product, viz. by mixing
itself with the filtrate. Fig. 6 shews a separate washing out apparatus which can
be connected to the outflow opening F Fig. 3.
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 filtering process consisting in passing the liquid to be filtered through a
tube or tubes of a sectional active area which gradually or stepwise decreases, in
or about the ratio of the decrease of volume of the liquid owing to abstraction of
the thin fluid portion which is forced out through the walls of the filtering tube
or tubes, and at a speed at least so high as to prevent clogging of the pores in the
filtering surface and to produce high and continuous filtering efficiency.
2. As an alternative of a further or final filtration or as an addition to the
filtering process firstly claimed a process consisting in washing out any valuable
liquid or any valuable solids yet remaining in the filtrate by causing a rinsing liquid
to be directed across the path of the filtrate whereby the solids are washed out and
recovered.
3. Filtering apparatus consisting of one or more tube elements with interior body
which increases in size at or about such a rate as to reduce the sectional area for
the liquid to flow through in the ratio of the decrease in bulk of the liquid.
4. Filtering apparatus consisting of one or more tube elements which decrease in
width at such a rate as to reduce the sectional area for the liquid to flow through
in or about the ratio of the decrease in bulk of the liquid.

page_text: 5. Filtering apparatus as described with reference to Figs. 1 and 2.
6. Filtering apparatus as described with reference to Figs. 3 and 4.
7. Combined filtering and washing out apparatus described with reference to
Fig. 5.
8. Washing out annaratus described with reference to Fig. 6.
Dated this 7th day of
1895.
JENSEN & SON,
77 Chancery Lane, London, W.C., Patent Agents.