Improvements in Filter Presses.
Year: 1894

page_text: Date of Application, 10th Jan, 1894
Complete Specification Left, 8th Nov., 1894-Accepted, 22nd Dec., 1894
Improvements in Filter Presses.
We ALBERT LUDWIG GEORG DEHNE of Halle on the Saale in the Empire of
Germany, Manufacturer, and CURT ALFRED HARZER of Billiter Buildings,
Billiter Street, London E.C., Merchant, do hereby declare the nature of this
invention to be as follows:-
This invention consists in providing a cleansing arrangement for filter presses,
for use in the filtration of substances leaving slimy residuums.
In the filtration of those fluids, the portions of which to be separated do not form
cake-like masses in the filter chambers, but merely leave slimy residuums on the
filter cloths, the great disadvantage is, that the cloths, after a very short time,
become completely impermeable, on account of the coating of slime upon them, and
the filtering action therefore ceases. It then becomes necessary to open the filter
press, and either to cleanse the cloths, or to replace them by fresh ones, which of
course occupies considerable time.
By the present invention, the filter press is so arranged that when the coating of
the cloths with slime commences to take place, and the filtration either ceases or
becomes less effective, a cleansing of the cloths, i.e., the removal of the coating of
slime, can take place without opening the filter press.
This object is effected by a special or peculiar arrangement of the filter cloths in
the chambers, by a novel method of and means for conveying the material to be
filtered and of leading away the filtrate, as well as by the conveyance of water to
the chambers for cleansing purposes, which together permit of the continuous
working of the apparatus without a change of filter cloths.
The press is in general of the ordinary kind, consisting of filter plates forming
chambers, and which plates rest on rods or bars connecting the "head" portion of
the apparatus with the screw portion, the plates being pressed against the former
by the action of the screw.
Between each two plates, a filter cloth is strained, which separates each chamber
into two divisions.
From the bottom of each chamber division, branches off a small side channel, all
of which channels terminate in a large duct or channel through which the fluid
matter to be filtered is conveyed into the various chamber divisions by means of
the small channels. Here the fluid material becomes filtered by means of the filter
cloths, leaving behind its slimy portions. In order that, through the incoming
fluid, no air bubbles should be formed on the entry side of the chambers, a small
air channel is formed at the top, from which the air can escape, in the well known
manner, by means of a channel which is provided with a small cock or tap.
From the bottom of every alternate chamber division, branches off also a small
channel; these channels terminate in a large exit channel, which conducts the
filtrate out of the press.
If, now, the process of filtration has so far proceeded, that the filtration has
become markedly defective, or has even completely ceased, through the closing of
the cloths, the cleansing of the cloths will take place without the opening of the
press being rendered necessary, therefore without any changing of the cloths.
For this purpose, the supply of material to the inlet channel will be cut off, and
after the filtrate has been run off, the exit channel will also be closed, & a tap on
the inflow channel will be opened, in order to empty the filled chamber divisions

page_text: by way of the ordinary channels, inlet channel, and tap. In order to quicken this
proceeding, it is advisable to open the air cocks on a channel, and to close the same
after the material has been run off. After the closing of tap before mentioned
two other & separate channels will be opened.
In
The 1st channel is in connection with a supply of water under pressure, which
water now enters the divisions of the filtering chambers, and fills the same.
order, here also, to prevent the formation of air bubbles, the air is allowed to
escape by suitably placed cocks or taps. After the latter have been closed, the
water rushes through the cloths, and out of the filtrate chambers, washing away,
at the same time, the coating of slime, and removes the same from the filter press
by way of the ordinary inlet channels &c.
The process of cleansing the cloths is effected, in this way, with great celerity
and completeness, so that in a short time the supply of water can be stopped, and
the filtering operation can again proceed as before.
It is advantageous to have the supply of water in a warm state. The
cleansing can take place periodically, so that an opening of the press will be
unnecessary.
Dated this 9th day of Junuary 1894
NEWTON & SON,
Agents for the Applicants.
I, ALBERT LUDWIG GEORG DEHNE of Halle on the Saale in the Empire of
Germany, Manufacturer, and CURT ALFRED HARZER of Billiter Buildings,
Billiter Street, London, E.C., Merchant, 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 consists in providing a cleansing arrangement for filter presses,
for use in the filtration of substances leaving slimy residuums.
In the filtration of fluids, the separated portions of which do not form cake-like
masses in the filter chambers, but merely leave slimy residuums on the filter cloths,
the great disadvantage is, that the cloths, after a short time, become completely
impermeable, on account of the coating of slime upon them, and the filtering action
therefore ceases. It then becomes necessary to open the filter press, and either to
cleanse the cloths, or to replace them by fresh ones, which of course occupies
considerable time.
By the present invention, the filter press is so arranged, that when the coating of
the cloths with slime commences to take place, and the filtration either ceases or
becomes less effective, a cleaning of the cloths, i.e., the removal of the coating of
slime, can be effected without the necessity for opening the filter press.
This object is carried out by means of a special or peculiar arrangement of the
filter cloths in the chambers, by a novel method of and means for conveying to the
press the material to be filtered & of leading away the filtrate, as well as by
the conveyance of water to the chambers for cleansing purposes, which together
pernit of the continuous working of the apparatus without a change of filter
cloths.
A filter-press constructed according to this invention is shewn in the accompanying
drawing, in which
Fig. 1 is a side elevation, Fig. 2 a sectional plan on the line A. B, Fig. 1, and
Fig. 3 is a cross section on the line C, D, Fig. 2.
Fig. 4 shews a sectional plan of a slight modification in the arrangement of the
filtering surfaces.

page_text: The press is in general of the ordinary kind, consisting of filter plates forming
chambers, and which plates rest on rods or bars connecting the "head" portion of
the apparatus with the screw portion, the plates being pressed against the former
by the action of the screw.
Between each two plates, a filter cloth t is strained, which divides each chamber
into two compartments.
From the bottom of each alternate compartment, branches off a small side
channel n, all of which channels terminate in a large duct or channel e, through
which the fluid matter to be filtered is conveyed into the various filtering compart-
ments, by means of the small channels n. Here the fluid material becomes filtered
by means of the filter cloths, leaving behind its slimy portions. In order that air
bubbles should not be formed on the entry side of the chambers by the incoming
fluid, a small air escape channel n', Fig. 3, is formed at the top of each chamber,
by which the air can escape to a channel m, which is provided with a small cock
or tap.
From the bottom of every other alternate compartment, a small channel o branches
off, and these channels terminate in a large exit channel h, which conducts the
filtrate out of the press.
If now the process of filtration has so far proceeded that the filtration has become
markedly defective, or has even completely ceased, through the clogging of the
cloths, the cleansing of the cloths can be effected without the opening of the press
being rendered necessary, & therefore without any changing of the cloths, by
means of an inflow of water under pressure.
For this purpose, the supply of unfiltered liquid to the inlet channel e will be cut
off, and after the filtrate has been run off, the exit channel h will also be closed,
and the tap p on the inflow channel e will be opened, in order to empty the filled
compartments by way of the channels n, channel e, & tap p. In order to quicken
this proceeding, it is advisable to open the air cocks on the channel m, which are
closed after the fluid has been run off. After the closing of tap p, two other
channels i & in connection with h and e respectively, will be opened.
The channel is in connection with a supply of water under pressure, which
water now enters the compartments of the filtering chambers by way of the channel h
& the channels o, & fills the same. In order here also to prevent the formation
of air bubbles, the air is allowed to escape by way of the channels o', channel e, &
the cocks or taps adapted thereto. After the latter have been closed, the water
rushes through the cloths, and out of the opposite compartment, washing away the
coating of slime, and carrying it out of the filter press by way of the inlet channels
channel e, and tap or cock g.
The process of cleansing the cloths is effected in this way with great celerity
nd completeness, so that in a short time the supply of water to i can be stopped,
whereupon, after closing 9 and opening e & h, the filtering operation can proceed
as before.
g
In the arrangement shewn, each filter chamber is divided by a cloth stretched
across its centre into two compartments, so that, in the operation of filtering, the
liquid to be filtered enters one compartment, & the filtrate, after being pressed
through the cloth, escapes from the other compartment. When the filter cloths
are being cleansed, the cleansing liquid enters, and passes in the reverse direction.
During both processes of filtration and cleansing, the cloth lies against the ribbed
surface of the chamber opposite the pressure, and is able thus to withstand, during
filtration, the pressure of the liquid to be filtered, & likewise, when being
cleansed, the pressure of the cleansing fluid, thus leaving channels to carry off the
filtrate, etc.
If it is desired to enlarge the filter-surface of a press like the present one (which
enlarged surface may also be cleansed without necessitating the opening of the
press), so that each filter chamber shall contain two cloths, which press against
opposite ribbed faces of the chambers & receive the slimy deposit during filtra-
tion, it is advantageous to place in each filter chamber, that is to say, between two

page_text: filter plates, a grate or grid s, or, it may be, a plate furnished on both sides with
perpendicular ribs (see Fig. 4), so that when filtration is wholly or partially stopped
by the clogging of both cloths with slime, and it is desired to cleanse the cloths
without opening the press, the cloths find a resistance against the pressure of the
cleansing fluid in the plate or grid s, so that the two slimy faces of the filter cloths
do not touch. On the contrary, each filter cloth is pressed with its slimy surface
against the ribbed plate or grid s, by means of the cleaning water which penetrates
the cloth from the opposite side, and in this way the rinsing of the cloths is easily
effected.
When this arrangement of two cloths in each chamber is employed for the object
indicated, it becomes necessary, for the purpose of cleansing the cloths without
opening the press, to alter the position of the passages leading to & from the filter
chambers, in such a manner that, as will be seen in Fig. 4, the passagen for the
liquid to be filtered, is formed in the thickness of the grid or plates, and leads into
each chamber between the two cloths from the common inlet passage e, while from
each compartment behind each cloth, a passage o for the escaping filtrate will lead
to the common outlet passage h, so that, when cleansing out the apparatus, the
passage h, with the two passages o behind the cloths, will serve as the inlet for the
rinsing water, & passage n between the cloths, with the common passage e, will
serve for the escape of the cleaning water & the slime deposit.
It is advantageous to use the supply of cleansing water at i in a warm state.
The cleansing can take place periodically, so that an opening of the press will be
unnecessary.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
1. A filter press in which the filtration of liquids with slimy residuums is effected
in filtering chambers each divided into two compartments by means of a distended
filter cloth, which cloth finds resistance on one side of the chamber during filtration,
and on the other side of the chamber during the cleansing operation, and in which
each chamber has a liquid inlet (n) and a liquid exit (o) at bottom, and an air
outlet n' and o' at top, on either side, in which apparatus, for the purpose of driving
off the slime collected on the cloths (after closing the entry & exit valves of the
filter press, as well as emptying the filled compartments), water under pressure
may be introduced in the reverse direction, thereby allowing of a periodical
cleansing of the cloths without opening the press, as herein shewn and
described.
2. In a filter press adapted for washing away the slime accumulated on the filter
cloths without opening the press, the combination of two filter cloths in each
chamber & a grid or grating s, or a plate ribbed on both sides, to provide a
resistance for the slimy sides of both filter cloths, against the pressure of the
cleansing water, and the said grid or plate being provided with a passage n leading
from between each two cloths to a common passage e, & behind each cloth in
each filter plate a passage o leading into the common escape passage h, all as
herein shewn and described.
Dated this 7th day of November 1801