AN IMPROVED FILTERING-APPARATUS
Year: 1879

page_text: LETTERS PATENT to Johann Kroog, of Halle-on-the-Saale, in Prussia, for the
Invention of "AN IMPROVED FILTERING-APPARATUS."
Sealed the 30th January 1880, and dated the 5th December 1879.
COMPLETE SPECIFICATION filed by the said Johann Kroog at the Office of
the Commissioners of Patents on the 5th December 1879.
JOHANN KROOG, of Halle-on-the-Saale, in Prussia.
APPARATUS."
"AN IMPROVED FILTERING-
This Invention relates to improvements in filtering-apparatus or filter-presses,
by means of which the cakes formed in the filtering-apparatus during the process
of filtration are freed from the fluid remaining in the pores or porous parts of the
same. These cakes always contain a more or less considerable quantity of the
filtered fluid.
The object of this Invention is to provide means for removing or abstracting this
fluid and for obtaining very dry cakes by compressing them within the filtering-
apparatus itself.
In the accompanying Drawing,-
Figure 1 is a horizontal section on the line A, B, Figure 2 shewing a filter-press
provided with my new contrivance for compressing.
Figure 2 is an elevation, partly in section, of the said filtering-press.
Figure 3 is a vertical section on the line C, D, Figure 1.
Figure 4 shows a pressing-plate d³ and its connections with a pressuro-pipe t.
Figure 5 shews a frame and its connections with an inlet-or feeding-pipe v.
Figure 6 illustrates in vertical section two cakes not yet compressed, with a
pressing-plated between them, and
Figure 7 illustrates also in vertical section the same cakes in their compressed
state.
The filtering-press or apparatus of six chambers, as illustrated in the accompanying
Drawing, and provided with my said new contrivance for compressing, contains, in
addition to the plates p, p, p, and 2%, to be used for the purpose of filtration,
other plates or apparatus d³, d, and d³, which are entirely novel and serve for the
purpose of compressing.

page_text: The urst-named plates I shall herein term nitering-plates and the last-mentioned
plates pressing-plates.
I form each of the said pressing-plates d¹, d, and d³, by providing both sides of
a filtering-plate, constructed as described in the Specification of former Letters
Patent granted to me the First day of October, A.D. 1879, No. 3948, a perfectly
impervious and elastic membrane or covering m. Depending on the character of
the fluid to be filtered, this covering is made either of undulating or corrugated
sheet-metal, or of india-rubber, skins, or some impervious texture, or vegetable, or
animal origin.
The filtering-plates pº, p¹, p², and p³, are provided with discharge-cocks nº, n¹, n²,
and n³.
The pressing-plates have no cocks. They are connected with the pressure-pipe t
by means of the small pipes q', q, and q³, and the elbows &¹, s³ and s³, the pressure-
pipe t being provided at one of its ends with the pressure-discharge-cock z, while
its other end terminates in a stuffing-box, the latter being provided with the
pressure inlet-cock o.
This pressure-cock o establishes the connection with a
pressure-reservoir, which may be filled either with compressed gases or with fluids
kept under pressure, or the pressure may be obtained by means of a pump.
The frames 7, 7, 73, 74, 75, and 70, serving for the reception and formation of the
cakes, can be shut off from the inlet-pipe v for the mass to be filtered by means of
the cocks h¹, h³, h³, h', h³, and hº. The connection of these cocks with the inlet-
pipe is formed in the same manner as is the connection with the pressure-pipo t,
that is to say, by means of the elbows y¹, y², y³, y', y³, and y6.
According to my present Invention, each frame intended for receiving a cake is
arranged between a filtering-plate and a pressing-plate, that is to say, in such a
manner that each frame with an odd number has a filtering-plate on its left hand
and a membrane or covering on its right hand, whilst each frame with an even
number has a filtering-plate on its right and a membrane or covering on its left
hand side.
The interior corners of the frames are rounded off at that side which is turned
towards the membranes or coverings.
The filtering-press provided with my said compressing-contrivance, as above
described, is used as follows, that is to say,-
--
After the filtering-plates, the frames, and the pressing-plates have been inserted
in accurate succession and have been screwed tightly together, the substance to be
filtered enters the frames 71, 72, 73, 70, 78, and 7, from the pipe v through the opened
cocks h¹, h2, h3, h4, h and hº. The fluid parts of the substance flow from here
through the filtering-plates and through the cocks into the trough below, while the
solid parts remaining behind will form the cakes. When the latter are ready the
cocks h, h2, h3, h³, h³ and h", are closed, thereupon the cock o of the pressure-pipe t
is opened, and the pressure from the pressure-reservoir at once enters the pressing-
plates d', d, and d³, and presses the membranes or coverings m tightly against the
adjoining cakes, whereby the latter are compressed, and the fluid which remained
in the pores of the same during the process of filtration is compelled to leave the
pores and to pass out through the filtering-plates. The degree to which tho
compression may be exerted is dependent on the pressure applied.
Figure 6 shews the position of the membranes or coverings m before the com-
pression, whilst Figure 7 shews the same after compression has taken place. As
the cakes, indicated in Figure 7 by cross-lines, occupy only about half the original
space, it is obvious that the cake contained about 50 per cent. of moisture before
the compression.
After the compression is finished to the desired extent the cock o is closed and
the pressure contained in the plates is allowed to escape through the cock 2, the
apparatus is then emptied in the usual manner.
Having thus fully described my said Invention, and the manner of performing
the same, I wish it understood that I claim,―
First. In a filtering-apparatus, the combination of filtering-plates and pressing

page_text: plates in such a manner that each space serving for the reception of a cake formed
by filtration in enclosed on one side by a permeable or pervious surface for the
purpose of filtration and on the other side by an impervious elastic membrane or
covering for the purpose of compressing the cake within the filtering-press,
substantially as herein set forth.
Second. The formation of pressing-plates or apparatus by providing filtering-
plates with impervious but elastic membranes or coverings of undulated or corru-
gated sheet-metal, india-rubber, skins, or some impervious texture of vegetable or
animal origin.
In witness whereof, I, the said Johann Kroog, have hereunto set my hand
and seal, this Twenty-fourth day of November, in the year of our Lord
One thousand eight hundred and seventy-nine.
JOHANN KROOG. (L.S.)