The invention relates to an apparatus for filtering fluids comprising
a magazine chamber from which the cloth is transported continuously
or intermittently over a supporting sieve to a receiving chamber.
As the cloth passes through the filtered product with the result
that the dimensional changes in the filter cloth due to temperature
differences do not come into effect in the filtration section proper.
What we claim is:
1. Apparatus for filtering fluids with a filter cloth wherein the
filter cloth is subjected to transport continuously or intermittently
over a supporting sieve plate, which comprises:
a. a housing, means mounted in the housing providing therein a
pressure chamber for receiving the unfiltered fluid and a filtrate
chamber for the filtered fluid, said means comprising said supporting
sieve plate for passage therethrough of fluid from the pressure
chamber to the filtrate chamber,
b. means within the housing defining a magazine chamber for holding
and supplying the filter cloth for said transport over the supporting
c. means for taking up the filter cloth after the transport thereof
over the supporting sieve,
d. filtering means communicating the pressure chamber and the magazine
chamber for introduction of filtrate into the magazine chamber for
immersion of the filter cloth in the magazine chamber in filtrate
before transport of the filter cloth over the supporting sieve,
e. means defining a slot between the magazine chamber and the pressure
chamber for passage of the filter cloth from the magazine chamber
to the pressure chamber, and means for sealing the slot for preventing
passage of unfiltered fluid into the magazine chamber.
2. Apparatus according to claim 1, said filtering means of the
magazine chamber comprising a second filter cloth, the second filter
cloth extending over the slot and onto said sieve plate and said
sealing means pressing said extension of the second filter cloth
against the sieve plate providing said seal between the pressure
chamber and the magazine chamber.
3. Apparatus according to claim 2, wherein the take up means is
disposed within the housing.
4. Apparatus according to claim 1, wherein the take up means is
disposed within the housing.
The invention relates to an apparatus for pressure filtering fluids
(liquids or gases) through a continuously or intermittently movable
Band filters are known in which the filter cloth is kept in continuous
motion, generally in the form of an endless band. When band filters
of this kind are used, the filter cake is usually the required product.
In cases where the purified filtrate is required as end product,
these known band filters cannot be used because the unfiltered product
is not sufficiently firmly sealed off against the filtrate and because
the filter cloth undergoes dimensional changes when impregnated
with the liquid which is to be filtered. In addition, the filter
cloth generally carries air into the filtration chamber where it
may have undesirable effects, especially in the case of sensitive
It is an object of this invention to develop a pressure filter
which is so designed that long contact times can be achieved but
no particles of gas will be carried into the filtration chamber
and the product which is to be filtered is firmly separated from
the filtrate by the filter cloth.
According to the invention, there is provided an apparatus for
filtering fluids comprising a magazine chamber from which the filter
cloth is transported continuously or intermittently over a supporting
sieve to a receiving chamber.
The main advantages achieved with this apparatus according to the
invention lie in the fact that as the cloth passes through the filtered
product it takes on the temperature of the product, which is advantageously
the same as the temperature of the product which is to be filtered,
with the result that the dimensional changes in the filter cloth
due to temperature differences do not come into effect in the filtration
section proper. As the filter cloth becomes soaked with filtered
product, the particles of gas caught in the filter cloth are expelled.
According to a particularly advantageous embodiment of the apparatus
of the invention, a magazine chamber which is separated from the
unfiltered product by a magazine filter cloth contains a rotatably
mounted magazine roll from which the filter cloth is unwound and
passed through a slot which is sealed off by the magazine cloth
and over a curved supporting sieve which forms the covering to a
filter chamber and on to a rotatably mounted winding roll in the
The particular advantages achieved by this arrangement is that
the filter cloth on the magazine roll is immersed in the filtered
product which is constantly replaced by fresh filtered product automatically
flowing into the magazine chamber as it is used up. Since the filtered
product in the magazine chamber is very close to the still unfiltered
product, the filtered and unfiltered product are both at the same
temperature so that in the filtration zone proper of the filter
chamber there are no disadvantageous dimensional changes in the
It is advantageous, particularly in the case of filtering volatile
liquids, if the magazine chamber and winding chamber are both arranged
inside a housing.
According to another feature of the apparatus according to the
invention, the magazine cloth overlaps the slot and is firmly pressed
into position by a spring mounted sealing lip in order to ensure
that no unfiltered product can enter the magazine chamber.
The supporting sieve can withstand high static loads if it is in
the form of a perforated metal sheet with the edges free from perforations.
In this case, a very efficient seal may be obtained by providing
sealing profils on the unperforated edges.
In the case of delicate filter cloths which cannot withstand friction
over the belt sections, the profils are arranged to be displaceable
according to another feature of the invention, for example they
may be in the form of endless belts.
In another advantageous embodiment of the apparatus according to
the invention, the magazine roll and winding roll are equipped with
brakes and locks in order to ensure that the filter cloth will fit
snugly over the supporting sieve and thus provide an effective seal.
An embodiment of the apparatus according to the invention is represented
in the drawing by way of example as described below. In the drawing,
FIG. 1 is a cross-section through an embodiment of an apparatus
according to the invention.
The filter consists of a cylindrical housing 1 having a fixed base
and pipe connection 2 for filling the filter. Inserted in the housing
is a filter insert which consists of a cylindrical metal jacket
in two parts 3, 4 which is partly perforated except for the marginal
zones and also has a fixed base. When the filter is put into operation,
the product which is to be filtered is in front of the filter insert.
The interior of the filter insert is subdivided into four chambers
9, 12, 13 and 14 by partitions 5, 6, 7 and 8. The first chamber
or magazine chamber 9 formed by the partitions 5 and 6 and metal
jacket 3 contains a magazine roll 10 from which a filter cloth 11
is removed as required. The filter cloth 10 passes through slot
18 formed between the elements 3, 4 of the filter insert. The second
chamber is the filter chamber 12 formed by the jacket 4 and partition
8, from which the required product, i.e. the filtrate which has
passed through the filter cloth 11 and perforated jacket 4, is removed
through a pipe. In the winding chamber 13, formed by the partitions
6 and 7, and the jacket 3, the used filter cloth 11 which has passed
over the perforated jacket 4 of the filter chamber 12 is rolled
up on to take up means in the form of roller 19. The fourth chamber
14 serves as a displacement chamber to keep the chambers 9, 12 and
13 as small as possible. It may also serve as temperature control
chamber for heating or cooling the contents of the filter. The chamber
formed by the housing 1 and filter insert 3 4, hereinafter referred
to as pressure chamber 15, is connected to the filter inflow by
the pipe connection 2. The jacket 3 is removable and while the apparatus
is in operation it is covered by a magazine chamber cloth 16 which
consists of a filter cloth which partly overlaps the filter cloth
11 drawn from the magazine roll 10. A sealing lip 17 presses the
overlapping magazine cloth 16 against the filter cloth 11 fed from
the magazine chamber 9. The pressure chamber 15, magazine chamber
9 and winding chamber 13 are all at the same pressure P.sub.1. A
pressure gradient P.sub.1 - P.sub.2 becomes established between
the pressure chamber 15 and filter chamber 12. This gradient increases
as the filter cloth 11 becomes progressively more soiled. The filter
cloth 11 and magazine cloth 16 cover the jackets 3,4 over their
whole width. If required, the filter cloth 11 may be pressed down
at the edges by two circumferential ring sections.