Note: Descriptions are shown in the official language in which they were submitted.
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TITLE OF THE INVENTION
SELF-CLEANING SYSTEM FOR FILTER PRESS
FIELD OF THE INVENTION
[0001 ]The present invention relates to a self-cleaning system obtained by
modifying standard circular or plate presses.
BACKGROUND OF THE INVENTION
[0002]The maple industry has produced maple syrup in the traditional way for
about a hundred years until about the decade 1960 to 1970. Thereafter, it has
undergone a transformation towards industrialization in order to cut
production
costs that became prohibitive. In the 60s, collecting maple sap was still done
through buckets hanging from maple trees. Then in the 70s, sap collection was
done through a network of tubing and gravity flow, then through vacuum
systems.
All to increase yields for collecting maple sap.
[00031The syrup which is made by boiling the sap in the spring, contains
suspended solids that appear during evaporation and cooking maple sap, which
reduces the volume of water from 30% to 50% to give a syrup 66% sugar (Brix)
and 34% water.
[0004] During collection, the average percentage of sugar in the sap varies
from
1% to 5% depending on the type and age of trees. One must therefore remove a
large volume of water to obtain a 66% concentrate of sugar syrup (Brix). The
boiling volume can be reduced by using a method of nano filtration membrane
commonly known as reverse osmosis.
[00051 Up to 90% of water molecules (H20) are removed, while retaining in the
concentrate all the mineral / particles and the specific sap molecules. During
the
evaporation process certain particles from wood fiber (the tree) will appear
as
residues giving an acrid taste and blurred maple syrup product. So to improve
quality, one must get rid of these suspended solids to obtain crystal clear
syrup
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by filtration through a filter of 5-100 micro according to degree of clarity
that is
desired.
[0006]These materials, known as in the popular jargon as "sugar sand", which
must be removed when the syrup comes out of the evaporator at 219F or 104C.
[0007] In the 1900s this filtration was done through a felt fabric installed
above a
circular container by gravity filtration. In time, this was replaced until
today by
cylindrical or plate presses, wherein filter papers or various membranes are
inserted and which are supported by grooved plates in order to withstand the
pressure of hot syrup (about 60 psi). Figure 1 illustrates an example of a
standard press. Under this pressure the fine particles present in the hot
syrup
rapidly clog the filter papers or filter membranes.
[000810ne way to solve this problem is to add an agglomerating powder which is
used to capture suspended solids in the syrup. This powder is extremely fine
diatomaceous earth consists of marine products (degradation product of
crustaceans). It must be added constantly to increase the volume of syrup
filtered
prior to disassembly of the press, during a period of 30 minutes to 3 hours
before
disassembly, which varies from the start to the end of the sugaring season.
There
is no other solution than to disassemble the press and change the filter
membranes several times during a day of production.
SUMMARY OF THE INVENTION
[0009]A preferred object of the present invention is to provide a self-
cleaning
system obtained by modifying standard filter presses in order to avoid
frequent
disassembly thereof requiring replacing filter membranes and to extend
significantly the operating time of the device without disassembly up to
several
days.
[0010]According to the present invention, there is provided a self-cleaning
system for a plate press or cylinder press for filtering a fluid product and
for
eliminating waste material accumulated on filter membranes in a waste
accumulation area of the plate press or cylinder press, said system comprising
a
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drain port adjacent to the waste accumulation area, said system comprising an
area creating a circulation of water and/or forced air jets within the waste
accumulation area to expel the waste to the drain port, whereby the waste
accumulation area is cleaned from the waste material without having to
disassemble the plate press or cylinder press.
[0011]Other objects, advantages and features of the present invention will
become more apparent upon reading of the following non-restrictive description
of specific embodiments thereof, given by way of example only with reference
to
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012]In the appended drawings:
[0013]Figure 1A is a perspective view of a standard press for filtering maple
syrup;
[0014]Figure 1B is front view of a press plate of the standard press shown in
Figure 1A;
[0015]Figure 2 is a perspective view of a standard press plate shown in Figure
1A;
[0016]Figure 3 is a perspective view of another typical plate and frame filter
press that is similar to the standard press shown in Figure 1A;
[0017]Figure 4 shows the details of a conventional filter plate and filter
frame of
the press shown in Figure 3;
[0018]Figure 5 is a perspective view of a self-cleaning press containing
several
removable plates and a draining system, according to a preferred embodiment of
the present invention;
[0019]Figure 6 is a section view of the self-cleaning press shown in Figure 5;
4
[0020]Figure 7 is a schematic section view of a plate filter assembly and
drain,
according to a preferred embodiment of the present invention;
[0021]Figure 8 is a perspective view of the self-cleaning press shown in
Figure
with valves being connected, according to a preferred embodiment of the
present invention;
[0022]Figure 9 is a detailed view of the front of the self-cleaning press
shown in
Figure 8; and
[0023]Figure 10 is a perspective view of a cylinder press.
DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
[0024]Referring to Figure 1A, there is shown a standard filter press 10. It
includes a motor M with a pump with an inlet I and an outlet 0 for pumping
syrup. The press 10 includes a plurality of removable plate assemblies
composed of a filter plate 9 between which is placed a filter paper or a
membrane filter 13. As shown in Figure 1B, each filter plate contains an entry
3
(IN) for receiving the syrup coming from the pump and an outlet 5 (OUT) from
which comes out filtered syrup.
[0025]Referring back to Figures 1A and 1B, the standard filter press 10 has an
inlet for syrup 3 and an outlet for returning the filtered syrup 5. As
explained
above, the filter plates 9 and filter papers or filter membranes 13 must be
frequently dismantled for cleaning of the press. Each plate assembly also
includes a zone of accumulation of waste material and filter powder that must
be removed for cleaning.
[0026]Referring to Figure 2, there is shown a standard plate assembly of the
press of Figure 1A. The standard plate assembly is composed of a solid filter
plate 11, a hollow filter frame 12 and a filter layer 13. The hollow filter
plate 12
defines an inner area thereof where waste material accumulates during
filtration
of the fluid product. The hollow filter frame 12 includes an inlet feed port
104 for
receiving the fluid product and an outlet exit port 105 for expelling the
filtrate.
The solid plate 11 includes an inlet feed port (not shown) and an outlet exit
port
(not shown) for respective alignment with the inlet feed port 105 and the
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outlet exit port 105 of the hollow filter frame 12. The solid plate 11
includes at
least one filtrate exit port 28 in an inner area thereof connected to the
outlet exit
port (not shown) for draining the filtrate. The filter layer 13 is configured
to be
installed between the hollow filter frame 12 and the solid plate 11 for
filtering the
fluid product. The filter layer 13 may be a filter paper or membrane.
[0027] Referring to Figure 3, there is shown a conventional industrial plate
and
frame filter press of another variant of a known standard press plate. The
plate
and frame filter press 10 is an assembly of alternate solid plates 11, the
faces
(not visible in this figure) of which are waffled to allow drainage of the
filtrate and
the hollow filter frames 12 in which the filter cake accumulates during
filtration. A
filter means 13, usually a layer of filter paper over a cloth fabric, covers
both
faces of each filter plate 11. The filter plates 11 and filter frames 12 are
hung in a
vertical position on a pair of parallel support rails 14 by means of support
lugs 15.
During the filtration process, the plates 11 and frames 12 are pressed to a
substantially liquid-type closure between two half end plates, one fixed half
end
plate 16 and one movable half end plate 17, by a capstan screw or some other
closing device 18. Openings 19a, 19b, 19c and 19d in the corners of the fixed
end plate 16 provide access to the passageways or pipes when the plates 11 and
frames 12 are stacked together since the plates 11 and frames 12 are generally
provided with similar holes. One of the openings 19a is used to introduce the
unfiltered feed to the filter frames 12 where the solids in the feed are
accumulated. Two of the openings 19b and 19c are normally used to remove the
filtrate from the press 10. The last opening 19d is normally used to flow
water or
solvent along the passageway backwash the filter cake at the end of a filter
run
by means of wash ports in the plates. Backwashing provides for removal of many
of the solubles in the filter cake while it is still in the filter press
chambers. This
backwash process is accomplished by passing water or an appropriate solvent
through the cake by means of ports in the plates to dissolve the solubles in
the
cake and wash out filtrate remaining in the cake. The wash liquor produced by
the backwash process is removed via opening 19b with opening 19c valved off.
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[00281 Referring now to FIG. 4, a typical standard filter frame 12 is shown.
The
rectangular frame 12 consists of two horizontal sections 21 and two vertical
sections 22 joined at their ends. At each of the inside corners arched members
23 extend from the horizontal and vertical sections to provide holes 24a, 24b,
24c
and 24d. Hole 24a is aligned with the feed opening 19a thereby creating part
of
the feed passageway or pipe. Similarly holes 24b, 24c and 24d are aligned with
half end plate openings 19b, 19c and 19d respectively. At the inside corner
arch
forming the hole 24a feed ports 25 connecting the open area of the frame 12 to
passageway provided by hole 24a whereby the unfiltered feed enters the
filtration
chamber 26 and it is in this filtration chamber 26 that the filter aid
accumulates.
There is a support lug 15 on either side of the frame 12 enabling each frame
to
be properly aligned with the other alternating plates 11 and frames 12 of the
press 10.
[0029] Referring again to Figure 4, a representation of a standard filter
plate 11 is
shown. The filter plate 11 consists of a solid metal plate 27 with a raised
area 27'
around its edges to provide a gasketing surface when placed against filter
frame
sections 21 and 22. The raised region 27' encloses a continuous imperforate
plate 27 both surfaces of which are waffled to provide support for the filter
cloth-
paper layers while allowing drainage of the filtrate from the plate area 27 to
the
filtrate exit passageway by means of filtrate exit ports. On the raised area
27', at
the corners of the plate 11, there are holes 24a', 24b', 24c' and 24d' which
match
and are concentric with the corresponding holes 24a, 24b, 24c and 24d on the
filter frame. One of the corners of the plate has the filtrate exit ports 28
which run
underneath the raised area 27' between the front and rear waffled plate
centers
27 and the corner hole 24c'. This allows the filtrate to leave an individual
plate 11
and flow out of the filter press 10. The filter plate 11 also has support lugs
15 on
either side. Both the front and the rear of the plate have the same details
and
configuration.
[0030] Even though the conventional industrial plate and frame filter press 10
may be cleaned via backwash as described above, this may only be suitable for
certain kinds of fluid products or slurry. However, performing a backwash when
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using maple syrup or similar fluid product becomes very problematic. Indeed,
the
nature of maple syrup makes it almost impossible to properly clean the filter
press by backwash alone. This is made worse if one adds an agglomerating
powder to capture suspended solids in the syrup.
[0031] Referring to Figures 5 and 6, there is shown a self-cleaning press 100
and
its drain arrangement 101, according to a preferred embodiment of the present
invention. The press 100 includes a plurality of removable plates each having
a
handle.
[0032] Referring to Figure 7, there is shown a plate assembly of the self-
cleaning
press shown in Figure 5, according to a preferred embodiment of the present
invention. The plate assembly includes a hollow filter frame 12 defining an
inner
area 102 thereof where waste material accumulates during filtration of the
fluid
product. The hollow filter frame 12 includes an inlet feed port 104 for
receiving
the fluid product, such as maple syrup, and an outlet exit port 105 for
expelling a
filtrate, such as filtered maple syrup. The plate assembly also includes a
solid
filter plate 11, which may be similar to the standard solid plate shown in
Figure 4.
The solid plate includes an inlet feed port 24a' (shown in Figure 4) and an
outlet
exit port 24b' (shown in Figure 4) for respective alignment with the inlet
feed port
104 and the outlet exit port 105 of the hollow filter frame 12. The solid
filter plate
11 includes a plurality of filtrate exit ports 28 in an inner area thereof
connected
to the outlet exit port 24b' for draining the filtrate. A filter layer 13 for
filtering the
fluid product is installed between the hollow filter frame 12 and the solid
plate 11.
[0033] The hollow filter frame 12 includes a plurality of jet ports 25 in an
inner
zone 103 thereof connected to the inlet feed port 104 for injecting a
pressurized
cleaning fluid onto the inner area 102 of the hollow frame 12 and for
dislodging
the waste material. The pressurized cleaning fluid may be pressurized water
and/or air.
[0034] The said hollow filter frame 12 further includes a drain port DP on the
inner
surface A thereof for draining the waste material being dislodged by the
pressurized cleaning fluid being injected through the plurality of jet ports
25.
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[0035]As illustrated, the hollow filter frame 12 may have two inlet feed ports
104,
an outlet exit port 105 and a bypass. The area for accumulating residues or
waste material 102 is in front of the filter membrane 13. The plurality of jet
ports
25 are located at the corners of the hollow filter frame 12, near the inlet
feed
ports 1040n the internal side of the filter frame plate12. These jet ports 25
define
an interior area 103 where air and/or water comes out for washing the plate
assembly.
[0036]The system functions as a self-cleaning water and air circulation, as
jets
emerge from the jet ports 25 of the area 103 between the plates of the press
to
remove impurities from the syrup diatomaceous earth and which are mixed
together and form a thick and sticky paste in between the hollow filter frames
12
and membranes 13 which receive the hot syrup on the entrance side of the
filter
membrane 13. The mixture can thus be very quickly discharged by the self-
cleaning and drainage system using the jet ports 25 in area 103, the drainage
device 101 containing a drain 107 and an outlet 108, and without dismantling
the
press 100. A lever 109 allows to open and close the drain 107. This
configuration
allows to operate an evaporator without frequent stops and even avoiding using
multiple presses for achieving the same operation time.
[0037]The waste accumulated in the hollow filter frame 12 can be cleaned
without removing the 100 press by means of the self-cleaning water and air jet
ports 25 in area 103 and all waste material going to the drain port DP.
[0038]The press 100 may have multiple syrup inputs 104, which have two
functions: a) an input function of the syrup into the hollow filter plate 12;
and b) a
function of creating an air and/or water shower in area 103 using a plurality
of jets
during the cleaning phase of the hollow filter plates 12 when the press is
clogged
with filtration waste.
[0039]Referring to Figure 9, there are shown different valve connections used
in
the filter press shown in Figure 8. A three-way control valve 200 is used to
select
the input of syrup 202 or to select the input of hot water 204 and air 206 for
cleaning the press. A water valve 205 controls the entry of hot water and an
air
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valve 207 control the entry of air. An air regulator 209 is connected the air
valve
207. The air regulator is connected to an air compressor (not shown). An
optional
output valve 211 may be connected to the air valve 207 for controlling a
diaphragm air pump (not shown). A monometer 213 is connected to the three-
way control valve 200 and between the two inlet ports. Two output valves 215
are
connected to the outlet port of the press. The output valves 215 is for
controlling
the flow of filtered syrup towards a collection recipient (not shown) and
towards a
flow control box (not shown) or maple sap container (not shown). A bypass
valve
217 is connected to the bypass outlet port. This bypass port is normally used
during the warming up of the press or when starting the press. The bypass
valve
217 is usually closed during both the filtering process and the cleaning
process.
[00401 In order to clean the filter press, one has to open the drainage valve
of the
drainage device 107, by moving the lever 109; open at least one of the water
valve 205 and the air valve 207; close the output valve 215. The air regulator
209
is to be set to a pressure that is less than a maximum pressure of 45 psi.
Ideally
the pressure is set between 40 psi and 45 psi to achieve proper cleaning.
[0041]Referring to Figure 10, there is shown a cylinder press which operates
substantially the same manner as the standard press shown in Figure 1. Those
skilled in the art will understand that the invention described above may also
be
implemented in a circular press.
[0042]The press of the present invention is designed primarily for use in the
maple syrup industry. It can, however, be used in many filtering applications,
such as honey, beer or wine processing.
[0043]The scope of the claims should not be limited by the preferred
embodiments set forth in the examples, but should be given the broadest
interpretation consistent with the description as a whole.
