Note: Descriptions are shown in the official language in which they were submitted.
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APPARATUS FOR FILTERING CONTAMINATED LIQUIDS,
SUCH AS IN PARTICULAR USED OIL
The invention relates to an apparatus for filtering contaminated
liquids.
An apparatus with a high throughput capacity filter, which can be
referred to as a high-performance filter, and a pump for feeding
the oil through the said filter is known making it possible to
filter very large foreign particles from the used or waste oil,
so that, whilst reducinglthe residues, the latter can be burnt.
The oil cleaned with such an apparatus cannot be reused, e.g. as
lubricating oil.
In addition, large plants and the like arè known for the purpose
of cleaning and reprocessing used oil, so that it can be reused.
Known large plants can only be manufactured on an industrial
scale whilst incurring costs of several tens of millions of DM
and are only economic if all the used oil can be transported in
from a large catchment area. This leads to very high transporta-
tion costs, which in turn have an effective on the used oil
supplies and it is not possible to make sufficiently economic
compared with new oil the reprocessed oil resulting therefrom.
In particular where used oil occurs, there is a tendency not to
supply it for reutilization, but instead to dispose of it in
other ways, some of which may not be legally allowed.
US-A-4 179 019 discloses an apparatus for the recovery of used
lubricating oil. It is based on the fact that large lubricating
oil quantities are poured away after use, particularly in car
workshops, which have to dispose of large quantities of used
motor vehicle engine oil. For recovery purposes such oil must be
collected and returned to an oil company in sealed barrels,
where large industrial oil treatment plants are available. Such
costs give little encouragement to vehicle workshops, filling
stations or oil users to save oil. In order to improve the reco-
very of used lubricating oils, US-A-4 179 019 provides an appar-
atus, which has pumps, filters, heat exchangers and an evaporator
2145~21
unit operating under vacuum and which are placed in a transport-
able housing. In this way individual workshops, filling stations
and oil users can have their own oil treatment unit, so that the
reprocessing of spent or used oil becomes much more attractive.
It can be gathered from the above that it is a small preparation
unit suitable for domestic use or a workshop, which can in an
acceptable period of time only treat a small amount of oil, such
as is present in a single vehicle engine,, such as e.g. a few
litres up to a maximum of 5 or 7 litres. A larger oil quantity
cannot be treated, because in series with a single 5 micron fil-
ter there is only a single filter with a passage width of 0.5
micron. Thus, the throughput is greatly reduced. In addition,
the known apparatus is only able to treat oil used in vehicle
engines and which only contain a few, clearly defined contamin-
ants, such as fuel and the resulting carbons. This apparatus
does not permit a more extensive processing of used oil, part-
icularly of the type mixed with metal shavings or the like during
industrial production processes.
US-A-4 352 739 relates to an apparatus for f iltering f luids,
namely those occurring during oil drilling and in the f orm of
cooling liquids. This document describes an apparatus according
to the prior art, which has three filters, but no specific infor-
mation is given on thè nature thereof. As only these filters
are provided, it is only possible to clean liquids with a narrow
range of solid particle contaminations or the cleaning is
unsatisfactory, because in the case of a wide particle range the
filters become very rapidly unusable and must be replaced. In
addition, the filters necessarily very rapidly become clogged if
metal particles occur.
US-A-l 624 385 discloses an apparatus for the recovery of solids
from liquids of printing presses with a very small solids per-
centage. For this purpose the apparatus has a tank into which
can be fed the contaminated liquid. Above a screen is positioned
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a liquid outlet. On the bottom is positioned an extruder in
which it is possible to convey out only the solid particles which
have settled.
The problem of the invention, whilst avoiding the aforementioned
disadvantages, is to so further develop an apparatus for the
filtering of oil, that it permits the treatment of contaminated
liquids and in particular used or waste oil with a larger through-
put of about 5,000 to 6,000 m monthly in such a way that they
can be reused as lubricating oils. The same applies for cooling
agents and cooling water.
The problem according to the invention is solved by an apparatus
according to claim 1.
The high-performance filter is a filter which, like that ment-
ioned hereinbefore, only filters out large particles and con-
sequently has a high throughput capacity. In order not to reduce
the overall capacity of the installation compared with that of
said first filter or high-performance filter, according to the
invention there is a parallel arrangement of several ultra-fine
filters.
As a result of the magnetic filter the loading of the ultra-fine
filters is reduced and consequently the necessary frequency for
the cleaning and replacement thereof is also reduced. Magnetiz-
able particles, i.e. in particular magnetizable metals are rem-
oved beforehand from the used oil and also particles from white
or black glistening metals down to a size of 5 um are removed
from the oil to be treated.
It has been found that by the additional provision of ultra-fine
filters, the normally still present particle size of about 120
~m and more can be reduced by a factor of 10 to 20, i.e. to 5 ,um,
so that oil cleaned and treated with the apparatus according to
the invention only contains particles down to this size and max
15 ~m and the particle proportion in the oil is also reduced by a
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factor of about 20. Thus, a specific test revealed that as a
result of the apparatus according to the invention the gravi-
metric contamination according to IS0/DIN 4405 could be reduced
from 427 mg/l to 26 mg/l.
The pump is preferably placed upstream of the first filter.
According to other preferred developments the ultra-fine filters
can be connected in groupwise for the treatment of liquid. As a
result, of the existing number of ultra-fine filters one or more
groups can continue to be used for filtering, so that the appar-
atus according to the invention remains in operation, whereas at
least one group is disconnected from the liquid flow and con-
sequently can be cleaned or the filter materials replaced. This
contributes to an economic operation of the apparatus according
to the invention.
The ultra-fine filters are preferably constructed in such a way
that they have a cylindrical housing with a central hollow shaft
and that between them is positioned filter material. Such
ultra-fine filters correspond per se to the filter part of fil-
ters such as can e.g. be gathered from DE-OS 39 38 686 or German
utility model 89 13 769, whose content is made by reference into
the sub~ect matter of the present applicatlon.
With regards to a possible running out of oil during the cleaning
and replacement of the ultra-fine filters, according to a pre-
ferred development below the ultra-fine filters are provided one
or more oil collecting pans or trays.
An effective cleaning of tar oils, which can also be provided
with sand, is preferably helped in that it is possible to posi-
tion upstream of the pump and the first high-performance filter
can be provided a heating device with a water devapourizing flow
device.
According to other preferred developments the inlet stage is a
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prestorage tank provided with a screen. Therefore it is possible
to remove a weight differing considerably from the oil to be
treated can be removed beforehand by storage in said tank, so
that they do not act in a pre~udicial manner on the filtering and
cleaning system.
Whilst in the first development according to the invention the
additional magnetic filter is preferably located within the ultra-
fine filter means, in another development of the apparatus the
magnetic filter is the inlet stage of the apparatus. Then, in
preferred manner, on the magnetic filter is positioned a pump
with a lever through which, as a function of the liquid used,
the latter can either be supplied to a continuous heater or to an
edge gap filter or separator. As a result of this development
it is possible to clean oil, used oil or tar oil, as well as
cooling agents and cooling water, the latter passing heated
following the passage through large plants to the magnetic filter
of the inlet stage. The heated liquid can then be cooled to the
necessary temperature by a cooling unit or heat exchanger prov-
ided according to the invention. Oil can be correspondingly
heated to the necessary temperature. By means of the edge gap
filter or separator oil present in the cooling agent or water is
separated from the water and abraded dust, so that the latter can
be separated from the liquid to be treated upstream of the ultra-
fine filters. Thus, there is no detrimental action on the filt-
ering and cleaning system. Correspondingly when cleaning oil
metallic particles are removed by means of a magnetic shocker, a
wide-surface filter and a fleece roll from said oil, so that
these particles do not have a detrimental action on the filtering
and cleaning system.
According to further developments a double filter is provided
through which in alternating manner by reversing liquid can be
filtered. Thus, in the second development of the apparatus
according to the invention only one unit is required for effec-
tively cleaning oil or cooling agents/water.
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For checking the operation of the apparatus according to the
invention inspection windows can be positioned upstream and/or
downstream and a sampling point is provided. In order to check
the throughput, a flowmeter ls provided in a preferred develop-
ment.
The invention provides an apparatus, which can be installed in
transportable manner at the used oil production point, such as
in transportation companies, bus companies, factories, where
machines are operated with oil, etc., so that these enterprises
can independently treat and reuse the used oil produced by them,
without requiring assistance from third parties. This also
applies with respect to larger motor vehicle workshops, which
act as service organizations for third parties and change the
oil of their customers.
In addition, apparatuses according to the invention, which are
transportable, can also be used as small regional, central coll-
ecting and treatment points for filling stations and smaller
vehicle workshops, where their own treatment system would not be
worthwhile.
This leads to less expensive transportation routes and reduced
transportation costs. The costs for a unit according to the
invention, despite the relatively high throughput and therefore
relatively high capacity from both the quantitative and qualit-
ative standpoint, namely the improvement of the purity level by a
factor of 100, are below those of central units or plants. The
apparatus according to the invention can be operated much more
economically than is the case in the known large units, because
in particular there is no need for a continuous large supply of
used oil to enable them to operate economically.
Although reference has been made hereinbefore to a monthly
capacity of 5,000 to 6,000 m3 with an apparatus purchase cost of
approximately DM 150,00 (without heating device), the unit can
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also be adapted to the actual used oil production quantity, by
designing it e.g. for a larger or smaller throughput and in part-
icular through a design with ultra-fine filters positioned
parallel to the oil feed path, a reduction of the volume through-
put can also have an advantageous price influence.
Further advantages and features of the invention can be gathered
from the following claims and description of an embodiment of an
apparatus according to the invention and with reference to the
attached drawings, wherein show:
Fig. 1 A diagrammatic overall view of a first embodiment of
the apparatus according to the invention.
Fig. 2 A larger-scale and somewhat more detailed represen-
tation of the filtering and cleaning unit in side
view.
ig. 3 A part sectional, front view of the unit of fig. 2.
ig. 4 A diagrammatic overall representation of a second
embodiment of the apparatus according to the invention.
ig. 5 A rear plan view of an ultra-fine filter set.
ig. 6 A side view of the ultra-fine filter set of fig. 5.
In the represented first embodiment the apparatus according to
the invention firstly has a prestorage tank 1, in which can take
place a settling of in particular larger particles with a much
higher specific weight or gravity than that of the liquid to be
filtered. Generally the liquid spends 24 hours in this pre-
storage tank before being supplied to the further processing or
treatment wlth the apparatus according to the invention. The
prestorage tank 1 has an inlet pipe 51, which pro~ects under
screens 52. Into the prestorage tank and over the screens 52
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projects a suction nozzle 2, by means of which the liquid can be
sucked out of the prestorage tank 1 by means of a pump. The
screens prevent coarse particles rising up to a suction head 2a
of the suction nozzle 2 and also being sub~ect to suction action.
The suction head 2a of the suction nozzle 2 is constructed as a
float, so that the head always rests on the liquid surface 53,
independently of the filling level, and the suction nozzle 2
only exerts a suction action on the upper liquid zone. In order
that the suction head 2a can follow the liquid level, the suc-
tion nozzle 2 is at least axially movable. For this purpose as
shown, it can be constructed as a telescopic tube 54, but could
alternatively be a flexible hose.
In the represented embodiment below the screens 52 in the vic-
inity of the opening of the inlet tube 1 is provided an extruder
55 with stationary magnets 56 located on its circumference.
The magnets attract magnetizable particles and in particular the
larger particles and this is facilitated by the movement of the
liquid through the extruder. This can be also helped by an air
supply to the liquid. The particles deposited on the magnets
56 are then stripped from the extruder and passed by the latter
out of the tank 1. An end coarse filter 57 is located on a suc-
tion line 2b connected to the suction nozzle 2. To said filter
57 can be connected, for the processing of tar oil, a heating
unit, in order to heat the tar oil to be cleaned and give same a
lower viscosity, whilst expelling from the liquid water moisture.
Por this purpose heating takes place to above 100C, so that
water can be evaporated and removed.
This takes place in a water devapourization flow device 4, which
can be connected to the heating unit 3. The latter is followed
by the actual filter means 6 with an inlet 7, a magnetic filter 8,
the pump unit 9, which is preferably a geared pump unit with a
pressure of 0.6 bar and a power of several kilowatts. The pump 9
is then connected to a first, relatively high-performance filter
11 for filtering out large particles and which is referred to
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g
hereinafter as a high-performance filter. Preferably use is made
of a filter such as is sold under the designation SLE 270 030
by EPE Eppensteiner GmbH & Co. Filterbau, D-68775 Ketsch. The
high-performance filter 11 is carried by a frame 12. The inlet
of the high-performance filter 11 is located laterally at 13
(fig. 2), whereas the outlet is positioned centrally below the
filter 11 at 14. Such power filters are known per se.
The oil filtered warm in the high-performance filter is then
supplied to the ultra-fine filters 16, which are able to filter
even the smallest particles from the warmed oil and by means of
the outlet 17 deliver same for further use or reuse.
The magnetic filter 8 has a very strong magnet by means of which
magnetizable particles can be drawn from the flow path. A vent
valve 21 is located on the top of the magnetic filter 8. The
magnetic filter 8 also has an indicator 22. It is also provided
with its own switch 23, so that it can be switched on and off as
required (fig. 3). A connection box 24 is provided for the elec-
tric supply and switching of the entire unit. Upstream of the
pump unit 9 is provided a -coarse filter 26 preventing large part-
icles from entering the pump unit 9 and impeding or damaging the
latter, to the extent that such particles have not already been
separated in the prestorage tank 1, e.g. because they do not have
a very different specific weight compared with the liquid or
if in certain cases no such prestorage tank is used.
In addition, between the magnetic filter 8 and the pump unit 9
a cutoff valve 8a is provided at the inlet 7a in order to option-
ally shut-off the system. In addition, an inspection window can
be provided permitting a check to be made on the consistency,
particularly cloudiness of the liquid compared with that deliv-
ered at the outlet, where an inspection window can also be pro-
vided.
The liquid cleaned by means of the high-performance filter 11 is
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supplied by means of a branch 46 of the outlet line of two para-
llel distributing tubes 27, 28 to two, i.e. in each case a group
of several ultra-fine filters 16. By means of the double-throw
or changeover switch 29 the liquid can be supplied either to one
or other group of ultra-fine filters, or simultaneously to both.
The two first alternatives make it possible, desplte the oper-
ation of the unit, to replace the ultra-fine filters to which
the liquid is not being supplied and consequently the unit does
not have to be completely shut down. The liquid passes via a
central inlet 31 located on the underside of the ultra-fine fil-
ter into an ultra-fine filter 16 and by a lateral outlet 32 on
the underside out of said filter again and is passed via collec-
ting lines to the main pipe 33 and in the latter to the drain
flange 34. In the main line 33 can be provided a flowmeter 36.
Upstream of the drain flange is provided a viewing panel 37.
Here again a cutoff device can be provided.
Used oil, as well as tar oil to be cleaned, is initially fed into
the prestorage tank and stored there for an adequate time, e.g.
24 hours, so that larger particles are separated therein. Option-
ally a plurality of prestorage tanks can be provided with which
in each case is connected the filtering means.
The oil is then sucked out of the prestorage tank 1 by means of
the suction nozzle 2 and the pump unit 9 and, in the case of
tar oil, passage initially takes place through the heating unit 3
in which heating takes place to about 100C, so that the water
moisture can be given off via the water devapourization flow
device 4.
The liquid to be cleaned then passes into the magnetic separator
8 in which the magnetizable particles are separated. The liquid
is then forced by the pump unit through a high-performance filter
11 and a first filtering takes place therein. The liquid is then
forced through the ultra-fine filters 16, in which even the
smallest particles down to a size of about 15 ~um can be filtered
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out. After passing through the ultra-fine filters 16 the cleaned
oil can be discharged through the outlet 34 and supplied for
reuse.
In another embodiment the apparatus according to the invention
firstly has a magnetic filter 101 with a self-cleaning device as
a prefilter, into which the liquid is fed via a gravity line 102.
A magnetic prefiltration takes place in the magnetic filter 101,
in that magnetizable particles are drawn by magnets from the
liquid. Coarse, iron-containing particles are so built up to a
filter cake that also smaller dirt particles can in this way be
removed from the liquid. If the not shown chamber for receiving
the filter cake has attained a certain filling level, then
automatic removal takes place.
The apparatus shown in fig. 4 can be used for filtering used oil,
hydraulic oil, tar oil, as well as for filtering and cleaning
cooling water used in machines and cooling agents used in tool
plants. During the filtering of the first-mentioned media the
liquid, following a corresponding setting of a lever 104 located
on a pump 103, passes via an inlet 105 into a continuous heater
106. The pump 103 with a pressure of 4 to 5 bar removes the
liquid precleaned by the magnetic filter 101 from a not shown
chamber, serving as a preliminary tank, and located below the
filter 101. In order in the case of a throughput of 2 m /h to
heat the liquid to 80C, the continuous heater 106 preferably
has a calorific power of 84.6 kW. By means of said continuous
heater 106 the oil to be cleaned is given a lower viscosity and
also any water or moisture present is expelled from the liquid.
The continuous heater 106 i8 provided with an excess pressure
valve and a heat regulator to prevent liquid overheating. To the
continuous heater 106 i8 connected an electromagnet shocker 107
and as a result of its influence the fine metallic particles
agglomerate. The electromagnet shocker 107 is followed by a
mechanical filter stage 108 as a high-performance filter. This
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filter stage is a wide-surface or wide-bed filter 108. On said
wide-surface filter are deposited the agglomerated particles such
as dust, sludge, soot, etc. and in this way form a filter cake.
The throughput is preferably 220 l/min. However, in large
plants it can also be 400 or 600 l/min. By means of a not shown
fleece roll serving as a continuous roll the particles forming
the filter cake are discharged almost dry at the end 109 of this
filtering zone 110.
By means of a second pump 111 the prefiltered liquid passes to a
double filter 102. This double filter 112, whose filters can be
connected in at random, prevents any coarser particles present
from entering the ultra-fine filter system. The double filter
112 can be a ceramic or paper cartridge filter. It is also pos-
sible to use a high-grade steel screen with a pore size of 3 to
5 ~um.
A continuous counter 113 can be directly connected to or follow
the double filter and can have a permanent or day counting mech-
anism. This makes it possible to check the throughput during
used oil cleaning. The filtered liquid then passes into the
ultra-fine filter system 114 and is supplied to the ultra-fine
filters 115, which filter even the smallest particles out of the
liquid and pass on the same via an outlet 116, by means of which
the fine-filtered medium passes into a not shown empty tank for
receiving the cleaned medium, particularly oil. By means of the
ultra-fine filter system 114 residual substances of metals such
as lead, zinc, aluminium, soot, emulsions and water are filtered
to a very high degree.
The apparatus according to the invention in this embodiment also
has a switch box 117 by means of which all the switching opera-
tions take place and which is provided with warning and overload
indicators so that, if necessary, the complete plant or unit can
be disconnected or shut down.
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If the apparatus according to the invention shown in fig. 4 is
used for cooling medium or water cleaning, then the medium
passes through the magnetic filter 101, particularly if high
water percentages have to be removed and which after passing
through large plants has a temperature of about 50 to 70C, in
the same way as the oil. Then the medium passes via the pump 103
no longer to the continuous heater 106, but instead after rever-
sing the lever 104 to an edge gap filter 118. By means of the
edge gap filter 118 the oil is separated from the water and dust.
By means of a not shown valve in the lower region of the edge
gap filter 118 the solid sludge contamination or the contamina-
tion itself is removed. A separator can be used in place of an
edge gap filter 118.
After this filtering the liquid medium passes to a heat exchanger
or a cooling unit 119 and is cooled there to approximately 20C.
This heat exchanger 119 is either directly followed by the ultra-
fine filter system 114, or the medium passes, following the
reversal of a lever 120, via the pump 111 to the double filter
112 and optionally the flowmeter 113 into the filtering system
114. The lever 120 is reversed by means of the switch box 117.
All the components 101 to 120 are mounted on a not shown, common
substructure, which can be reinforced with a steel frame. The
complete unit is constructed in transportable or stationary man-
ner, including all the necessary pipes, connections and fittings.
At the installation location it is then merely necessary to prov-
ide the power connections, as well as the supplies and outflows
for the liquid.
The arrangement of the ultra-fine filters 201 shown in figs. 5
and 6 is usable both for the ultra-fine filter 16 of figs. 1 to 3
and the ultra-fine filters 115 of fig. 4. The ultra-fine filter
system has an ultra-fine filter set 202, which in the represented
embodiment has reciprocally displaced or staggered units 203,
204, 205 with the ultra-fine filters 201. Below the ultra-fine
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filter set 202 is located a tank 206 for receiving the cleaned
medium. By means of an inlet 207 with distributing tubes 208
the heated or cooled medium is supplied to the individual units
203, 204, 205. On the individual distributing tubes 208 are in
each case provided shutoff cocks 209, so that in each case one
unit 203, 204, 205 can be shutdown in order to replace the ultra-
fine filters 201. In each case the filters 201 have a filter
housing 210 with a lid and a clip closure. Upstream of the
ultra-fine filter housing 201 is located the inlet with a baro-
meter 211. Between the shutoff cock 209 and the barometer 211
is provided a drain 212 for the sludge and dust. After cleaning
has taken place in the ultra-fine filter 201 the cleaned medium
passes to the outlet 213, which preferably has a check valve.
By means of said outlet 213 the medium either passes into the
tank 206 or into a pipe, 80 that it can be supplied to its
reutilization.
