FI62956B - FOERFARANDE FOER FILTRERING AV EN SUSPENSION ELLER EMULSION SAT FILTRERINGSAPPARAT FOER UTFOERANDE AV FOERFARANDET - Google Patents

Description

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Patent and Registration Office ............. , . .. ... 04.09.77 _, _. *, (44) Nlhtivtlttlyma | » kimtjullalwin date—

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Sweden-Sverige (SE) 7602999-0 (71) Rederiaktiebolaget Nordstjernan, Stureplan 2, Stockholm,

Sweden-Sweden (SE) (72) Ulf Hjelmner, Nynäshamn, Hans Folke Larsson, Västerhaninge,

Ruotsi-Sverige (SE) (7¾) Qy Roister Ab (5¾) Method for filtering a suspension or emulsion and filtration apparatus for carrying out the method - Förfarande för filtrering av en suspension or emulsion samt filtreringsapparat för utförande av förfarande t

The present invention relates to a method for filtering a suspension or emulsion and also to a filter device for carrying out the method.

It is known in the art that in order to filter a suspension or emulsion, it is passed to a filter bed of granular filtrate arranged in a tank included in the filter device, the suspension is allowed to flow up through the filter bed and in some suitable manner to filter the filtered liquid phase out of the filter bed. with a protective device, e.g. a slat wall or a sieve, to prevent the filter medium from flowing out together with the filtered liquid phase. It is also known in one type of filtration device constructed to provide a continuously operating filtration device, i.e. without interrupting filtration when cleaning the filter medium, allowing the filter medium to flow downwards through the filtration tank during filtration, removing and directing the filter media washed from the washing device back to the top of the filtration layer in the tank. In another known filtration device, which is likewise provided with a washing device 2 62956 on the side of the filtration tank but without countercurrent filtration between the filter medium and the suspension, the filter medium is washed countercurrently against the used washing liquid, which is then removed from the suspension or equivalent

It is an object of the present invention to provide a continuously operating filter which, in addition to efficiently utilizing the filtration layer by means of a countercurrent flow between the filter medium and the suspension during filtration, is also improved by simple means, reliable operation gives a high capacity in relation to the required space, which has continuously substantially the same filtration capacity and which at the same time ensures a higher efficiency when washing the filter medium.

The present invention then relates, as initially indicated in connection with the prior art description, to a method for filtering a suspension or emulsion in a filtration device, which suspension or emulsion is introduced into the granular filter medium zone and flows upstream wherein during filtration the filter medium flows down through the filter bed zone upstream of the suspension past its inlet and is then moved separately from the filter bed to the scrubber to wash the contaminated filtrate obtained by filtration as it flows countercurrently to the scrubbing liquid in the scrubber.

What is new and characteristic of the method according to the invention is that at least a part of the filtered liquid phase leaves in order to maintain the filter bed zone above it, that the contaminated filter medium is transferred separately through the taken from said zone of the filtered liquid phase to the wash path.

Thus, the entire filtration and washing operation can take place inside the filtration device, and the filtered liquid phase obtained in the filtration, a clear solution, is used as the washing liquid in a simple and inexpensive manner.

5 62956

Within the framework of the method according to the invention, as is apparent from the following claims, further improvements are provided, the purpose of which is to further increase the efficiency of both washing and filtration. Thus, during washing, measures can be taken to momentarily increase the relative speed of the filter medium and the washing liquid at least once, which creates particularly favorable conditions for washing the filter medium, braking the filter medium at least once, so that the contact time between the filter medium and the washing liquid increases. before carrying out the filter media components. Furthermore, according to the invention, the amount of washing liquid flowing in the washing path can be controlled. With respect to the amount of filter media transferred to the wash path, this can also be adjusted automatically according to the invention in order to continuously obtain a suitably adjusted flow of filter media to the wash path, knowing the amount or pressure of the suspension before it enters the filter bed zone. Finally, the method according to the invention makes it possible to prevent air penetrating from the air introduced into the soiled filter medium for conveying the soiled filter medium into the filter bed layer by collecting it beforehand and draining it, so that

The invention also relates to a filtration device for carrying out the above-mentioned method, wherein the filtration device comprises a zone in the filter device vertically which is a granular filter medium and forms a filtration layer, an inlet for the suspension or emulsion to be filtered. a space between the filter bed upstream of the inlet and in free communication with the filtration bed zone, to which the filter media is continuously passed downwards through the filter bed zone, and a space for washing and from which the washed filter medium is returned to the filtration layer zone gen äsivulle. The filtration device according to the invention is then characterized in that 4 62956 filtered liquid phase zones obtained by filtration are held above the filtration layer zone. with at least one inlet »connected to the zone of the filtered liquid phase.

In a preferred functionally and structurally simple embodiment of the filtration device according to the invention, the washing device is immersed in the zone of the filtered liquid phase and its lower end is located above the zone of the filtration layer.

Other features and advantages of the invention will become apparent from the following claims and from the following description of an embodiment of a filtration device, with reference to the accompanying drawing.

Figure 1 shows the filtration device in vertical section.

Figure 2 shows the same vertical section of the top of the filter device, but on a larger scale for a more detailed illustration of the washing device included in the filter device.

Finally, Figure 5 is a somewhat schematic top view of a number of filtration devices integrated into a filtration apparatus.

In the embodiment, as shown in Fig. 1, the granular filter medium 1 is enclosed in a container with walls 2 and a conical or pyramid-shaped base 5 with the tip facing downwards. The bottom of the cone or pyramid should preferably correspond to the shape of the container defined by the walls 2.

Sand is very suitable as a baemic filter medium. However, other materials may be used, such as plastic or mixtures of several materials. A mixture of several fractions of this material in a continuous filter according to the present invention may be used in contrast to conventional technology, however, depending on what needs to be filtered and how efficiently the filtration should be performed. After the tests, the person skilled in the art will find the most suitable material and grain size in each individual case.

The suspension or emulsion to be filtered is fed, as indicated by arrow A, into the tank through the inlet 4, most preferably through the bottom of the tank. The inflow of the suspension into the filtration layer takes place in the lower part of the filtration layer through pipes 5 provided with pipe nozzles 6. A roof 7 is arranged above each pipe mouth to prevent direct contact of the filter medium with the pipe mouths and to expose a larger surface area of the filter medium against the incoming suspension. This reduces the risk of clogging the filter due to strong momentary contamination of the filter media in the pipe openings.

62956

The V-shape of the roofs and the placement of the pipe openings above the roofing material provide the least possible obstacle to the downward flow of the filter media. The placement of the inlet pipe mouths 6 in the lower part of the filtration layer gives the advantage that the dirty part of the filter medium, i.e. the one which passes the roofs and the pipe openings, continues downwards and is no longer used for filtration. This prevents clogging of the inlet openings and continuously exposes the new filter medium against the incoming suspension. The incoming suspension flows upstream of the filter medium upwards through the zone of the filter bed, always towards a cleaner filter medium. As the suspension flows upwards through the filter bed zone, the filtered liquid phase obtained is kept as the filtered liquid phase zone 8 above the filter bed and its level is determined in the illustrated embodiment so that the filtered liquid phase exits the filter device through the overflow opening 9 (arrow B).

At the bottom, in the conical or pyramidal part 5 »of the container, into which the filter medium contaminated by filtration flows, an opening of a suitable lifting device 10 is arranged. As can be seen from the embodiment shown, the lifting device extends centrally through the device and can be, for example, a mammoth pump. Such a pump acts as an air transport medium and the air is supplied from top to bottom along a line 11 which runs along a transport pipe 12 included in the lifting device. Air is supplied to the transport pipe through holes (not shown) at the lower end of the line. The air conveys the filter medium (arrow C) through the pipe 12 to the washing device 15 above the filtration layer, which is described in more detail.

If, for some reason, the air supplied to the mammoth pump were to penetrate through the lower part of the transport pipe 12 and into the filter material, then there is a risk that the filter material would fluid locally. This would cause a sharp decrease in the filtering capacity of the filter.

To prevent such interference, an upturned funnel 14 is placed around the mammoth pump above the lower orifice, which receives any stray air and leads it through holes in the narrow bottom of the funnel to a line 15 along the conveying tube. uniform flow profile for device cross section.

The roofs 7 above the inlet openings 6 described above, like the funnel 14, also contribute to achieving the desired flow profile. Such ceilings, although not shown, may be fitted to the filter bed at other suitable points and without being connected to the inlets of the suspension in order to further ensure the desired flow profile.

6 62956

Figure 2 shows the laundry 13 on a larger scale.

From the upper part of the transport support tube 12, the filter medium becomes washable, turns (arrow D) and flows downwards along the washing path formed between the transport tube 12 and the outer jacket 16 of the washing machine. The sheath 16 is preferably formed concentrically around the transport tube 12. The filter media may contain compressed particles due to contamination. These possible particles break when they encounter a protrusion 17 or the like in the flow path of the filter medium, at the same time as the rate of fall of the filter medium is braked. The filter medium then encounters a midsole 18 with holes 19 below in the washing path, which is preferably followed by a number of similar midsoles. The example shown has five midsoles. The holes 19 in the two successive intermediate bases are preferably moved relative to each other so as to prevent the vertical free passage of the filter medium. * Thus, the filter medium is continuously braked as it passes through the washing device. The filter medium constantly encounters the washing liquid in the washing device and the speed of the washing liquid in the openings in the midsoles becomes momentarily higher, which creates particularly favorable conditions for washing the filter medium.

The washing liquid is a zone 8 of filtered liquid phase above the filtration layer. The washing device is then immersed in a layer 8, which is a filtered liquid phase, and as shown by arrow E in the illustrated embodiment, the washing liquid, filtered liquid phase, is introduced into the washing path through the opening 20 and flows upwards along the washing path. The washing liquid contaminated in the washing, the reject, is discharged from the washing path, as shown by arrow F, and removed through the overflow opening 21 and discharged from the device as shown by arrow G. This overflow opening can be adjusted in height and width to adjust the amount of washing liquid. If the overflow opening is lowered, the amount of washing liquid will increase. The amount of washing liquid also increases automatically if the level of the clear solution above the filtration layer rises, e.g. due to the increased load on the filtration device.

To direct the filter medium from the transport tube 12 down to the wash path and to separate the reject from the incoming filter media, a tube 22 is arranged between the jacket 16 and the transport tube 12 and lowered somewhat past the upper end of the transport tube. The pipe 22 extends upwards through the jacket 16 and the air inlet line 11 and the deaeration line 19 are pulled through the pipe. The pipe 22 also includes a device 23 for collecting air with the filter medium from the transport pipe 12.

7 62956

In the illustrated embodiment, this assembly device has alternately arranged downwardly turned cones and upward truncated cones.

Although not shown, if desired, part of the filtered liquid phase obtained by filtration can be removed in the filtration bed zone from below its upper side by fitting there and preferably substantially vertically above the inlet pipes 6 for outlet pipes for the filtered liquid phase. These outlet pipes can then advantageously be provided with roofs according to the roofs 7 located above the inlet pipes 6. By removing the filtered liquid phase through outlet pipes located in the filtration layer zone below the upper side of the filtration layer, a perfectly good filtered liquid phase is also guaranteed, e.g. in the event of a malfunction of the washing machine, whereby the filtered liquid phase above the filtration layer could become dirty.

Below the lower part of the washing device, a cone 24 is placed to disperse the filter medium from the washing device onto the surface of the filtration layer. In addition, in order to provide the inflow of filter media granules to the surface of the layer below the cone, the cone 24 is provided with a suitable number of suitably spaced holes 25 for the passage of the granules.

In addition to the automatic adjustment of the amount of washing liquid described above, an automatic adjustment of the amount of filter basin to be washed can also be provided, although not shown. By fitting a quantity-sensing or pressure-sensing element to the suspension supply line (indicated by arrow A in Fig. 1), a signal is obtained indicating a change, e.g. an increase in pressure due to the accumulation of suspended material in the filter bed. This signal can be made in a known manner to adjust the capacity of the lifting device 10 so that the amount of filter medium to be washed is increased or correspondingly decreased.

In the embodiment of the filtration device described above and shown in the drawing, the washing device is embedded in the layer Θ of the filtered liquid phase, from which the filtered liquid phase is taken as a washing liquid through the lower opening 20. Alternatively, the filtered liquid phase utilized for washing can also be taken from the side through one or more openings in the jacket 16 at the bottom thereof. In another alternative embodiment not shown, in which the filtered liquid phase of zone Θ is likewise utilized as washing liquid, at least part of the washing device is lowered into the filter bed and arranged separately therefrom, whereby one or more lines are drawn from zone Θ to the lower part of the washing device.

8 62956

The filtration device according to the invention, e.g. the preferred embodiment described above and shown in Figures 1 and 2, enables a relatively small design, thus achieving the advantage that the device is not clumsy to handle and difficult to maintain in use. In addition, since all the various devices required for a continuously operating device are located inside the filtration device, in which case certain devices, e.g. from the laundry and the lifting device, can also be shaped as units, Thus, if necessary, larger filtration capacities than can be obtained by a single device can be used in a simple and advantageous manner to combine several filtration devices into a filtration device. Such a filtering device is schematically shown in Fig. 3 ee showing eight groups of interconnected modular filtration devices. Each module then includes all the different devices required for the open filter device of the invention illustrated in Figures 1 and 2, except that the walls 2 adjoining each other in the group have been removed (the dashed lines in Figure 3 are intended to illustrate the top edge of 29 has a common outlet 26 for the filtered liquid phase leaving each filtration device (arrow B in Figures 1 and 2), and both rows 29 have a common outlet 27 for reject from the scrubber (arrow G in Figures 1 and 2). These common outlets 26 and / or 27 el are of course not necessary to be arranged as shown, but they obviously simplify the structure of the filtration equipment. The outer wall 28 surrounding the filtration device may be formed by the walls 2 included in each filtration device, but alternatively all the walls 2 of each filtration device may also be removed and a separate outer wall built around the filtration device.

As can also be seen in Figure 3, each device module has a hexagonal cross-section, which shape allows simple connection into larger filtration equipment. But other shapes, e.g. rectangular or square shape, are also possible for use, which also gave simple connection. However, a rectangular or square shape may occur. be less suitable than the hexagonal shape because the filter medium, which is located close to the corners, becomes braked when moving downwards and also does not participate so actively in the filtration;

Claims (31)

9 62956 A method for filtering a suspension or emulsion in a filtration apparatus, which suspension or emulsion is introduced into a zone forming a filter layer of granular filter medium and flows upwards through the filtration layer during filtration and leaves the filtration layer as a filtered liquid phase. the suspension and then transferred separately from the filter bed to the scrubber to wash the contaminated filtrate obtained by filtration as it flows countercurrently against the scrubbing liquid along the scrubber, after which the washed filter media is returned to the filter bed zone. in order to maintain the zone above this, that a separate transfer of the contaminated filter medium takes place in the filter bed belt; upstream of the jet and that the washing of the contaminated filter medium upstream of the washing path takes place as it flows against the flow of the filtered liquid phase used as the washing liquid, which liquid phase is taken from said zone of the filtered liquid phase to the washing path. Method according to Claim 1, characterized in that during the washing the relative speed between the filter medium and the washing liquid increases momentarily at least once. Method according to Claim 1 or 2, characterized in that the flow rate of the filter medium is braked at least once during the washing. Method according to claims 2 and 3, characterized in that said braking takes place in the zone of the washing track and is followed by said momentary increase. Method according to one of the preceding claims, characterized in that the compressed particles of the filter medium caused by fouling are decomposed before washing. Method according to one of the preceding claims, characterized by adjusting the amount of washing liquid flowing in the washing path. Method according to Claim 6, characterized in that the amount of washing liquid is adjusted by adjusting the outflow of the contaminated washing liquid obtained in the washing. 10 62956 Method according to Claim 6, characterized in that the amount of washing liquid is adjusted by changing the level of the zone of the filtered liquid phase. Method according to one of the preceding claims, characterized by adjusting the amount of filter medium transferred to the base path by knowing the amount or pressure of the suspension before it is introduced into the filter bed zone. A method according to any one of the preceding claims, wherein the air is used to transfer the contaminated filter medium, characterized in that the air infiltrated from the air introduced into the contaminated filter medium prior to transfer is prevented from entering the filtration bed zone by collecting it before and draining it. A filter device for carrying out the method according to any one of the preceding claims, which filter device comprises a zone in the vertical filter device which is a granular filter medium and forms a filter layer, an inlet for the suspension or emulsion to be filtered, the inlet being in a ratio providing an upwardly through the filtration bed, a space below the inlet and in free communication with the filtration bed zone, into which the filter medium is continuously introduced in a downward flow through the filtration bed zone, and a for washing between the filter medium and the washing liquid and from which the washed filter medium is returned to the filtration layer zone to the upper side, characterized in that a zone (θ) of the filtered liquid phase obtained by filtration is held above the filtration layer zone (1), that the conveying device (10) is a tube (12) drawn from said space through the filtration layer zone (1) (13), and that the lower part of the washing device (15) is provided with at least one inlet (20) connected to the zone (θ) of the filtered liquid phase. 11 62956 Filtration device according to Claim 11, characterized in that the washing device (13) is immersed in the zone (8) in the filtered liquid phase and its inlet opening (20) is located above the filtration layer zone (1). Filtration device according to Claim 11 or 12, characterized in that the conveying device (10) and the washing device (13) are located centrally in the device. Filtration device according to Claim 12 or 13, characterized in that the washing device (13) is a tube (16), the inlet opening of the filtered liquid phase into the washing tube (16) being formed by an open lower end (20) thereof. Filtration device according to Claim 14, characterized in that the washing tube (16) is arranged concentrically around the upper part of the transport tube (12). Filtration device according to one of Claims 11 to 13, characterized in that the washing device (13) is provided with at least one element (17.1θ) for momentarily increasing the speed of the washing liquid. Filtration device according to one of Claims 11 to 16, characterized in that the washing device (13) · η is provided with at least one member (18) for braking the speed of the filter medium. Filtering device according to claims 16 and 17, characterized in that said speed-increasing member is the same as said braking member. Filtration device according to claim 18, characterized in that said speed-increasing and braking member (18) is a perforated plate extending over the cross-section of the washing device. Filtration device according to Claim 19, characterized in that at least two plates (ΐθ) are arranged in the washing device at a distance from one another, the holes (19) in the two plates being offset relative to one another. Filtration device according to one of Claims 11 to 20, characterized by a member (17) in the upper part of the washing device for disintegrating the compressed filter media particles caused by soiling. Filtration device according to one of Claims 11 to 21, characterized in that the washing device (13) is provided with a washing liquid outlet (21) which is adjustable in height and / or width for adjusting the amount of washing liquid. 12 62956 Filtration device according to one of Claims 11 to 22, characterized in that the conveying pipe (12) is provided with an air inlet opening for conveying the contaminated filter medium to the washing device, the air being introduced through the scrubber (1j) . Filtration device according to claim 23, characterized by a member (24) arranged above said air intake opening to collect air penetrating into the contaminated filter medium in the space. Filtration device according to claim 24, characterized in that said air collecting member (24) also acts as a control means for guiding the filter medium down into said space. Filtration device according to claim 24 or 23, characterized in that said air collecting member (24) is an inverted funnel tightly arranged around the conveying tube (12) and provided with an outlet open at its inner end into the distribution channel (13). for air, which duct is drawn through the filtration layer zone (1) separately from the filtration layer. Filtration device according to Claim 26, characterized in that the distribution channel (15) is pulled upwards along the conveying pipe (12) through the washing device (13). 2Θ. Filtration device according to one of Claims 11 to 27, characterized in that at least the part of the device surrounding the filtration layer (1) and the filtered liquid phase zone (θ) is constructed of flat walls (2) which form a polygonal shape, preferably a hexagonal shape, and that a plurality of such devices are connected in a single unit so as to be located immediately adjacent to each other to form a filtration apparatus in which the opposite walls (2) of adjacent devices are removed and the other walls form a unitary outer wall (28) or other walls of the filtration apparatus. along is fitted such an outer wall. Filtration device according to Claim 29, characterized in that a common outlet channel (26) for the liquid phase flowing out of the zone of the filtered liquid phase is arranged for a plurality of adjacent filtration devices in the group. 13 62956 A filtering device according to claim 29, characterized in that the filtering devices in the group are arranged in at least two rows (29) and a common outlet channel (26) is provided for all the filtering devices in each row. Filtration device according to one of Claims 28 to 50, characterized in that a common outlet channel (27) for the contaminated washing liquid obtained in the washing is provided for a plurality of filter devices which are in order in the group. Filtration device according to Claims 30 and 31, characterized in that a common outlet channel (27) for the contaminated washing liquid is provided for all filtration devices included in the adjacent rows (29). 14 Patent: 6295 6