SEPARATION APPARATUS AND COMPONENTS THEREOF

Abstract: The invention relates to an improved separation device in which a plate unit containing the filter comprises a separate abutment ring (20) and a cassette (30) which can be easily connected thereto, said cassette comprising at least one filter (15) together with, if required, a frame belonging thereto so as to support the filter. If the filter consists of a flexible membrane, this is fitted into a special frame. However, if the filter is a rigid, self-supporting filter of a porous material, for example, a ceramic filter or the like, a separate frame is not needed to support the filter. The separation device according to the present invention does not require a separate outer cover.

Description: SEPARATION APPARATUS AND COMPONENTS THEREOF The present invention relates to a device based on cross flow membrane filtration for separation of separable cons¬ tituents from a liquid medium. Additionally the invention relates to a filter cassette and an abutment ring intended to be used in said separation device. In a cross flow filter a liquid is supplied to a chamber comprising at least one dynamic membrane. The liquid being supplied is divided into a permeate flow penetrating the dynamic membrane and a reject flow flowing along the filter without penetrating it. Cross flow filtration apparatuses are described in the patent literature, for example, in the Swedish Publication Prints SE 451429, 457607, 459475, 463241 and 465040. Methods based on the use of such apparatuses are successfully applied for separating solid constituents from a liquid phase and for separation of liquid from liquid, for example, for separation of oil from water. The above mentioned Publication Print SE 463241 describes such a fluid/fluid separation method. SE 459475 describes a separation device comprising several adjacently arranged cells. Figure 1 shows a section of such a stack. Each unit or cell consists of a plate 10 provided with a central opening through which extends a shaft 11 provided with rotor blades 12. On each side of the plate 10 a filter 15 is fastened by means of clamp rings 13 and 14, The liquid to be treated is supplied through a common channel 16 formed by through-holes in the plates 10. The liquid stream is supplied into the chamber 17, whereby part of it (the permeate) passes through the filter and is gathered via channels 18 in the plate to be finally discharged through a common outlet (not shown). The portion of the liquid flow (the reject) which does not penetrate through the filter, is discharged through holes in the plate. Said holes form a common conduit 19 for the outgoing reject. The liquid is pushed across the filter surface 15 by means of the rotor blades 12. When the filter is changed in the above mentioned device the plate containing the filter to be changed is taken out. The removing of the plate itself from the stack is carried out relatively easy in a way more closely described in the Publication Print in question. However, the removal of the used filter from the plate and inserting of a new filter is very time consuming and hard because the filter is fastened by means of numerous screws to the clamp rings securing the filter to the plate. This causes for its part long shutdowns in the separation plant. According to the present invention a separation device is achieved in which it is possible to change the filters in a very easy and fast way. The invention is based on the idea of instead of fastening the filter directly onto the plate it is fastened on a frame constituting a separate unit or a so called filter cassette. Alternatively, the filter can be a rigid, self-supporting filter of a porous material, for example, a ceramic filter or the like. In this case a separate frame is not required in order to support the filter, instead the filter itself comprises the cassette. The cassette can easily be fitted in an abutment ring intended for the purpose. Thus the abutment ring and the cassette replace the above described plate provided with filters. The filter cassettes can be produced in advance and kept in stock to be at hand when the filter needs to be changed. An essential advantage of the present invention is that the abutment rings together with the end plates, between which the abutment rings are pressed together, form the outer cover of the apparatus. Said construction is very advantageous with respect to mounting, especially when it comes to high filtration units. If the filtration unit would be positioned inside a separate cover the mounting of the cover would require a free space above the filtration unit corresponding at least to the height of the cover. Alternatively it could be possible to divide the cover vertically in separate portions, but such a solution would not be appropriate in practice. The abutment ring according to the present invention forms a portion of the outer cover of the apparatus corresponding to the thickness of the ring. The fitting and removal of said abutment rings requires minimal working space. Another essential feature of the abutment rings is that they form channels for the liquid streams in the separation device. Adjacent abutment rings form a common channel for the ingoing liquid flow, another common channel for the outgoing reject flow and a third common channel for the outgoing permeate. In addition each separate abutment ring contains channels for distributing incoming liquid over the filter and for gathering the reject flow which has not passed through the filter. Additionally each abutment ring comprises a channel for gathering permeate from the filter. A third essential feature of the abutment rings is that they form the frame for the separate cassettes, whereby the thickness of the abutment rings determines the mutual distance between the separate cassettes. The characteristic features of the invention are disclosed in claims 1, 10 and 16. The invention will be described in greater detail with reference to the enclosed drawings, in which Figure 1 shows a section of a separation device according to prior art, Figure 2 shows a section of a separation device according to the invention, Figure 3 shows an enlargement of a detail in figure 2, Figure 4 shows a partial section of a filter cassette, Figure 5 shows a cross-section of the filter cassette along the line A-A in figure 4, Figure 6 shows an abutment ring for the filter cassette, Figure 7 shows a cross-section along the line B-B in figure 6, Figure 8 shows a cross-section of the abutment ring along the line C-C in figure 6, Figure 9 shows an abutment ring according to figure 6 together with a filter cassette according to figure 4 fitted into it, Figure 10 shows an alternative embodiment of the support plate for the filter cassette, Figure 11 shows a cross-section of the support plate according to figure 10, and Figures 12A - 12C showing sections of the separation device illustrate alternative ways of arranging the liquid flow in said device. Figure 2 shows a section of a separation device according to one embodiment of the invention. The separation device consists of a number of adjacently placed cells or units. The stack can comprise horisontal units, as shown in the figure, or vertical units, which is advantageous in liquid/liquid separation. The units comprise an abutment ring 20 to which a filter cassette 30 is connected, whereby the cassette at its periphery is fitted between two adjacent abutment rings. The cassette, which is shown more closely in figures 4 - 5, is a circular plate with a center opening 31 for the rotor shaft 11 supporting rotor wings 12. Clamp rings 32 extend around the center opening 31 and act as a sealing and keep the cassette together. In the embodiment shown in the figure the cassette contains two filters 15. The liquid to be treated is supplied (not shown in figure 2) into the chamber 17, i.e. the area which according to this embodiment is delimited in the direction of the stack by the filter surfaces between the two cassettes. (The chamber is delimited by the filter of the cassette and the end plate at the ends of the stack). The permeate (P) is conveyed out to the periphery of the cassette and flows into the permeate channel 21 of the abutment ring, said channel extending along said abutment ring. The permeate is discharged through a common channel 23 formed by through-holes in the adjacent abutment rings 20. The reject is discharged from the chamber 17 through a common channel which is also formed by through-holes in the adjacent abutment rings (not shown in figure 2). The periphery of the cassette is provided with a sealing 33 (see figure 3) so that the liquid chamber 17 is separated from the permeate channel 21. A sealing groove 22 with a sealing 29 extends in the abutment ring on the outside of the permeate channel (figure 3). The adjacent units are pressed together between the bottom plate 50 and the cover (not shown) in a manner known per se. Figure 3 is an enlargement showing more clearly the fitting of the periphery of the cassette between adjacent abutment rings 20. Figure 4 shows the filter cassette 30 in a partly sectional view at the periphery. A clamp ring 32 extends around the center opening 31 keeping the inner edge together. Under the filter 15, which in this embodiment is a flexible membrane, for example, a porous textile cloth, paper cloth or a dynamic membrane of the type described in the above mentioned patent publications, is a support net 40 separating the filter 15 from a massive support plate 41 lying under the support net 40. Radially directed grooves 42 extend in the periphery of the support plate discharging the permeate from the cassette. A sealing 33 extending along the periphery of the cassette is to some extent directed inwards along each side of the cassette. Figure 5 shows a cross-section of the cassette 30 at the periphery along the section line A-A in figure 4. In this embodiment the cassette contains two filters 15 separated by a support net 40, respectively, from the support plate 41 of the cassette. The support net 40 keeps the space between the support plate 41 and the filter 15 stretched so that the permeate can flow towards the periphery where it is gathered in the radial grooves 42 to finally be discharged from the cassette. The end edge 34 of the sealing 33 is provided with radially directed holes 35 for discharging the permeate P from the cassette. The plane sections 36 of the sealing profile are, however, not perforated. The ends 37 of the sealing profile, which are directed inwards in the direction of the cassette, are curved in against the filter surface in an angle exceeding 90 degrees so that the edges 37 touch the filter 15 and are obliquely directed outwards towards the periphery of the cassette. By means of this construction the edges 37 will be pressed outwards and obliquely against the filter surface when the sealing profile 33 is pressed together between two adjacent abutment rings . Hereby a tightening of the filter is obtained. In figure 5 the liquid flows are indicated with arrows. The incoming liquid flow is designated with I and the outgoing permeate with P. Figure 6 shows an abutment ring 20 with a through-hole 16 for the incoming liquid flow and another through-hole 19 for the outgoing reject. When several similar abutment rings 20 are placed against each other in a stack, the holes 16 and 19, respectively, will form through-channels. The holes 16 and 19, respectively, communicate with the liquid chamber 17 through channels in the abutment ring (24 and 25, respectively). Additionally, the abutment ring has a through-hole 23, which together with similar holes in adjacent abutment rings forms a common channel for the outgoing permeate. A permeate channel 21 gathering the permeate being discharged from the filter cassette, extends in the same manner as the sealing groove 22 along the whole abutment ring. Figure 7 shows a section of the abutment ring along the section line B-B in figure 6. Figure 8, which is a section along the line C-C in figure 6 shows also the design of the channel 24 viewed from the side. Figure 9 shows an abutment ring 20 and a filter cassette 30 fitted into it. The permeate P flowing under the filter 15 is gathered by the permeate channel 21 of the abutment ring to finally be discharged through the outlet 23. The liquid flow I supplied through the inlet channel 16 and the channel 24 of the abutment ring is spread across the filter surface 15 by means of the rotor wings 12 or similar means. The reject R is gathered from the filter surface 15 and discharged through the channel 25 extending inside the abutment ring 20 and flows into the common reject outlet 19. Figure 10 shows an alternative embodiment of the support plate 41 in which sid plate comprises two thin plates 41a and 41b joined together. The sides of the plates 41 and 41b facing the filter are smooth. The sides of the plates 41a and 41b facing each other are provided with channels with branches which flow into the periphery of the support plate 41. The liquid which has passed the filter membrane 15 (not shown in figure 10) flows into the channels 42 through slits 43 in the plates, said slits communicating with said channels. According to the arrangement in figure 10 the channel system is alternately located in the upper plate 41a and the lower plate 41b. This is best seen in figure 11 which shows a cross-section of the support plate according to figure 10. It is evident that the channels 42 in plates 41a and 41b, respectively, can be arranged in alternative ways. The flow space between the plates 41a and 41b, respectively, can also be achieved in such a way that a net or a porous material is placed between the plates . Alternatively the compact plates 41a and 41b can be replaced with a porous support plate which in itself allows a filtrated liquid to flow through. By means of the abutment ring according to the invention it is possible to vary the flow of the liquid to be treated. Figures 12A - 12C show alternative ways to arrange the liquid flow. Figure 12A shows parallel driving, where the supplied liquid flows in the common supply channel 16 formed by the abutment rings after which the liquid stream is evenly divided in the channels 24 in the separate abutment rings and flows into the space 17 between the filter cassettes. The reject flow is discharged from the space 17 through channels 25 in the separate abutment rings and flows out in the common outlet channel 19. A modified version of parallel driving is shown in figure 12B where every other inlet channel 24 is blocked with plugs 26 and every other outlet channel 25 is also blocked with plugs 27, but in such a way, however, that it is either the channel 24 or the channel 25 in an abutment ring which is blocked. In this case the liquid flowing into the space 17 through the channel 24 will flow through the center opening of the filter cassette to the opposite side of the cassette to be then discharged through the channel 25 in the next abubment ring. This embodiment increases the turbulence and thereby improves the filtration. Figure 12C shows a separation device divided into a number of units connected in series. The division has been achieved by blocking the inlet channel 16 and outlet channel 19, respectively, by means of a plate 28 between two adjacent units. The center opening has also been blocked by means of a ring 28a. As a result of this, the reject from the first unit will be the flow supplied into the following unit. By means of this arrangement a high concentration of solid material is achieved in the reject flow which is finally discharged from the separation device. It is obvious that the three ways of driving mentioned above can be combined in different ways in one separation device. The separation device according to the present invention can be used both for separating solid particles, solved high-molecular substances and colloids from liquid and for separating a liquid from another liquid, for example, in the way described in SE 463241. The filter material is chosen according to the separation process to be carried out. The filter membrane itself can be provided with one or more layers of a porous material when required, for example, of the type described in the above mentioned patent publications . In the embodiment described above the filter cassette is fitted between two abutment rings. Naturally the filter cassette can also be fitted in only one abutment ring, but the described alternative is to be preferred. The filter cassette does not necessarily have to have a frame comprising a support plate and a support net in the way described above. The components of the frame are chosen on the basis of the properties of the filter membrane, possible porous covering, etc. The essential purpose of the frame is to give the filter stability, ensure that the filter is kept stretched and to enable fastening of the cassette in the abutment ring. Alternatively the filter can be a rigid, self-supporting filter of a porous material, for example, a ceramic filter or the like. In this case a separate frame is not required in order to give the filter stability because the filter itself forms the cassette. In the embodiment according to figure 2 the separation device is provided with a rotor. This does by no means mean that the invention is restricted to the employment of rotor. It is obvious that the rotor can be replaced with another device in order to achieve sufficient liquid turbulence and transport. As examples of such equipment transmitters sending sound waves of varying frequences can be mentioned; transmitters of sound waves of varying frequences together with a device for accomplishing electric fields; and a rotor together with a device for accomplishing electric fields. The above embodiments can also be combined. It is obvious to a person skilled in the art that the various embodiments of the invention may vary within the enclosed claims.

Claims: CLAIMS 1. A device for separation of constituents, separable in a filter, from a liquid medium containing such constituents, whereby said device comprises a cell or a stack of a plurality of adjacent cells, whereby each cell consists of - a plate unit containing -- at least one filter (15), -- at least one inlet (16) for supplying the liquid medium into a chamber (17), — at least one outlet (19) for discharging part of the liquid medium, the reject, whereby said inlet and outlet are positioned on the first side of the filter, -- at least one outlet (23) on the second side of the filter for discharging a liquid medium which has passed through the filter (the permeate), whereby the inlet (16) and the outlets (19 and 23) in adjacent plate units, respectively, form uniform channels extending through the device for said flows, and - equipment arranged on the first side of the filter for achieving liquid turbulence and transport, characterized in that each plate unit consists of a separate abutment ring (20) and an easily connectable cassette (30) comprising at least one filter (15) and, if necessary, a frame belonging to it in order to give the filter stability. 2. The device according to claim 1, characterized in that each cassette contains at least one filter and that each cassette is fitted between two adjacent abutment rings. 3. The device according to claim 2, characterized in that the frame of the cassette comprises of a support plate (41) and fastening elements for fastening two filters on each side of the support plate. 4. The device according to claim 3, characterized in that the support plate is a massive piece in the periphery of which radial grooves (42) are formed for discharging the permeate from the cassette, and that support nets (40) are applied on each side of the support plate, whereby the two filters individually are adjacent to a support net. 5. The device according to one of claims 1 - 4, characterized in that the abutment ring (20) is provided with a channel (21) for receiving the permeate from the cassette and passing it on to the permeate outlet (23). 6. The device according to one of claims 1 - 5, characterized in that the periphery of the cassette is provided with an elastic sealing profile (33) extending at some distance inwards on each side of the cassette and which at least partially fastens the filter or filters to the frame of the cassette. 7. The device according to claim 6, characterized in that the end edge (34) of the sealing profile is provided with radially directed holes (35) for discharging the permeate from the cassette. 8. The device according to claim 7, characterized in that the edge (37) of the sealing profile, which is directed in the direction towards the center of the cassette, is curved in an angle > 90° so that the edge (37) comes into contact with the filter and is directed obliquely outwards towards the periphery of the cassette, whereby the edge (37) designed in this way stretches the filter when the sealing profile (33) is pressed together. 9. The device according to one of claims 1 - 8, characterized in that the abutment ring is provided with channels (24, 25) extending in the plane of the abutment ring and inside the abutment ring, whereby one channel (24) connects the liquid chamber (17) to the inlet (16) for a supplied liquid flow and the other channel (25) connects the liquid chamber (17) to the outlet (19) for the reject f low . 10. A filter cassette (30) comprising at least one filter (15) and possibly a frame belonging to it, whereby the cassette (30) is intended to be used in the device according to claim 1, characterized in that - the filter is a rigid, self-supporting filter of a porous material, for example, a ceramic filter, or - the filter is a flexible membrane fitted in a frame comprising of a support plate (41) and a fastening element for fastening the filter or filters to the support plate. 11. The cassette according to claim 10, characterized in that the support plate (41) is an essentially circular, massive piece in the periphery of which radial grooves (42) are formed in order to discharge the permeate from the cassette, and that on each side of the support plate is provided support nets (40), which in turn are adjacent to a filter, respectively. 12. The cassette according to claim 10, characterized in that the support plate (41) consists of two adjacent plates (41a and 41b) between which a flow space (42) flowing out into the periphery of the support plate is arranged, and that the plates are provided with slits (43) communicating with said space (42). 13. The cassette according to claim 10, 11 or 12, characterized in that the periphery of the cassette is provided with an elastic sealing profile (33) extending some distance inwards on each side of the cassette and which at least partially fastens the filter or filters to the frame of the cassette. 14. The cassette according to claim 13, characterized in that the end edge (34) of the sealing profile is provided with radially directed holes (35) for discharging the permeate from the cassette. 15. The cassette according to claim 14, characterized in that the edge (37) of the sealing profile which is directed towards the center of the cassette is curved in an angle > 90° so that the edge (37) comes into contact with the filter and is directed obliquely outwards in the direction of the periphery of the cassette, whereby the edge (37) designed in this way stretches the filter when the sealing profile (33) is pressed together. 16. An abutment ring (20) intended to be used in the device according to claim 1, characterized in that it is provided with at least - one channel (21) for receiving the permeate from the cassette and passing it on to the permeate outlet (23) in the abutment ring, and - channels (24, 25) extending in the plane of the abutment ring and inside the abutment ring, whereby one channel (24) connects the liquid chamber (17) to the inlet (16) for a supplied liquid flow, and the other channel (25) connects the liquid chamber to the outlet (19) for the reject flow.

Inventors: HENTTONEN VESA, KARLSSON CLAES, LEIMU PASI, PAATERO JAAKKO, SUIKKI MIKKO, TEPPLER MILAN, HENTTONEN, VESA, KARLSSON, CLAES, LEIMU, PASI, PAATERO, JAAKKO, SUIKKI, MIKKO, TEPPLER, MILAN
Applicants: HENTTONEN VESA, KARLSSON CLAES, LEIMU PASI, PAATERO JAAKKO, RAISIO CHEM OY, SUIKKI MIKKO, TEPPLER MILAN, HENTTONEN, VESA, KARLSSON, CLAES, LEIMU, PASI, PAATERO, JAAKKO, RAISIO CHEMICALS OY, SUIKKI, MIKKO, TEPPLER, MILAN
Application year: 1997
Main classification: B01D29
IPC codes: B01D25, B01D29, B01D63, B01D65