Manifold and manifold segment for tangential flow filtration apparatus

Abstract: A tangential flow filtration apparatus which utilizes a single manifold formed of manifold segment or manifold segments to introduce liquid to be filtered into the apparatus and to remove a filtrate stream and a retentate stream from the apparatus is provided. A plurality of filtration modules are stacked between the manifold and a plate. Holes and sealing means are provided within the filtration modules to effect flow of the filtrate, retentate and incoming liquid through the stack and manifold while preventing admixture of the filtrate with the retentate or the incoming liquid. All manifold segments with the exception the most downstream manifold segment or most upstream manifold segment from the point of introducing incoming liquid must have a filtrate to exit from both ends of the manifold segment. The most downstream or the most upstream manifold segment also can have filtrate exits from both of its ends.

Description: BACKGROUND OF THE INVENTION This invention relates to an apparatus for fluid filtration as defined by the features of the preamble of claim 1, wherein filtration is effected by tangential flow of the liquid across a filter surface. Prior to the present invention, liquids, primarily aqueous liquids have been filtered by tangential flow segments wherein a plurality of filters are stacked between two manifolds, one at the bottom of the stack and one at the top of the stack. The filtration module stack comprises a collection of one or more filtration modules and associated intermodule gaskets. The filters are separated by appropriate screens and liquid impervious layers to permit liquid flow, as well as filtrate and retentate flow into and from the stack. In addition, flow holes are provided through the layers within the stack. The holes are sealed appropriately to prevent admixture of filtrate with incoming liquid or retentate. The manifolds in each segment are designed so that filtrate is removed from both the top and bottom manifolds while incoming liquid is introduced into one manifold and retentate is removed from the second manifold. This manifold arrangement necessitates fittings to both manifolds in order to supply and remove liquid to and from the stacks. This is undesirable since additional manipulative steps for removing and connecting the fittings are required when it is desirable to replace the filtration elements forming the stack. In addition, the use of two manifolds to remove filtrate from the stack undesirably increases the filtrate volume retained within the stack. Furthermore, the requirement of two manifolds is undesirably expensive. It has been proposed in U.S. Patent 4,849,102 to provide a manifold for a plurality of filtration segments. However, this manifold arrangement is limited since only two filtration segments can be accommodated while avoiding the need for conduits external the manifold . That is, when more than two filtration segments are utilized, external connecting conduits are required. From EP-A-345 209 A3 there is known a bidirectional ultrafiltration apparatus in which a pair of membrane ultrafiltration cells are mounted one on each of the front an back surfaces of a central bidirectional manifold having an exit an an entrance conduit connector on the same side wall of the manifold. Although plural manifolds may be connected to each other in the filter system for increased filtering capacity, the multiple filtration modules for interconnection require external conduits (cf. Figure 6) to provide the necessary fluid communication between the filtration modules and the manifolds for directing feed, retentate and filtrate so that the overall apparatus comprising multiple filtration modules will be comparatively bulky and will require a large space. Accordingly, it would be desirable to provide an apparatus for fluid filtration comprising a manifold or a plurality of tangential flow filtration segments which utilizes only one manifold and which accommodates any number of a plurality of filtration segments without the need for conduits external of the manifold . Such an arrangement should greatly reduce the number of sealed fittings and should reduce the required apparatus volume for processing a given volume of liquid. OBJECT OF THE INVENTION According to the invention there is provided an apparatus for fluid filtration as defined in claim 1. In accordance with this invention, an apparatus for fluid filtration is provided which can be in fluid communication with any number of a plurality of filtration segments without the need for conduits external of the manifold . The apparatus is comprised of one or a plurality of manifold segments which interconnect with one another to form a stack of manifold segments. A manifold segment comprises a single piece which holds filtration modules on each side and has internal conduits for the feed, filtrate and retentate. All manifold segments with the exception of the most downstream or most upstream manifold segment from the point of introducing incoming liquid must have a filtrate exit from both ends of the manifold segment. The most downstream or the most upstream manifold segment also can have filtrate exits from both of its ends. The retentate exit and incoming liquid inlet can be at the same ends of the manifold segments. The filtrate from filtration segments connected to the manifold is collected from all filtrate exits from the stack and the feed fluid is in fluid communication with retentate within the stack. The filtration segments are secured to the manifold in a manner so that filtrate is separated and collected without admixing with the feed or the retentate. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an isometric view of the apparatus of this invention in use. Fig. 2 is a side view of a manifold apparatus of this invention suitable for parallel feed to the manifold segments. Fig. 3 is a side view of a manifold apparatus of this invention suitable for serial feed to the manifold segments. Fig. 4 is a side view of a manifold apparatus of this invention which combines both serial and parallel feed to the manifold segments. Fig. 5 is a side view of a manifold apparatus of this invention which combines both serial and parallel feed to the manifold segments and which includes a manifold segment having one filtrate exit. Fig. 6 is a cross sectional view of the apparatus of Fig. 2 taken along line 6-6. Fig. 7 is a cross sectional view of the apparatus of Fig. 3 taken along line 7-7. Fig. 8 is an exploded view of a filtration module suitable for use with this invention. Fig. 9 illustrates the function of a filtration module suitable for use with this invention. Fig. 10 is a side view of a manifold segment useful alone as a manifold of this invention. Fig. 11 is a side view of an alternative manifold segment useful alone as a manifold of this invention. Fig. 12 is a side view of an alternative manifold segment useful alone as a manifold of this invention. DESCRIPTION OF SPECIFIC segmentS Referring to Fig. 1, the manifold apparatus of this invention includes one or a plurality of center manifold segments 2, 4 and 6 connected together and which can be secured to manifold frame 8. Each end of the stack of manifold segments 2, 4 and 6 is provided with a fitting block 10 or 12 to provide suitable inlets and outlets to the manifold apparatus. A fluid feed inlet 14 and a filtrate outlet 16 are provided on fitting block 12, each of which are in fluid communication with suitable fluid storage means (not shown). A retentate outlet 18 and a filtrate outlet 20 are provided on fitting block 10, each of which are in fluid communication with a suitable fluid storage means (not shown). A plurality of filtration modules 22 are secured to manifold segments 2, 4 and 6 by means of a plate 19 and a plurality of compression assemblies 24 such as bolts. Referring to Figs. 2, and 6, the gaps between fitting blocks 10 and 12 and manifold segments 2,4 and 6 are provided with conventional gasket means to effect desired sealing of filtrate from retentate and feed. A parallel feed and retentate arrangement is shown in Fig. 2. Fluid feed is introduced through inlet 14, feed channel 25 and into filtration modules 22 through fluid feed inlet means 26. Filtrate is removed from filtration module 22 through filtrate outlet means 28 and 29 positioned on opposite sides of manifold segment 2, 4 and 6, filtrate channel 21 and filtrate outlets 16 and 20. Outlet means 28 do not extend through manifold plates 30, 32 and 34 while outlet means 29 extend through manifold plates 30, 32 and 34 to fluid communication with filtrate outlets 16 and 20. Filtrate is removed from the manifold through filtrate outlets 16 and 20. The filtrate outlet means 28 and 29 are connected by slots 31 in manifold plates 30, 32 and 34. Retentate is removed from the filtration modules 22 through retentate outlet means 33 comprising holes in plates 30, 32 and 34, retentate channel 23 and retentate outlet 18. Holes 35 are provided in the manifold segments 2,4 and 6 for bolts or tie rods to secure the filtration modules 22 to the manifold segments 2, 4 and 6. Tie rods 37 and nuts 39 are utilized to secure the manifold segments 2, 4 and 6 together. Referring to Figs. 3 and 7, where like elements to those of Fig. 1 and 2 are numbered the same, manifold segments 3, 5 and 7 are similar to the manifold segments 2, 4 and 6 of Fig. 2 except that only the feed passages 9 and retentate passages 11 pass only through a portion of the thickness of manifold segments 3, 5 and 7 thereby to effect a serial flow through the manifold segment rather than parallel flow. Referring to Figs. 4 and 5 wherein like elements shown in Figs. 2 and 3 are represented by the same numeral reference as shown in Fig. 4, the manifold apparatus utilizes manifold segments to effect both parallel and serial flow of feed through the manifold apparatus. Manifold segments 6, 7, 5 and 2 are provided. Feed enters manifold segment 6 and an attached filtration segment (not shown) through liquid inlet 14 and fluid inlet means 26. Filtrate is removed from manifold segment 6 through filtrate outlet means 29 and filtrate outlets 16 and 20. Retentate passes from manifold segment 6 through conduit 13 and into manifold segment 7 through conduit 27. Feed passes from manifold segment 6 from conduit 17 into manifold segment 7 through conduit 27. Feed passes from conduit 27 through feed inlet means 26 into a filtrate module (not shown). Filtrate is removed from manifold segment 7 through filtrate outlet means 29 and filtrate outlets 16 and 20. Retentate is removed from manifold segment 7 through retentate channel 23 and into feed channel 21 of manifold segment 5. Thus, feed and retentate pass in parallel flow through manifold segments 6 and 7. Retentate from manifold segment 7 becomes feed in segments 5 and 2 so that the feed in segments 5 and 2 is removed as retentate through conduits 23 and 25 and retentate outlet 18. Filtrate is removed through filtrate outlet means 29 and filtrate outlets 16 and 20. Thus the feed between manifold segments 7 and 5 become series flow and the feed between manifold segments 5 and 2 becomes parallel flow. The arrangement shown in Fig. 5 is the same as that shown in Fig. 4 except that there is only one filtrate outlet 16 rather than two filtrate outlets 16 and 20. End 27 of outlet 16 is capped within manifold segment 1. The flow paths of feed and a retentate is the same as that described above for Fig. 4. Only one filtrate outlet 16 can be utilized in segment 1 so long as two filtrate outlet means are utilized in segments 5, 6 and 7. In the same manner, only one filtrate outlet can be utilized in the arrangements shown in Figs. 2 and 3. Referring to Fig.8, a filtration module useful with the manifold of this invention is described. A filtration element 40 is positioned between manifold 47 and plate 19. Manifold 47 is provided with liquid inlet 14, filtrate outlets 16 and 20 and retentate outlet 18. The manifold 47 includes a plurality of feed inlet means 42 and a plurality of retentate outlet means 44. One set of filtrate outlet means 28 is provided on one end of the manifold 7 while a second set of filtrate outlet means 28 is provided on the opposite end of manifold 47. The filtrate outlet means 28 are connected to filtrate outlets 16 and 20 by filtrate conduit paths 46 and centrally located means 29. The paths 46 are of a size which permits filtrate to flow therethrough while avoiding sagging of a filtrate screen (not shown) into the paths 46, typically about 15.2 to 3 mm (0.6 to .12 inch) wide. The filtration segment 40 includes holes 48 which communicate with liquid inlet means 42 and holes 50 which communicate with permeate outlet means 28. As seen in Fig. 9, the filtrate side 52 of the filter layer 52 having mesh spacer 54 in contact therewith is exposed. The filtration segment 40 is also provided with holes 56 which communicate with retentate outlet means 44. The plate 19 serves as a seal for the top surface of the filtration module 40. Referring to Fig. 9, the filtration module 40 includes a filtrate spacer 54, a filter layer 52, a retentate spacer 60 and a filter layer 62 with a second filtrate spacer 54 (not shown) and which can contact conduit paths 46. The liquid feed represented by arrow 58 passes through holes 48 in layer 62 into spacer 60. A portion of the liquid passes through spacer 60, as represented by arrow 64 and through filter 52 as represented by arrow 66. The remaining portion of the incoming liquid passes upwardly as represented by arrow 68, through holes 48 in filter 52, holes 48 in filtrate spacer 54 and into the next adjacent filtration member (not shown) wherein it proceeds as described above with reference to filtration member 40. The filtrate passes into holes 50 and passes in a direction as shown by arrows 70 and 72 toward filtrate outlet means 28 (Fig. 8). The retentate passes across retentate spacer 60 as shown by arrows 64 and 65, through holes 56 and to retentate outlet means 44 (Fig. 8) in a direction as shown by arrow 78. The filtrate passes into holes 28, grooves 46, outlet means 29 (Fig. 8) toward filtrate outlets 16 and 20. The retentate passes through holes 44 and to rententate outlet 18. Referring to Fig. 10, feed fluid is introduced into manifold segment 4 through feed inlets 14 and retentate removed from retentate outlets 18. Filtrate is removed from filtrate outlets 16 and 20. Feed enters filtration modules (not shown) through feed inlet means 26 from feed channel 25 and retentate is removed through retentate outlet means 33, retentate channel 23 and retentate outlet 18. Referring to Fig. 11, feed fluid is introduced into manifold segment 3 through feed inlet 14 and retentate is removed from retentate outlet 18. Filtrate is removed from filtrate outlets 16 and 20 through feed inlet means 26 from feed channel 25 and retentate is removed from retentate outlet means 33, retentate channel 23 and rententate outlet 18. Referring to Fig. 12, feed fluid is introduced into manifold segment 6 through feed inlets 14 and retentate is removed from retentate outlet 18. Filtrate is removed from filtrate outlets 16 and 20. Feed enters filtration modules (not shown) through feed inlet means 26 from channel 25 and retentate is removed through retentate outlet means 33, retentate channel 23 and retentate outlet 18. The manifold segments shown in Fig. 10, 11 and 12 can be utilized as a manifold or with other manifold segments without the need for conduits connecting the manifold segments which conduits are external of the manifold segments.

Claims: An apparatus for fluid filtration which comprises a plurality of manifold segments (2, 3, 4, 5, 6, 7) connected to each other, each of said manifold segments having first and second opposing surfaces and third and fourth surfaces spaced apart from each other and positioned between said first and second surfaces, each of said manifold segments being connected at said third and fourth surfaces to a corresponding filtration module (22) capable of separating a feed fluid into a retentate fluid and a filtrate fluid, characterized in that at least one of said plurality of manifold segments (2, 3, 4, 5, 6, 7) has the first surface which includes a feed port (14) and a first filtrate port (16), the second surface which includes a retentate port (18) and a second filtrate port (20), and the third and fourth surfaces which include a feed fluid conduit (25, 26) in fluid communication with both said feed port (14) and said filtration module (22), a retentate conduit (23, 33) in fluid communication with said retentate port (18) and said filtration module (22), and a filtrate conduit (21, 28, 29, 31, 46) in fluid communication with each filtration module (22), said first filtrate port (16) and said second filtrate port (20), and each of said manifold segments being stackably interconnected to one another by connecting said first surface of said at least one manifold segment to said second surface of an adjacent manifold segment to effect fluid communication between said feed fluid conduit (25, 26), said retentate fluid conduit (23, 33) and said filtrate fluid conduit (21, 28, 29, 31) of interconnected manifold segments. The apparatus of claim 1 wherein said second surface of said manifold segments includes a second feed port (14) in fluid communication with said feed port in said first surface. The apparatus of claim 1 or 2 wherein said first surface of said manifold segments includes a second retentate port (18) in fluid communication with said retentate port (18) in said second surface. The apparatus of claim 1 wherein said feed fluid conduit (25, 26) of each manifold segment is in fluid communication with all other feed fluid conduits of said interconnected manifold segments and one end of said apparatus includes a feed port (14) and a first filtrate port (16) and the opposite end of said apparatus includes a retentate port (18) and a second filtrate port (20). The apparatus of claim 1 wherein the retentate fluid outlet of one or more of said manifold segments serves as the feed fluid inlet for an adjacent manifold segment. The apparatus of any one of the claims 1 to 5 wherein the filtrate of said filtration module is conveyed to a plurality of substantially parallel grooves (31) in fluid communication with said first and second filtrate ports (16, 20). The apparatus of any one of the claims 1 to 5 wherein the filtrate of said filtration module is conveyed to a plurality of converging grooves (46) in fluid communication with said first and second filtrate ports (16, 20).

Inventors: PROULX ANDREW, PROULX, ANDREW
Applicants: MILLIPORE CORP, MILLIPORE CORPORATION
Application year: 1992
Main classification: B01D65
IPC codes: B01D29, B01D65, B01D63