AN ARRANGEMENT FOR THE DIFFUSION OF SUBSTANCES BETWEEN TWO FLUIDS

Abstract: Semipermeable membranes (2) are arranged in a stack separated by supporting plates (1) having a first plane face and a second plane face (10,12) and comprising through-openings (7,8) connected to an inlet and outlet, respectively, for a first fluid, by means of which this first fluid is conducted to the one side of the respective membrane, whilst a second fluid is conducted ot the other side of the membrane, the stack of membranes and supporting plates having an elongated shape with a flow-through duct formed of the said through-openings (7,8) arranged straight through the stack near its two ends. The invention is characterized by channels (11,11′) originating from end edges (9,9′) of the supporting plates, open towards a frist plane face (10,12), for the conducting of the said second fluid past a seal (13,13a′) arranged on the opposite plane face (12,10) to an opening (14,14′) passing through the plate for the conducting of this second fluid to, respectively from, the space inside the said seal (13,13a′) on the said opposite plane face (12,10) of the plate. The arrangement in accordance with the invention is intended in particular to be used in connection with dialysis, haemofiltration and similar extracorporeal procedures for the treatment of blood.

Description: The present invention relates to an arrangement for the diffusion and/or filtration of substances between two fluids via semipermeable membranes which are arranged in a stack separated by supporting plates having a first plane face and a second plane face and comprising through-openings connected to an inlet and oulet respectively for a first fluid, by means of which this first fluid is conducted to the one side of the respective membrane, whilst a second fluid is conducted to the other side of the membrane, the stack of membranes and supporting plates having an elongated shape with a flow-through duct formed by the said through-openings arranged straight through the stack near each of its two ends. The membrane in arrangements of the above mentioned type may be arranged singly between adjacently placed supporting plates. Preferably, though, they are arranged in pairs. The present invention can be said to constitute a further step in series of developments described in more detail in the American patents 3 411 630, 3 501 011, 3 511 381, 3 516 548, 3 734 298, 3 837 496, 4 051 041, 4 062 778, 4 224 159, 4 390 424, 4 113 625, 4 422 936 and 4 447 326. The devices in accordance with the above mentioned patents have been improved more and more especially regarding the sealing between the respective fluids, in particular at the inlets and outlets for the same, at the same time as the number of components included has been reduced in parallel with a simplification of the remaining parts. The present invention relates to a further simplification and improvement of arrangements of the aforementioned type. An arrangement improved in accordance with the invention is characterized principally by channels originating from end edges of the supporting plates open towards a first plane face for the conducting of the said second fluid past a seal arranged on the opposite plane face to an opening passing through the plate for the conducting of this second fluid to, respectively from, the space inside the said seal on the said opposite plane face of the plate. The invention is intended in particular to be applied to dialysis and/or filtration of blood and will be described, therefore, in the following primarily in connection with such an application. The said first fluid then is constituted of the blood, whereas the second fluid may be constituted of dialysis liquid or filtrate. Designs which are particularly simple and gentle to the blood are achieved, if the membranes are arranged in pairs between respective supporting plates. The blood then can be conducted between the membranes in such a manner that it does not come into contact with the actual supporting plates which, therefore, can be manufactured from a simpler material than if they were to be wholly flooded by the blood. When membranes arranged in pairs are used, open channels are arranged on the said opposite plane face originating from the said through-openings for the conducting of the second fluid further past a seal provided on the first plane face up to an opening passing through the second plate for the distribution of the second fluid to the two opposite plane faces of the plate. The through-openings for the first fluid are provided preferably on the centre line of the plate near its end edges. If the channels originating from end edges of the plates are arranged in two groups on either side of the through-openings for the first fluid and are made to extend substantially up to these, and preferably partly past them, the quantity of residual blood is reduced on emptying of the arrangement when used as a dialyser. The quantitity of residual blood is also favourably affected, if the said seals are made to include an essentially V-or U-shaped part extending transversely over the respective plane face which surrounds the respective through-opening for the first fluid, that is to say the blood when a dialyzer is concerned. A particularly simple and, from a point of view of sealing, reliable arrangement is obtained, if the said stack is arranged fixed in a boxlike enclosure with inlet ducts provided for the said second fluid between the enclosure and the end walls of the stack. On application to a dialyser this second fluid thus consists of dialysis liquid. The enclosure may be composed of two boxlike parts, each being provided with a flange projecting along the orifice edge, which are held together through being cast into a retaining band. This retaining band and thus is cast in situ after the remainder of the arrangement has been assembled. At the same time inlet nipples for the said second fluid, that is to say the dialysis liquid when a dialyser is concerned, may be cast in one piece with the retaining band. This too has a favourable effect on the sealing. The above mentioned seals are arranged appropriately so that they co-operate in pairs at different distances from the two end edges. The seals in the respective pairs preferably are designed as a sealing bead which co-operates with a plain sealing surface. It will be obvious to those versed in the art, however, that other types of seals may also be used. For example, two plain sealing surfaces may co-operate. Fig 1 shows a cross-section through an arrangement in accordance with the invention. Fig 2 and 3 show opposite ends of one and the same side of a supporting plate in accordance with the invention. The opposite side is of the same design but with the ends reversed. Fig 4 and 5 show sections along the lines IV-IV and V-V in the figures 2 and 3, respectively. Fig 6, finally, shows on a larger scale a partial view of the top side of a plate near one of its ends. The embodiment of the arrangement in accordance with the invention shown on the drawings by way of an example consists of a stack of supporting plates 1 with membranes 2 arranged in pairs between the plates. The stack is fixed in an enclosure 3 which consists of two enclosure parts 3a and 3b. A flange 4a and 4b, respectively, runs along the orifices of the boxlike enclosure parts which are partially cast into a retaining band 5. Nipples 6, which lead to a distributing or collecting channel 24 for the said second fluid, are preferably cast in one piece with this retaining band 5. When a dialyser is concerned, these nipples 6 serve as inlet and outlet, respectively, for the dialysis liquid. If instead a haemofilter is concerned, it would be enough with one nipple 6 intended to serve as an outlet for the filtrate. When the supporting plate shown in figures 2-5 is used in a dialyser, the blood is supplied in a manner known in itself to a flow-through duct formed by through-openings 7 arranged straight through the stack near its one end. At the same time the blood is withdrawn in a manner known in itself through a flow-through duct formed by through-openings 8 arranged straight through the stack near its other end. On membranes arranged in pairs this supply and withdrawal, respectively, takes place with the help of blood distributing buttons of the type described in more detail in the above mentioned American patents 3 837 496 and 3 841 491. The dialysis liquid is furnished instead, as can best be seen in figures 3 and 5, through channels 11 originating from the end edges 9 of the supporting plates and open towards the undersides 10 of the plates. At that a seal 13, provided on the other side 12 of the plate, is passed. The dialysis liquid subsequently passes through an opening 14 leading through the plate so as to flow out into channels 15 open towards the top side of the plates. Finally, the dialysis liquid is distributed to both sides of the plates through a second set of through-openings 16. Finally, the dialysis liquid is conducted out in channels 17 distributed over the whole working surface of the plate. The dialysis liquid then leaves the plate via a system of channels which are shown best in figure 4. They are similar to the channel system according to figure 5 and have been given, therefore, the same reference designations, but with the addition of a prime sign. The dialysis liquid this flows first through an opening 16' passing through the plate into a channel 15' on the underside 10 of the plate. From there the dialysis liquid flows through a further opening 14' passing through the plate out into a channel 11' which lastly opens out at the opposite end edge 9' of the plate. The difference compared at the arrangement according to figure 5 lies primarily in the seal 13' which here is retracted to a location straight before the channel 15'. In this manner the seals 13 and 13' can constitute two parts of a seal which extends around the whole working surface of the plate including inlet and outlet openings for the blood. This seal, thus being in the form of a sealing bead, co-operates with a plain sealing surface provided on the opposite side of the plate, the corresponding sealing components being designated 13a and 13a'. Numerals 18 and 18', respectively, designate a ridge shown schematically as a line provided in the channels 15 and 11', respectively. This narrow ridge, which appropriately extends up to the surface of the plate, is intended to prevent the membrane being pressed down into these channels. As is evident, these ridges after an interruption for the openings 16 and 16', extend a short distance inward on the supporting plate up to the actual working pattern of the plate. In figure 6 is shown the region adjoining the blood inlet 8 on a larger scale. This blood inlet 8 is arranged in the centre of a conical recess 19 which is surrounded by a circular row of bevelled studs 20. Between the studs 20 and the working channels 17 is provided a great number of hexagonal studs 21. To the right in the figure some through-openings 14 and 16 are shown. As can bee seen, the working channels 17 are surrounded by alternately wide and narrow ridges 22 and 23, respectively. These are designed appropriately of the same height as the studs 20 and 21. During the assembly of the device shown in fig 1 every other supporting plate is turned by 180° in its own main plane, that is to say so that the beads 13 and 13' always point either upwards or downwards. If the beads instead were to be exchanged for plain sealing surfaces, the plates can be turned instead by 180° either round the longitudinal centre axis or the transverse centre axis in order to achieve the same result.

Claims: An arrangement for the diffusion and/or filtration of substances between two fluids via semipermeable membranes (2) which are arranged in a stack separated by supporting plates (1) having a first plane face and a second plane face (10,12) and comprising through-openings (7,8) connected to an inlet and outlet, respectively, for a first fluid, by means of which this first fluid is conducted to the one side of the respective membrane, whilst a second fluid is conducted to the other side of the membrane, the stack of membranes and supporting plates having an elongated shape with a flow-through duct formed of the said through-openings (7,8) arranged straight through the stack near each of its two ends, characterized by channels (11,11') originating from end edges (9,9') of the supporting plates, open towards a first plane face (10,12), for the conducting of the said second fluid past a seal (13,13a') arranged on the opposite plane face (12,10) to an opening (14,14') passing through the plate for the conducting of the said second fluid to, respectively from, the space inside the said seal (13,13a') on the said opposite plane face (12,10) of the plate. An arrangement in accordance with claim 1, characterized in that the membranes (2) are arranged in pairs between respective supporting plates (1). An arrangement in accordance with claim 1, characterized by open channels (15,15') arranged on the said opposite plane face (12,10) originating from the said through-openings (14,14') for the conducting of the second fluid further past a seal (13a,13') provided on the first plane face (10,12) up to an opening (16,16') passing through the second plate for the distribution of this second fluid to the two opposite plane faces (10,12) of the plate. An arrangement in accordance with anyone of the preceding claims, characterized in that the through-openings (7,8) for the first fluid are provided on the centre line of the plate, near its end edges (9,9'). An arrangement in accordance with claim 4, characterized in that the channels (11,11') originating from the end edges (9,9') of the plates are arranged in two groups on either side of the through-openings (7,8) for the first fluid and extend substantially up to these and preferably partly past them. An arrangement in accordance with claim 3, characterized in that the said seals (13,13';13a,13a') comprise an essentially V- or U-shaped part extending transversely over the respective plane face, which surrounds the respective through-opening (7,8) for the first fluid. An arrangement in accordance with anyone of the preceding claims, characterized in that the said stack is arranged fixed in a boxlike enclosure (3) with inlet ducts (24) provided for the said second fluid between the enclosure and the end walls of the stack. An arrangement in accordance with claim 7, characterized in that the enclosure is composed of two boxlike parts (3a,3b), each provided with a flange (4a,4b) projecting along the orifice edge, which are held together through being cast into a retaining band (5). An arrangement in accordance with claim 8, characterized by inlet nipples (6) for the said second fluid being cast in one piece with the retaining band (5). An arrangement in accordance with claim 3, characterized in that the said seals (13,13'; 13a,13a') are arranged so that they co-operate in pairs at different distances reckoned from the two end edges (9,9') of the plate. An arrangement in accordance with claim 10, characterized in that the said seals in the respective pairs consist of a sealing bead (13,13') co-operating with a plain sealing surface (13a,13a').

Inventors: FLANK, HANS PEDER, NILSSON, NILS-JOEL EDDIE, RIEDE, GERHARD
Applicants: GAMBRO AG
Application year: 1988
Main classification: B01D63
IPC codes: B01D63