188宝金博页面版

FILTERING UNITAND METHODOF SEALING SAMEField ofthe inventionFieldofthe inventionFieldoftheinventionThe invention relates to filtration by means of crossflow technique and filtering elements5 havinga filter membraneona porous carrier.Particularly, the invention relates toa crossflow membrane filtering unit havinga sealingsystem includinga channel enabling the detection ofa leak without the quality of thefiltrate being impaired.10 Background of the inventionBackground of ltte inventionBackground of theinventionThe removal of solids froma liquid by filtration can take place in several, principallydifferent manners. In so-called dead end filtration,a suspension is driven in its entiretytowardsa filter, and a filter cake is formed which the filtrate penetrates. In cross-flowfiltration, the mixture tobe filtered is pumped across the filter elementina circuit, wherebypart of the mixture penetrates the filtering elements forminga permeate stream. In the idealcase, no cake is formed, but the material to be separated is enriched in the circulatingphase, anda certain fraction is continuously being removed therefrom asa reject stream.The quality of the permeate is basically dependant on thepore size of the filtering element20 membrane. This pore size can be very narrowly defined. In microfiltration, the porediameter can be 0.1 - 10 qm, and in ultrafiltration down to1 rim. Thus, separation ofmolecules on the basis of size is possible by means of filtration. One application is theremoval of pyrogens from water, pyrogens having relatively large molecules.Membrane filtration elements have porous carrier structures, on the filtering surfaces of25 which membranes having well defined pore sizes havebeen formed.Membranes with small pore sizes can be formed from e.g. polymer films. These are not,however, particularly resistant to mechanical and thermal stress, which isa drawback insterilisation and cleaning. Ceramic membranes on porous, ceramic carrier phases have alsobeen developed. Most ceramic materials resist heat in addition to being mechanically30 durable. On a ceramic element, as on other materials, surfaces can also be sealed, i.e. madeimpermeable. Thus, three types of surfaces may occur on a ceramic filter element:membrane coated, sealed, and untreated, through which permeate flows freely.