Liquid purification or separation – Processes – Separating
Patent
1999-01-04
2000-02-22
Fortuna, Ana
Liquid purification or separation
Processes
Separating
210636, 210650, 210231, 21032163, B01D 3700, B01D 6300
Patent
active
060276568
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a method and device based on cross flow membrane filtration for separation of separable constituents from a liquid medium.
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 said filter.
Cross flow filter 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 separation of solid constituents from a liquid phase and for separation of liquid from liquid, for example, for separation of oil from water.
FIG. 1 shows a section of a separation device of the type disclosed in SE 451429. The device comprises a chamber 10 in which plates 11 provided with center holes 12 are arranged. A dynamic filter membrane 13 is fastened on the plates. A rotor shaft 14 provided with rotor wings 15 runs through the center holes of the plates. The liquid to be prepared is supplied into the rotor chamber through the channel 16 whereby part of it (the permeate) passes through the filter and is collected via channels 17 in the plate to be eventually discharged through a permeate outlet. The portion of the liquid flow (the reject) which does not permeate the filter is discharged through the channel 18. By means of the rotor wings 15 the liquid is pushed across the filter surface 13 and a possible porous layer applied onto it.
SE 459475 describes a separation device comprising a number of adjacently arranged units or cells according to SE 451429. The liquid to be treated is supplied through a joint channel formed by through-holes in the plates. The collected permeate is discharged through a common outlet and the reject is discharged through a common conduit for the outgoing reject.
The filter membrane itself can also be provided with one or more layers of a porous material, for example, of the kind described in the above mentioned patent publications.
Clogging of the pores of the filter membrane or the porous material applied onto it due to deposit of separated constituents is a big problem. Due to the clogging the separation capacity rapidly diminishes and because of this it is necessary to regenerate the filter with regular intervals. According to the publication SE 451429 the regeneration is carried out in such a way that elements (brushes, valves or the like) connected to the rotor wings are brought into contact with the porous layer on the filter membrane. Hereby the constituents separated from the liquid flow are removed and a portion of the porous material as well. New porous material is added when necessary.
Mechanical regeneration of this type, which involves touching of the filter membrane or the porous layer on it, is always connected with the risk of disturbing the wanted pore size. Therefore it is highly desirable to avoid regeneration methods of this kind.
According to the present invention a separation method and a separation device is obtained in which the filter is kept free of deposition of separated substance.
The characteristic features of the invention are disclosed in the independent claims 1 and 2.
The advantages of the invention are based on the supplied liquid medium being subjected to a strong turbulence created by a suitably formed rotor, possibly in connection with sound waves, preferably ultrasound, and/or an electric field, whereby the depositition of separable particles on the filter is prevented or essentially reduced.
According to one embodiment of the rotor it is designed in such a way that the essentially plane surfaces of the wings directed towards the filter are provided with irregularities deviating from the plane of the wing surface. The irregularities may, for example, be through-holes, recesses or slots, or bosses.
According to another advantageous embodiment the surface of the rotor wings directed toward
REFERENCES:
patent: 3541004 (1970-11-01), Cooper et al.
patent: 3948776 (1976-04-01), Donovan
patent: 4722789 (1988-02-01), Kupka
patent: 4740312 (1988-04-01), Dahlquist et al.
patent: 4919806 (1990-04-01), Yagishita
patent: 5019255 (1991-05-01), Dahlquist et al.
patent: 5415781 (1995-05-01), Randhahn et al.
patent: 5707517 (1998-01-01), Rolchigo et al.
Henttonen Vesa
Karlsson Claes
Leimu Pasi
Paatero Jaakko
Teppler Milan
Fortuna Ana
Valmet Flootek Oy
LandOfFree
Separation method and apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Separation method and apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Separation method and apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-517681