US 4,227,999 AGranted

Ultrafiltration process and apparatus

AssigneeHeinrich Frings GmbH & Co. KG

InventorHeinrich Ebner

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Abstract

In the ultrafiltration of liquids such as vinegar, wine, etc., the liquid to be filtered is fed from and back to a circulating tank through at least one filtration circuit including at least two serially connected, vertically spaced, non-horizontal filter modules through each of which the liquid flows from top to bottom. Each filter module consists of a pipe enclosing a bundle of capillary tubes of semi-permeable membrane material and having a lateral outlet for filtered liquid. Each two successive filter modules are separated from one another by a fall interval zone through which unfiltered liquid can flow with a negligibly low pressure drop from the outlet of the upper filter module to the inlet of the lower one, and each fall interval zone is so arranged that the pressure drop occurring in the upper one of each two successive filter modules is equalized, to the extent of about 0.5 to 1.5 times, by the weight of the liquid column in that fall interval zone, thereby to establish and maintain at the inlet of the lower one of each two successive filter modules approximately the same hydrostatic pressure as is established and maintained at the inlet of the upper one. This abstract is not to be taken either as a complete exposition or as a limitation of the present invention, however, the full nature and extent of the invention being discernible only by reference to and from the entire disclosure.

Claims11

Dependent claims

In a process for the continuous ultrafiltration of liquids, wherein (a) the liquid to be filtered is circulated from and back to a circulating tank through at least one filtration circuit, (b) each filtration circuit is provided with a respective plurality of serially connected filter modules each having an inlet and an outlet for the liquid being filtered, (c) each of said filter modules gives rise, under the conditions of the process, to a substantial drop of the hydrostatic pressure prevailing at its inlet, (d) filtered liquid is extracted from each filter module intermediate the inlet and outlet of the same, and (e) the liquid level in the circulating tank is maintained substantially constant by replenishment of the liquid to be filtered as required;

the improvement comprising that:
(A) in each filtration circuit (i) each of the serially connected filter modules defines a non-horizontal path of flow for the liquid to be filtered, each of said filter modules has its inlet at the top and its outlet at the bottom, and each outlet is located above the level of the inlet of the respective next lower filter module, and (ii) the liquid to be filtered flows in sequence through all of the associated filter modules downwardly from the top to the bottom of each of the same,
(B) a hydrostatic pressure of between 200 and 700 mbar is established and maintained at the inlet of the uppermost first filter module in each filtration circuit,
(C) the liquid exiting from the outlet of the upper one of each two successive filter modules of each filtration circuit is permitted to flow downwardly in a non-horizontal path to the inlet of the respective next lower filter module substantially without pressure loss through a respective fall interval zone arranged between each two successive filter modules, the height of each such fall interval zone being such (i) that the pressure drop occurring in the upper one of each two successive filter modules is equalized, to the extent of from 0.5 to 1.5 times, by the weight of the liquid column in the associated fall interval zone immediately therebelow and (ii) that as a consequence about the same hydrostatic pressure is established and maintained at the inlet of the lower one of each two successive filter modules as at the inlet of the upper one, and
(D) the hydrostatic pressure at the outlet of the lowermost last filter module in each filtration circuit is established and maintained at between 100 and 400 mbar as a function of the weight of the liquid column in said circulating tank above the level of said outlet of said last filter module.

2 more elements

In an apparatus for the continuous ultrafiltration of liquids, which apparatus includes (a) a circulating tank for the liquid to be filtered, (b) means for effecting an automatic feed of liquid into said tank, (c) means for controlling said feed means so as to maintain a substantially constant level of liquid in said tank, (d) means for circulating the liquid to be filtered from and back to said tank and including at least one filtration circuit having an intake end and a discharge end both connected to said tank, (e) a plurality of serially connected filter modules incorporated in each filtration circuit between said intake and discharge ends thereof, (f) each of said filter modules having an inlet and an outlet for the liquid being filtered, and (g) each of said filter modules further having intermediate its inlet and outlet a connection for enabling filtered liquid to be extracted from that filter module;

the improvement which comprises:
(A) each of the serially connected filter modules incorporated in each filtration circuit defines a non-horizontal path of flow for the liquid to be filtered, each of said filter modules has its inlet at the top and its outlet at the bottom, and each outlet is located above the level of the inlet of the respective next lower filter module, so that in each filtration circuit the liquid to be filtered flows in sequence through all of the associated filter modules downwardly from the top to the bottom of each of the same, and
(B) means defining a non-horizontal path of flow and establishing between the outlet of each of said filter modules and the inlet of the respective next lower filter module of each filtration circuit a fall interval zone constructed and arranged to permit liquid to flow substantially without pressure loss downwardly from the outlet of the upper one of each two successive filter modules to the inlet of the immediately following lower filter module, the height of each such fall interval zone being such that the pressure drop occurring in the upper one of each two successive filter modules is equalized, to the extent of from 0.5 to 1.5 times, by the weight of the liquid column in the associated fall interval zone immediately therebelow and that as a consequence about the same hydrostatic pressure is established and maintained at the inlet of the lower one of each two successive filter modules as at the inlet of the upper one.

Dependencies are inferred from the claim text.