Filtering process and apparatus

Claim 1

A filtering process comprising a. tangentially introducing a liquid having entrained solid particles therein into a separating chamber confined by a downwardly converging, essentially conically shaped wall which is porous to said liquid but essentially impervious to said solid particles; b. withdrawing a first portion of said liquid as a lean liquid approximately at the axis of said separating chamber from the upper section of said separating chamber and reintroducing at least a portion thereof tangentially into said separating chamber; c. withdrawing a second portion of said liquid as a mixture of said solids and said liquid from the lower section of said separating chamber; d. recovering a third portion of said liquid as clean liquid that has passed through said wall which is porous to said liquid as a product of the process, and wherein the solids content of said first portion of liquid is sensed, a corresponding signal is generated and said withdrawal of said second portion of said liquid is actuated responsive to said signal, whenever said signal has reached a value corresponding to an upper limit of solids concentration in said first portion withdrawn from the upper section of said separating chamber.

Claim 6

An apparatus for filtering a liquid containing solid particles comprising a. a separating chamber having an upper section and a lower section confined by an essentially conically shaped wall, said wall aa. converging in downward direction and bb. being of sufficient porosity to permit passage of liquid but essentially impervious to solids; b. first conduit means attached to said apparatus for essentially tangential introduction of a liquid into the upper section of said separating chamber; c. second conduit means attached to said apparatus for withdrawal of lean liquid essentially in an axial and upward direction, said second conduit having a suction opening arranged in the upper portion and on the axis of said separating chamber and an outlet connected to said first conduit means such as to recycle the lean liquid from the separating chamber to the inlet thereof; d. third conduit means connected to the lower portion of said separating chamber to remove a solids-rich liquid; e. collecting means for collecting and removing from said apparatus the liquid penetrating through said conically shaped wall; f. sensing means for sensing the solids content of the liquid in the second conduit means; g. signal generating means connected to said sensing means for generating a signal corresponding to the solids content sensed; h. a valve connected to said third conduit means; and i. valve actuating means the input of which is connected to said signal generating means and the output of which is connected to said valve such as to actuate said valve whenever a signal is received which corresponds to an upper limit of the solids content in the liquid in the second conduit means.

Claim 7

An apparatus for filtering a liquid containing solid particles comprising a. a separating chamber having an upper section and a lower section confined by an essentially conically shaped wall, said wall aa. converging in downward direction and bb. being of sufficient porosity to permit passage of liquid but essentially impervious to solids; b. first conduit means attached to said apparatus for essentially tangential introduction of a liquid into the upper section of said separating chamber; c. second conduit means attached to said apparatus for withdrawal of lean liquid essentially in an axial and upward direction, said second conduit having a suction opening arranged in the upper portion and on the axis of said separating chamber and an outlet connected to said first conduit means such as to recycle the lean liquid from the separating chamber to the inlet thereof; d. third conduit means connected to the lower portion of said separating chamber to remove a solids-rich liquid; e. collecting means for collecting and removing from said apparatus the liquid penetrating through said conically shaped wall; f. sensing means for sensing the solids content of the liquid in the second conduit means; g. signal generating means connected to said sensing means for generating a signal corresponding to the solids content sensed; h. a valve connected to said third conduit means; and i. valve actuating means the input of which is connected to said signal generating means and the output of which is connected to said valve such as to actuate said valve whenever a signal is received which corresponds to an upper limit of the solids content in the liquid in the second conduit means.