Method and apparatus for separating gaseous bubbles and sand from a liquid flow

摘要

A filtering process for and apparatus separating air bubbles and granular filter medium from a filtrate contaminated by the filter medium and bubbles when passing through a filter bed formed by the filter medium for treatment of a suspension or liquid solution, a gas being passed through the filter medium in contact therewith, includes providing a treated filtrate zone (3) above the filter bed (2), collecting the treated filtrate in the filtrate zone, conducting granular filter medium from the filter bed (2) upwardly through a conveying pipe (4) to a position above the filter bed and thereafter downwardly through a washing apparatus (5) from which the filter medium is precipitated onto a plate (11) above the filter bed. Treated filtrate flows through a separate chamber formed by a cylinder (12) around the washing apparatus (5) and then upwardly through the lower end of the washing apparatus and outwardly through the upper end of the washing apparatus and thereafter leaves the system through an overflow outlet pipe (7). The filtrate leaves the system through a separate filtrate outlet (8). The filtrate flowing downwardly through the separate chamber functions as the washing liquid and flows at a rate sufficiently low for separation of gas bubbles in the chamber therefrom. The filtrate washing liquid flowing upwardly through the washing apparatus (5) flows at a rate sufficiently low for separating the downwardly conducted granular filter medium.