Filter for a tangential flow of fluid for treatment, for nano- or ultra- or microfiltration, has ring zone between bladder and housing for structured and controlled back filtration flow

摘要

The filter system, with a tangential flow of the fluid to be treated, has a bladder (33) within the housing (21) around the filters (26). It divides the interior at least partially into the chamber (38) to collect the filtrate and a ring zone (39), linked to an inlet (13) and an outlet (14) for back filtration connected to the recirculating fluid for treatment. During normal filtration, the collection chamber is set at maximum and the ring zone at minimum, and vice versa for back filtering. The filter system, with a tangential flow of fluid to be treated, has a protective shrouding (41) within the filtrate collection chamber, around the filters, to allow the filtrate to pass through and act as a barrier during back filtration. The bladder has a tubular section (34) with its symmetrical axis parallel to the longitudinal axis of the filter tube. The ratio of the bladder tubular surface to the surface of the filter tubes is 0.3-10.0 and preferably 0.5-1.0. The tubular section of the bladder is extended at each end by a flange (35) for mounting to the lateral walls (23) of the drum (22). An Independent claim is included for a filter installation, with a circuit for the circulation of the fluid for treatment, and a pump with controlled valves for the filtering and back filtering flows. The circuit to take the filtrate has a controlled valve. A control system determines the valve settings and the direction of fluid flow. Preferred Features: The dimensions of the filter unit and the flow circuits are set to give a back filtering flow speed of 1-10 mm/sec. and preferably 6 mm/sec. The pump for the fluid to be treated has the dimensions to give a tangential flow speed of 0.5-3.0 m/sec. and preferably 1 m/sec.