GB2220229A - Fluidic pumping systems - Google Patents

Abstract

A fluidic pumping system includes filter elements 1,2 in the opposed outlets of a reverse flow diverter 3 and liquid entrained at the inlet 5 of the diverter is passed through the filters to outlet 9 by alternating gas pressure in displacement vessels 6,7 of the pumping system. A backflow retarder, such as a vortex diode 4, can be included in the inlet of the reverse flow diverter. <IMAGE>

Description

Fluidic Pumping Systems The present invention relates to fluidic pumping systems.

British Patent Specification 1480484 describes a pumping system including reverse flow diverters (RFD).

An RFD has a plenum chamber from which extend two opposed flow passages each of which diverges as it extends away from the chamber, at least one further passage extending laterally from the chamber to form an inlet passage for liquid.

According to the present invention a fluidic pumping system comprises a single RFD with the opposed flow passages each communicating with an associated filter element.

A backflow retarder, conveniently in the form of a vortex diode or a diffuser, can be included in the said further passage extending laterally from the RFD chamber.

The invention will be described, by way of example, with reference to the accompanying schematic drawing of a fluidic pumping system.

In the drawing, two permeable cylindrical filter elements 1 and 2 are connected to a single symmetrical RFD 3. A vortex diode 4 is included in the inlet flow passage 5 to the RFD to function as a backflow retarder, Alternatively a diffuser can be employed for this purpose. The ends of the filters remote from the RFD are connected to respective displacement vessels 6 and 7 containing liquid and the inlet 5 is immersed in the liquid to be pumped. The walls of the two filters are connected through a line 8 to an outlet 9.

In operation, liquid is pushed back and forth by alternating gas, generally air, pressure in the displacement vessels. Considering one operating phase when the left-hand vessel 6 is pressurised and liquid flows from left to right. The flow from the vessel 6 enters the filter element 1 sweeping away any collected material on its inner surface. This flow in passing through the RFD entrains liquid from the inlet 5 and discharges the combined flow to the right where it enters the second filter element 2. This is at a lower pressure than the first filter 1 but still at a higher pressure than the inlet so that it also contributes radial filtered flow to the outlet 9. However, most of the flow travels to the right into the low-pressure displacement vessel 7.

In the other phase of operation, the vessel 7 is pressurised and flow travels from right to left. The same action occurs but left and right components exchange their roles.

At the changeover from one phase to the next a transient pulse of liquid is ejected from the inlet.

This detracts from the overall pumped flow and generally impairs performance. This transient leakage can be reduced by including backflow retarder 4 in the inlet 5.

The filter elements 1 and 2 can be as used in ultra-filtration techniques. The pumping system provides a large back-and-forth flow through the filter elements to wash away filtered material from the walls of the elements and at the same time provide high pressure within the filter elements to force a small proportion of the flow radially outwards through the walls of the cylindrical filter elements.

Claims (4)

Claims

1. A fluidic pumping system comprising a reverse flow diverter with the opposed flow passages each communicating with an associated filter element.

2. A fluidic pumping system as claimed in claim 1 including a backflow retarder in the inlet flow passage to the reverse flow diverter.

3. A fluidic pumping system as claimed in claim 2 in which the backflow retarder comprises a vortex diode.

4. A fluidic pumping system substantially as herein described with reference to and as illustrated in the accompanying drawing.