GB2084888A

GB2084888A - Filtration apparatus

Info

Publication number: GB2084888A
Application number: GB8031853A
Authority: GB
Original assignee: UK Atomic Energy Authority
Current assignee: UK Atomic Energy Authority
Priority date: 1980-10-02
Filing date: 1980-10-02
Publication date: 1982-04-21

Abstract

Filtration apparatus comprises a reservoir 2 for a liquid connected in closed circuit to a coarse filter 7, for example a mesh of wires, fibres or the like of large diameter. The liquid is pumped continuously through the filter until a required degree of clarity is obtained in the liquid in the reservoir. The filter is then isolated from the reservoir and can be backwashed for further use. <IMAGE>

Description

SPECIFICATION Filtration apparatus The present invention concerns filtration apparatus. The efficiency of a filter depends on a number of parameters and generally the finer the filter, that is the smaller the cross-sectional area of the flow passages in the filter, then the better the collection efficiency. However, filters having small cross-sectional flow passages have a limited particle holding capacity and can be difficult to back-wash.

For filtering small quantities of liquid it is proposed to employ a coarse filter and to recycle the liquid a number of times through the filter to achieve a required clarification of the filtrate. Such a filter will have an improved holding capacity and can be back-washed for cleaning without undue difficulty.

The aim of the invention is to provide an apparatus for filtering small quantities of liquids using coarse filters.

According to the present invention a filtration apparatus comprises a reservoir for a liquid to be filtered, a filter, a first flow path for cycling the liquid to be filtered from the reservoir, through the filter and back to the reservoir, a second flow path for passing a wash liquid through the filter and selectively operable means in the first and second flow paths for controlling the flows of the liquids.

The invention will be described by way of example, with reference to the accompanying diagrammatic drawing of an embodiment of a filtration apparatus.

In the drawing, liquid 1 to be filtered is supplied to a reservoir 2 through a feed conduit 3 controlled by a valve 4. The liquid flows from the reservoir through conduits 5 and 6 to a filter 7 and returns to the reservoir through conduits 8 and 9. A pump 10 is provided to maintain the circulation of the liquid and valves 11, 12 and 13 are arranged in the liquid flow path. An inlet conduit 14 controlled by a valve 15 communicates with the conduits 8, 9 at the downstream side of the filter 7. An outlet conduit 16, controlled by a valve 17, communicates with the conduits 5, 6.

Conveniently the filter comprises a chamber containing a mesh of wires, fibres or the like of relatively large diameter and having a low collection efficiency. Alternatively, the filter can comprise a bed of relatively large individual bodies or can be a magnetic filter.

In operation, a supply of liquid to be filtered is introduced into the reservoir 2 and the valve 4 is then closed. Initially, the valves 15 and 17 are closed with the remaining valves 11, 12 and 13 open whereby the pump 10 can circulate the liquid around the path defined by the conduits 5, 6 and 8, 9. The cycling of the liquid continues until a required degree of liquid clarification is obtained in the reservoir. Valve 12 is then closed and valve 17 is opened to pump the filtered liquid from the reservoir through the outlet 16.

For back-washing, the valves 13 and 11 are closed and the valves 15, 12 and 17 are opened to enable backwash liquid to flow through the filter along the path defined by the conduits 14, 8, 6 and 16.

The apparatus effectively filters small quantities of liquid to a high degree of clarification utilising a coarse filter having the advantages of high holding capacity and ease of backwashing.

Claims

1. A filtration apparatus comprising a reservoir for a liquid to be filtered, a filter, a first flow path including the reservoir and the filter having means for cycling the liquid to be filtered from the reservoir, through the filter and back to the reservoir, a second flow path including the filter for passing a wash liquid through the filter and selectively operable means in the first and second flow paths for controlling the flows of the liquids.

2. A filtration apparatus as claimed in claim 1 in which the filter comprises a mesh of wires, fibres or the like of large diameter.

3. A filtration apparatus substantially as herein described with reference to and as illustrated in the accompanying drawing.

4. A method of filtering which comprises cycling a quantity of liquid to be filtered around a path including a filter and a reservoir for the liquid until a required degree of clarity is obtained in the liquid in the reservoir, isolating the filter from the reservoir and backwashing the filter.

5. A method of filtering substantially as herein described with reference to the accompanying drawing.