HU205273B - Method for regenerating the filtering layer of thin-layer closed sand-filter of fine grain serving for filtering fluids - Google Patents

Abstract

The equipment contains a sand filter layer with max. sand granule size of 0.2 mm and max. layer height of 20 cm. It also contains a space above the filter layer for back flushing and regeneration. - The regeneration procedure involves stopping filtration and emptying the space above the sand layer. The filter layer and the pollutant held in it are suspended by backflushing water introduced from below. Backflushing is stopped, and a short pause is followed by further backflushing at such a speed that the sand particles will continue to settle while the pollutants are kept floating and are removed.

Description

There are various types of sand filters for filtering liquids, each of which poses a significant problem in regenerating the filter layer. Hungarian Patent No. 180,715 discloses a filter tower where the filtration direction is horizontal. The filter is regenerated with a strong jet of water, which circulates the sand particles that make up the filter. The disadvantage of this apparatus is that the apparatus itself is a large, expensive tower filter, and that only a particulate filter layer which cannot be removed by the flushing water can be used. Thus, the smaller the particle size of this filter, despite its complexity, is significant for the quality of the filtration. British Patent No. 2151940 discloses a thin-layer sand filter in which the filter layer is located on an arched filter bottom. In this filter, regeneration of the filter layer is performed by flushing water through nozzles built into the filter bottom, which circulates the sand filter particles through the outer casing of the filter. Again, no filter can be found in this filter to ensure that a fine particulate filter layer is used to provide the appropriate filter quality.

British Patent No. 2118452 discloses a filter or filtration process wherein the filter is regenerated by means of bottom-fed rinse water and additionally supplied air, whereupon the sand particles are cleaned during recirculation within the filter. Neither this filter, nor the filtering process, can ensure that a thin and fine particulate filter layer can be applied, without compromising the removal of fine particles during regeneration. A further disadvantage of this solution is the relative complexity of the apparatus, considering that, in addition to the flow of liquid, it is also necessary to circulate air.

SUMMARY OF THE INVENTION It is an object of the present invention to overcome the drawbacks of the above-described solutions and to provide a process for regenerating a sand filter filter layer that can provide, by very simple means, a thin filter layer of fine particles to obtain a filtrate of sufficient purity.

The invention thus provides a process for regenerating a filter layer of a fine-grained closed sand filter for filtering liquids by converting a dirty filter to a regeneration.

The object of the invention is to remove the liquid to be filtered from the space above the filter layer and to convert the filter layer into a slurry of at least three times its volume by flushing the bottom layer at high speed, and then settling at flow from below and after the filter layer has settled, the rinse water flow is stopped and the filter is adjusted to filtration.

As can be seen from the foregoing, the process according to the invention enables the fine-grained thin-layer sand filter to be regenerated and thus at all applicable by very simple means or steps. The method according to the invention is also economical for the filter because it does not require any additional expensive equipment.

The process according to the invention, in connection with the operation of an apparatus for carrying out the process according to the invention, is illustrated in FIG. Referring to FIG.

No. 1 Figure 1 is a schematic diagram of a filtration apparatus carrying out the process. The filtering device consists of a closed filter container (1) having a filter layer (2) of fine granules, i.e. 0.06-0.2 mm in diameter, on the bottom of the filter (3). There is space inside the closed filter container (1) above the filter layer (2). At the top of the filter tank fi) is a vent valve (7) and an air intake valve (8), while a color sensor (19) is provided at the top.

A conduit (9) is connected to the upper side of the container for the liquid to be filtered and for the discharge of the slurry water, while a conduit (10) is connected to the filter container (1) from above, but extending to the filter layer (2). A valve (14) is installed in the conduit (9) and then the conduit splits into two parts. One branch is provided with a pump (5) for transporting the fluid to be filtered, while the other branch (15) is provided with a valve (13). The pre-pump line (5) is connected to the pre-regenerative drain line (10) and there are valves (12) and (20) installed before and after this connection point (10).

A line (11) is connected to the bottom of the filter tank (1), i.e. to the bottom of the filter bottom (3), for both drainage of the filtrate and for the introduction of rinse water. A control valve (16) and a pump (6) for flushing water are integrated in the conduit (11). The line (11) divides the line (1) between the container (1) and the adjustable valve (16) with a valve (18), and the line (17) between the control valve (16) and the flushing water pump.

The process according to the invention will be described below in connection with the operation of the apparatus. During filtration, the water to be filtered is sucked by the pump (5) through the open valve and fed through the open valve (14) or line (9) into the space (4) above the filter layer (2) of the filter tank. The valve (12) and valve (13) are then closed.

The filtrate (11) passing through the filter layer (2), i.e. being filtered and appearing at the bottom of the container, is discharged through a conduit and an open valve (18). The control valve (16) is now closed.

When the filter is blocked, which is known in the art, for example, by pressure measurement, regeneration occurs. The pump (5) is then stopped and the flow of liquid to be filtered is stopped. The valve (14) in the conduit (9) is then closed and the valves (12) and (13) are opened. Also, the fluid inlet valve (20) to be filtered is closed. Thereafter, the liquid to be filtered from the filter tank (1) above the filter layer (2) is removed, for which the pump (5) is

EN 205 273 Β, which sucks the liquid through line (10) through valve (12) and removes it through open valve (13) or line (15).

Of course, during the above operations, the vent valve (7) and the air intake valve (8) automatically ensure that no vacuum or excess pressure is created in the filter tank (1).

To start the regeneration, the control valve (16) is opened and the valves (17), (18) are closed. The pump (6) is then started, which presses the flushing water into the filter container (1) below the filter bottom (3) at a rate such that the filter layer (2) is at least three times its volume. When the slurry reaches the level sensor (19), the control signal is given to adjust the control valve (16) to the extent that the pump (6) then supplies the flushing water at a speed less than that of the sand particles. sedimentation rate, but higher than the sedimentation rate of the dirt. This means that dirt is discharged through conduit (9) and conduit (15) through open valves (14) and (13) and the sand particles settle. When the sand particles forming the filter layer have completely settled, i.e. the filter layer of the original thickness is located in (3). filter, the pump (6) is stopped. The filter is now regenerated. The filter state is then reset by resetting the valves.

For a brief explanation, the pump for flushing water (6) is capable of delivering filtered fluid collected in a container (not shown) to an outlet via an open valve (17).

Claims (1)

A method for regenerating a filter layer of a fine-grained closed sand filter for filtering liquids, wherein the contaminated filter is regenerated by removing the liquid to be filtered from the space above the filter layer (4) and then rinsing the filter layer (2) at high speed. flowing water down to the filter layer (2) and flowing down the filter layer (2). and adjusting the filter for filtration.