GB2062502A - Apparatus for clarifying water - Google Patents

Abstract

Apparatus for clarifying water by the separation of and removal therefrom of undissolved solids includes four chambers A, B, C, D separated from each other by weirs 5, 6 and 7. The water to be clarified is introduced into chamber A and extracted therefrom by a pump 10 and passed to a vortex or cyclone separator 11. This discharges clarified water into chamber B from which water overflows into chamber A. Water from chamber B is passed by pump 14 into a pair of vortex or cyclone separators 15 connected in parallel and discharging clarified water into chamber C from which water overflows into chamber B. Water from chamber C is extracted by pump 18 and is introduced into a pair of vortex or cyclone separators 19 connected in parallel and discharging clarified water into chamber D from which water overflows into chamber C. Thus there is a continuous overflow of water from chamber D into chamber C from chamber C into chamber B and from chamber B into chamber A. The water is progressively clarified as it is recirculated by the pumps 10, 14 and 18 and so sufficiently-clarified water is extracted by pump 22 from chamber D. <IMAGE>

Description

SPECIFICATION Apparatus for clarifying water The invention relates to apparatus for clarifying water or other liquid (but hereinafter called "water") by the separation and removal therefrom of undissolved solid material.

The invention is particularly but not exclusively concerned with the separation and removal of undissolved solid material from water used in industrial processes, for example, in metallic plating processes or printed circuit production, where metallic particles would be present in the plating or etching solution, or from other industrial liquid effluents. Where water used in an industrial process is to be recirculated, it is necessary to remove the undissolved solid material before recirculation, otherwise the process or the machinery for performing the process may be impaired. Alternatively where water from an industrial process or other industrial liquid effluent is to be discharged into a public sewer system, regulations make clarification necessary before the discharge of the water or other effluent can be permitted.

Separation of undissolved solid material from water is often effected by using a vortex or cyclone separator of the kind (hereinafter called "a separator of the kind described") having a vortex chamber through which the water to be clarified is passed, the vortex chamber having an inlet for the water to be clarified, a top outlet or "overflow" from which a clarified lighter fraction of the water after separation of the solid material is discharged and a bottom outlet or "underflow" from which a denser fraction of the water which is richer in undissolved solids is discharged.

In accordance with the invention, the apparatus includes a separator of the kind described, a first chamber into which water to be clarified is introduced before it is passed to the separator, a first pump arranged to extract said water from said first chamber and to transfer that water to the inlet of the vortex chamber of the separator, the top outlet from the vortex chamber of the separator communicating with a second chamber positioned for overflow of water therefrom into said first chamber, the second chamber having an outlet leading to a second pump operable to extract water from the second chamber, the relative rates of introduction and extraction of water to and from the second chamber being such that, during operation of the apparatus, water in the second chamber will overflow into the first chamber, thereby to effect recirculation through the separator of part of the water which has previously been clarified by passage through the separator, clarified water being discharged downstream of said second pump.

The apparatus may also include a third chamber arranged to overflow into the second chamber, the second pump being arranged to transfer water from the second chamber to the inlet of the vortex chamber of a second separator of the kind described, the top outlet of said second separator leading into the third chamber, the third chamber having an outlet leading to a third pump by which water is extracted from said third chamber, the rate of flow of said first and second pumps relative to said third pump being such that the water levels in said second and third chambers will rise to effect, during use of the apparatus, overflow of water from said third chamber into said second chamber and from said second chamber into said first chamber, thereby to effect recirculation through each separator of part of the water that has previously flowed therethrough, clarified water being discharged downstream of said third pump.

By having three chambers, as hereinbefore described, the water finally discharged from the third chamber may be sufficiently clear for most applications of the apparatus. However where the initial water contains excessive quantities of solid material, a fourth chamber or any number of subsequent chambers may be arranged in series with the first three chambers, whereby water will overflow, during operation, into the immediately preceding chamber, each chamber other than the final chamber having a pump to transfer water therefrom to the next successive chamber via a separator, the final chamber having an outlet pump to discharge clarified water.

Conveniently the chambers may be arranged in a common tank and are separated one from another by partitions within the tank forming weirs over which the overflow will occur from the or each chamber, except the first chamber, to the next preceding chamber.

Where a third chamber is employed, or there is a third and a fourth or subsequent chamber, each of the third, fourth or subsequent chambers may be supplied by the top outlet of each of two or more separators of the kind described, each having substantially the same capacity as the separator supplying the second chamber, connected in parallel, whereby the rate of flow of recirculated water into the third, fourth or any subsequent chamber is greater, for example twice, that of the rate of flow of water recirculated from the first chamber to the second chamber.

The bottom outlet of the separator which is supplied by the first pump may be arranged to discharge selectively into a settling tank, from which separated solid material may be extracted, or into an intermediate settling tank, from which water may be recirculated to the first pump for reintroduction to the separator supplying the second chamber. The top outlet of the first separator, which outlet normally supplies recirculated water to the second chamber, may alternatively discharge part of the clarified lighter fraction of water for recirculation to that separator via the intermediate settling tank. The or each separator which is arranged to receive water from the second or subsequent chamber may be so arranged that its bottom outlet discharges directly into the intermediate settling tank.

By way of example, one form of the waterclarifying apparatus will now be described with reference to the accompanying flow diagram.

As shown in this diagram, untreated water to be clarified flows through a pipe 1 and a course mesh strainer 3 into the first chamber A of a mixing tank 4. The mixing tank is divided into four chambers A, B, C and D positioned side-by-side by weir-like partitions 5, 6 and 7.

The height of the partition 6 is greater than that of partition 5 and the height of partition 7 is greater than that of partition 6 and so there will be overflow from chamber D into chamber C, from chamber C into chamber B and from chamber B into chamber A. Chamber A has an outlet pipe 8 leading from the bottom of that chamber to a control valve 9 and a transfer pump 10 (the aforesaid first pump) which is arranged to discharge water to the inlet of a first separator 1 1.

The separator 11 is of the kind described, that is it is a vortex or cyclo#ne separator having an inlet leading to a vortex chamber, a top outlet through which the lighter or clarified fraction of the water is discharged and a bottom outlet through which the denser fraction of the water is discharged. The top outlet from the vortex chamber of the separator 1 1 leads through pipe 12 to the second chamber B.

An outlet pipe 13 from the second chamber B leads to another transfer pump 14 (the aforesaid second pump) to the inlets to the vortex chambers of a pair of second separators 1 5, connected in parallel and each similar to the separator 1 1. The top outlet of each of the second separators 1 5 leads through a pipe 16 into the third chamber C.

An outlet pipe 17 from the third chamber C leads to another transfer pump 18 to the vortex chambers of a pair of third separators 19, connected in parallel and each similar to the separator 11. The top outlet of each of the third separators 19 leads through a pipe 20 into the fourth chamber D. An outlet pipe 21 from the fourth chamber D leads to an outlet pump 22 which discharges the finally clarified water to be returned to a supply tank or to a process by pipe 23.

The rate of transfer flow effected by the pumps 1 8 and 14 is such that water will continuously overlow from chamber D into chamber C, from chamber C into chamber B and from chamber B into chamber A.

The rate of flow of inlet water into the chamber A through the supply pipe 1 may be adjusted by a valve (not shown) relative to the outflow therefrom through the transfer pump 10 and the overflow into chamber A from chamber B, thereby to maintain the level of water in the chamber A a required distance below the top of the partition 5.

During operation of the apparatus, there may be a loss of water, and so the water level in chamber A may be restored, as necessary, automatically by admitting mains water into the chamber A through an inlet pipe 24 under the control of a float-operated valve 25 responsive to the level of water in chamber A.

The bottom outlet of the separator 1 1 leads via a pipe 26 and a valve 27 to a settling tank 28 in which the suspended solids are collected and can be emptied. An overflow pipe 29 for surplus liquid may be provided. The tank 28 may be divided into compartments which can be emptied separately.

The pipe 26 may have a branch 30 leading into an intermediate settling tank 31 and which can be brought into use by closing or partly closing the valve 27. The intermediate settling tank 31 may also receive via a pipe 32 controlled by a valve 33, water discharged from the top outlet of the separator 11. Thus by opening the valve 33 part of the water discharged from the top outlet of separator 11 may be introduced into the intermediate settling tank instead of passing through the pipe 12 into the chamber B. The bottom outlet of each of the separators 1 5 and 19 discharges directly into the intermediate settling tank 31. At the bottom of the intermediate settling tank 31 there is an outlet pipe 34 which communicates through a valve 35 with the inlet to the pump 10.Thus by opening the valve 35 the partly clarified water in the intermediate settling tank 31 may be recirculated through the separator 11 and reintroduced into chamber B or, by opening the valve 33 back into the intermediate settling tank 31, according to the clarity of the discharged w#ater in pipe 23 or the amount of the contamination of the inlet water through pipe 1.

During use of the apparatus which has been described with reference to the drawing, untreated water, that is water containing undissolved solid material from an industrial process is passed through the pipe 1 into chamber A of the mixing tank 4. Valve 9 is open and the transfer pump 10 is operative and so water from the chamber A enters the inlet of the separator 1 The clarified fraction of water from the separator 1 1 passes into the chamber B and the denser fraction together with the solid material passes through the outlet of the separator into the pipe 26 and hence to the settling tank 28. There will be partially clarified water already in chamber B from a previous operation and so the partially-clarified water entering chamber B will cause overflow from the partition 5 into chamber A.The partiallyclarified water will then be recirculated by the transfer pump 10 and through the separator 1 1.

Similarly, partially-clarified water from chamber B will be introduced by the transfer pump 14 to the inlets of the separators 1 5. A clarified fraction from the top outlet of each of the separators 1 5 will then enter chamber C through the pipes 1 6 while the denser fraction from the bottom outlet and containing undissolved solid material will pass into the intermediate settling tank 31. There will be partially-clarified water already in chamber C from a previous operation and so this will overflow the top of the partition 6 and enter chamber B.

Similarly partially-clarified water will be recirculated by the pump 18 through the separators 19 into the chamber D. This chamber will already contain water from a previous operation and so water will overflow the partition 7 and enter chamber C. Thus during operation there will be a continuous overflow of water from chamber D into chamber C, from chamber C into chamber B and from chamber B into chamber A.

Therefore, the water in the chambers A, B, C and D will become successively more clarified. Water in the chamber D will be sufficiently clarified for return to the process or for discharge to a main sewer and therefore this water is removed through the pipe 21 by the discharge pump 22. The adjustment of the rates of flow of the transfer pumps 10, 14 and 18 relative to the discharge pump 22 will provide a faster recirculation than removal of fully clarified water through the pipe 23. Thus the continuous overflow over the partitions 7,6 and 5 will be accomplished. If the incoming rate of flow of untreated water through the pipe 1 is insufficient to make up for any loss of water through the discharge pipe 29 from the final settling tank 28 mains water is automatically introduced to maintain the level in the chamber A through the water supply pipe 24 controlled by the float valve 25.

Depending on the amount of contamination of the water being clarified, some of the water recirculated through the separator 11 by the pump 10 may be directed, by opening the valve 33 into the intermediate settling tank 31 instead of being returned to the chamber B. Also or additionally by opening or closing the valve 27, the rate of flow of discharge from the bottom outlet of the separator 11 into the final settling tank 28 may be controlled, thereby controlling the rate of flow of discharge from the bottom outlet of the separator 11 into the intermediate settling tank 31, the rate of flow of water from the bottom of the intermediate settling tank 31 to the pump 10 being controlled by opening or closing the valve 35. In this way the rate of flow of partially-clarified water from the separators 1 5 and 1 9 can be controlled.

Solid material collected in the final settling tank 28 is normally retained therein and is removed therefrom either during shut-down of the apparatus or periodically during operation. To enable solids to be removed during operation, the valve 27 would be fully closed first.

Although it is unlikely that sufficient clarification of water would be provided by having only two or three chambers A and B or A, B and C in the mixing tank 4, it is possible that such apparatus could function where the water to be clarified is not highly contaminated.

Similarly more than four chambers and associated transfer pumps may be necessary in the event of highly contamined water, although normally only four chambers together with the facility for recirculation of water through the intermediate settling tank will produce water at the delivery pipe 23 of required clarity.

Claims (9)

1. Apparatus for clarifying water or other liquid (herein called "water"), the apparatus comprising a separator of the kind described, a first chamber into which water to be clarified is introduced before it is passed to the separator, a first pump arranged to extract said water from said first chamber and to transfer that water to the inlet of the vortex chamber of the separator, the top outlet from the vortex chamber of the separator communicating with a second chamber positioned for overflow of water therefrom into said first chamber, the second chamber having an outlet leading to a second pump operable to extract water from the second chamber, the relative rates of introduction and extraction of water to and from the second chamber being such that, during operation of the apparatus, water in the second chamber will overflow into the first chamber, thereby to effect recirculation through the separator of part of the water which has previously been clarified by passage through the separator, clarified water being discharged downstream of said second pump.

2. Apparatus as claimed in Claim 1 also including a third chamber arranged to overflow into the second chamber, the second pump being arranged to transfer water from the second chamber to the inlet of the vortex chamber of a second separator of the kind described, the top outlet of said second separator leading into the third chamber, the third chamber having an outlet leading to a third pump by which water is extracted from said third chamber, the rate of flow of said first and second pumps relative to said third pump being such that the water levels in said second and third chambers will rise to effect, during use of the apparatus, overflow of water from said third chamber into said second chamber and from said second chamber into said first chamber, thereby to effect recirculation through each separator of part of the water that has previously flowed therethrough, clarified water being discharged downstream of said third pump.

3. Apparatus as claimed in Claim 2 also including a fourth chamber or any number of subsequent chambers arranged in series with the first three chambers, whereby water will overflow, during operation, into the immediately preceding chamber, each chamber other than the final chamber having a pump to transfer water therefrom to the next successive chamber via a separator, the final chamber having an outlet pump to discharge clarified water.

4. Apparatus as claimed in any one of the preceding claims in which the chambers are arranged in a common tank and are separated one from another by partitions within the tank forming weirs over which the overflow will occur from the or each chamber, except the first chamber, to the next preceding chamber.

5. Apparatus as claimed in Claim 2 or 3 in which each of the third, fourth or subsequent chambers is supplied by the top outlet of each of two or more separators of the kind described, each having substantially the same capacity as the separator supplying the second chamber, connected in parallel.

6. Apparatus as claimed in any preceding claim in which the bottom outlet of the separator which is supplied by the first pump is arranged to discharge selectively into a settling tank, from which separated solid material may be extracted, or into an intermediate settling tank from which water may be recirculated to the first pump for reintroduction to the separator supplying the second chamber.

7. Apparatus as claimed in Claim 6 in which the top outlet of the first separator, which outlet normally supplies recirculated water to the second chamber, is arranged to discharge alternatively part of the clarified lighter fraction of water for recirculation to that separator via the intermediate settling tank.

8. Apparatus as claimed in Claim 6 or 7 in which the or each separator which is arranged to receive water from the second or subsequent chamber is so arranged that its bottom outlet discharges directly into the intermediate settling tank.

9. Apparatus for clarifying water or other liquid (herein called "water") constructed and arranged substantially as described herein with reference to the accompanying drawing.