DE2348175A1 - SEPARATION BASIN FOR SEPARATING SOLIDS AND LIQUIDS - Google Patents

Description

Dipl. Phys. Dr. rer. η at Wolfgang Kempe

PATENT ADVOCATE

D-68OO Mannheim 1 o e, 10

P.O. Box 1273

Telephone CO621) 2 89 97

September 24, 1973 Mc 3

Paterson Candy International Ltd. 21, The Mall, Ealing London W5 2PU / England

"Separation basin for separating solids and liquids"

The invention relates to a separation tank for separating solids and liquids, which has a sludge funnel, the surface level of which coincides with the level of a liquid filter layer in the separation basin and the one Has outlet line through which the contents of the funnel can be drained from the separation basin.

In clarifying basins with vertical flow, which are mainly used as Secondary clarifier with biological clarification stages for the purification of water or other liquids are used, a liquid filter layer made of suspended particles, the

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can have a flaky structure, maintain that for example is formed by hydrolysis of an aluminum or iron salt. Such particles have a very low specificity Density, which is often in a range that only

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1-5 χ 10 is greater than the density of water. The inflowing, water to be clarified contains suspended solids that coagulate with the iron or aluminum salts, so that there is a constant influx of solid matter into the liquid filter layer.

The separation basin operates in such a way that clean water can be drawn from the top of the separation basin. That does it It is necessary that the solids in the form of a slurry must be removed from the liquid filter layer in order to achieve the solids balance get in the filter layer. It is only common practice to withdraw the filter suspension from the separation basin. If the solids concentration in the inflowing water is, for example, half a volume percent and the Filter layer concentration twenty percent, then the emptying rate must be forty times, i.e. 2 1/2%, of the main flow for the sludge to the filter ratios to be kept in balance in the separation tank. The sludge can then be further concentrated in a separate container and the supernatant water is returned to the main river.

When the entire separation plant at a high flow rate is operated, then it is more economical to use the further concentration container in the form of a funnel inside of the separation basin. The emptying cycle for this funnel can then be set to one in the above example

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theoretical value can be reduced by 1/2%. That is the cycle in which the funnel with a 100 percent Sludge concentration is filled.

When operating the separation basin in question, it is necessary to maintain a predetermined minimum filter layer depth. The edge of the sludge funnel, i.e. the point at which the sludge can flow into the funnel, is normally arranged in a plane with the desired surface level of the filter layer, so that the filter layer, if it builds up at the top, it can overflow into and drain from the funnel. Needless to say that if the filter layer level does not reach this point, what can occur at low flow rates through the separation tank, the purified water instead of the sludge from the Hopper is pumped when a constant pump-out speed is set and when the pump-out speed is set for the purified water is calculated for a maximum flow rate and a certain expected solids concentration. then the entire system works excessively expensive and therefore uneconomical.

If the water loss in such a system is to be reduced, it is desirable to have an automatic control system to be provided for opening and closing the sludge discharge device, so that the sludge is only withdrawn when it is necessary. This can be done, for example, by using a photometric measuring method done in which the level of the filter layer is measured and a drain valve by suitable means is operated.

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In & r mining industry, a float is used, which is moved upward as the deposited solids build up and the density of the filter layer increases and a drain valve opens. In some applications, however, the density of the sludge is critical to use the above method is too low. For example, the difference in density between water and the filter layer is

-4 a concentration of 10 percent by volume only 10, which corresponds to a difference in density that occurs with a change in temperature of just a few degrees. The float device is unreliable or at least unreliable under these circumstances impractical.

The present invention was therefore based on the object of providing a separation basin of the type described in the introduction in an improved manner To develop a design in which, in particular, the automatic emptying of the sludge funnel is more reliable and more economical is working. This object is thereby achieved in accordance with the invention solved that a device is provided which responds to the weight of the funnel in such a way that when exceeded a first predetermined fourth with the discharge of the funnel contents via the outlet line is started until the weight of the funnel is reduced to a second predetermined value.

The weight of the funnel is of course the total weight of the Funnel and its respective content understood. In the separation basin according to the invention, the surface of the Filter layer can be kept constant without being excessive Quantities of liquid have to be pumped out and in which the density of the filter layer differs only slightly from that the liquid differs. The sludge funnel can

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for example by springs, counterweights or a float arrangement be held so that it moves downward as sludge flows into the hopper. In a typical Assembly, the sludge hopper is a few feet in diameter and the settled solids are in the hopper flow in, weigh a few pounds. That is more than enough to move the funnel. "The movement The funnel can be used to open a valve to suck the sludge from the bottom of the funnel. When the sludge is sucked off, the total weight of the funnel decreases and the valve closes again accordingly. At a Such a device is therefore only pumped out sludge and the loss of liquid is avoided.

In another device according to the invention, the remains The position of the sludge hopper is constant in relation to the separation basin, but its weight is continuously controlled by a device which controls the emptying of sludge from the hopper. This device can contain a force-sensitive measuring cell, on which the hopper weight acts, conventionally via a lever system, and which controls a sludge discharge pump or a valve located in a conduit extending from the bottom of the funnel. Further details of the invention and expedient developments are listed in the subclaims and are shown below with reference to in the drawing Embodiments described and explained in more detail.

Show it:

Prop. 1 shows a vertical section through the schematic representation of a separating basin according to the invention with two different embodiments of control devices for the sludge funnel; _c

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2 shows a vertical section through the schematic representation an outlet valve at the lower end of each sludge funnel in the separation basin of FIG. 1;

3 shows a schematic representation of a further embodiment the control device for the sludge hoppers and

4 shows a vertical partial section through the schematic representation of a further separating basin according to the invention with another embodiment for the Control device of the sludge hopper.

The embodiment according to FIG. 1 shows a separation basin 1 with a conventional conical shape, which has an inlet pipe 2 for the has to be clarified liquid with a mouth 3 in the immediate vicinity of the separating basin bottom. The liquid to be clarified flows vertically upwards through a liquid filter layer and, after clarification, out of the separation basin 1 via outlet troughs 5. Two conical sludge collecting funnels 6 and 7 are held in the filter layer / that their edges are at the same height on which the surface of the filter layer 4 is to be held. The two funnels 6 and 7 represent alternative designs and are usually not used together.

The funnel 6 is suspended from ropes 8 which are connected via a pulley 9 are out and are provided with a counterweight 10, which is sufficiently heavy to the funnel in its upper position hold when the sludge has drained from it. An outlet line 11 is provided for drawing off the sludge from the funnel, which protrudes into the funnel up to the bottom. There is a valve 12 is provided with the open end face of the

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Outlet line 11 cooperates. When the funnel 6 has risen to its highest position, the outlet line 11 is closed, and when it sinks it opens, allowing the collected sludge to flow out of the funnel via the outlet line to pump out. A guide rod 13 prevents the valve 12 from tilting sideways. A plug 14 made of concrete gives the Hopper 6 an additional weight. To prevent the funnel 6 from sinking too far when it is filled with sludge, rods 15 with anchor lines 16 are provided on which the Hopper hangs when valve 12 is fully open. The funnel 6 preferably has a conical shape, but he can of course have any other shape if so desired. The outlet line 11 is laid in a fixed, rigid manner, in order to be able to offer resistance to the upward pressure of the valve 12.

So that the funnel 6 can also be freed of its contents when the separation basin is empty, it has at its bottom an exhaust valve not shown in the drawing.

On the right in Fig. 1, a funnel 7 is shown, which is supported by floats 17, which on the edge of the funnel through Ropes or chains 18 are attached. The buoyancy, i.e. H. the buoyancy of the float 17 is adjusted so that the funnel 7 is raised enough to close valve 12 when the required amount of sludge is pumped out of the hopper has been.

The device shown in Fig. 3 also aims to make the funnel 7 buoyant. This is where the edge is

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of the funnel 7 in the form of a collar from a around the circumference circumferential tube 19 is formed, which is divided into three or more equal sections by radial partition walls 20 is ^ where each section is independent with a source of compressed air 22 is connected via a flexible hose 24, a shut-off valve 23 and a pressure regulating valve 24. The subsections are each provided with a hole 21 in their bottom surface for the air to escape. The funnel 7 is in turn conical, the sections of the tubes 19 are arranged so that the pressure regulating valves 24 a precise adjustment of the Enable the funnel's ability to swim.

In the exemplary embodiment according to FIG. 4, a separating basin 31 has an inlet pipe 32 with an orifice 33 and a liquid one Filter layer 34 on. The liquid to be clarified flows out the mouth 33, and rises through the filter layer 34 after at the top, above the filter layer 34, the cleaned one collects Liquid withdrawn through troughs 34.

A conical funnel 36 is suspended from a rope 37, see above that its upper open cross-section is arranged horizontally at a height that corresponds to the desired surface level of the Filter layer 34 in the ^ separation basin 31 corresponds. The lower The end of the funnel 36 is via a flexible hose 38 with an outlet stuffing box 39 in the wall of the separating basin 31 tied together. A pipe 40 leads from the stuffing box 39 to a solenoid valve 41, which opens when the in the ". Hopper 36 collected sludge is to take place. The solenoid valve 31 is controlled by a device 42 which acts on the tension in the rope 37 and thus on the weight of the Funnel 36 and its content appeals.

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The device 42 has a lever 43 with an axis of rotation, which is fastened to a holding plate 45 on the underside is, in turn, with an extending over the separation basin Carrier is firmly connected. At one of its two ends, the lever 43 carries a roller 46 over which one end of the rope 45 leads horizontally to a fixed point 47 on the wall of the separation basin 31, while at the other end of the rope the funnel 36 is suspended from a bracket 48. The lever carries an upwardly directed switch pin at its other end 50, which acts on a pressure-sensitive switch 49, which actuates a switching differential and the excitation of the Solenoid valve 41 controls.

If, during operation, the filter layer 34 rises and parts of its surface overflow into the funnel 36 as sludge, it rises the weight of the funnel. As soon as enough sludge is collected in the funnel 36, the lever 43 pushes due to the the hopper weight hanging on it, the switching rod 50 upwards, which in turn actuates the switch 49. The solenoid valve 41 is then opened and the emptying of the funnel 46 via the Hose 38 can take place until the funnel weight has been reduced to a value at which switch 49 the solenoid valve 41 closes again. Since the switch 49 with a switching differential, So different response thresholds works, there is no risk that control oscillations occur.

The examples described show ways in which the invention can be carried out. Countless modifications are of course possible. For example, the signal that is generated to indicate that the hopper is to be emptied can also be used to control the actuation of other sludge pumps.

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funnels are used, which are at lower levels in the separation tank than the one from whom the signal was issued. Such a battery of secondary funnels can simultaneously emptied under the control of a main hopper, the weight of which triggers the entire emptying operation. The emptying cycle of the secondary hoppers can be controlled at the same time as that of the main hopper. Alternatively the emptying cycles of all hoppers can be triggered by the main hopper, but by separate time switches which are assigned to the individual secondary hoppers and which start to run when the main hopper starts running its emptying cycle begins. In this way, the advantages of the invention can be gained through minor modifications Existing separation tanks containing sludge funnels for concentrating the sludge can be used. The invention can also-be applied to other forms of separation basins than the types described with vertical flow.

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Claims (8)

September 21, 1973 Mc 3 claims 1. Separation basin for separating solids and liquids with a sludge funnel, the surface level of which corresponds to the level of a liquid filter layer in the Train basin and which has an outlet line, through which the funnel contents from the separation basin is drainable, characterized in that that a device (8, 10; 17, 18; 21 to 25; 37, 41, 42) is provided which is based on the weight of the Funnel (6; 7; 36) responds in such a way that when a first predetermined value is exceeded with the discharge of the funnel contents via the outlet line (11; 38) is started until the weight of the funnel on one second predetermined value is reduced. 2. Separation basin according to claim 1, characterized in that the funnel (6) on a roller (9) running Rope (8) is suspended, which carries a counterweight (10) at its free end, and that the outlet line (11) depending on the vertical position of the funnel in the separation basin (1) is evident and closable. 3. Separation basin according to claim 1, characterized in that that the funnel (7) of floats (17) is held, the - 12 409813/0484 September 21, 1973 Mc 3 in the liquid accumulated above the filter layer (4). speed swim, and that the outlet line (11) depending on the vertical position of the funnel in the separation basin (1) is evident and closable. 4. Separation basin according to claim 1, characterized in that the funnel has a buoyant collar (20), the bottom openings (21) and has flexible Hoses (25), pressure regulating valves (2 4) and shut-off valves (23) are connected to a compressed air source (22). 5. Separation basin according to claim 1, characterized in that the device (42) is supported on a lever (43) Has rope (37) which is applied to a pressure-sensitive switch (49) with differential actuation a force passes, which depends on the weight of the funnel (36) and its contents, and that the switch is a valve (41) controls through which the contents of the funnel from the separation basin (1) is drainable. 6. Separation basin according to claim 5, characterized in that the rope (37) is attached with its one end to a fixed point (47) and runs over a roller (46) which - 13 409813/048 4 September 21, 1973 Mc 3 is arranged on the lever (43) in such a way that the rope tension acts as a force and the switch (49) acts as a load. 7. Separation basin according to one of the preceding claims, characterized in that a second sludge funnel is provided in the separation basin, the sludge inflow level of which below that of the first sludge funnel (6; 7; 36) and in which the contents of the funnel are discharged via its outlet line through the device (8, 10; 17, 18; 21 to 25; 37, 41, 42) for controlling the Emptying of the first sludge funnel can be initiated. 8. Separation tank according to claim 7, characterized in that a timing element is provided for controlling the length of the emptying period for the second sludge funnel the activation of which can be triggered by the device (8, 10; 17, 18; 21 to 25; 37, 41, 42). 40981 3/0484