CA2295692A1

CA2295692A1 - Method and device for separating materials and guiding device therefor

Info

Publication number: CA2295692A1
Application number: CA002295692A
Authority: CA
Inventors: Dieter Frankenberger
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-07-11
Filing date: 1998-07-07
Publication date: 1999-01-21
Also published as: EP0998341A1; DE19729802A1; DE19729802C2; WO1999002237A1

Abstract

The invention provides for a method and device for separating solid mineral grain materials, such as sand, from organic materials, suspended mateterials, easily or hardly soluble materials contained in a liquid-solid mix, for instance a mix from waste water purification plants. According to said method, the liquid-solid mix is tangentially introduced into a vessel (1), at an inlet port (13). Said liquid-solid mix flows towards an outlet port (16), in said vessel (1), at a sufficiently low rate so that when flowing said heavy components from liquid-solid mix, that is essentially solid mineral grain materials, settle forming a sediment bed (22). Said components forming sediment bed are removed and optionally dehydrated. The method according to the invention is characterized in that said liquid-solid mix is forcibly conveyed, in order to flow in a spiral fashion, between the inlet port (13) and the outlet port (16), at least through a partial deep area.

Description

A method and device for separatincr materials and a auidina device for them S Technical field The invention concerns a method for the separation of granular mineral solids such as sand from organic substances, suspended materials, easily or hardly soluble substances in a liquid-solid mix, for example a mixture from waste water purification plants, in which the liquid-solid mixture is introduced tangentially at a radially external inlet point into a container. In the container the liquid-solid mixture flows at such a low speed from the inlet point to a radially inner outlet port, so that during this period the heavy mixture components, substantially the granular mineral solids of the liquid-solid mixture, sink down to form a sediment bed. The settled components of the sediment bed are then removed and optionally dehydrated. In addition, the invention concerns a totally new type of guiding device for the improvement of the method named above.
Furthermore the invention concerns a device for the separation of granular, mineral solids such as sand from organic substances, suspended materials, easily and hardly soluble substances in a liquid-solid mixture, such as, for example, a mixture from waste water purification installations, which has a container to accommodate the liquid-solid mixture and to form a sediment bed of substantially settled solid particles.
In addition, for the tangential introduction of the liquid-solid mixture into the container, there is a correspondingly designed radially outward inlet. In addition on the device there is a radially inward outlet port to remove the surplus liquid and the suspended materials which are located in it, the organic substances and the like.
The method as well as the device are intended, in particular, for the separation of sand which is in a solid-water mixture from organic substances, suspended materials, easily and hardly soluble substances, which are carried therein and optionally for the purification of it by an additionally introduced washing medium, for example water, air or an air-water mixture. This means, in particular, that the invention concerns sand catchers or sand washing plants and/or their modus operandi, in which the sand from waste water purification plants and street sweeping machines is separated from organic substances which are capable of rotting.
Prior art A device for the separation of floating materials and settling substances from a liquid is known, for example, from DE 195 O1 034 A1. In a container there is a substantially vertically extending closed separating wall, which projects with its upper zone above the level of the liquid and in its lower zone it is open or at least designed to be permeable. From Fig. 3 of this publication it is discernible that this vertical partition wall has a circular cross-section, in which a liquid with the floating and settling substances is introduced tangentially.
Round sand catchers and/or sand classifiers or settling basins are disclosed, for example in DE 43 18 522 A1 in the round constructional method, in which the basin is centrally charged. The central charging of these known devices has the disadvantage that because of the flow direction which is directed from the interior to the exterior, flow losses occur which should be avoided.
A general process and a device for the separation of solids from a suspension is also known from DE 43 12 540 C1. In this case there is tangential introduction on the outside of the container and central removal. It is emphasized that the flow to the center of the clarifying chamber is carried out substantially in spiral form, but that this is mainly achieved in that the flow takes effect by technical flow means before the entry into the clarifying chamber and in the clarifying chamber it is moved via a spiral route to the center. Due to the cross flow losses, this device is, however, not optimal with respect to the possible degree of separation.
A modus operandi as well as a device of the type named initially is known from DE 44 10 969 C1. The device which is described there is used for the separation of easily soluble substances, suspended materials and substances which are soluble with difficulty from a solid or liquid-solid mixture and it comprises a washing and separation container as well as a worm conveyor device which is motor-driven and connected in the bottom zone of the washing and separating container and is directed to the exterior at an incline and which leads to the outlet port, with a spiral conveyor for the removal of the separated mineral solids. In addition there is an outlet device for the removal of the liquid on the upper edge of the container. In the bottom zone of the washing and separating container there is an inlet port to permit the entry of a washing liquid. An outlet device is used for the removal of the washed, easily soluble substances, suspended materials and hardly soluble substances. In addition, it is spaced vertically from the bottom zone of the washing and separating container and extends within the latter. substantially vertically.
This device which is known therefrom is in fact well suited for the separation and/or removal in general of the granular mineral solids, in particular of the sand which is found in waste water. However, it has been discovered that the possible degree of efficiency of a device of the type named initially, in particular of a sand catcher or a sand washing plant, is not yet totally exhausted in the present constructional mode.
Description of the invention The invention is based on the technical problem of increasing the efficiency of a modus operandi which was explained initially and/or of a corresponding device, as well as of making available a design element with which existing devices can be re-equipped without major expenditure for this purpose.
This technical problem is solved by a method which has the features of claim 1. In addition, to solve the technical problem a guide device with the features of claim 6 is made available. Lastly the technical problem which is the basis of the invention is solved by a device which has the features of claim 11 and/or 19.
The invention is based on the idea that in the introduction of the liquid-solid mixture, the flow which is formed should be compulsorily guided between a radially outer inlet port and a radially inner outlet port in spiral form, so that the degree of separation is increased, which is achieved by prolonging the route and therefore the duration time of the mixture which is supplied. In addition, the available space in a container is exploited in optimal manner, in order to achieve over a greater route length a separation by sedimentation of the granular mineral solids which are in the liquid-solid mixture.
Due to the invention, it is prevented for the first time that so-called "short circuit flows" take place from the exterior 5 to the interior of the container, which does not lead to an optimal result in the sedimentation of the solid particles which are carried in the mixture.
In fact, so-called round sand catchers are known, in which the water with the sand in it is introduced tangentially, whereby in part a spiral flow is formed, which assists the deposit of the sand. However, the spiral flow is only present due to the outer edge of the container and the tangential introduction, and thereby favourable separation conditions are created only in the outer edge zone of the container. The separation and/or sedimentation process is reduced due to the above-mentioned short circuit flows transversely to the main flow. In these known sand catchers, the deposit is carried out towards the center, where the sand is then conveyed outwardly by compressed air from a sand shaft.
For the first time, due to the invention the spiral flow which forms in the case of the prior art in the edge zone per se is optimally forwarded, namely as far as the outlet port, whereby any cross flows or short circuit flows are avoided, so that the settlement of the sand is still more effectively supported. Thereby the degree of efficiency of the separation of granular mineral solids in a liquid-solid mixture is increased.
The enforced guidance in the spiral form has only to take place in the upper partial zone of the total level of the liquid which is in the container. For only there does a still detectable substantially horizontal flow take place.

A very even flow, which also makes possible the optimal sedimentation of the solid particles which are in the mixture is present when the enforced flow guidance is carried out in evenly wound windings. However, in accordance with the type of construction of the container, rectangular windings are also possible but here speed fluctuations may still occur, in particular in the corner zones. However, the corner zones can in turn also form eddies which increase the sedimentation in an optimal manner.
Due to the fact that the spiral distance between the individual windings decreases towards the outlet port, the flow speed from the inlet port to the outlet port can be kept constant in the main, which still further increases the degree of deposit.
A guiding device in accordance with the invention for spiral guidance between an inlet and an outlet port in a container, in which due to sedimentation the heavier components of the liquid-solid mixture, primarily the granular mineral solids, are deposited can be installed without any difficulty in existing devices or plants, such as were explained initially for example. For this purpose the guiding device must simply be secured in the upper zone of the container. In particular, it is possible to secure the guiding device at intervals on a container cover.
The degree of efficiency of the device can be still further increased when before the inlet port there is a mechanical pre separation device for separating a part of the suspended materials in the liquid-solid mixture and the easily and hardly soluble substances. Thereby, in the device downstream for the separation of granular mineral solids, as was explained initially, the guidance device in accordance with the invention is provided, achieving a still better sedimentation.

A constructionally simple but very efficient primary stage separation device consists of a rotatable sieve, in the wall of which there are small holes. The interior of the drum of the sieve is connected with an outlet for mixture components which do not pass through the holes of the liquid-solid mixture. Below the drum of the sieve there is a collector line which leads to the inlet port on the container of the downstream combustion device. In the drum of the sieve, which has a plurality of holes with a diameter between ca. 2 and 5 mm, the organic substances are sieved off and the sand attached to them is washed away.
In particular, it is advantageous when the drum of the sieve has a gradient, whereby better preseparation takes place and the removal of the water becomes possible without further ancillary means.
It is very advantageous when the liquid-solid mixture which is introduced is guided before the inlet port over a gradient, so that the liquid-solid mixture has at the inlet port in the container the low speed which is advantageous for sedimentation, and which amounts, depending on the mix ratios and on the solids which are to be settled, to about 0.3 m per second or less.
The outlet port comprises advantageously an outlet funnel, which is dimensioned in its angled length so that only a minimal suction effect is caused by the exit speed.
As in the case of the prior.art, the sand and/or generally the granular mineral solids which form the bed of the sediment is drawn off in small batches and optionally is dehydrated. For this purpose a worm conveyor device is advantageous, such as is also described in DE 44 10 969 C1, which was explained initially.
In an optimal embodiment, the "groove width" which is provided by the guide device is kept constant. In combination with the outlet (in particular the overflow height which is predetermined by its form), the maximally even flow unit is achieved.
Preferably the inlet and outlet are located on the same level, so that "short circuit flows" beneath the guiding device are further minimized.
The guiding device extends - setting out from a maximal charge amount - optimally about 100 mm above the surface of the water.

Short description of the drawings For further explanation and for better understanding of the invention, several examples of embodiments are described in more detail and explained below with reference to the enclosed drawings. They show:
Fig. 1 a schematic side view of a sand washing plant in accordance with the invention, which is provided with a new guiding device, Fig. 2 a plan view of the device in accordance with fig. 1, Fig. 3 a schematic perspective view of a guide sheet in accordance with the invention and Fig. 4 a schematic plan view of another embodiment of a guide device in accordance with the invention.
Description of examples of embodiments of the invention With reference to figures 1 to 3, a first embodiment of the invention will be described in more detail below. The sand washing plant shown in fig. 1 has a washing and separating container 1, which comprises a funnel part which extends downwards. Container 1 is supported y means of supports 2 on the base. As can be seen from the plan view of fig. 1, container 1 has a circular form in its upper partial range and is also designed to be cylindrical over this partial range. On one side, in the figures on the righthand side above an inlet port 13, there is a prestage separation device 9 which is arranged in the washing and separating container 1 and which comprises a rotatable sieve 10 with holes in it and a collector groove 12 under it. Both the sieve drum 10 as well as the collector groove 12 are inserted in a housing 11. The entirety of the prestage separation device has a length which corresponds almost to the diameter of the washing and separating container 1. The sieve 10 is driven by a rotor which is not shown here and it has a gradient. In the interior of the drum of the sieve there is an intake for the mixture which comes, for example, from a waste water purification plant, and which contains the granular mineral solids such as 5 sand, organic substances, suspended materials, easily and hardly soluble substances. The collector groove in its turn leads to an outlet 14, which is arranged to be higher than the inlet port 13 in the washing and separating container 1. The outlet 14 and the inlet port 13 are connected with each other 10 by a pipeline.
In the middle of the container there is a funnel 16 which leads to an exit port 17. The upper edge of the funnel determines the liquid level WSP. The incline which is seen in cross-section of the exit funnel 16 is designed so that a minimal suction effect results due to the exit speed of the surplus liquid, in this case water with suspended substances carried in it, easily and hardly soluble substances, as well as organic substances.
In the bottom zone of the washing and separating container 1 there is a stirrer device 18. In fig. 1 the stirrer device is arranged to be inclined, but it is also possible to arrange this stirrer device to be perpendicular. the stirrer device 18 has individual blades, which are rotated in the sediment bed 22 which is formed by the settled granular mineral solids, mainly sand, by a stirrer drive 20 and an interposed gear 19.
This is connected with a worm conveyor device 3, which is connected with the container part 1 and which projects at an inclination upwards supported by a support 5. The worm conveyor device 3 has a hollow spiral 4 which is driven by a worm drive 7 and an interposed gear 6. In the top end zone there is an ejection shaft 8, via which the sand which is removed and is conveyed from the hollow spiral 4 is ejected.
As can very well be seen from the plan view in accordance with fig. 2, in the upper part of container 1 there is a guidance device arranged in accordance with the invention in the form of a guide sheet 15. Guide sheet 15 is a spirally formed sheet which at the beginning forms together with the edge of the container a channel of substantially constant width, which then is formed by the adjacent walls of the guide sheet and continues in spiral form as far as the funnel 16. Thereby a spiral enforced guidance is provided for the liquid-solid mixture which is introduced into the container. This means that the result is an even mix flow guidance towards the interior.
The guide sheet 15 only covers a partial depth zone below the liquid level WSP, namely to such a depth in which a substantially horizontal flow can still be determined. In addition, it extends above the liquid level WSP, so that floating substances, for example organic substances or suspended materials on the surface of the liquid, cannot spray over it or cannot overflow.
In fig. 3 the spiral form and design of the guide sheet 15 is again clearly seen, in particular; especially the spiral winding and the constructional height.
Below the modus operandi of such a device will now be described. The water which is mixed with sand, organic substances, suspended materials, easily and hardly soluble substances from e.g. a waste water purification plant is introduced into the rotating sieve 10. Through the holes which are in sieve 10 with a hole size of between 2 and 5 mm, the organic parts are sieved off and the sand attached to them is rinsed away. The residual sand-water mixture is accepted by the collector groove 12 and is guided through the outlet 14 to the inlet port 13. Due to the gradient between the outlet 14 and inlet port 13, a suitable speed is provided for the sand-water mixture for the sedimentation which takes place in the container.
At this speed, this mixture is tangentially introduced at the inlet port 13 into the washing and separation container 1 which is filled with water, as can best be seen from fig. 2.
Due to the guiding device 15 in accordance with the invention, this tangentially introduced flow now becomes even, i.e.
substantially with constant speed, about 0.3 m/sec. or less, is guided in spiral form to the outlet port, the funnel 16.
During the period in the container 1, the granular mineral solids, primarily the sand, settles from the organic substances, suspended materials, easily and hardly soluble substances, which were present in the mixture which was introduced, and form a sediment bed 22 in the bottom part of container 1. The surplus water is drawn off via the funnel 1 with the residual substances in or on it through the outlet 17.
In the sediment bed 22 which is formed, the stirring device 18 is operated for thorough mixing. The sand which is collected is continuously removed in batches via the worm conveyor device. Due to the hollow spiral design, dehydration of the sand which was conveyed is carried out simultaneously in the output device 3. The sand which is conveyed via the hollow spiral 3 is filled into a suitable container via the ejection shaft 8.
In the second embodiment which is shown in fig. 4, this concerns a rectangular container 31, in which in order to optimize the length of the route which is available for sedimentation, there is a guiding sheet which has rectangular windings. In fact, in the zone of the corners of the rectangular windings changes in the flow speed result, but in principle there is also in this case better distribution and enforced guidance of the surface which is available.

Claims

claims

1. A method for the separation of granular mineral solids such as sand from organic substances, suspended materials, easily and hardly soluble substances in a liquid-solid mixture, such as e.g. a mixture from waste water purification plants, in which - the liquid-solid mixture is tangentially introduced into a container (1) at a radially outward inlet port (13), - the liquid-solid mixture flows from the input port (13) at low, constant speed over a partial depth range of the liquid solid mixture, forcibly guided spirally to a radially inner outlet port (16) in container (1), so that during this time the heavier components of the mixture, substantially the granular mineral solids of the liquid-solid mixture, settle with the formation of a sediment bed (22), and the settled components of the sediment bed (22) are removed and optionally dehydrated.

2. A method in accordance with claim 1, characterized in that the enforced flow guidance is carried out in evenly wound windings.

3. A method in accordance with claim 1, characterized in that the enforced flow guidance is carried out in rectangular windings.

4. A method in accordance with one of the preceding claims, characterized in that the enforced guidance is performed by a spirally wound guiding device (15; 32), which extends both above as well as below the liquid level (WSP).

5. A method in accordance with claim 4, characterized in that the spiral spacing of the guiding device (15; 32) from the outlet port (16) becomes smaller to such an extent that the flow speed remains substantially constant.

6. A device for the separation of granular mineral solids such as sand from organic substances, suspended materials, easily and hardly soluble substances in a liquid-solid mixture, such as e.g. the mixture from waste water purification plants, having - a container (1) to accept the liquid solid mixture and to form a sediment bed (22) of substantially the sedimented solid particles, - a radially outer inlet port (13) for the liquid-solid mixture for tangential introduction into container (1) , a radially inner outlet port (16) to discharge the surplus liquid and the suspended substances, the organic materials and the like which are in it, - a removal device (3) to remove and optionally to dehydrate the settled component parts of the sediment bed (22), and - a guiding device (15; 32) for the spiral enforced guidance of the liquid-solid mixture is arranged between the inlet port (13) and the outlet port (16) in container (1), in which - the guiding device (15; 32) extends over a partial depth range of the container and - the guiding device (15; 32) is designed so that the liquid-solid mixture flows between the inlet port (13) and the outlet port (16) at constant speed, whereby due to sedimentation the heavier components of the liquid-solid mixture, substantially the granular mineral solids, are deposited.

7. A device in accordance with claim 6, characterized in that before the inlet port (13) there is a mechanical pre-stage separation device (9) to separate out a part of the suspended materials, easily and hardly soluble substances which are in the liquid-solid mixture.

8. A device in accordance with claim 7, characterized in that - the mechanical pre-stage separation device (9) consists of a rotatable sieve (10),and in the walls of said sieve there are small holes, - the interior of the sieve is connected with an off-take line for the mix components of the liquid-solid mixture which do not pass through the holes and - below the sieve (10) there is a collector line which leads to the inlet port (13).

9. A device in accordance with claim 8, characterized in that the sieve (10) has a gradient.

10. A device in accordance with claim 6, characterized in that the guiding device extends both above as well as below the liquid level (WSP).

11. A device in accordance with claim 6, characterized in that the guiding device (15; 32) extends to a depth below the liquid level (WSP), at which a substantial horizontal flow can still be determined.

12. A device in accordance with claim 6, characterized in that the spiral spacing of the guiding device (15; 32) is continuously reduced toward the outlet port (16).

13. A device in accordance with claim 6, characterized in that the guiding device is a guide sheet (15; 32).

14. Use of a guide device (15; 32) in the form of a spirally wound wall element in a device for the separation of granular mineral solids such as sand from organic substances, suspended materials, easily and hardly soluble substances in a liquid-solid mixture, such as e.g. a mixture from waste water purification plants, for the enforced guidance of the liquid-solid mixture from an inlet port (13) which is located radially externally on the device for the separation of granular mineral solids to a radially inward outlet port (16).