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Title:
DEVICE FOR DEWATERING AND PURIFICATION OF SLUDGE OR DREDGED MATERIAL
Document Type and Number:
WIPO Patent Application WO/2017/044028
Kind Code:
A1
Abstract:
The invention concerns an arrangement for the dewatering and purification of slurry in the form of dredged material or similar suspensions of particles, comprising a tank (2) that has at a first end an inlet (25) for the input of slurry, a sorting arrangement (50) arranged in association with the inlet for the separation of coarse objects from the incoming sludge, a first outlet (26) for the discharge of purified water from the tank, and a second outlet (29) for the discharge of precipitated sediment that has collected on a bottom (9) that is a component of the tank. For improved efficiency, the tank (2) comprises a number (n) of sedimentation plates (14:1 -14:n) that are arranged to divide the tank with respect to its longitudinal direction into a number of consecutive parts, where each such part forms a sedimentation chamber (15:1 -15:n).

Inventors:
HAHLIN, Torbjörn (Storberget 23, Dorotea, 917 32, SE)
Application Number:
SE2016/050830
Publication Date:
March 16, 2017
Filing Date:
September 06, 2016
Export Citation:
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Assignee:
LAPPLANDS TEKNIK AB (Östra Polarvägen 10, Dorotea, 917 32, SE)
International Classes:
B01D21/00; E02F7/00
Foreign References:
US20030164341A12003-09-04
US20130327724A12013-12-12
KR20110030841A2011-03-24
US20040112816A12004-06-17
CN2778888Y2006-05-10
US4536286A1985-08-20
US20150068969A12015-03-12
Attorney, Agent or Firm:
ZACCO SWEDEN AB (P.O. Box 5581, Valhallavägen 117N, Stockholm, 114 85, SE)
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Claims:
CLAIMS

1. An arrangement for the dewatering and purification of slurry in the form of dredged material or similar suspensions of particles, comprising a tank (2), designed as a container, and that has at a first end an inlet (25) for the input of slurry, a sorting arrangement (50) arranged in association with the inlet for the separation of coarse objects from the incoming sludge, a first outlet (26) for the discharge of purified water from the tank, and a second outlet (29) for the discharge of precipitated sediment that collects on a bottom (9) that is a component of the tank, a number (n) of transverse sedimentation plates (14:1 -14:n) that limit the tank with respect to the longitudinal direction of the tank into a series of consecutive sedimentation chambers (15:1 -15:n), characterised in that the sedimentation plates (14:1 -14:n) comprise perforations (18) through which flow is possible, and in that the sedimentation plates (14:1 -14:n) end a certain distance above the inner surface of the bottom (9) of the tank in which a fluid passage 23 is formed between the lower edge (22) of each sedimentation plate and the inner surface of the bottom.

2. The arrangement according to claim 1 , whereby each sedimentation plate (14:1 -14:n) demonstrates an essentially rectangular principal surface of perforated sheet steel that for the purposes of reinforcement is limited at opposing ends and at an upper edge along one side by a frame section (19, 20) that extends along the edges of the steel plate.

3. The arrangement according to any one of claims 1-2, whereby the sedimentation plates (14:1 -14:n) are arranged to extend between two opposing side walls (7, 8) of the tank.

4. The arrangement according to any one of claims 1-3, whereby the sedimentation plates (14:1 -14:n) are manufactured of stainless steel and demonstrate perforations (18) whose degree of opening amounts to at least 60% (the degree of opening is greater than 60%).

5. The arrangement according to any one of claims 1 -4, whereby the tank (2) demonstrates the form of a vessel that is open at the top, and in that the sedimentation plates (14:1 -14:n) are arranged such that they may be exchanged in such a manner that the sedimentation plates can be displaced downwards from above and withdrawn upwards from the tank.

6. The arrangement according to any one of claims 1 -5, whereby the tank (2) and the sedimentation plates (14:1 -14:n) demonstrate such a mutual form that the sedimentation plates can be located at freely chosen locations along the longitudinal direction of the tank and in this way the size relationships between the sedimentation chambers (15: 1 -15:n) in the tank can be varied.

7. The arrangement according to any one of claims 1 -6, whereby the sorting arrangement (50) is mounted in a first sedimentation chamber (15: 1 ) that is limited in the direction of flow between a first sedimentation plate (14:1 ) and a forward end wall (5) that is a component of the tank, in which the inlet (25) for the introduction of slurry to the tank is arranged.

8. The arrangement according to any one of claims 1 -7, whereby the sorting arrangement (50) comprises a sieving screen (51 ) that runs in an endless pathway and that, rotating between an upper and a lower end (52, 53), is set transverse relative to the longitudinal direction of the tank, and is arranged obliquely at an angle upwards from the horizontal plane in such a manner that it demonstrates well defined upper and lower surfaces (56, 57),where the said upper surface of the sieving screen faces the inlet (25) for the sludge.

9. The arrangement according to any one of claims 1 -8, comprising a transporter (60) that is arranged supplementary to the sorting arrangement (50), and arranged to receive coarse material that has been separated out by means of the sorting transporter.

10. The arrangement according to any one of claims 1 -9, comprising a vibration arrangement (30) that is located on the outer surface of the bottom (9) of the tank (2).

11. The arrangement according to any one of claims 1 -10, whereby the first outlet (26) comprises a channel (31 ) that is mounted at an upper edge of a rear end wall (6) that is a component of the tank, where the said channel communicates with the tank through a lowered edge section (32) of the rear end wall.

12. The arrangement according to any one of claims 1 -1 1 , comprising a lifting means intended to interact with a corresponding lifting means at a lifting arm mounted on a vehicle for the handling and transport of the arrangement to and from the location of its use.

13. The arrangement according to claim 12, whereby the lifting means comprises indentations (1 1 ) into which a lifting fork 10 arranged at the lifting arm can be inserted.

14. The arrangement according to any one of claims 1 -13, comprising a second outlet (27), located at a rear end wall (6) that is a component of the tank and that makes it possible, when required, to achieve stepwise cleaning through one through one or several dewatering and purification arrangements of the present type being connected in series.

Description:
Device for dewatering and purification of sludge or dredged material

The present invention concerns a device for the dewatering and purification of sludge and dredged material according to the introduction to claim 1.

One problem with current devices for the dewatering and purification of contaminated sludge and dredged material is that it is normally a case of large stationary facilities dimensioned to dewater and purify very large volumes of sludge or dredged material. This type of stationary facility requires a large space and is therefore difficult to install in urban regions with a dense population. In addition, the facilities exhibit high operating costs and in many cases are located geographically far from the canals and water courses that require dredging and purification.

There is, for this reason, a requirement for simple transportable devices for the dewatering of sludge that are compact, inexpensive to manufacture, demonstrate low operating costs and that can, when required, be moved simply from one location to another. The device can, for example, be simply moved to a second water course when the dredged material from one water course has been treated which contributes to a high use of its capacity and that dewatering and purification of dredged material are possible at locations where these operations otherwise would not have been economically possible.

The expression "transportable" will be used in the following to denote not only "portable", i.e. a facility that can be carried to the site of use by means of, for example, lifting arms at a load-bearing machine, a transport vehicle equipped with a lifting crane, or similar, but also a device provided with wheels in a similar manner to that of a trailer that can be coupled to a vehicle in order to be moved in this way. The expression "raw sludge" will be used in the following to denote in general a slurry i.e. a suspension of solid material or substances in a fluid such as water. Particularly viscous fluids, in the form of dredged material that contains principally clays, and that can be transported by pumping along pipelines or tubes. "Sludge" is used to denote also solid substances separated from a suspension in a fluid and containing bound "interstitial" water (water between solid particles). The expressions "suspension" and "sol" (sometimes also "paste" or "slurry") are used to denote a colloidal mixture of solid particles dispersed in a fluid such as water. It should be understood that "sludge" can also include organic material in water, such as, for example, eukaryotic organisms, such as fibrous algae or similar organisms in water. The sludge may be derived also from separated fibres or parts of fibres in water, as may be the case for paper pulp.

Several different types of transportable device have been proposed in recent times.

There is known from, for example SE 532 693, a transportable dewatering arrangement comprising a tank, an inlet for contaminated dredged material, a first outlet for purified water and a second outlet for sedimented sludge. The tank comprises a mixing chamber to which the inlet for contaminated dredged material leads to a collection pocket and a sedimentation chamber in which the first and second outlets are arranged, whereby the mixing chamber and the sedimentation chamber are in fluid-mediated connection with each other. The tank is, in the manner of a container, closed from the surrounding atmosphere in which existing equipment is fixed mounted inside the tank, i.e. without the possibility that the equipment be moved, adapted or in another manner altered such that it corresponds in a desired manner to the operating conditions prevalent at the location such as type and properties of the sludge and dredged material that are to be purified.

One problem with the said known transportable dewatering arrangement is that the sedimentation chamber must be regarded as relatively inefficient, since it must demonstrate a significant length in order to achieve the required sedimentation and precipitation of slurry onto the bottom of the tank. In other words, the currents of suspensions of particles that can comprise fractions of clay and minerals must be transported a relatively long distance in the tank before the required precipitation has taken place, and the water that has been purified in this way can be led out through the first outlet. One consequence of the significant length of the sedimentation tank is, of course, that it contributes to the arrangement becoming relatively large and bulky, and in this way becoming of limited transportability.

A second problem with the said known dewatering arrangement is that the mixing chamber with a collection pocket for the incoming slurry constitutes a relatively large and bulky part of the arrangement, and in this way must be regarded as inefficient. A third problem with the said known dewatering arrangement is that the equipment inside the tank is fixed, and in this way cannot be adapted to correspond to the type and properties of the slurry and dredged material that are to be purified present at the location.

There exists, therefore, a desire to achieve, starting from the known prior art, an arrangement for the dewatering and purification of contaminated slurry and dredged material that is significantly more efficient, and that demonstrates smaller dimensions and in this way significantly higher transportability. Furthermore, there exists a desire to achieve an arrangement that can be adjusted, and that can be adapted to the existing type and properties of the slurry and dredged material that are to be purified present at the location. In this respect, it is important that all types of collection pocket and similar that slow down the flow of slurry through the tank are avoided.

A first purpose of the present invention, therefore, is to achieve a more efficient and in this way less bulky arrangement for the dewatering and purification of slurry and dredged material. A compact arrangement offers improved transportability. A second purpose of the present invention is to achieve an arrangement for the dewatering and purification of slurry and dredged material with improved capacity for adjustment and the possibility of adaptation to the operating conditions that are prevalent at the location, such as type and properties of the sludge and dredged material that are to be purified. A third purpose of the invention is to achieve an arrangement for the dewatering and purification of slurry that allows the purification to take place in several steps that follow one after the other.

These purposes are achieved through an arrangement that has been given the characteristics and distinctive features that are specified in claim 1. Further advantages of the invention are made clear by the characteristics and distinctive features specified in the non-independent claims.

The invention will be described below in more detail with reference to an embodiment that is shown in the attached drawings, of which:

Figure 1 shows a perspective view obliquely from above and from a forward end of an arrangement for the dewatering of slurry and dredged material according to the invention,

Figure 2 shows a perspective view obliquely from above and from a rear end of an arrangement for the dewatering of slurry and dredged material according to the invention, Figure 3 shows a longitudinal section of an arrangement for the dewatering of slurry and dredged material according to the invention,

Figure 4 shows schematically a perspective view obliquely from above one design of a system consisting of a first and a second arrangement according to the invention connected in series.

Figures 1 -3 display an arrangement for the dewatering and purification of raw sludge and dredged material according to the invention general denoted by 1. The arrangement 1 comprises a tank 2 that is open to the atmosphere and designed as a fluid-tight box supported on four supports 3 whose height can be adjusted and that have an associated foot 4 intended to rest on a base.

The tank 2 is, in the manner of a vessel, open at the top and is limited outwardly in the sideways direction by opposing forward and rear end walls 5, 6, a first and a second opposing side wall 7, 8, and is separated from the base by a bottom 9 (see Figure 3). The arrangement is intended to be handled and transported with the aid of a lifting arm (not shown in the drawings), for example of the type that is commonly found on loaders and tractors. The arrangement is equipped for this with a lifting means that corresponds to the said lifting arm, which in the design described here comprises a corresponding lifting means arranged at the free end of the lifting arm in the form of a lifting fork 10, and indentations 1 1 arranged at the lower surface of the bottom 9 of the tank into which indentations the shanks of the lifting fork 10 can be inserted. As an alternative, the lifting arm can be constituted by a crane arm of the type that is often installed on a crane vehicle with loading bed. Conceivable lifting means for the handling of the arrangement between the loading bed and the base with the crane arm may include any prior art lifting equipment for use with containers, such as corner boxes that can be inserted into rotational pegs of the type that is standard for lifting containers, loops for lifting slings, where the tank is handled suspended under the crane arm in a lifting hook, etc.

As is most clearly shown by Figure 3, a number (n) of transverse sedimentation plates 14: 1 -14:n are arranged in the tank 2. These sedimentation plates form a series of transverse walls that are parallel to each other in the vertical plane and that, extending between the side walls 7, 8 of the tank, limit the tank with respect to its length in a number of parts 15: 1 -15:n. Each such part forms a sedimentation chamber 15: 1 -15:n through which the current conditions for the slurry and dredged material that flow through the tank are intended to be distributed, i.e. to be controlled and monitored in a manner that has been determined in advance such that particles in the flowing fluid, i.e. the slurry that is moving through the tank, are sedimented and precipitated onto the inner surface of the bottom 9 of the tank, which forms in this way a collecting trough for sediment.

It should be understood that neighbouring sedimentation plates 14: 1 -14:n limit between them several (n) such consecutive sedimentation chambers 15: 1 -15:n along the longitudinal direction of the tank 2, whereby a first sedimentation chamber 15: 1 is limited between a first sedimentation plate 14: 1 in a sequence and the forward end wall 5 of the tank, and a final sedimentation chamber 15:n is limited between a final sedimentation plate 14:n in the sequence and the rear end wall 6 of the tank. The term "longitudinal direction" of the tank 2 is used in the following to denote the principal direction of flow of the slurry and dredged material through the tank.

With reference once again to Figures 1 and 2, the sedimentation plates 14: 1 -14:n form transverse walls between the opposing side walls 7, 8 of the tank 2. It is preferable that the sedimentation plates 14: 1 -14:n be manufactured of stainless steel that has been perforated such that it has a degree of opening that can amount to, but does not necessarily amount to, at least 60%, i.e. the degree of opening is greater than 60%. The task of the perforations 18 is to distribute the flows of water and to cause turbulence to diminish. Each sedimentation plate 14: 1 -14:n demonstrates an essentially rectangular principal surface of perforated sheet steel that for the purposes of reinforcement is limited at opposing ends and at an upper edge along one side by a frame section 19, 20 that extends along the edges of the steel plate. The sedimentation plates 14: 1 -14:n extend from the upper surface of the tank 2 from a level just above the surface of the water in the tank downwards, where they terminate a certain distance above the inner surface of the bottom 9 of the tank.

As is shown in Figure 3, a fluid passage 23 is formed between the lower edge 22 of each sedimentation plate 14: 1 -14:n and the inner surface of the bottom 9, the open area of which can be varied, depending on the selected downwards extent of the sedimentation plate, i.e. through selection of the height of the sedimentation plate. An inlet 25 is located at one end of the tank 2, in the forward end wall 5, in order to lead contaminated dredged material into the tank, which takes place through the action of a pump. At the second end of the tank 2, in the rear end wall 6, a first outlet 26 for purified water is located at a high location, together with a series of other outlets 27, known as "flange outlets", which make it possible when necessary to achieve stepwise purification through the connection in series of one or several dewatering and purification arrangements of the present type. The connection takes place through one or several lines 28, such as tubes.

As is shown in Figure 3 a third outlet 29 is located in the bottom 9 of the tank for the emptying or removal of sedimented slurry. The compact and relatively water-depleted slurry that collects at the inner surface of the bottom 9 is intended to be removed from the tank in an appropriate manner through the said outlet by means of a drainage plug, screw transporter or similar. It is conceivable also to empty the tank 2 of the water-depleted slurry with the aid of what is known as "vacuum suction". A vibration arrangement 30 is located on the outer surface of the bottom of the tank 2, with the aid of which precipitated slurry can be compacted even more effectively.

Figure 4 displays an example of a dewatering and purification system that operates in a stepwise manner, formed through the connection in series of several arrangements according to the invention. It is an advantage that such a system can be used during the processing of dredged material and sludge that are particularly difficult to dewater and purify. As is shown in the drawing, when connection in series is used a line 28 is connected between one of the said outlets 27 of a first arrangement according to the invention for the dewatering and purification of slurry denoted 1 :1 and a subsequent arrangement denoted 1 :2. Partially purified water is thus gradually transferred from the first arrangement 1 :1 to the subsequent arrangement 1 :2. It is obvious that a purification system of the type described above may comprise a freely chosen number (n) of connected arrangements.

With reference to Figure 1 , the first outlet 26 for the discharge of purified water comprises a channel 31 that is mounted at an upper edge of the rear end wall 6 and arranged to extend parallel with and on the outer surface of this wall. The channel 31 communicates with the tank 2 through a lowered edge section 32 of the rear end wall 6, whereby the said lowered edge section is designed such that surface water in the tank can flow efficiently down in the channel. As a result of the channel 31 , the first outlet 26 is prevented from withdrawing water by suction from below. A water discharge pipe that has an upper opening 36 and a lower flange connection 37 is denoted by reference number 35, with which water discharge pipe the water level in the tank 2 can be regulated through the upper opening 36 of the water discharge pipe being tipped downwards in order to lead the surface water of the tank outwards through the discharge pipe and onwards out through the flange connection.

The arrangement can be adapted such that it corresponds efficiently to the operating conditions at a location, in particular with respect to the type and properties of the sludge and dredged material that are to be purified at the location. The sedimentation plates 14: 1 -14:n are for this purpose arranged such that they can be exchanged, whereby they can be simply displaced downwards and withdrawn upwards out of the tank 2. Furthermore, the sedimentation plates 14: 1 -14:n may be located at freely chosen locations along the longitudinal direction of the tank 2. By placing neighbouring sedimentation plates 14:1 -14:n closer or further from each other, not only the number of sedimentation chambers 15: 1 -15:n but also the effective sedimentation lengths of these can be varied in the tank.

As is shown in Figure 2, the upper edges of the side walls 7, 8 of the tank 2 are, in order to make this adaptation possible, folded to form outwardly directed edge reinforcements 40, while support brackets 41 extend laterally outwards from an upper side edge of the side frame piece 19 that is a component of each sedimentation plate 14: 1 -14:n, which support brackets rest in a supporting manner on the edge reinforcements 40 when the sedimentation plate has been lowered into the tank. The sedimentation plates 14: 1 -14:n are fixed in their location through interaction between interacting fixing means, which in this case comprise holes 42 and pegs 43 that operate between the said support brackets and edge reinforcements.

As is most clearly shown by Figures 1 and 3, the inlet 25 for contaminated dredged material leads immediately into a first sedimentation chamber 15: 1 in which an endless sorting transporter 50 has been mounted, with which coarse particles of fractions of the sludge that have been determined in advance, such as pieces of plastic and pieces of metal that risk being pumped into the tank 2, can be sorted out.

The endless sorting transporter 50 comprises a sieving screen 51 that runs in an endless manner around a pathway and that rotates between an upper and a lower end 52, 53. The sieving screen 51 is supported on opposing sides in known manner by endless running transmission means 54, such as chains. The sieving screen 51 is equipped with carriers 55 that extend in the form of transverse elements across the complete width of the sieving screen between the said transmission means 54. Coarse particles can be separated from the sludge with the aid of these carriers 55 and carried upwards on the sieving screen. The sieving dimension of the sieving screen 51 has been so selected that the fraction of particles of a particular dimension, which has been determined in advance, i.e. finer particles in the sludge, can pass through and onwards into the tank 2. The endless running sieving screen 51 is set transverse to the longitudinal direction of the tank and demonstrates such a width that it extends over essentially the complete width of the first sedimentation chamber 15:1 and is arranged obliquely at an angle upwards from the horizontal plane such that it demonstrates well defined upper and lower surfaces 56, 57. The said upper surface 56 faces towards the inlet 25, and is so arranged relative to it that the inflowing sludge efficiently meets or impacts onto the rotating sieving screen 51. The lower surface 57 of the sieving screen faces towards the centre of the tank. An endless running transporter 60, in this case of lamellar type, extends transverse to the tank 2 and in association with the upper end 52 of the sieving screen 51 and parallel to the band. The task of the said transverse endless transporter 60 is to receive and transport out from the arrangement coarse material that has been sieved out by means of the sorting transporter 50.

The invention is not limited to what has been described above and shown in the drawings: it can be changed and modified in several different ways within the scope of the innovative concept defined by the attached patent claims.