A FLOW

Technical field of the invention

The present invention relates to a separator for separating particles from a flow, comprising an inlet providing a flow and a first outlet for discharge of said flow, said inlet is arranged at a lower position than said first outlet. Furthermore the present invention relates to use of such a separator and to a method to separate particles from a flow.

Technical Background

There is a need in different areas of applications to separate particles from a fluid and sometimes to separate the particles from each other, for example sorting particles depending on their size or density.

Such an area of application may be where an abrasive waterjet is used for slicing into metal or other materials by using a jet of water mixed with an abrasive substance such as garnet. Before the waterjet is discharged, the garnet is added into the water. As the waterjet passes through a work piece, it is collected in a catch tank below. The garnet has such properties that after it has been used for cutting once, its cutting abilities are rather improved why it is desirable to recycle the garnet particulate. Another area of application may be a pipe system in a water treatment plant where particles have a tendency to cause blockage which interrupts the system.

It is well known in the art to separate particles from a fluid by

sedimentation or filtration processes.

US 7 438 803 discloses a system for separating garnet from a waterjet cutting machine waste water. The system comprises a box shaped settling tank having an input and an output near the upper region of the tank. The water containing garnet particulate is pumped into the tank where the volume of the fluid contained therein reduces the flow and turbulence within the tank, allowing the heavier particulate matter to settle towards the bottom and the fluid to flow out through the outlet. Thus, the garnet may be collected from the bottom of the tank and reused.

However, a problem with the known technique in this area is that is difficult to control the sizes of the separated particles. Further, a settling tank as the one disclosed in US 7 438 803 is rather bulky and requires large space.

GB451942 discloses an apparatus for separating granular material in an ascending current of a flow. It shows a separating vessel with toothed plates projecting from its walls in order to maintain turbulent flow, an inlet for the separating medium, an inlet for material to be treated, an overflow and an outlet for the material at the lower end to be treated. However, the vessel, which may be complicated to manufacture, has to be relatively large in the vertical direction in order to be sure that the separation is done properly.

Further, it is hard to control that all material which shall be treated is

separated properly.

Hence, there is still a need for a separator which may be less spacious, which also may be used to separate different particles from each other and in which it is easy to control which particle sizes are separated from the flow. Summary of the Invention

The object of the present invention is to provide a separator that at least to some extent meets the above mentioned needs. Hence, the invention according to claim 1 discloses a separator for separating particles from a flow, comprising an inlet providing a flow and a first outlet for discharge of said flow, said inlet is arranged at a lower position than said first outlet, wherein said flow which is ejected from said inlet is adapted to drive at least a part of said flow in an upwards direction through said separator with an upwards directed flow velocity, and said flow comprises a liquid and said particles and said liquid and said particles are adapted to enter said separator from said inlet together, and said separation of at least a fraction of said particles from said liquid occurs as a velocity of vertical descent for said fraction of particles exceed said upwards directed flow velocity. By letting both the liquid and the particles, i.e. the flow, enter the separator together and letting the flow self drive at least a part of the flow in an upwards direction a simple separator is created, in which it is easy to control the separation of particles. This is sometimes needed since the separator may be optimized for a certain flow mixture in order to get a desired separation of the particles. Further, the flow mixture may be controlled before it enters the system by being mixed together in a separate container before it is enters the separator through the inlet. Another alternative is letting the flow mixture be mixed together just before it leaves the inlet.

Another advantage of having an inlet, which introduces both the fluid and particles, is that the flow mixtures may be taken directly from another process and introduced into the separator. For example, such a process is where abrasive waterjets are used (see Background of invention).

By arranging the inlet at a lower position than the outlet and letting the liquid and the particles flow in an upwards direction through said separator with an upwards directed flow velocity, a separator which has a vertical extension may be accomplished. A vertical extended separator may be much smaller in the horizontal direction than other separation systems, which reduces the space needed for the separator. Even if the separator is working in the vertical direction, it may be relatively low, thanks to the common inlet for the liquid and the particles.

Said inlet may direct generally all of said flow in said upward direction. By letting the inlet direct the flow in an upwards direction the flow that leaves the inlet gets a laminar flow faster which may be desirable for the separation of some particles. For some particles a turbulent flow will work , however this is not always desirable.

Advantageously, a cross section of said inlet is smaller than a cross section of said separator where said flow is entering. When the flow is introduced into the separator it is introduced with a predetermined velocity. When the flow passes the inlet and is introduced into the separator the flow will rise inside the separator with a velocity which is approximately the supply quantity divided with the cross section area of the separator. By having the cross section of the separator larger than the cross section area of the inlet, the velocity of the flow inside the separator is slower than the one entering. The upwards directed flow velocity decides which particles shall be sorted depending on their velocity of vertical descent, since the separation takes place when the velocity of vertical descent for said fraction of particles exceed said upwards directed flow velocity.

Another advantage is that when the flow is introduced into the separator the liquid and the particles are spread inside the separator and they get a larger area where they can separate. Particles having a velocity of vertical descent which exceeds the upward directed flow velocity may fall down without forcing the particles, which have a velocity of vertical descent which is lower than the upward directed flow velocity, down and below the inlet.

Said first outlet may be connected to a flow collecting device.

Advantageously, said separator further comprises a second outlet which is arranged at a position vertically beneath said inlet in order to remove said fraction of particles which has been separated from said liquid. This second outlet is used to empty the lower part of the separator where the particles which are separated from the liquid are collected.

Said second outlet may be one end of a tubular organ, said tubular organ is vertically arranged inside or outside said separator in order to remove the separated particles in an upwards direction.

Depending on how the upper part and the other end of the vertically arranged tubular organ are arranged, the siphon principle may be used in order to empty the collecting device from particles in a sufficient manner.

Advantageously, said separator has a vertically longitudinal extension. A vertically extended separator may be much smaller in the horizontal direction than other separation systems, which reduces the space needed for the separator.

An agitator may be arranged at a lower position than said inlet. After separation some particles, depending on their characteristics, may lump together and establish a sediment at the lower part of the separator which is more or less difficult to remove. To be able to remove these particles the sediment may be exposed to intermittent or continuous stirring so that the particles are kept in circulation. Said agitator may be a second inlet through which a part of said flow, which is intended to be ejected from said inlet, is passing into the separator in an angle to said upwardly directed flow derived from said inlet, or said agitator may be an impeller.

Advantageously, said separator is arranged in series with at least another separator, said other separator has an upwardly directed flow velocity which is lower that the upwardly directed flow velocity of the first separator. By connecting several separators in series to each other the particles which are to be separated may not only be separated from the liquid, they may also be separated from each other depending on their sizes, density and/or material. By changing the upwardly directed flow velocity of the flow from the inlet, differently sized particles may be separated.

Advantageously, said inlet is the only inlet into the separator, at least the only inlet of liquid and particles.

Use of a separator as described above may be in a pipeline system and/or abrasive waterjet system and/or mining industry.

A method to separate particles from a flow may comprise the following steps: - ejecting a flow, comprising a liquid and particles, from an inlet into a separator in order to drive at least a part of said flow in an upwards direction through said separator with an upwards directed flow velocity, and said liquid and particles enters the said separator from said inlet together

- separating said particles from said fluid by letting the velocity of the vertical descent for said particles exceed said upwards directed fluid velocity.

- removing said flow through a first outlet which is arranged above said inlet.

The method may further comprise the step:

- collecting said separated particles in a position which is arranged at a lower vertical position than said inlet.

The method may further comprise the step: - removing said separated particles through a second outlet which is arranged vertically underneath said inlet.

This method has the same advantages as described above in relation to the separator.

Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the [element, device, component, means, step, etc]" are to be interpreted openly as referring to at least one instance of said element, device, component, means, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

Other objectives, features and advantages of the present invention will appear from the following detailed disclosure, from the attached dependent claims as well as from the drawings.

Brief Description of the Drawings

Fig. 1 shows a first embodiment of a separator according to the invention in a partially open perspective view.

Fig. 2 shows a vertical cross-section view through a second

embodiment of a separator according to the invention.

Fig. 3 shows a vertical cross-section view through a third embodiment of a separator according to the invention.

Fig. 4 shows a separator shown in fig. 1 connected in series to other separators.

All the figures are highly schematic, not necessarily to scale, and they show only parts which are necessary in order to elucidate the invention, other parts being omitted or merely suggested.

Detailed Description of the Drawings

The above, as well as additional objects, features and advantages of the present invention, will be better understood through the following illustrative and non-limiting detailed description of example embodiments of the present invention, with reference to the appended drawings, where the same reference numerals will be used for similar elements.

Fig. 1 shows a separator 1 having an inlet 2 providing a flow 5 and a first outlet 3, i.e. a flow outlet 3 for discharge of said flow 5. The inlet 2 is arranged at a lower position than the first outlet 3. The inlet 2 is distributing the flow 5 and it is adapted to drive the flow in an upwards direction through said separator 1 with an upwards directed fluid velocity.

The flow 5 comprises a mixture of liquid and particles 6, and the particles of certain size and/or density are to be separated from the liquid and/or from each other. The liquid and the particles 6 enter the separator 1 from the inlet 2 together. The inlet 2 is the only inlet into the separator 1 . By having only one inlet which distributes both the liquid and the particles and letting the flow self drive at least a part of the flow in an upwards direction a simple separator is created, in which it is easy to control the separation of particles. This is sometimes needed since the separator may be optimized for a certain flow mixture in order to get a desired separation of the particles. Further, the flow mixture may be controlled before it enters the system by being mixed together in a separate container before it is enters the separator through the inlet. In GB451942, which is mentioned in the Technical Background, two inlets are arranged at different heights inside the vessel. One inlet is for the separating medium and the other inlet is for the material to be treated. The two inlets are arranged at different heights and arranged in different directions. A relative large volume is needed between them in order to mix the particles with the fluid in order get a sufficient separation of the particles. Further, it is hard to control the mixture inside the vessel.

The liquid may be water, oil or any other liquid suitable for the application. The particles 6 may be particles of different materials and/or different density and/or different sizes. The flow 5 which is introduced into the separator may be an already finished mixture, for example a mix of garnet and water used by abrasive waterjets which shall be reused. Or the flow mixture may be mixed just before the separation stage or before it leaves the inlet 2. For example, sometimes a dry material i.e., just particles shall be separated from each other. A liquid may then be added to the dry material in order to create a suitable mixture which is adapted to the separator. The separator is usually designed and adapted to get a desirable and

predetermined outcome from a predetermined fluid mixture.

The separator 1 has cylindrical shape with a vertical extension in order to minimize the space needed for the separator 1 . However, the separator 1 is not limited to be cylindrical or to have a vertical extension. Most of the separation takes place above the inlet 2, in a separation volume 29 and it is restricted by a hollow cylindrically shaped part 7, into which the inlet 2 is distributing the flow 5. The hollow cylindrically shaped part 7 has an open downward facing end 1 1 , which is connected with an underlying particle collecting device 8, i.e. a collecting volume. On the other end of the hollow cylindrically shaped part 7 is also an open end 12, i.e. an upwardly facing end 12, located in order to allow the upwardly flowing flow to flow over the upwardly facing end 12 which forms an outlet 3. The downwardly facing end 1 1 of the hollow cylindrically shaped part 7 is flat and lies in one plane, which is perpendicular to the longitudinal direction of the hollow cylindrically shaped part 7. The end 1 1 may however be designed differently, for example it may be only partially open.

The inlet 2 is here exemplified as the opening 10 of a pipe 17 which is coming through the particle collecting device 8 from the side. The opening 10 is flat and lies in one plane, which is perpendicular to the vertical direction of the hollow cylindrically shaped part 7 and it is arranged in the centre of the hollow cylindrically shaped part 7 and at the same vertical level as the downwardly facing end 1 1 of the hollow cylindrically shaped part 7. The cross section of the inlet 2 is smaller than the opening at the downwardly facing end 1 1 of the hollow cylindrically shaped part 7, i.e. the cross section. Preferably, the ratio of the openings is in the range of 1 :15-1 :20.

The inlet 2 and the pipe 17 are not limited to the above. The pipe 17 may enter the separator 1 from any direction, not necessary through the particle collecting device 8, as long as the flow which is ejected from the inlet drives at least a part of said flow in an upwards direction through said separator with an upwardly directed fluid velocity. The inlet is not limited to be arranged at the same vertical level as the downwardly facing end 1 1 . The inlet may be arranged higher up in the separator, and then the cross section of the inlet 2 is smaller than the cross section of the separator, i.e. where the separation takes place. The pipe 17 is not limited to be a pipe, it may be any kind of tubular device, for example a tube which may be flexible or rigid and it may be of any kind of material suitable for the application. The inlet, i.e. the opening of the pipe/tube, may direct the flow in the upward direction. As an alternative, a device may be arranged in the opening, i.e. in the inlet, in order to direct the flow or at least a part of the flow in the upward direction. As an alternative, the fluid may be directed by the inlet itself in a horizontal direction or through some kind of device. The vertical upwards velocity will then be reduced when the flow is entering the separator. The advantage is then that the separator can be made shorter.

The inlet 2 as said before distributes the flow 5 into the hollow cylindncally shaped part 7 in an upward direction. When the hollow

cylindncally shaped part 7 is filled up with flow 5 to its upwardly facing end 12, the flow will flow over that end 12. The end 12 is part of the flow outlet 3, i.e. the liquid outlet 3.

The flow outlet 3 is connected to a flow collector 13 which collects this flow. The flow collector 13 is restricted by a cylindrical container 14, which is arranged over the hollow cylindncally shaped part 7, i.e. upside-down, and forms together with the hollow cylindrically shaped part 7 and a flange 9 a closed container. The flange 9 is arranged to the hollow cylindrically shaped part 7 close to its downwardly facing end 1 1 . The flow outlet 3 is in this case also restricted by the bottom 23 of the container 14. The bottom 23 is arranged at a distance from the upwardly facing end 12 of the hollow cylindrically shaped part 7. The bottom 23 also contributes to a closed separator. However, the container 14 could be replaced by a hollow

cylindrical piece which is arranged around the hollow cylindrically shaped part 7. It is then important that the upwardly facing end of the hollow cylindrical piece is at a higher vertical level than the upwardly facing end of the hollow cylindrically shaped part 7 (not shown). A lid (not shown) can be placed on the upwardly facing end of the hollow cylindrical piece in order to get the same structure as the container 14. The position of the flange 9 is not limited to be arranged at the downwardly facing end of the hollow cylindrically shaped part 7, it may for example be higher up. The flow collector would then get smaller. The flow outlet 3 may as an alternative also be an opening of a pipe or a tube through which the flow may flow into before it reaches the upwardly facing end of the hollow cylindrically shaped part 7 (not shown). At the bottom of the flow collector 13 another outlet 15 is arranged in order to discharge said flow 5. Preferably, the outlet 15 is arranged above the flange 9 and above the inlet 2. An emergency fluid outlet 16 is arranged at the top of the fluid collector 13 in case of blockage of the outlet 15.

When the inlet 2 is distributing the flow 5 containing both fluid and particles 6 into the hollow cylindrically shaped part 7 with a predetermined velocity, the flow 5 will when it reaches the hollow cylindrically shaped part 7 rise with a velocity which is approximately the supply quantity divided with the cross sectional area of the hollow cylindrically shaped part 7. The separation of the particles 6 from the fluid takes place when the velocity of vertical descent for said particles exceeds said upwardly directed flow velocity. The particles, which have a velocity of vertical descent which exceeds the upwardly directed flow velocity, will fall down into the particle collecting device 8. Particles 6 which do not have a velocity of vertical descent that exceeds the upwardly directed flow velocity will proceed upwards with the flow through the flow outlet 3 into the flow collector 13.

The particle collecting device 8 is formed by letting the cylindrical container 14 protrude over the flange 9 and the downwardly facing end 1 1 of the hollow cylindrically shaped part 7 and arranging an end part 22 at the bottom of the separator 1 .

The end part 22 forms the bottom 22 of the particle collecting device 8 and close to the bottom 22 a particle outlet 18 is arranged in the horizontal direction, which enables the particles 6 to be discharged from the separator. The particle outlet 18 is here exemplified as the end of a pipe 28. It may however be a tube or anything suitable for the application. For example the bottom 22 of the separator 1 may be an openable aperture. The particle collecting device 8 is not limited to the above, it may for example be a separate device arranged to the downwardly facing end 1 1 of the hollow cylindrically shaped part 7. After removal of the separated particles the particles may be reused or treated in another way.

The separator may be used for different particles with different properties. Some particles may lump together and establish a sediment which may be difficult to remove from the particle collecting device 8. The sediment can then be exposed to an intermittent or continuous stirring, so that the particles are kept in circulation which makes them easier to remove. This is accomplished by an impeller 21 , which is arranged at the bottom of the separator, i.e. in the particle collecting device 8. The impeller is driven by an engine (not shown).

A separator which gives a sufficient result may have the following properties: The flow which is entering the separator is a mixture of garnets and water, where the relationship between the garnet and the water is 1 :5. The diameter at the separation area, i.e. at the downwardly facing end 1 1 of the hollow cylindrically shaped part 7 is 200 mm, and the flow travels in the upward direction with 80 liters per minute. Particles having a size bigger than 150 micron will then be separated from the flow.

Fig. 2 shows a separator 1 which is also shown in fig 1 and is described above, but with a vertically directed particle outlet 35. The stirring is here accomplished by letting part of the flow 5, which is intended to be ejected from the inlet 2, flow into the particle collecting device 8 via another pipe 24 with an inlet 20. The inlet 20 of the pipe 24 is arranged so that the flow from this pipe 24 is entering the particle collecting device 8, from the side in order to create a movement between the particles. The pipe 24 has a valve 25 which may be intermitted opened and closed in order to create an intermitted stirring, or the pipe 24 may always be open in order to create a continuous stirring. The pipe 17, which comprises the inlet 2, that is adapted to drive at least a part of said flow 5 in an upwards direction through the separator 1with an upwardly directed fluid velocity, also has valve 26 in order to be able to control the inlet 2.

The vertical particle outlet 35 is one end of a vertically arranged pipe 27. The pipe is arranged inside the separation volume 29, which is limited by the hollow cylindrically shaped part 7. The vertical particle outlet 35 and its pipe 27 may however be arranged outside the hollow cylindrically shaped part 7. The outlet 35 is arranged close to the bottom of the particle collecting device 8. Depending on how the upper part and the other end of the vertically arranged pipe 27 are arranged, the siphon principle may be used in order to empty the particle collecting device 8 from particles in a sufficient manner. The upper part of the pipe 27 is here arranged above the upwardly facing end 12 of the hollow cylindrically shaped part 7. Another way to empty the particle collecting device 9 is by attaching a priming pump to the pipe 27.

Close to the particle outlet 35 another pipe 30 is connected. An apparatus for creating air pressure may be attached to this pipe in order to raise the material in the pipe to simplify the emptying. The separated particles are here being emptied into a separate container 19. Some liquid may accompany the separated particles when removing the particles from the particle collecting device 8, especially if the last one of the above mentioned methods is used to create a movement between the particles. This liquid may be removed by emptying the particles in the upper part of a container, the particles will then fall down by gravity and the water may be lead away.

Fig. 3 shows a third embodiment of the separator 1 . The separator 1 comprises a circular vessel 31 with an inlet 2 arranged at a distance from the bottom 32 of the vessel 31 . The inlet 2 is the opening of a pipe 17, which is entering the vessel 31 from the side, and the inlet 2 is arranged upwards, i.e. in the flow direction. The volume underneath the inlet 2 is where the separated particles will accumulate. A particle outlet 18 is arranged at the bottom 32 of the vessel 31 in order to be able to remove the separated particles. The distance between the bottom 32 and the inlet 2 depends on how large volume is needed or desired for collecting the particles. Around the opening of the vessel 31 a flow collector 13 is arranged. When the flow 5 from the inlet is rising inside the vessel 31 the flow 5 will flow over the top edge 33 of the vessel 31 , which forms an outlet 3. The flow 5 is then collected in the flow collector 13. The flow collector 13 is a receptacle which is arranged around the vessel 31 where the separation takes part. At the bottom of the flow collector 13 another flow outlet 15 is arranged. As an alternative a pipe may replace the flow collector 13. The pipe may then be arranged at the upper end of the vessel (not shown). A lid may close the open end of the vessel (not shown).

Fig. 4 shows three separators 1 , Γ, 1 ^" as described in fig. 1

connected to each other in series. The flow is entering the first separator 1 through the inlet 2 and flows through the hollow cylindrically shaped part 7 to the flow outlet 3. The flow outlet 3 from the first separator 1 is connected to the inlet 2 Of a second separator 1 ^' and the flow outlet 3 ^' from the second separator 1 ^' is connected to the inlet 2 ^" of a third separator 1 ^" . The third outlet 3 ^" may be connected to a fourth separator or to a container (not shown). The hollow cylindrically shaped parts 7, 7 ^' , 7 ^" , in all three separators have different cross sectional areas and different lengths. However, the lengths of the hollow cylindrically shaped parts 7, 7 ^' , 7 ^" and their cross sections may be the same. The liquid and the particles which have not been separated in the first separator 1 are at least partly separated in the second separator 1 ^' . By changing the velocity of the flow, i.e. reducing the upwardly directed velocity in the second separator 1 ^' , lighter particles, i.e. lighter than the particles which were separated in the first separator 1 , may be separated. The velocity of the upwardly directed flow may be adjusted by changing the flow velocity from the inlet and/or by changing the cross-sectional area of the volume into which the flow is flown into. Here the cross-sectional area is getting larger for every separator. By connecting the flow outlet 3 ^' from the second separator 1 ^' to a third separator 1 ^" with a third velocity, which is lower then the one in the second separator 1 ^' , the particles left in the fluid may be separated. By connecting several separators in series to each other the particles which are to be separated may not only be separated from the fluid, they may also be separated from each other depending on their sizes, density and/or material. Each separator 1 , 1 ^' ,1 ^" has a particle outlet 18, 18 ^' , 18 ^" at each respective bottom. The particle outlet 18, 18 ^' , 18 ^" is one end of a pipe 28, 28 ^' , 28 ^" . Each particle outlet 18, 18 ^' , 18 ^" is connected to a separate container 34, 34 ^' , 34 ^" into which the separated particles may be emptied.

The invention has mainly been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the invention, as defined by the appended patent claims.