Pump for sludge removal device

Abstract

To provide a sludge removal device in which lack of moving parts can extend a lifespan of a pump as compared to other pumps.SOLUTION: A pump 1 for a sludge removal device comprises: a pump housing having a pumping inlet at the front end and a pumping outlet 4 at the rear end defining the rearwards direction; and a pumping nozzle 10 arranged within the housing and oriented to direct fluid along the housing towards the pumping outlet 4. The housing comprises: an inlet portion 7 decreasing in cross-section from the front end toward the rear end; and an outlet portion 9 increasing in cross-section from the front end toward the rear end, which is arranged adjacently to a throat portion 8 if the throat portion 8 is present, or which is arranged adjacently to the rear end of the inlet portion 7 if the throat portion 8 is not present. The pumping nozzle 10 is arranged within the housing in front of the inlet portion 7 of the pump housing.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to the removal of sludge from aquatic sediments. [Background technology]

[0002] Sludge can accumulate over time at the bottom of man-made bodies of water, such as tanks or ponds, or at the bottom of natural bodies of water, such as lakes and oceans.

[0003] Removal of sludge may be desirable to increase water volume or flow, to remove contaminants contained in the sludge, to collect the sludge for use as a resource, or for other reasons.

[0004] Sludge sources can be natural, such as the settling of suspended particles in water, or man-made, such as the result of mining or drilling. Sludge may consist of particles of a defined size or of particles of various sizes. The size or size range may vary substantially depending on the deposit. Sludge may contain various percentages of water within its structure. As a result of the deposition pattern, sludge may be homogeneous or layered. Post-deposition physical or chemical processes may result in particles bonding together into a solid mass, or they may be held together only by gravity. For purposes of this specification, the term "sludge" should be construed to include dense liquids and semi-solids, such as waxes, that are not essentially particulate but have similar properties and are easily fluidized, particularly with the use of pressurized water.

[0005] An example of sludge that needs to be removed is sediment at the bottom of ponds storing nuclear waste. Because these ponds are artificially constructed, the bottom is assumed to be flat and uniform, although the possibility of relatively large objects falling into the pond cannot be ruled out. Because such sludge contains radioactive materials, it requires efficient collection and careful disposal, which must be done remotely to avoid the presence of human operators. Because such sludge accumulates slowly over a long period of time, it can become layered and relatively tightly bound.

[0006] GB 2,515,890 discloses a blade cutter device for removing accumulated sludge, particularly useful for removing radioactive sludge. The blade cutter includes a housing having a front and a rear, an outlet through which sludge can be removed from the rear of the housing, a blade on the housing having a cutting edge facing forward and a surface facing the interior of the housing behind the cutting edge, and one or more nozzles directing jets of water onto the blade surface to fluidize the sludge cut by the cutting edge. The device operates by forcing the cutting edge forward to cut into the surface of the sludge, separating the sludge layer and directing it into the housing. The water jets fluidize the water and carry it toward the rear of the housing. A second row of jets can be provided to further carry the fluidized sludge toward the rear of the housing. A jet pump is provided at or near the rear of the housing to remove the water and fluidized sludge from the rear of the housing and deliver it outside the device for further processing.

[0007] Figures 1 and 2 of the present application show one embodiment of a prior art blade cutter from GB 2525890, where the forward and rearward directions are typically vertical and the device is lowered by gravity from a crane or actively pushed down into the bulk sludge pile. Such an embodiment may be provided by lowering into the sludge pile via a vertical pipeline. The diameter of such a vertical pipeline may be 4 inches (10.2 cm) or less. Therefore, in such an embodiment, it is preferable that all components, including any pumps, be able to fit into a pipeline of this diameter.

[0008] During operation of the blade cutters of Figures 1 and 2, it has proven difficult to balance the speed of the jet pump with the rate of sludge removal by the cutting blades. Additionally, mechanical pumps have been found to rapidly degrade in performance when placed in environments containing radioactive sludge. Consequently, there is a need for improved pumps for sludge removal systems, such as those requiring the removal of fluidized sludge that may contain radioactive materials. Summary of the Invention

[0009] The present invention provides a pump for a sludge removal system, a method for operating the pump, and a sludge removal system including the pump.

[0010] The pump according to the present invention comprises: a pump housing having a pumping inlet at a forward end and a pumping outlet at a rearward end defining a rearward direction; a pumping nozzle disposed within the housing and oriented to pump fluid along the housing toward the rear end; The housing is an inlet portion whose cross-sectional area decreases from the front end to the rear end; optionally, a throat portion having a constant cross-sectional area disposed immediately adjacent the aft end of the inlet portion; an outlet section having a cross-sectional area that increases from its forward end to its aft end, the forward end being located immediately adjacent to the throat, if a throat is present, or immediately adjacent to the aft end of the inlet section, if no throat is present; The pumping nozzle is located within the housing, forward of the inlet of the pump housing.

[0011] The pump of the present invention is advantageous in that it is a simple structure that provides powerful pumping for a blade cutter, capable of pumping fluidized sludge a significant vertical distance. Furthermore, the pump of the present invention can eliminate moving parts, making it suitable for use in hostile environments, such as those containing radioactive sludge. Furthermore, the pump can be generally cylindrical, with a narrow diameter that allows it to fit through narrow pipes to reach the sludge environment.

[0012] In embodiments of the invention, the housing may have a generally cylindrical interior cross-section along its length. The embodiment may be generally cylindrical and configured to easily slide down the length of the pipe. The embodiment of the invention is sized and shaped to operate along a standard 4-inch (10.2 cm) diameter pipeline.

[0013] The outlet section of the pump can have an inner wall that forms an angle with respect to the longitudinal axis of the housing. The angle can be relatively shallow, such that the cross section of the outlet section gradually widens along its longitudinal length toward its rear end. The inner wall of the outlet section can form an angle of between 2° and 10°, between 4° and 8°, or between 5° and 7° with respect to the longitudinal axis of the housing. An angle of about 6° is currently preferred.

[0014] The inlet section of the pump can have an inner wall that forms an angle with respect to the longitudinal axis of the housing. The angle can be relatively steep, such that the cross section of the inlet section narrows rapidly along its longitudinal length toward the rear end. The inner wall of the inlet section can form an angle with respect to the longitudinal axis of the housing of between 15° and 75°, between 30° and 60°, or between 45° and 60°. An angle of about 60° is presently preferred.

[0015] The pumping nozzle may be of any size and shape deemed appropriate for a particular embodiment of the invention. In embodiments of the invention, the pumping nozzle may have a diameter of 1 mm to 15 mm, 1 mm to 10 mm, or 1 mm to 5 mm. A nozzle diameter of 3 mm is currently preferred.

[0016] The pumping nozzle can be located at the inlet or a predetermined distance from the inlet. Generally, the pumping nozzle should be located relatively close to the inlet, for example, between 0 mm and 60 mm, between 0 mm and 40 mm, between 0 mm and 20 mm, or between 0 mm and 10 mm from the inlet. Currently, it is preferred to have the nozzle 2 mm from the inlet.

[0017] The throat of the present invention may have any suitable length. In embodiments of the present invention, the throat has a longitudinal length between 0 mm and 50 mm, between 0 mm and 30 mm, between 0 mm and 20 mm, or between 0 mm and 10 mm. It is currently preferred that the throat length be 5 mm.

[0018] The present invention also provides a method of operating a pump according to any one of claims 1 to 8, in which a fluid is pumped through a pumping nozzle. It is generally preferred that the fluid is water, although any other suitable pumped fluid may be used. The fluid is generally provided under pressure from a remotely operated pump along a pipeline terminating in the pumping nozzle. The remotely operated pump may be located a predetermined distance from the pump body and may be any suitable pump for providing pressurized fluid.

[0019] Water or other fluid may be provided to the pumping nozzle at any suitable flow rate apparent to one skilled in the art. The fluid may be provided at a flow rate between 40 liters per minute and 60 liters per minute, or between 40 liters per minute and 50 liters per minute. For example, approximately 47 liters per minute of fluid may be provided.

[0020] Water or any other fluid may be provided to the pumping nozzle at any suitable pressure apparent to one skilled in the art. The fluid may be provided at between 100 bar (10 MPa) and 150 bar (15 MPa), or between 110 bar (11 MPa) and 140 bar (14 MPa), or between 120 bar (12 MPa) and 130 bar (13 MPa). For example, the fluid may be provided at a pressure of about 123 bar (12.3 MPa).

[0021] The present invention also provides a sludge removal apparatus, the sludge removal apparatus comprising: a pump according to the invention as described above and as defined in the claims; a blade cutter device; The blade cutter is a blade cutter housing having a front and a rear; an outlet for removing sludge from behind the blade cutter housing; a first blade on the blade cutter housing, the first blade having a cutting edge facing forward and a first blade surface facing the interior of the blade cutter housing rearward of the cutting edge; and at least one first nozzle positioned and oriented to direct a jet of water onto the blade surface, the jet having a backward motion component relative to the blade surface.

[0022] For example, a sludge removal device may include the blade cutter device according to the prior art described above and the pump according to any one of claims 1 to 9 of the present application.

[0023] The pump may be attached directly to the outlet of the blade cutter device, or may be located a predetermined distance from the outlet of the blade cutter device and directly connected to the pump by a suitable conduit, such as a pipe or other object capable of holding a fluid. For example, the pump may be located between 0 mm and 3000 mm, between 0 mm and 2000 mm, or between 0 mm and 1000 mm from the outlet of the blade cutter device. In an embodiment of the present invention, the pump may be located 500 mm from the outlet of the pump.

[0024] In embodiments of the present invention, the or each nozzle of the blade cutter device may be supplied with fluid from the same source as the pumping nozzle of the pump. Any suitable pipe or conduit may be provided for providing fluid to the nozzle of the blade cutter device.

[0025] Further features and advantages of the present invention will become apparent from the preferred embodiments shown and described below. Unless otherwise stated in the claims or context, any feature of the illustrated embodiments of the present invention may be included in an embodiment of the present invention independently of any other feature. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a side view of one embodiment of a prior art blade cutter device. [Figure 2] 2 is a cross-sectional view of the device of FIG. 1 taken along line BB. [Figure 3] 1 is a side view of a pump according to the present invention; [Figure 4] FIG. 4 is a cross-sectional view of the pump of FIG. 3 taken along line AA. DETAILED DESCRIPTION OF THE INVENTION

[0027] 1 and 2 show one embodiment of a prior art blade cutter device for removing sludge from deep deposits that may not be layered or resting on level ground.

[0028] The apparatus includes a housing 52 defining a forward direction (indicated by arrow 53) and an opposite rearward direction. In this embodiment, the forward and rearward directions are typically vertical, and the apparatus is either lowered by gravity from a crane or actively pushed down into a bulk sludge pile, although the apparatus may be used in virtually any orientation when pushed down. The apparatus may be imparted with a reciprocating motion or may use vibrations up to ultrasonic frequencies to assist the passage of the blades through the sludge.

[0029] The housing 52 includes a collection chamber surrounded by side walls 55 and end walls 56, which are generally open in a forward direction. The collection chamber 54 tapers to a port 58 at its rear end, from which water and fluidized sludge can be removed by a pump (not shown) for further processing outside the device. A grid (not shown) of appropriate spacing can be installed to prevent objects over a certain size from entering the collection chamber 54 through the opening.

[0030] A central boss 60 extends across the collection chamber 54 between the end walls 56. A blade 62 projects forwardly from the boss 60 through an opening in the collection chamber 54. The blade 62 may be integral with the boss 60 or may be a separate part attached to the boss 60 that is optionally replaceable when worn.

[0031] As the device advances, the forward blade 62 cuts through the bulk sludge, deflecting it to either side of the blade 62 and into the opening of the collection chamber 54. The leading edge of the side wall 55 also functions as a cutting edge 64, which penetrates the sludge and directs some of it into the collection chamber 54. If the sludge is sufficiently soft, the cutting edge 64 does not need to be particularly sharp. As shown in FIG. 6, the cutting edge 64 preferably converges slightly forward to promote a good seal against unstirred sludge. This helps prevent the escape of fluidized sludge circulating within the collection chamber. An inlet (not shown) delivers high-pressure water from an external water source to a manifold 66 extending along the central boss 60. A first set of nozzles 68 is positioned along one side of the manifold 66 to direct a first row of pressurized water jets 69 toward the surface of the cutting edge 64 (i.e., the side wall 55). A second set of nozzles 70 is positioned along the opposite side of the manifold 66 to direct a second array of jets of pressurized water onto the other side (i.e., the other sidewall 55) of the cutting blade 64. Thus, the apparatus is mirror symmetrical about the centerline, although the symmetry can be slightly broken by alternating the first nozzles 68 and second nozzles 70 along the length of the manifold 8.

[0032] The jets 69, 71 preferably fan out from the nozzles 68, 70 to form an uninterrupted line where they impinge on the side wall 55. The angle of incidence of the jets 69, 71 with the side wall 55 may vary substantially as long as the jets have a backward component of motion relative to the surface of the side wall so that jets bouncing off the side wall carry fluidized sludge toward the rear of the collection chamber.

[0033] 3 and 4 show an embodiment of a pump 1 according to the invention.

[0034] Pump 1 has a generally cylindrical housing 2 extending from a forward end 3 to a pumping outlet 4 at its rear end. Housing 2 generally defines a forward section 5 and a pumping section 6 located aft of front section 5. Housing pumping section 6 includes a relatively short inlet section 7 having an internal cross-sectional area that rapidly decreases from the forward end to the rear end, a throat section 8 of constant internal cross-sectional area, and a relatively long outlet section 9 having an internal cross-sectional area that gradually increases from the forward end to the pumping outlet 4. Housing 2 is generally circular in cross section along its entire length.

[0035] A pumping nozzle 10 is centrally located within the front section 5 of the housing, prior to the pumping section 6, and is centrally located and oriented within the housing to push water along the longitudinal axis of the pump (along line AA). Water is supplied to the pumping nozzle 10 by a supply pipe 11 formed through the wall of the front section 5 of the housing and connected to an external pressurized water supply (not shown). During operation, water is pumped from the pump 1 through the pumping nozzle 10 and along the longitudinal axis of the pump 1 to the pumping outlet. The shape of the pumping section 6, with its rapidly converging inlet and gradually expanding outlet, acts as a pump to draw fluid into the pump 1 from the front end 3 toward the pumping outlet 4.

[0036] Inlet section 7 has inner walls that form an angle of 60° with respect to the longitudinal axis of pump 1, although embodiments of the present invention can have the walls at an angle between 15° and 75°. Outlet section 9 has inner walls that form an angle of 6° with respect to the longitudinal axis of pump 1, although embodiments of the present invention can have the walls at an angle between 2° and 10°. The inner diameter of throat section 8 is 20 mm and the throat is 5 mm long. Pumping nozzle 10 has a diameter of 3 mm and is located 2 mm from the inlet section.

[0037] It should be understood that the pump 1 of the present invention may be fitted to the blade cutter as shown in Figures 1 and 2 to form a blade cutter according to the present invention. In particular, the pump 1 of Figures 3 and 4 may be mounted to the port 58 of the blade cutter of Figures 1 and 2 and function as a pump for pumping fluid from the blade cutter. In embodiments, the first and second nozzles 68, 70 may be fed from the same water supply as the pressure nozzle 10. The pump 1 may be located a predetermined distance from the blade cutter. In embodiments of the present invention, the pump may be located anywhere within 3000 mm of the blade cutter.

[0038] Importantly, the pump 1 of the present invention has no moving parts and can be configured to fit small diameter pipes, such as the 4-inch (10.2 cm) diameter pipes commonly used to access radioactive sludge. This makes the pump practical, and the lack of moving parts may extend the pump's lifespan compared to other pumps. Additionally, a single pressurized water supply may be used to supply water to both the pump's pressure nozzle 10 and the blade cutter's first and second nozzles 68, 70.

Claims

1. A pump for a sludge removal device, the pump for the sludge removal device comprising: a pump housing having a pumping inlet at a forward end and a pumping outlet at a rearward end defining a rearward direction; a pumping nozzle disposed within the housing and oriented to pump fluid along the housing toward the rear end; The housing includes: an inlet portion whose cross-sectional area decreases from the front end to the rear end; optionally, a throat portion having a constant cross-sectional area disposed adjacent the aft end of the inlet portion; an outlet section having a cross-sectional area that increases from a forward end to an aft end, the forward end being located adjacent the throat, if the throat is present, or adjacent the aft end of the inlet section, if the throat is not present; The pump for a sludge removal device, wherein the pressure-feeding nozzle is disposed within the pump housing in front of the inlet portion of the pump housing.

2. The pump of claim 1 , wherein the housing is generally circular in cross section.

3. 3. The pump of claim 1 or 2, sized and shaped for placement in a 4 inch (10.2 cm) diameter pipeline.

4. A pump according to any one of claims 1 to 3, wherein the inner wall of the outlet section forms an angle of between 2° and 10° with respect to the longitudinal axis of the housing.

5. A pump according to any preceding claim, wherein the inner wall of the inlet section forms an angle of between 15° and 75° with respect to the longitudinal axis of the housing.

6. The pump of any one of claims 1 to 5, wherein the pumping nozzle has a diameter of between 1 mm and 15 mm.

7. The pump according to any one of claims 1 to 6, wherein the pressure-feed nozzle is disposed at a position between 0 mm and 60 mm from the front end of the inlet portion.

8. The pump according to any one of claims 1 to 7, wherein the throat portion has a length in the front-to-rear direction of 0 mm to 50 mm.

9. A method of operating a pump according to any one of claims 1 to 8, wherein water is pumped through the pumping nozzle to operate the pump.

10. 10. The method of claim 9, wherein the water is pumped through the pumping nozzle at a flow rate of between 40 liters per minute and 60 liters per minute.

11. 11. The method of claim 9 or 10, wherein the water is pumped through the pumping nozzle at a pressure of between 100 bar (10 MPa) and 150 bar (15 MPa).

12. A sludge removal apparatus, comprising: A pump according to any one of claims 1 to 8; a blade cutter device, the blade cutter comprising: a blade cutter housing having a front and a rear; an outlet through which sludge can be removed from the rear of the blade cutter housing; a first blade on the blade cutter housing, the first blade having a cutting edge facing forward and a first blade surface facing the interior of the blade cutter housing rearward of the cutting edge; at least one first nozzle positioned and oriented to direct a jet of water onto the blade surface, the jet having a backward motion component relative to the blade surface; Sludge removal equipment.

13. 13. The sludge removal apparatus of claim 12, wherein the pump is attached directly to the outlet.

14. 14. A sludge removal apparatus according to claim 12 or 13, wherein the at least one first nozzle is supplied with water from an inlet pipe of the pump.

15. 13. The sludge removal apparatus of claim 12, wherein the pump is located between 0 mm and 3000 mm from the outlet of the blade cutter.

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