Centrifugal pump for pumping multiphase suspensions and gas removal device for use in a centrifugal pump

Abstract

The present invention relates to a centrifugal pump (10) for pumping a multiphase suspension comprising liquid, solid material and gas, the pump comprising: - a pump housing (11) having a suspension inlet (12) and a suspension outlet (13) and a flow passage (110) between the inlet (12) and the outlet (13); - a shaft (14) mounted by bearings for rotation about its central axis (A-A); - an impeller (18) rotatable via the shaft (14), aligned with and arranged to the inlet (12). The impeller (18) rotates about an axis (A-A) in a flow channel (110). A gas collection opening (20) for gas removal is arranged in the flow channel (110). The inlet end (120) of the flow channel (110) is provided with a plurality of static blades (2) including the gas collection opening (20). These blades (2) extend radially from the inner wall (111) of the flow channel (110) toward the center of the flow channel (110), and are located upstream of the impeller (18). The invention also relates to a corresponding gas removal device.

Description

Technical Field

[0001] This invention relates to a centrifugal pump for pumping multiphase suspensions comprising liquid, solid materials, and gas, as described in the preamble of claim 1. More specifically, this invention relates to a centrifugal pump for pumping multiphase suspensions comprising liquid, solid materials, and gas, the pump comprising:

[0002] - Pump housing, having a suspended solids inlet and a suspended solids outlet, and a flow passage between the inlet and outlet.

[0003] - A shaft, which is mounted by bearings to rotate about its central axis AA.

[0004] - An impeller, which can be rotated by a shaft, aligned with the inlet, and arranged to rotate about axis AA in the flow channel.

[0005] - A gas collection opening for gas removal, which is arranged in the flow channel.

[0006] The present invention also relates to a gas removal device for use in a centrifugal pump. Background Technology

[0007] Prior art document EP 0298693A2 discloses a centrifugal pump, which in Figure 1 The pump is generally indicated by reference numeral 10. It includes a main housing 11 with a suspended matter (e.g., slurry) inlet 12 and a suspended matter outlet 13 generally transverse to the inlet 12. A shaft 14 is mounted by bearings or the like (not shown) for rotation about an axis AA, which is generally aligned with the inlet 12. The shaft 14 is hollow and has a plurality of elongated slots 15, 16 that are generally (though not typically completely) parallel to the axis AA and allow communication between the interior and exterior of the hollow shaft 14. In the depicted embodiment, gas from the slurry is collected at the shaft 14, enters the shaft 14 through the opening 15, and then exits through the slots 16 and is discharged with the slurry through the outlet 13.

[0008] The purpose of this invention is to provide a centrifugal pump capable of pumping multiphase suspensions containing liquids, solids and gases, wherein the gases can be efficiently separated and the pump can operate with high net efficiency and low net positive suction head, resulting in a significant performance improvement compared to existing solutions.

[0009] The present invention also aims to reduce the axial bearing load on the shaft caused by gas removal in some prior art solutions.

[0010] The present invention also aims to provide a gas removal arrangement structure that can be easily cleaned or have any possible blockages removed.

[0011] Another object of the present invention is to provide a centrifugal pump capable of pumping multiphase suspensions containing liquid, solid materials and gas, wherein the gas removal arrangement of the pump can be easily configured to various operating conditions in terms of suspension type, gas content, consistency and pressure. Summary of the Invention

[0012] The objectives of the invention can be substantially satisfied, as disclosed in the independent claims and in other claims that describe further details of different embodiments of the invention.

[0013] According to an embodiment of the present invention, a centrifugal pump for pumping multiphase suspensions comprising liquid, solid materials and gas is provided, the pump comprising:

[0014] - Pump housing, having a suspended solids inlet and a suspended solids outlet, and a flow passage between the inlet and outlet.

[0015] - A shaft, which is mounted by bearings to rotate about its central axis AA.

[0016] - An impeller, which can be rotated by a shaft, aligned with the inlet, and arranged to rotate about axis AA in the flow channel.

[0017] - A gas collection opening for gas removal, which is arranged in the flow channel.

[0018] The inlet end of the flow channel is provided with a number of static blades including gas collection openings connected to a gas passage configured to pass through the blades. The blades extend radially from the inner wall of the flow channel toward the center of the flow channel and are located upstream of the impeller.

[0019] Centrifugal pumps with this gas removal arrangement provide a highly efficient way to remove gas from multiphase suspensions at the beginning of the flow path, preventing gas from entering the pump impeller and reducing efficiency. Since the blades are located upstream of the impeller, the distance from the impeller to the blades depends on several factors, such as the relative amount of gas, flow velocity, pressure, rotational speed, and other flow characteristics. This distance can range from very short (i.e., very close to less than 0.1*D (where D represents the inlet diameter)) to inlet diameter (1*D) or greater (e.g., 2 to 3*D). The efficiency performance of the centrifugal pump according to the invention is significantly improved. This arrangement also reduces the axial load on the shaft bearings, because in some prior art configurations, the impeller is provided with a gas removal opening leading to the back side of the impeller. This creates a pressure difference between the front and back sides of the impeller, thus generating equal axial loads on the impeller and, further, on the shaft bearings.

[0020] According to an embodiment of the present invention, a gas removal device for use in a centrifugal pump is provided. The gas removal device includes a tubular element having a first axial end and a second axial end, and a flow channel between these ends. The gas removal device is configured to be coupled to the inlet of the centrifugal pump. The gas removal device includes static blades extending radially from the inner wall of the flow channel toward the center of the flow channel, and these blades are provided with gas collection openings. The gas removal device is configured to be located axially upstream of the impeller of the centrifugal pump. According to an embodiment, the blades extend radially from the tubular element, which is configured to the inlet end of the flow channel. This gas removal device can be mounted or attached to virtually any centrifugal pump capable of pumping multiphase suspensions, provided that the tubular element includes an annular ring or flange attachable to the pump housing.

[0021] According to embodiments of the invention, a gas collection opening is connected to gas channels configured to pass through blades(s) to guide gas away from a flow channel. There may be only one opening and gas channel, or multiple gas openings and gas channels, or multiple gas openings connected to a single gas channel. The gas collection opening is connected to a system for collecting the gas, such as a network of pipes or conduits. The system for collecting the gas provides a pressure difference between the gas in the suspension and the outside of the pump. The gas is guided away due to this pressure difference, which may be a natural pressure difference between the inlet channel and the outside of the pump housing, or an auxiliary pressure difference achieved by providing a vacuum system to generate a sufficient pressure difference across the gas channels.

[0022] According to embodiments of the invention, the blade has an annular, elliptical, triangular, or airfoil-shaped outer cross-section along the flow direction of the suspended matter. One aspect of designing the blade shape is to prevent solid material from accumulating on the leading edge of the blade. The gas collection opening is suitably positioned at the trailing edge of the blade to reduce the risk of solid material accumulation, and also because the fluid pressure is lower at the trailing edge, it improves the gas removal efficiency. For the same reason, the gas collection opening can also be positioned on the back side of the blade relative to the flow direction during use. For similar reasons, it is also possible that the gas collection opening is positioned at the blade tip radially towards the central axis AA.

[0023] Still according to an embodiment of the invention, the gas collection opening and the subsequent gas passage are kept free of any solid matter residue, allowing a certain amount of multiphase suspended matter (most preferably liquid, such as dilution water) to be pushed into the gas passage in the countercurrent direction and further pushed into the gas collection opening. If high pressure or high impact is applied to the liquid, any blockages are pushed back into the flow passage.

[0024] An embodiment of the present invention is a pump designed for use with multiphase suspensions having a consistency of 0.1 to 18 wt% cellulose fibers or other multiphase suspensions having a consistency of 0.1 to 20 wt%.

[0025] The exemplary embodiments of the invention presented in this patent application shall not be construed as limiting the applicability of the appended claims. The verb "comprising" is used in this patent application as an open-ended limitation, which does not exclude the presence of features not yet described. Unless expressly stated otherwise, the features described in the dependent claims may be freely combined with each other. Novel features considered characteristic of the invention are specifically set forth in the appended claims. Attached Figure Description

[0026] In the following description, the invention will be illustrated with reference to the accompanying exemplary schematic diagrams, in which:

[0027] Figure 1 The illustration shows a centrifugal pump based on the prior art according to EP0298693A2.

[0028] Figure 2 The illustration shows a cross-sectional overview of a centrifugal pump according to an embodiment of the present invention.

[0029] Figure 3 The illustration shows a cross-sectional overview of a centrifugal pump according to another embodiment of the present invention.

[0030] Figure 4 An overview of a centrifugal pump according to an embodiment of the present invention is illustrated.

[0031] Figure 5A and Figure 5B An embodiment of the gas removal apparatus of the present invention is illustrated.

[0032] Figure 6 Some embodiments of possible cross-sections of the static blades used in this invention are illustrated. Detailed Implementation

[0033] Figure 1An embodiment of prior art document EP 0298693A2 is schematically depicted. It discloses a centrifugal pump, generally indicated by reference numeral 10. The pump includes a main housing 11 comprising a suspended matter (e.g., slurry) inlet 12 and a suspended matter outlet 13 generally transverse to the inlet 12. A shaft 14 is mounted by bearings or the like (not shown) for rotation about an axis AA, which is generally aligned with the inlet 12. The shaft 14 is hollow and has a plurality of elongated slots 15, 16 that are generally (though not typically completely) parallel to the axis AA and allow communication between the interior and exterior of the hollow shaft 14. In the depicted embodiment, gas in the slurry is collected at the shaft 14, enters the shaft 14 through the opening 15, and then exits through the slots 16 and is discharged with the slurry through the outlet 13.

[0034] exist Figure 2 The image presents a cross-sectional overview of a centrifugal pump according to an embodiment of the present invention. A centrifugal pump 10 for pumping multiphase suspensions comprising liquid, solid materials, and gases is shown, the pump comprising:

[0035] - Pump housing 11, having a suspended matter inlet 12 and a suspended matter outlet 13, and a flow passage 110 between the inlet 12 and the outlet 13.

[0036] - Shaft 14, which is mounted by bearings to rotate about its central axis AA.

[0037] - Impeller 18, which can be rotated via shaft 14, is aligned with inlet 12 and arranged to rotate about axis AA in flow channel 110.

[0038] - A gas collection opening 20 for gas removal is arranged in the flow channel 110.

[0039] - The inlet end 120 of the flow channel 110 is provided with a plurality of static blades 2 including a gas collection opening 20. These blades 2 extend radially from the inner wall 111 of the flow channel 110 toward the center of the flow channel 110. These blades 2 are located upstream of the impeller 18.

[0040] Gas collection openings 20 are connected to gas passages 21 configured to pass through the blade 2. According to an embodiment, these gas collection openings are located at the trailing edge of the blade, such as... Figure 2As shown in the diagram. This trailing edge position is advantageous for several reasons, its effect being to prevent clogging, and it is also optimal for gas removal due to the pressure changes in this area. The blades 2 can also be configured such that these gas collection openings are located at the blade tips radially towards the central axis AA. Suitably, the number of blades 2 is 1 to 6, preferably 2 to 4 blades. The blades 2 are attached to the pump housing 11 at the inlet end 120 of the flow passage 110.

[0041] exist Figure 3 The image presents a cross-sectional overview of a centrifugal pump according to another embodiment of the present invention. A centrifugal pump 10 for pumping multiphase suspensions comprising liquid, solid materials, and gases is shown, the pump comprising:

[0042] - Pump housing 11, having a suspended matter inlet 12 and a suspended matter outlet 13, and a flow passage 110 between the inlet 12 and the outlet 13.

[0043] - Shaft 14, which is mounted by bearings to rotate about its central axis AA.

[0044] - Impeller 18, which can be rotated via shaft 14, is aligned with inlet 12 and arranged to rotate about axis AA in flow channel 110.

[0045] - A gas collection opening 20 for gas removal is arranged in the flow channel 110.

[0046] - The inlet end 120 of the flow channel 110 is provided with a plurality of static blades 2 including a gas collection opening 20. These blades 2 extend radially from the inner wall 111 of the flow channel 110 toward the center of the flow channel 110. These blades 2 are located upstream of the impeller 18.

[0047] Figure 3 The embodiments shown are similar in other respects Figure 2 The embodiments, but Figure 3 The embodiment also includes a rotatable inducer (or "guide wheel") 4 arranged upstream of the blade 2 along the flow direction. The inducer 4 and the impeller 18 can be connected by means of... Figure 3 The common axis 14 shown can be rotated via a separate axis or rotating device (not shown). Figure 3In an embodiment having a common shaft 14 for both the impeller 18 and the guide vane 4, the blade 2 may optionally have a gas collection opening 20 at its tip, providing a gap between the tip of the blade 2 and the shaft 14 to allow the bubble layer to enter the gap and further into the gas collection opening 20. This location of the gas collection opening is highly effective because the gas phase tends to find its path to the flow center in a rotating flow of multiphase suspension. The guide vane 4 functions to feed the multiphase suspension toward the flow channel 110 and the impeller 18.

[0048] exist Figure 4 The present invention illustrates an embodiment of a centrifugal pump 10 for pumping multiphase suspensions comprising liquid, solid materials, and gas, the pump comprising:

[0049] - Pump housing 11, having a suspended matter inlet 12 and a suspended matter outlet 13, and a flow passage 110 between the inlet 12 and the outlet 13.

[0050] - Shaft 14, which is mounted by bearings for rotation about its central axis.

[0051] - An impeller, which can be rotated via shaft 14, aligned with inlet 12, and arranged to rotate about an axis in flow channel 110.

[0052] - A gas collection opening for gas removal is arranged in the flow channel 110.

[0053] - The inlet end 120 of the flow channel 110 is provided with a plurality of static blades 2 including a gas collection opening. These blades 2 extend radially from the inner wall 111 of the flow channel 110 toward the center of the flow channel 110. These blades 2 are located upstream of the impeller but downstream of the guide vane 4. Figure 4 An embodiment is shown in which the blade 2 extends radially from the tubular element 23, which is configured to the inlet end 120 of the flow passage 110. The tubular element 23 includes an annular ring or flange that can be attached to the pump housing 11.

[0054] exist Figure 5A and Figure 5B The image presents an embodiment of a gas removal device used in a centrifugal pump. The gas removal device includes a tubular element 23 having a first axial end and a second axial end, and a flow channel 110 between these ends. The gas removal device is configured to be coupled to the inlet of the centrifugal pump. The gas removal device includes static blades 2 extending radially from the inner wall 111 of the flow channel 110 toward the center of the flow channel 110, and these blades 2 are provided with gas collection openings 20. These gas collection openings 20 are connected via a gas channel 21 to a system 3 for collecting gas. The gas removal device is configured to be located axially upstream of the impeller of the centrifugal pump.

[0055] exist Figure 6 The diagram presents several possible embodiments of the cross-section of blade 2. Blade 2 may have an annular, elliptical, triangular, or airfoil-shaped outer cross-section along the flow direction of the suspension. The choice of shape is highly dependent on the properties of the multiphase suspension; different suspensions require different shapes. Some embodiments can be observed from this cross-sectional view, showing how the gas collection opening 20 can be connected to the gas passage 21 configured to pass through blade 2. In these embodiments, the gas collection opening 20 is located at the trailing edge of the blade. Other possibilities are also available, but these have been observed to function correctly and rarely tend to cause blockage. Another possibility is that the gas collection opening, in use, is located at the back side B of blade 2 relative to the flow direction F. Figure 6 In the diagram, the back side is illustrated based on the annular blade 2 and the elliptical blade 2. The flow direction F is indicated by an arrow, and the back side B is the surface area of ​​the blade 3 positioned opposite the flow side and located between two parallel lines, both of which are tangent to the blade and parallel to the flow direction.

[0056] While the invention has been described herein by way of example with reference to embodiments now considered to be the most preferred embodiments, it should be understood that the invention is not limited to the disclosed embodiments, but is intended to cover various combinations or modifications of its features and several other applications included within the scope of the invention as defined in the appended claims. When such a combination is technically feasible, the details mentioned in conjunction with any of the foregoing embodiments may be used in conjunction with another embodiment.

[0057] Parts list

[0058] 10 pumps

[0059] 11 Pump casing

[0060] 110 flow channel

[0061] 111 Inner Wall

[0062] 12 entrances

[0063] 120 Inlet End

[0064] 13 Exports

[0065] 14-axis

[0066] 15 slots

[0067] 16 slots

[0068] 18 impellers

[0069] 2 blades

[0070] 20 gas collection openings

[0071] 21 gas channels

[0072] 23 tubular elements

[0073] 3. Systems for collecting gases, vacuum systems

[0074] 4 diverters

[0075] AA central axis

[0076] B dorsal side

[0077] F is the direction of flow.

Claims

1. A centrifugal pump (10) for pumping multiphase suspensions comprising liquid, solid materials and gas, said pump comprising: - Pump housing (11) having a suspended matter inlet (12) and a suspended matter outlet (13) and a flow passage (110) between the inlet (12) and the outlet (13). - Shaft (14), which is mounted by bearings for rotation about its central axis (AA), - An impeller (18) rotatable via the shaft (14), aligned with the inlet (12) and arranged to rotate about the axis (AA) in the flow channel (110), - A gas collection opening (20) for gas removal is arranged in the flow channel (110). The feature is that the inlet end (120) of the flow channel (110) is provided with a plurality of static blades (2) including the gas collection opening (20), the gas collection opening is connected to a gas channel (21) configured to pass through the blades (2), the gas collection opening (20) is provided at the trailing edge of the blades (2), or in use is provided on the back side of the blades (2) relative to the flow direction (F), the blades (2) extend radially from the inner wall (111) of the flow channel (110) toward the center of the flow channel (110), and the blades (2) are located upstream of the impeller (18).

2. The centrifugal pump (10) according to claim 1, characterized in that, The blade (2) has an annular, elliptical, triangular or wing-shaped outer cross section along the flow direction of the suspended matter.

3. The centrifugal pump (10) according to claim 1, characterized in that, The gas collection opening (20) is located at the end of the blade (2) facing the central axis (AA) radially.

4. The centrifugal pump (10) according to claim 1, characterized in that, The blade (2) extends radially from the tubular element (23), which is configured to the inlet end (120) of the flow channel (110).

5. The centrifugal pump (10) according to claim 1, characterized in that, The blade (2) is attached to the pump housing at the inlet end (120) of the flow channel (110).

6. The centrifugal pump (10) according to claim 1, characterized in that, A rotatable guide vane (4) is arranged upstream of the blade (2) along the flow direction.

7. The centrifugal pump (10) according to claim 6, characterized in that, The flow guide (4) and the impeller (18) can be rotated via a common shaft (14) or via a separate shaft (14) or rotating device.

8. The centrifugal pump (10) according to claim 3 or 7, characterized in that, The blade (2) has a gas collection opening (20) at the end of the blade (2) such that a gap is provided between the end of the blade (2) and the shaft (14) so ​​that the bubble layer can enter the gap and further enter the gas collection opening (20).

9. The centrifugal pump (10) according to claim 4, characterized in that, The tubular element (23) includes an annular ring or flange that can be attached to the pump housing (11).

10. The centrifugal pump (10) according to claim 1, characterized in that, The gas collection opening (20) is connected to the system (3) for collecting gas.

11. The centrifugal pump (10) according to claim 10, characterized in that, The system (3) for collecting gas is configured to provide a pressure difference between the gas in the suspension and the outside of the centrifugal pump (10).

12. The centrifugal pump (10) according to claim 1, characterized in that, The pump (10) is designed for multiphase suspensions having a consistency of 0.1 to 18 wt% cellulose fibers or other multiphase suspensions having a consistency of 0.1 to 20 wt%.

13. The centrifugal pump (10) according to claim 1, characterized in that, The number of leaves (2) is 1 to 6.

14. The centrifugal pump (10) according to claim 1, characterized in that, The number of leaves (2) is 2 to 4.

15. A gas removal device for use in a centrifugal pump (10), characterized in that, The gas removal device includes a tubular element (23) having a first axial end and a second axial end and a flow channel (110) between the ends. The gas removal device is configured to be connected to the inlet (12) of a centrifugal pump (10). The gas removal device includes a static blade (2) extending radially from the inner wall (111) of the flow channel (110) toward the center of the flow channel (110). The blade (2) is provided with a gas collection opening (20) connected to a gas channel (21) configured to pass through the blade (2). The gas collection opening (20) is located at the trailing edge of the blade (2) or, in use, at the back side of the blade (2) relative to the flow direction (F). The gas removal device is configured to be located axially upstream of the impeller (18) of the centrifugal pump (10).

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