BEARINGLESS VERTICAL PUMP

Description

BACKGROUND OF THE INVENTION1. Field of the Invention

[0001] The present invention relates to a vertical pump; and more particularly to a vertical turbine pump.2. Brief Description of Related Art

[0002] Figure 1 shows a vertical turbine pump that is known in the art. Such a vertical pump is shown for example in the book named " Vesconite and Vesconite Hilube - Pump Bearing Design Manual" published on the 8 May of 2018. The pressure generating portion of the vertical turbine pump, frequently called a bowl assembly, makes use of bearings of varying materials (such as bronze), e.g., including a bowl bearing located above each impeller, and a suction bearing located below a bottom impeller in a suction bell or suction bowl of the bowl assembly. In Figure 1, the bowl bearing located above each impeller is arranged between an inner part of each bowl of the bowl assembly and the power transmission shaft, and the suction bearing located below the bottom impeller is arranged between a suction bearing retainer of the suction bell or suction bowl and the power transmission shaft. These bearings have a primary function to maintain the alignment of the power transmission shaft with the centerline of the static pressure containing elements. An additional function is to raise the resonant frequency of the bowl assembly to ensure lateral vibration of the power transmission shaft is not observed. In Figure 1, the vertical turbine pump includes a wear ring for each impeller that is located between an impeller bottom outside surface of each impeller and a bowl bottom inside surface of each bowl. Wear rings are primarily employed as a replaceable, ablative wearing surface between two elements that translate relative to each other, e.g., such as in the case of a rotating impeller element and a stationary bowl element. Wear rings also allow for reduced circulation between the high pressure side of a rotating impeller and the low pressure side, thereby improving the pump's mechanical efficiency. This is accomplished by reducing the running clearances between the rotating impeller and the stationary bowl, this reduction in area increases the pressure drop across the high pressure side to the low pressure side of the rotating impeller, and with a reduction in potential, there is a corresponding reduction in the undesirable recirculating flow.Some of the Shortcomings of the Above Mentioned Devices:

[0003] The suction bearing and its corresponding suction bearing retainer located in the suction bell / bowl of the pump partially obscures the eye of the bottom impeller and therefore increases the required ambient pressure in the surrounding fluid to prevent the cavitation of the pump. This increase in required suction pressure correspondingly increases the required submergence in open applications, and increases the required suction line pressure in closed-loop applications. Less significantly, the overall efficiency of the pump is reduced due to this increase in pump entrant losses.

[0004] The inclusion of the suction bearing retainer in the suction bell mandates a degree of material strength that would not otherwise be required. This increases product weight and cost.

[0005] The principal driver of vibration in a pump is due to the imbalance in the rotating impeller. By using a bearing above and below the rotating impeller, the driving imbalance is equidistant between the two bearing supports. This configuration maximizes the deflection in the power transmission shaft, when the most desirable result is to minimize the deflection in the power transmission shaft.

[0006] Hydraulic thrust is generated from a difference in fluid pressure on the top side of the rotating impeller relative to the bottom side of the rotating impeller. This hydraulic thrust can cause the power transmission shaft to be oversized to either increase its strength in some applications, or else to reduce its deflection (stretch) in others. Alternatively, hydraulically balanced impellers may be employed to reduce the effects of the pressure differential, but this introduces an undesirable flow re-circulation that reduces the pump's hydraulic efficiency.

[0007] Special care must be taken when using wear rings comprised of materials that will gall. While desirable for corrosion resistance reasons, these materials can cause premature failure of the pump if clearances are not increased, this in turn, increases undesirable re-circulation and a corresponding loss of pump efficiency.SUMMARY OF THE PRESENT INVENTION

[0008] The vertical pump of the present invention includes the features of the attached claim 1. the respective impeller top and bottom outside surfaces of each impeller may be configured to rotate directly against the respective top and bottom wear-ring bearings.

[0009] The non-galling bearing material may be a non-metallic material, including Vesconsite ®< .

[0010] The top and bottom wear-ring bearings may be configured to expose a top side of at least one of the impellers to a low pressure side of preceding material being pumped through the stationary bowl assembly.

[0011] The top wear-ring bearings may also be configured to isolate the top side of at least one of the impellers from pressure generated by the at least one of the impellers.

[0012] The top and bottom wear-ring bearings may be configured to provide substantially reduced running clearances between the at least one impeller and the at least one bowl of the stationary bowl assembly.

[0013] The vertical turbine pump may include a suction bell configured to guide flow of the material being pumped into an eye of a bottom impeller.

[0014] The suction bell may be made of a non-metallic material, including a non cast iron material. The non-metallic material may be plastic.Advantages

[0015] By transferring all functions of the suction bearing to the bottom wear ring / bearing, all of its associated retainer structure can be removed from the stationary bowl assembly. This removes all obstructions from the inlet into the eye of the bottom impeller. Eliminating the obstruction consequently minimizes the required pressure of the surrounding ambient fluid in open pit applications or in the suction line in closed loop applications. This translates directly into a reduction of the Net Positive Suction Head required (NPSHr). Additionally, with the entrant losses minimized, the overall efficiency of the pump will be increased.

[0016] Since the suction bell no longer needs to function as a support for the loads associated with the suction bearing retainer, its only remaining function is to guide flow into the eye of the bottom impeller. This function can be accomplished with lower strength materials such as plastic, reducing both weight and cost of the traditional cast iron construction.

[0017] The inclusion of both upper and lower wear rings, and with each of these wear rings being constructed from a non-galling bearing material such as Vesconite ®< , enables the incorporation of all functions of the bearing into the wear ring. With the impeller now rotating directly against the effective bearing of the pump rather than suspended between two bearing supports in other works in the prior art, the deflection in the power transmission shaft is eliminated, and the corresponding vibration is significantly reduced.

[0018] Relocation of the bowl bearing functions to the wear ring and the associated bearing retainer material now exposes the top of the impeller to the low pressure side of the preceding material. Additionally, the presence of the top wear ring now isolates the top of the impeller from the pressure generated by the impeller. This reduces the hydraulic load on the impeller, and consequently reduces the load on the shaft, and the corresponding shaft deflection (stretch).

[0019] Inclusion of upper and lower wear rings now eliminates the need to increase running clearances in cases where special corrosion resistant materials susceptible to galling are used. This further decreases field galling issues as well increasing the product hydraulic efficiency as opposed to the observed reduction in hydraulic efficiency associated with the previous method of increasing the running clearances of the galling parts.

[0020] The manner in which the product is operated is not altered by the inclusion of the present invention. Instead, the operational efficiency and NPSHr of the pump is improved with the removal of the suction bearing and its associated housing, and with the removal of the now redundant bowl bearings and associated retainers. Inclusion of the non-metallic wear rings eliminates galling in harsher environments, and with the reduction in product vibration, the operational life of the pump is extended.BRIEF DESCRIPTION OF THE DRAWING

[0021] The drawing, which is not necessarily drawn to scale, includes the following Figures: Figure 1 shows a partial cross-sectional view of a vertical turbine pump that is known in the art, e.g., having a bowl bearing above each impeller, a suction bearing below a bottom impeller in a suction bell / bowl of a stationary bowl assembly, and a suction bearing retainer coupling the suction bearing to the suction bell / bowl of the stationary bowl assembly. Figure 2 shows a cross-sectional view of a vertical turbine pump according to some embodiments of the present invention, having indications of removed material (e.g., the bowl bearing above each impeller like that shown in Figure 1), of no suction bearing below the bottom impeller in the suction bell / bowl, and of no suction bearing retainer, by implementating of the present invention. Figure 3 shows a cross-sectional view of the vertical turbine pump in Figure 2 without showing the bowl bearing above each impeller that is removed in embodiments according to the present invention.

[0022] Similar parts or components in Figures are labeled with similar reference numerals and labels for consistency. Every lead line and associated reference label for every element is not included in every Figure of the drawing to reduce clutter in the drawing as a whole.DETAILED DESCRIPTION OF THE INVENTION

[0023] By way of example, and according to some embodiments, Figures 2 and 3 show a vertical pump according to the present invention and generally indicated as 10, featuring a stationary bowl assembly 20, a rotating power transmission shaft 30, impellers 40, bottom wear-ring bearings 50 and top wear-ring bearings 60.

[0024] The stationary bowl assembly 20 may include three bowls 22, a top member 23 and a lower suction bell 70, e.g., coupled together using fasteners, one of which is labeled 80. The present invention is not intended to be limited to the number of bowls in the stationary bowl assembly 20, e.g., which may include more than three bowls 22 or fewer than three bowls 22.

[0025] Each bowl 22 includes a respective bowl bottom inside surface 24 and a respective bowl top inside surface 26, e.g., designated and corresponding to impeller top and bottom outside surfaces described below. Each bowl 22 may include an inner circumferential rim 25 that protrudes inwardly perpendicular to the rotational axis A of the rotating power transmission shaft 30. The bowl top inside surface 26 is configured to extend circumferentially around the inner circumferential rim 25 inside the bowl 22. The respective bowl bottom inside surface 24 is configured on a corresponding bowl portion 27 of an adjacent lower bowl 22 or a corresponding bell portion 72 of the suction bell 70, e.g., consistent with that shown in Figure 3.

[0026] The rotating power transmission shaft 30 is configured to extend through the stationary bowl assembly 20 along the rotational axis A.

[0027] The impellers 40 may include three impellers 40 arranged on the rotating power transmission shaft 30 and configured in relation to the three bowls 22 to rotate and draw material through the stationary bowl assembly 20. Each impeller 40 includes a respective impeller bottom outside surface 42 and a respective impeller top outside surface 44, e.g., corresponding to the bowl bottom and top inside surfaces 24, 26 described above. Each impeller 40 has a respective impeller vane 41 configured to draw the material, and includes a respective impeller upper vane portion 43 and a respective impeller lower vane portion 45. The respective impeller top outside surface 44 is configured to extend circumferentially around the respective impeller upper vane portion 43, and the respective impeller bottom outside surface 42 is configured to extend circumferentially around the respective impeller lower vane portion 45, e.g., consistent with that shown in Figure 3.

[0028] Each bottom wear-ring bearing 50 is arranged between the respective impeller bottom outside surface 42 of each impeller 40 and the respective bowl bottom inside surface 24 of each bowl 22, is made from a non-galling bearing material, and configured to maintain the alignment of the rotating power transmission shaft 30 in relation to the stationary bowl assembly 20. By way of example, each bottom wear-ring bearing 50 may be arranged, coupled or fastened to the respective bowl bottom inside surface 24 of each bowl 22, e.g., using adhesive, fasteners, etc. The respective impeller bottom outside surface 42 of each impeller 40 may be configured to rotate directly against the respective bottom wear-ring bearing 50.

[0029] Similarly, each top wear-ring bearing 60 is arranged between the respective impeller top outside surface 44 of each impeller 40 and the respective bowl top inside surface 26 of each bowl 22, is made from a corresponding non-galling bearing material, and configured to maintain the alignment of the rotating power transmission shaft 30 in relation to the stationary bowl assembly 20. By way of example, each top wear-ring bearing 60 may be arranged, coupled or fastened to the respective bowl top inside surface 26 of each bowl 22. The respective impeller top outside surface 44 of each impeller 40 may be configured to rotate directly against the respective top wear-ring bearing 60.

[0030] By way of example, the scope of the invention is intended to include, and embodiments are envisioned, using a combination of bottom and top wear-ring bearings 50, 60.

[0031] According to some embodiments, the top and bottom wear-ring bearings 50, 60 may be configured to expose a top side 46 of at least one of the impellers 40 to a low pressure side of preceding material being pumped through the stationary bowl assembly 20.

[0032] According to some embodiments, the top wear-ring bearings 60 may be configured to isolate the top side 46 of at least one of the impellers 40 from pressure generated by the at least one of the impellers 40.

[0033] According to some embodiments, the top and bottom wear-ring bearings 50, 60 may be configured to provide substantially reduced running clearances between the at least one impeller 40 and the at least one bowl 22 of the stationary bowl assembly 20.The Suction Bell 70

[0034] The suction bell 70 may be configured to guide flow of the material being pumped into an eye of a bottom impeller 40. The suction bell 70 may be made of a non-metallic material, including a non cast iron material. The non-metallic material may be plastic.Vesconite ®<

[0035] By way of example, the non-galling bearing material may include a non-metallic material such as Vesconsite ®< .

[0036] Vesconite ®< is a specialized hard-wearing thermopolymer / thermoplastic made from internally lubricated polymers and designed for challenging operating conditions that is manufactured by a company having the name, Vesconite Bearings (see vesconite@vesconite.com), and that may provide up to 10 times the life of traditional bronze or nylon bushings. By combining its high load-bearing strength, internal lubrication, low friction coefficient and low wear rate, Vesconite ®< does not require external lubrication, even in harsh, dry and dirty working environments.Fastening of the Wear-ring Bearings 50, 60

[0037] By way of further example, the scope of the invention is intended to include coupling or fastening the bottom wear-ring bearing 50 to the respective impeller bottom outside surface 42 of each impeller 40.

[0038] By way of further example, the scope of the invention is intended to include coupling or fastening the top wear-ring bearing 50 to the respective impeller top outside surface 44 of each impeller 40.Possible Applications:

[0039] The present invention can be used in all applications supported by the unmodified vertical turbine pump, but is particular advantage in cases where corrosion materials, higher product efficiency and low NPSHr is required. Some typical examples include, but are not limited to the following: Cooling towers Fire suppression Power Plants Process water Municipal water transport The Scope of the Invention

[0040] The embodiments shown and described in detail herein are provided by way of example only; and the scope of the invention is limited by the following claims.

[0041] It should be understood that, unless stated otherwise herein, any of the features, characteristics, alternatives or modifications described regarding a particular embodiment herein may also be applied, used, or incorporated with any other embodiment described herein.

Claims

1. A vertical pump (10) comprising: a stationary bowl assembly (20) having bowls (22), each bowl (22) having a respective bowl top inside surface (26) and also having a respective bowl bottom inside surface (24); a rotating power transmission shaft (30) configured to extend through the stationary bowl assembly (20); and impellers (40) arranged on the rotating power transmission shaft (30) to rotate and draw material through the stationary bowl assembly (20), each impeller (40) having a respective impeller top outside surface (44) and also having a respective impeller bottom outside surface (42), characterized in that the vertical pump (10) further comprises top and bottom wear-ring bearings (60, 50), each top wear-ring bearing (60) arranged between the respective impeller top outside surface (44) of each impeller (40) and the respective bowl top inside surface (26) of each bowl (22), each bottom wear-ring bearing (50) arranged between the respective impeller bottom outside surface (42) of each impeller (40) and the respective bowl bottom inside surface (24) of each bowl (22), the top and bottom wear-ring bearings (60, 50) being made from a non-galling bearing material, and configured to maintain the alignment of the rotating power transmission shaft (30) in relation to the stationary bowl assembly (20).

2. The vertical pump (10) according to claim 1, wherein the non-galling bearing material is a non-metallic material, including a hard-wearing thermopolymer or thermoplastic.

3. The vertical pump (10) according to claim 1 or 2, wherein the respective impeller top and / or bottom outside surface (44; 42) of each impeller (40) is configured to rotate directly against a respective top and / or bottom wear-ring bearing (60, 50).

4. The vertical pump (10) according to one of the preceding claims, wherein each top wear-ring bearing (60) is configured to expose a top side of a respective impeller (40) to a low-pressure side of preceding material being pumped through the stationary bowl assembly (20).

5. The vertical pump (10) according to one of the preceding claims, wherein each top wear-ring bearing (60) is configured to isolate a top side of a respective impeller (40) from pressure generated by the respective impeller (40).

6. The vertical pump (10) according to one of the preceding claims, wherein the top and bottom wear-ring bearings (60, 50) are configured to provide reduced running clearances between the impellers (40) and the bowls (22) of the stationary bowl assembly (20).

7. The vertical pump (10) according to one of the preceding claims, wherein the vertical pump (10) comprises a suction bell (70) configured to guide flow of the material being pumped into an eye of a bottom impeller (40).

8. The vertical pump (10) according to claim 7, wherein the suction bell (70) is made of a non-metallic material.

9. The vertical pump (10) according to claim 8, wherein the non-metallic material is plastic.

10. The vertical pump (10) according to claim 7, wherein the suction bell (70) is made of a non-cast iron material.

11. The vertical pump (10) according to one of the preceding claims, wherein the top and bottom wear-ring bearings (60, 50) of each impeller (40) provide for a driving imbalance that is equidistant between each impeller (40).