Horizontal pumping system with primary stage assembly and separate NPSH stage assembly

1. A horizontal pumping system comprising:

a motor;

a suction chamber; and

a pump assembly driven by the motor, wherein the pump assembly comprises:

a primary stage assembly, wherein the primary stage assembly includes a pump housing; and

a low NPSH stage assembly connected between the primary stage assembly and the suction chamber, wherein the low NPSH stage assembly comprises:

a diffuser that is fastened between the pump housing and the suction chamber;

an impeller contained within the diffuser, wherein the impeller includes a plurality of blades each having an inlet meridional curvature, a length (h) and a radius (r 2 ), and wherein each of the plurality of blades has a ratio of length (h) to radius (r 2 ) of greater than 0.6; and

an intermediate shaft.

2. The horizontal pumping system of claim 1 , wherein the diffuser comprises a pressure vessel.

3. The horizontal pumping system of claim 1 , wherein the impeller comprises a radial flow impeller.

4. The horizontal pumping system of claim 1 , wherein the impeller comprises a mixed flow impeller.

5. The horizontal pumping system of claim 1 , wherein the impeller includes fewer than five blades.

6. The horizontal pumping system of claim 1 , wherein each of the plurality of blades has a curvilinear leading edge.

7. The horizontal pumping system of claim 1 , wherein each of the plurality of blades comprises a leading edge and a trailing edge, and wherein each leading edge overlaps the trailing edge of an adjacent one of the plurality of blades by an amount greater than 30°.

8. The horizontal pumping system of claim 1 , wherein the impeller exhibits an inlet flow coefficient of less than 0.25.

9. The horizontal pumping system of claim 1 , wherein each of the plurality of blades has a blade body and a leading edge, and wherein the blade body has a blade body thickness and the leading edge has a leading edge thickness, and wherein the leading edge thickness is less than one-half the blade body thickness.

10. The horizontal pumping system of claim 1 , wherein each of the plurality of blades is configured to provide a blade angle of less than 17°.

11. The horizontal pumping system of claim 1 , wherein the impeller includes a shroud.

12. A pumping system comprising:

a motor;

a suction chamber;

a shaft driven by the motor and extending through the suction chamber;

a pump driven by the motor, wherein the pump comprises:

a primary stage assembly, wherein the primary stage assembly includes a pump housing having a pump housing outer diameter and a plurality of turbomachinery stages contained within the pump housing;

a low NPSH stage assembly removably connected between the pump housing and the suction chamber, wherein the low NPSH stage assembly includes a diffuser having a diffuser outer diameter connected to the pump housing and a low NPSH impeller contained within the diffuser; and

wherein the diffuser outer diameter is larger than the pump housing outer diameter.

13. The pumping system of claim 12 , wherein the primary stage assembly and low NPSH stage assembly are driven by a common shaft.

14. The pumping system of claim 13 , wherein the low NPSH stage includes an intermediate shaft and wherein the primary stage assembly includes a pump shaft and a shaft coupling, wherein the shaft coupling connects the intermediate shaft to the pump shaft.

15. A pumping system comprising:

a motor;

a pump driven by the motor, wherein the pump comprises:

a primary stage assembly, wherein the primary stage assembly includes a pump housing having a pump housing outer diameter and a plurality of turbomachinery stages contained within the pump housing;

a low NPSH stage assembly, wherein the low NPSH stage assembly includes a diffuser having a diffuser diameter and a low NPSH impeller contained within the diffuser; and

wherein the diffuser diameter is larger than the pump housing outer diameter.