Durable pumps for abrasives

Abstract

Durable pumps for abrasives are provided. An example centrifugal pump stage for subsurface operation has a thrust washer located inside the circumference of an outboard clearance seal between an impeller shroud and the diffuser. Relocation of the thrust washer allows the clearance seal to protect the thrust washer from abrasives. A centrifugal action of an outboard seal lip effects a separation of the particles from the fluid nearest the gap of the outboard seal and drives the particles away from the gap of the outboard seal. When an abrasive particle in the leakage flow does clear the outboard seal, the particle is readily flushed across the thrust washer by the leakage flow to the central fluid inlet to prevent wear of the thrust washer. In an implementation, the inside diameter of the thrust washer is approximately flush with the bore of a central fluid inlet of the pump stage.

Description

RELATED APPLICATIONS[0001]This continuation patent application claims the benefit of priority to U.S. patent application Ser. No. 13 / 174,343 to Eslinger, filed Jun. 30, 2011 and entitled “Durable Pump for Abrasives,” which is incorporated herein by reference in its entirety, which in turn claims priority to U.S. Provisional Patent Application No. 61 / 365,695, filed Jul. 19, 2010, and entitled, “Centrifugal Pump with Increased Abrasion Resistance,” and to U.S. Provisional Patent No. 61 / 360,431, filed Jun. 30, 2010, and entitled, “Device and Means to Reduce Downthrust in a Multistage Centrifugal Pump,” both of which are incorporated herein by reference in their entirety.BACKGROUND[0002]Oilfields sometimes use electric submersible pumps staged in series to pump downhole fluids. A number of centrifugal pump stages can be stacked together along their axial direction for ganged lift in a subsurface environment. Such subsurface multistage pumps are frequently employed to move fluids consist...

AI Technical Summary

Benefits of technology

[0003]Durable pumps for abrasives are provided. An example centrifugal pump stage for subsurface operation has a thrust washer located inside the circumference of an outboard clearance seal betwe en an impeller shroud and the diffuser. Relocation of the thrust washer allows the clearance seal to protect the thrust washer from abrasives. A centrifugal action of an outboard seal lip effects a separation of the particles from the fluid nearest the gap of the outboard seal and drives the particles away from the gap of the outboard seal. When an abrasive particle in the leakage flow does clear the outboard seal, the particle is readily flushed across the thrust washer by the leakage flow to the central fluid inlet to prevent wear of the thrust washer. In an implementation, the inside diameter of the thrust washer is approximately flush with the bore of a central fluid inlet of the pump stage. This summary section is not intended to give a full description of durable pumps for abrasives. A detailed description with example implementations follows.

Problems solved by technology

Such heterogeneous “liquid sandpaper” may result in cavitation and abrasion issues for pumps, especially if the solids cause deposits to build up against some surfaces of the pump or if the fluid itself has a slurry-like consistency.

The viscosity and other flow characteristics of a particular liquid mixture may result in high velocity flow of the abrasive fluid around certain pump parts.

Impellers used in downhole centrifugal pumps experience significant abrasion of the downthrust washers (hereinafter, “thrust washers”) when pumping fluids containing abrasives.

Images