System and Method to Improve Operation of Hydraulic Pump for Subsea Service

Abstract

The operating performance and reliability of a pump, e.g. a hydraulic pump, can be significantly improved by incorporating an actively controlled positive displacement control valve in fluid communication with a fixed displacement pump, supply fluid line, and return fluid line. In use, the pump may be used to move fluid from the suction side to the discharge side of the pump, including fully opening the suction circuit to the pump cylinder and fully closing the pump discharge circuit during a pump suction stroke, fully closing the suction circuit and fully opening the pump discharge circuit to a downstream circuit during a pump discharge stroke, and allowing fluid to be pumped without the fluid passing through a valve spring loaded check valve.

Description

CLAIM TO PRIORITY[0001]This application claims the benefit of priority under 35 U.S.C. §119(e) from U.S. Provisional Patent Application No. 61 / 762,743 entitled “Method to Improve Operation of Hydraulic Pump for Subsea Service”, filed Feb. 8, 2013, which is incorporated herein in its entirety by this reference.FIELD OF THE INVENTION[0002]The operating performance and reliability of a pump, e.g. a hydraulic pump, can be significantly improved by incorporating “Positive Displacement Control Valve” technology as shown in the following figures and description.BACKGROUND OF THE INVENTION[0003]A single cycle of a reciprocating piston pump typically has two components: a suction stroke and a discharge stroke. During the pump suction stroke, fluid flows through a pump suction port into the pump cylinder. The movement of the pump piston usually draws the fluid from a local reservoir or supply conduit. With the pump discharge stroke, the fluid within the pump cylinder is pushed out of the pump...

AI Technical Summary

Benefits of technology

The patent text describes a method to improve the operation and reliability of hydraulic pumps for subsea service by incorporating a technology called "Positive Displacement Control Valve." This technology can overcome limitations of conventional check valves used in pumps, such as being sensitive to solid contaminants and being unable to control fluid volumetric metering. The technical effects of this patent include improved pump performance and reliability, better fluid flow direction control, faster ice plug melting, and better chemical metering control.

Problems solved by technology

However, as will be explained below there are several disadvantages with using check valves in the unconventional applications as we have in deepwater subsea oilfield service.

Check valves are sensitive to solid contaminants in the fluid being pumped.

This is a major limitation of check valves in any service involving contaminated liquids.

There are several limitations to using conventional pump check valves in certain applications.

The oilfield piping circuit containing the ice plug can contain significant solid contaminants that can become lodged in the pump check valves resulting in pumping system failure.

The pressure in the piping circuit can only be reduced to the opening pressure of the pump suction check valve; increasing the time that it takes to melt the ice plug.

The basic design of a reciprocating pump in gas service is limited by the “pressure ratio” which is an engineering relationship between pump stroke volume and operating pressure of the pump check valves.

There is also a significant limitation to using conventional check valves in unconventional subsea pumping applications.

However this type of device is subject to high mechanical stresses, sensitive to contamination, and must be adjusted for changing conditions over the field life.

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