Reciprocating Pump Flow Control via Plunger Phase Shifting
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Solution Overview
Problem
Reciprocating pumps in the oil-and-gas industry face challenges in efficiently controlling volumetric flow, as changing liners and plungers is labor-intensive and requires downtime, while speed control with electric motors necessitates expensive and inefficient speed controls, and multispeed transmissions lead to fluid flow interruptions.
Innovation Solution
A differential mechanism is used to couple the crankshafts of multiple plungers, allowing for phase shifting between their strokes to modulate fluid flow, enabling active stroke control and efficient flow management without the need for frequent pump disassembly or expensive speed control systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the speed of the pump is changed to control volumetric flow, then flow control is achieved, but expensive and inefficient speed controls are required when using electric motors
Solution Approach 1:
The patent changes the phase angle parameter between multiple plungers to control volumetric flow. By adjusting the phase shift angle of the second plunger relative to the first plunger through the differential mechanism, the effective displacement per cycle is modified, achieving flow control without changing pump speed or requiring expensive VFD/DC controllers.
2Productivity
If multispeed transmissions are used to match pumping requirements with engine capabilities, then flow control is achieved, but momentary interruptions in fluid flow occur during speed shifting
Solution Approach 1:
The patent implements a dynamically adjustable phase shift mechanism using a differential housing that can be rotated to any angle during operation. This continuous dynamic adjustment allows smooth transition between different flow rates without discrete speed changes, eliminating flow interruptions that occur during transmission shifting.
3Productivity
If liners and plungers are changed to control volumetric flow, then flow control is achieved, but labor-intensive work and pump downtime are required
Solution Approach 1:
The patent makes the pump configuration dynamically adjustable through rotation of the differential housing, which changes the phase relationship between plungers. This eliminates the need to physically replace liners and plungers, allowing flow control adjustments to be made quickly during operation without pump disassembly or extended downtime.
4Device complexity
If a single plunger is used in the pump, then the pump structure is simple, but the pump lacks efficiency and flow control flexibility
Solution Approach 1:
The patent combines multiple plungers (first and second plungers) operating in parallel within the same pump housing, sharing common inlet and outlet ports. This merging approach increases pump efficiency by utilizing multiple displacement chambers while the differential-coupled crankshafts provide synchronized operation and phase control for enhanced flow management.
Solution Approach 2:
The differential mechanism serves multiple functions: it couples the crankshafts of multiple plungers, enables phase angle adjustment between plungers, and provides flow control capability. This multi-functionality allows the pump to achieve superior performance with a relatively simple added mechanism.
Data Source
AI summary
A multi-throw reciprocating pump is provided. The pump provides active stroke control. Fluid flow is controlled by canceling out at least a portion of a discharge stroke of one plunger with a suction stroke of another plunger. Controlling the degree to which the discharge stroke is cancelled out is used to control the actual volume of fluid being pumped.