Reversible Hydraulic Pump Motor-Generator Energy Recovery
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current energy recovery systems for rod pumps in oil fields are complex, costly, and require specialized components like accumulators, capacitors, and exotic pumps, making them unreliable and inefficient.
Innovation Solution
A simplified energy recovery system using a reversible hydraulic pump and motor-generator connected to a hydraulic cylinder, which operates in both motor and generator modes to recover energy by pumping hydraulic fluid during the downstroke, eliminating the need for complex components and enhancing robustness and cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional energy recovery systems with accumulators, capacitors, and exotic pumps are used, then energy recovery capability is improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent combines the pump and motor functions into a single reversible pump-motor unit. During upstroke, the motor drives the pump to pressurize hydraulic fluid. During downstroke, the same unit reverses to function as a pump driven by the rod string weight, generating electricity. This merging eliminates the need for separate accumulators, capacitors, and exotic pumps, reducing device complexity while maintaining energy recovery capability.
Solution Approach 2:
The reversible pump-motor unit serves multiple functions: it acts as a motor during upstroke to drive the hydraulic pump, and as a pump-generator during downstroke to recover energy. This multi-functionality eliminates the need for specialized components like accumulators and capacitors, simplifying the system while achieving energy recovery.
2Loss of energy
If traditional energy recovery systems with specialized components are implemented, then energy recovery is achieved, but reliability decreases due to more components
Solution Approach 1:
By merging the motor and pump functions into a single reversible unit, the system reduces the total number of components. Fewer components mean fewer potential failure points, thereby improving reliability while maintaining energy recovery functionality.
Solution Approach 2:
The system uses the weight of the rod string during downstroke to naturally drive the reversible pump-motor unit, eliminating the need for complex control systems and external energy storage components. This self-service approach reduces component count and improves reliability.
3Loss of energy
If complex valve structures and exotic pumps are used for energy recovery, then energy recovery performance is improved, but manufacturing cost increases
Solution Approach 1:
The reversible pump-motor unit replaces complex valve structures and exotic pumps with a single, standardized component that can be manufactured using conventional processes. This merging significantly reduces manufacturing cost while maintaining energy recovery efficiency.
Solution Approach 2:
The system uses conventional, easily manufactured components instead of expensive exotic pumps and specialized valves. The reversible pump-motor unit can be produced at lower cost using standard manufacturing techniques, making the energy recovery system more economically viable.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system efficiently recovers potential energy stored in the rod string during the upstroke and converts it into electricity during the downstroke, reducing energy loss and operational costs while maintaining system reliability.
Implementation Method 1
a motor-generator having a rotor shaft connected to the coupling shaft; wherein the motor-generator operates in a motor mode to rotate the rotor shaft and the coupling shaft in a forward direction
Implementation Method 2
the reversible hydraulic pump pumps hydraulic fluid to the pressure chamber to displace the piston in the cylinder barrel and raise the rod string in an upstroke
Implementation Method 3
operates in a generator mode in which a weight of the rod string lowers in a downstroke and displaces the piston in the cylinder barrel to pump hydraulic fluid from the pressure chamber through the reversible hydraulic pump
Implementation Method 4
the motor-generator generates electricity
Data Source
AI summary
A system includes, in an exemplary embodiment, a hydraulic cylinder having a barrel, a piston connected to a rod string of the rod pump, and a pressure chamber; a reversible hydraulic pump connected to the pressure chamber; and a motor-generator having a rotor shaft connected to a coupling shaft of the pump. The motor-generator operates in a motor mode to rotate the rotor and coupling shafts in a forward direction so that the hydraulic pump pumps hydraulic fluid to the pressure chamber to raise the piston and rod string in an upstroke, and operates in a generator mode in which a weight of the rod string displaces the piston in a downstroke to pump hydraulic fluid from the pressure chamber to rotate the pump coupling shaft and the rotor shaft in a reverse direction such that the motor-generator generates electricity. A variable speed drive modulates the speed of the motor-generator.