ESP Motor Stator Slot Openings for Rotor-Driven Oil Cooling
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Solution Overview
Problem
Non-encapsulated stator slots in electrical submersible pumps face issues with insufficient oil circulation and cooling, leading to thermal events and rapid deterioration due to trapped oil during operation, especially in applications like steam-assisted gravity drainage and geothermal operations.
Innovation Solution
The system and method forcibly circulate oil within stator slots using the rotating rotor to create a pumping or suction effect through strategically designed slot openings, enhancing oil flow without additional components, ensuring effective cooling and replenishment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If non-encapsulated stator slots are used to avoid thermal events in high-temperature applications, then thermal capability is improved, but oil circulation and cooling efficiency deteriorate
Solution Approach 1:
The stator slots are pre-filled with dielectric oil during assembly before the motor operates. This preliminary action ensures that the slots contain adequate cooling oil from the start, preventing oil depletion and maintaining effective cooling throughout the motor's operational life in high-temperature applications.
Solution Approach 2:
Dielectric oil serves as an intermediary substance that transfers heat from the stator windings to the stator core and ultimately to the produced fluid. The oil circulates through the non-encapsulated slots, absorbing heat and carrying it away, thus enabling effective cooling without encapsulation materials that would limit thermal capability.
2Reliability
If mechanical means are added to force dielectric oil through stator slots, then oil circulation is improved, but device complexity increases
Solution Approach 1:
The motor design utilizes the motor's own operational characteristics to drive oil circulation. The rotating stator windings and magnetic field generation create forces that naturally circulate the dielectric oil through the non-encapsulated slots, eliminating the need for separate mechanical pumping systems while maintaining effective cooling.
Solution Approach 2:
The system employs hydraulic principles by utilizing the dielectric oil as both an insulating medium and a cooling fluid. The oil circulation is achieved through pressure differentials and flow dynamics created during motor operation, leveraging fluid mechanics rather than mechanical components to maintain cooling efficiency.
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
This approach improves oil circulation and cooling efficiency, enhancing motor performance and reliability by maintaining optimal thermal conditions, thereby extending the motor's run life and reducing the risk of thermal events.
Implementation Method 1
The system and method forcibly circulate oil within stator slots using the rotating rotor to create a pumping or suction effect through strategically designed slot openings
Implementation Method 2
For cooling, these motors rely mainly of conduction of the losses through to motor casing where it is rejected to the produced fluid
Implementation Method 3
The system and method forcibly circulate oil within stator slots using the rotating rotor to create a pumping or suction effect through strategically designed slot openings
Data Source
AI summary
A stator core for an electric submersible pump includes laminations aligned with each other and each including an outer rim; teeth extending radially inward from the outer rim of each of the laminations; and segments extending in an angular direction from ends of the teeth to collectively form an inner rim. Gaps are formed between ends of the segments and the ends of the teeth for allowing oil to flow from an airgap between the inner rim and a rotor into slots defined by the outer rim, the teeth, and the inner rim.