ESP Anti-Backspin Pawl Mechanism for Reverse Rotation Lockout
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Solution Overview
Problem
Electrical submersible pumps (ESP) systems experience backspin, which can lead to hazardous high voltage electricity being generated and transmitted to the surface, posing a risk to personnel when the impellers rotate in the opposite direction, especially during operations like killing a well or acidizing, due to insufficient formation pressure in wells.
Innovation Solution
An anti-backspin device is integrated into the ESP system, comprising a tooth mounted on the shaft and a pawl mechanism that restricts rotation in the backspin direction by engaging when the shaft rotates in reverse, preventing the generation of high voltage electricity during backspin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the impellers are allowed to rotate freely in both directions, then the pump can operate in forward direction for fluid pressurization, but the impellers can rotate in backward direction causing backspin and generating hazardous high voltage electricity
Solution Approach 1:
The anti-backspin device applies preliminary anti-action by using a pawl mechanism that engages with a tooth on the drive shaft to prevent backward rotation before hazardous voltages can be generated. The pawl freely permits forward rotation but arrests backward rotation, thereby preventing the harmful effect of backspin-induced voltage generation.
Solution Approach 2:
The invention converts the potential harmful backspin rotation into a beneficial safety feature by allowing the pawl mechanism to engage and arrest backward rotation. The same rotational freedom that could cause harm is now controlled to prevent hazard while maintaining operational flexibility.
2Object-affected harmful factors
If the anti-backspin device is added to prevent backspin, then hazardous high voltage electricity generation is eliminated, but the device complexity of the ESP system increases
Solution Approach 1:
The anti-backspin function is segmented as a separate, independent device with distinct components (pawl, tooth, resilient member) that can be added to the existing ESP system without redesigning the entire pump. This modular approach minimizes overall system complexity while achieving the safety function.
Solution Approach 2:
The pawl acts as an intermediary mechanism between the drive shaft and the housing, providing a simple mechanical interface that prevents backward rotation without interfering with forward operation. This intermediary component isolates the backspin prevention function from the main pump components.
3Reliability
If the pawl is constantly engaged with the tooth to prevent backspin, then backspin is effectively prevented, but friction and wear between the pawl and tooth increase
Solution Approach 1:
The pawl is designed to be dynamic rather than static, freely rotating on its pivot to engage only when needed. The resilient member provides dynamic biasing that allows the pawl to maintain light contact during normal operation while firmly engaging during backspin attempts, reducing continuous friction and wear.
Solution Approach 2:
The pawl engages periodically only when backspin is attempted rather than maintaining constant engagement. The resilient member allows the pawl to disengage during normal forward rotation and only engage when reverse rotation is detected, minimizing friction and wear while maintaining reliability.
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
Effectively prevents backspin of the impellers, thereby eliminating the risk of hazardous high voltage electricity transmission to the surface, ensuring safer operational conditions during various well operations.
Implementation Method 1
a resilient member that biases the pawl radially inward
Implementation Method 2
energizing the windings creates an electromagnetic force that rotates the rotor and motor shaft
Data Source
AI summary
A shaft in an electrical submersible pumping system is prevented from rotation in a backspin direction, which is in a direction opposite from its typical forward rotation during normal operation. Backspin rotation is prevented with a device that includes teeth coupled to the shaft and a stationary pawl disposed in a rotational path of the teeth. Each tooth has a forward surface that contacts the pawl during forward rotation of the shaft, the forward surfaces are each configured with a profile to slide along and past the pawl without impeding shaft rotation. Rotation in the backspin direction engages the pawl with rearward surfaces of the teeth, which are configured to impede shaft rotation when engaged. Fluid being handled by the pumping system flows through a passage in the device and absorbs friction generated thermal energy from the device.