Screw Pump Motor Speed Control for Gas-Liquid Mixture
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional screw spindle pumps require similar power for pumping liquids and gas-liquid mixtures, leading to inefficient energy use and high acquisition costs, as they are designed for pure liquid transport and do not effectively adapt to high gas contents.
Innovation Solution
The method involves operating the asynchronous motor in the field weakening range and adjusting the target frequency based on liquid content, allowing for reduced drive power consumption when pumping fluids with high gas content, and using a control device to switch between target frequencies to maintain sufficient torque for both high gas and pure liquid transport.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the asynchronous motor is designed to provide sufficient power for pure liquid transport, then the pump can handle pure liquid phases, but the motor size and acquisition costs increase unnecessarily for high gas content operations
Solution Approach 1:
The patent applies dynamics by making the motor speed variable through frequency adjustment. The control device dynamically adapts the motor operating frequency based on the actual fluid composition (liquid content detection). When high gas content is detected, the frequency is reduced to operate in the field weakening range, thereby reducing the required motor power and size. When pure liquid is detected, the frequency is increased to provide full power for liquid transport. This dynamic adaptation resolves the contradiction by allowing the motor to be sized for maximum capability only when needed.
Solution Approach 2:
The patent changes the operating parameters of the asynchronous motor based on fluid composition. Specifically, the frequency and voltage parameters are adjusted according to the detected liquid content. For high gas content fluids, the motor operates at lower frequency with reduced voltage, utilizing the field weakening effect to provide sufficient torque at lower power. For pure liquid transport, full voltage and frequency are applied. This parameter change approach allows the same motor to serve both functions without being oversized for gas handling applications.
2Use of energy by moving object
If the motor operates in the field weakening range at high speeds, then energy consumption is reduced for high gas content fluids, but the available torque decreases
Solution Approach 1:
The control device dynamically adjusts the motor frequency based on liquid content detection. When high gas content is detected, the frequency is reduced to operate in the field weakening range where energy consumption is lower. When pure liquid is detected, the frequency is increased to provide maximum torque. This dynamic switching allows the system to optimize between energy efficiency and torque availability based on actual operating conditions.
Solution Approach 2:
The patent employs feedback through a liquid content detection device that continuously monitors the fluid composition and provides signals to the control device. Based on this feedback, the control device adjusts the motor frequency and voltage to maintain appropriate torque levels while optimizing energy consumption. The feedback loop ensures that torque is sufficient for the actual load conditions, preventing both energy waste and torque deficiency.
3Reliability
If the pump is designed for pure liquid transport with fixed geometry and speed, then it provides consistent performance for liquids, but it cannot efficiently adapt to high gas content fluids
Solution Approach 1:
The patent makes the pump system dynamic by introducing variable speed control through frequency-adjustable asynchronous motors and liquid content detection. The system continuously monitors fluid composition and adapts the motor operating parameters accordingly. This dynamic capability allows the pump to maintain reliable liquid transport performance while also efficiently handling high gas content fluids by reducing motor speed and power consumption when gas is present.
Solution Approach 2:
The patent creates a universal pump system that can handle both pure liquid transport and high gas content fluid conveyance using the same hardware configuration. The control device with liquid content detection and frequency adjustment capability enables the pump to adapt its performance characteristics to match the actual fluid being pumped, making it versatile for joint oil and gas production applications without requiring separate specialized equipment.
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 reduces drive power requirements by up to 25% for high gas content fluids while maintaining pumping performance, enabling the use of a smaller asynchronous motor and lowering energy and acquisition costs, with the ability to efficiently handle both high gas and pure liquid phases.
Implementation Method 1
operate the asynchronous motor in the so-called field-weakening range, in which the maximum voltage used to energize the windings of the asynchronous motor is insufficient to achieve maximum currents and thus maximum field strengths in the asynchronous motor due to the inductance of the coils and the frequency used
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Method for conveying a fluid by means of a screw spindle pump (1), wherein at least one drive spindle (5) of the screw spindle pump (1) is driven by an asynchronous motor (10), wherein - the asynchronous motor (10) is operated with a first setpoint frequency (37), wherein a gas-liquid mixture is conveyed as the fluid (45), - a measured quantity (46) dependent on a liquid fraction of the fluid (45) is recorded, and - after a frequency change condition (47) dependent on the measured quantity (46) has been fulfilled, the asynchronous motor (10) is operated with a second setpoint frequency (38) reduced compared to the first setpoint frequency (37).