Adaptive Anti-Surge Control for Centrifugal Compressors
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Solution Overview
Problem
Centrifugal compressors processing wet gas face challenges in accurately determining the liquid volume fraction (LVF) without expensive and cumbersome flowmeters, especially in extreme conditions, which affects anti-surge control and efficiency.
Innovation Solution
A method that iteratively estimates the liquid volume fraction by measuring compressor operating parameters, using stored data to adjust tentative LVF values until an error threshold is met, allowing for precise LVF determination without direct measurement, and optimizing anti-surge control based on the estimated LVF.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If flowmeters are used to directly measure liquid volume fraction, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses compressor operating parameters (power, compression ratio) as intermediary measurements to indirectly determine liquid volume fraction. Instead of directly measuring LVF with complex flowmeters, the system measures easily obtainable operating parameters and uses stored operative curves to calculate LVF, thereby avoiding the need for complex direct measurement devices
Solution Approach 2:
The patent replaces mechanical flowmeters with a computational approach using stored data representing compressor operative curves. The system substitutes physical measurement hardware with data-based calculation, where operating parameters are processed through stored performance curves to determine liquid volume fraction without requiring specialized measurement equipment
2Measurement precision
If flowmeters are used to directly measure liquid volume fraction, then measurement precision is improved, but cost increases
Solution Approach 1:
The patent uses inexpensive, readily available compressor operating parameters (power, compression ratio) as substitutes for expensive flowmeters. These parameters can be obtained from standard sensors already present in the compressor system, eliminating the need to invest in costly specialized measurement equipment while maintaining adequate measurement precision for anti-surge control
3Measurement precision
If flowmeters are used in extreme environmental conditions, then measurement precision is improved, but reliability decreases
Solution Approach 1:
The patent uses compressor operating parameters as intermediary measurements that are inherently more reliable in extreme conditions. These parameters (power, compression ratio) are measured by standard sensors that are already designed to withstand the harsh environment, avoiding the introduction of additional fragile measurement equipment that would be susceptible to environmental damage
4Productivity
If anti-surge control is optimized for dry gas, then compressor efficiency is improved, but adaptability to wet gas decreases
Solution Approach 1:
The patent makes the anti-surge control system dynamic by adjusting the surge control line based on the actual liquid volume fraction. Instead of using a fixed surge control line optimized for dry gas, the system dynamically modifies the control parameters according to the measured operating conditions and calculated LVF, allowing optimal anti-surge performance across varying gas compositions
Solution Approach 2:
The patent changes the control parameters adaptively by selecting different surge control lines corresponding to different liquid volume fractions. The system stores multiple operative curves for different LVF values and uses these to dynamically adjust the anti-surge control strategy, enabling the compressor to maintain optimal efficiency whether processing dry gas or wet gas with varying liquid content
Data Source
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Figure 3A~3B
AI summary
A method of determining a liquid volume fraction in a multi-phase gas is disclosed. The method comprises the following steps: a) measuring a first compressor operating parameter; b) selecting a tentative liquid volume fraction of the gas processed by the compressor; c) based on stored data representing a compressor operative curve for the tentative liquid volume fraction, determining an estimated value of a second compressor operating parameter, as a function of the first compressor operating parameter; d) measuring an actual value of the second compressor operating parameter; e) comparing the actual value of the second compressor operating parameter to the estimated value of the second compressor operating parameter and determining an error therefrom; f) based on the error, selecting a different tentative liquid volume fraction and repeating steps (c) to (e) until an error value equal to or lower than an error threshold is obtained.