Centrifugal Compressor Anti-Surge Control via Single Backflow Valve
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Solution Overview
Problem
Centrifugal compressors experience unstable operation and surge due to fluctuations in suction flow rate and pressure, leading to vibration and noise, and existing anti-surge systems are economically inefficient with multiple inlet guide vanes and backflow valves.
Innovation Solution
A segmented anti-surge system for centrifugal compressors with a single intermediate gas extraction pipeline, utilizing a first and second throttle device, pressure and temperature sensors, and a control system to dynamically adjust backflow valves and prevent surge by dividing the compressor into two sections with independent anti-surge controls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple inlet guide vanes and backflow valves are provided for anti-surge control in each compression section, then surge prevention capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent merges the anti-surge control functions of multiple compression sections into a single backflow valve. The control system integrates surge margin calculations from different sections and coordinates a single backflow valve to prevent surge across all sections, eliminating the need for separate backflow valves in each section and reducing device complexity while maintaining reliability
Solution Approach 2:
The single backflow valve is designed to perform anti-surge control for multiple compression sections simultaneously. The valve serves universal anti-surge functions across different sections by responding to integrated surge margin signals from the control system, replacing multiple section-specific valves with one multi-functional component
2Quantity of substance
If intermediate gas extraction is increased to supply public facilities, then economic benefit is improved, but air flow rate through the compressor decreases leading to surge risk
Solution Approach 1:
The control system continuously monitors surge margin in each compression section and provides feedback to the backflow valve control. When intermediate gas extraction reduces flow rate and approaches surge conditions, the feedback mechanism triggers backflow valve opening to increase backflow, thereby maintaining sufficient surge margin and operational stability while allowing maximum intermediate extraction
Solution Approach 2:
The backflow valve opening degree is dynamically adjusted based on real-time surge margin conditions in different compression sections. The system automatically modifies backflow quantity in response to changing intermediate extraction rates, enabling flexible operation that maximizes intermediate gas supply while preventing surge across the entire compression process
Data Source
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Figure 3
AI summary
An anti-surge system for a centrifugal compressor, the centrifugal compressor including first to Nth compression stages (C1, C2, C3, C4), and an intermediate gas extraction pipeline (IA/PA) being disposed between an (M-1)th compression stage and an Mth compression stage, wherein N is an integer ≥ 2, and M is an integer ≤ N, comprises: a first throttle device (Fa); a first pressure sensor (Pa); a first temperature sensor (Ta; a second pressure sensor (Pb); a second throttle device (Fb); a second temperature sensor (Tb); a third pressure sensor (Pc); a branch pipeline (Bp); an anti-surge backflow valve (ASV); and a control system, comprising a first anti-surge controller (ASC1), a second anti-surge controller (ASC2) and a selector (HY).