Centrifugal Compressor Surge Control via Dynamic Diffuser and IGV Adjustment

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Solution Overview

Problem

Centrifugal compressors face challenges in achieving efficient operation while maintaining surge-free conditions, as various combinations of inlet guide vane and variable diffuser geometry settings result in different efficiencies and stability issues.

Innovation Solution

A method utilizing pressure measurements along the flow path, specifically the maximum obtainable diffuser pressure recovery, to determine optimal positioning of the diffuser and inlet guide vanes, ensuring stable and efficient operation by keeping the diffuser pressure recovery close to its maximum value, thus avoiding surge.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If variable diffuser geometry and inlet guide vane settings are adjusted to improve compressor efficiency, then efficiency is improved, but surge stability may deteriorate

Engineering Contradiction:

Improvecompressor efficiencyVSAvoidsurge-free operation

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The patent implements dynamic control of diffuser geometry and inlet guide vane positioning based on real-time operating conditions. The system continuously adjusts these parameters to maintain optimal efficiency while preventing surge, transitioning from static to dynamic control strategies that adapt to changing compressor demands and flow conditions.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The control system employs feedback mechanisms by monitoring compressor performance parameters and using this information to adjust diffuser and inlet guide vane settings. This closed-loop control ensures that efficiency optimizations do not push the system into surge conditions, as the feedback detects early signs of instability and corrects positioning accordingly.

Inventive Principle:

Principle #23Feedback

2Stress or pressure

If diffuser geometry is optimized for maximum pressure recovery, then pressure recovery is improved, but the compressor operates closer to surge conditions

Engineering Contradiction:

Improvediffuser pressure recoveryVSAvoidoperating stability

Core Design Contradiction:

Stress or pressureVSReliability

Solution Approach 1:

The system dynamically changes diffuser geometry parameters to optimize pressure recovery at different operating points. By adjusting the diffuser angle and configuration based on real-time conditions, the system maximizes pressure recovery while maintaining a safety margin from surge, rather than using a fixed geometry optimized for a single operating point.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The control system applies partial optimization of diffuser geometry, achieving sufficient pressure recovery without pushing to the theoretical maximum that would cause surge. This controlled sub-optimization at extreme points maintains stability while capturing most of the efficiency benefit, avoiding the excessive action that would trigger surge.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS7824148B2Centrifugal compressor performance by optimizing diffuser surge control and flow control device settings

Publication Date: 2010.11.02 CARRIER CORP

AI summary

A method is provided for controlling operation of a compressor having an inlet and an outlet, a variable geometry diffuser communicated with the outlet, and inlet guide vanes communicated with the inlet, wherein the method includes the steps of: determining a loading parameter indicative of onset of surge; and independently controlling the inlet guide vanes and the variable geometry diffuser based upon the loading parameter so as to allow increase in efficiency and stable operation of the compressor.