Chiller plant with dynamic surge avoidance
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Solution Overview
Problem
Centrifugal compressors in chiller systems are prone to surge, leading to energy loss, component stress, and potential failure due to existing control techniques that can push the system into operating conditions causing compressor surge, despite efforts to optimize energy consumption and cost.
Innovation Solution
A method is introduced to determine predicted surge lift temperature differences and establish anti-surge condenser water temperature and flow rate limits, setting operational points within these limits to prevent compressor surge, using a processor and memory-based system that calculates and adjusts setpoints for the chiller system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If optimizing controllers use AI or MPC techniques to minimize energy consumption, then energy efficiency is improved, but the system may be pushed into operating conditions that cause compressor surge
Solution Approach 1:
The patent applies preliminary anti-action by establishing anti-surge boundaries and constraints before the optimizing controller can push the system into surge conditions. The controller is configured with predefined safe operating regions that prevent the optimization algorithm from selecting setpoints that would cause compressor surge, thereby proactively preventing the harmful effect while allowing energy optimization within safe limits
Solution Approach 2:
The patent implements feedback by continuously monitoring compressor operating conditions and adjusting the optimization constraints dynamically. The anti-surge boundaries are updated based on real-time system state, allowing the optimizing controller to adapt its energy minimization strategy while maintaining safe operation, thus resolving the conflict between energy efficiency and surge prevention
2Use of energy by moving object
If centrifugal compressors operate at high efficiency points, then energy consumption is reduced, but they may operate near surge conditions causing component stress
Solution Approach 1:
The patent applies local quality by creating a specialized safe operating region in the compressor's operating map that identifies high-efficiency points distant from surge conditions. This local optimization approach allows the system to operate at peak efficiency while maintaining a safety margin from surge, thereby reducing both energy consumption and component stress simultaneously
Data Source
AI summary
Systems, apparatus and methods for efficiently operating a chiller plant while minimizing or eliminating the occurrence of centrifugal compressor surge. Taking into account chiller design specifications and current operating conditions, a compressor lift point at which surge is predicted to occur is established. Minima and maxima for various chiller setpoints that avoid or eliminate the occurrence of compressor surge are imposed on setpoints provided by a conventional optimizing chiller controller. The chiller system is operated in accordance with the resultant anti-surge setpoints. Energy savings is realized by modulating coolant tower flow to enable the compressor to operate at near-surge conditions while preventing the onset of actual surge.