Dynamic Compressor Anti-Surge Control Using Equivalent Polytopic Head
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing surge protection methods for dynamic compressors are inadequate due to impractical measurements of volumetric flow and polytropic head, leading to inadequate real-time protection and sensitivity issues, especially with variations in gas composition and compressor load.
Innovation Solution
A method utilizing an equivalent map surge parameter, calculating an equivalent flow and polytropic head parameter, and defining a control parameter (R) to dynamically adjust the anti-surge valve based on the distance to the surge limit line, ensuring high sensitivity and invariance to changes in suction conditions and gas composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If volumetric flow and polytropic head measurements are used to determine surge control, then surge protection can be provided, but the measurements are not practical and inadequate for real time surge protection
Solution Approach 1:
The patent introduces intermediate parameters (inlet temperature, inlet pressure, molecular weight, compressibility factor, specific heat ratio, shaft speed, and differential pressure) that serve as measurable proxies for the difficult-to-measure volumetric flow and polytropic head. These intermediate parameters are used to calculate equivalent flow and equivalent head, which then determine the surge control parameter, enabling practical real-time surge protection without direct measurement of the original difficult parameters.
2Adaptability or versatility
If existing methods for invariant parameter calculations are used, then surge control parameters are derived that are theoretically invariant to changes in suction conditions or gas composition, but variations in gas composition still make the surge parameter and surge limit line move
Solution Approach 1:
The patent explicitly incorporates gas composition variables (molecular weight, compressibility factor, specific heat ratio) as input parameters in the surge control calculation. By dynamically adjusting the surge control parameter based on actual gas composition measurements, the system maintains accuracy despite variations in gas makeup, resolving the contradiction between theoretical invariance and practical gas composition variability.
3Productivity
If existing distance to surge line calculation methods are used, then surge control can be implemented, but the method is dynamically insensitive or sluggish especially as compressor load increases
Solution Approach 1:
The patent creates a dynamic surge control parameter that continuously adapts to changing compressor operating conditions and load. The parameter is recalculated in real-time based on current measurements of temperature, pressure, flow, and gas properties, enabling the control system to respond rapidly to changing conditions regardless of compressor load level, thus resolving the sluggish response issue.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A method of surge protection for a dynamic compressor (12) that has a corresponding compressor map (32). A control system continually calculates an equivalent polytropic head parameter heq in order to define a surge limit line (38). The system then calculates a control parameter and determines the distance of the control parameter from the surge limit line wherein the control parameter is dynamic to changes in compressor load and invariant to changes in suction conditions and gas compressibility. As a result of the distance of the control parameter to the surge limit line, a surge valve (20) of the dynamic compressor is actuated to prevent surge.