Compressor Control System for Synthesis Plants
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Solution Overview
Problem
Existing control systems for rotary compressors in synthesis plants, such as those used in ammonia production, require manual intervention due to variations in gas mixture composition, leading to unstable compressor speed and performance, as they are not fully automatic in compensating for disturbances.
Innovation Solution
A dual-control system comprising a first control subsystem for performance parameters like suction pressure and a second for rotation speed, with a selector to automatically choose between control signals to maintain stable compressor operation, eliminating the need for manual intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If a typical control system determines load demand based on suction pressure and generates control signals, then the control system can operate automatically under consistent conditions, but it becomes unstable and requires manual intervention when gas mixture composition varies
Solution Approach 1:
The control system dynamically adapts its control strategy based on operating conditions. When gas composition is consistent, it operates in automatic mode using suction pressure feedback. When composition varies causing instability, it transitions to manual mode, allowing the operator to adjust control signals dynamically to maintain stable compressor operation throughout the full range of operating conditions.
2Productivity
If the control system operates in automatic mode to maintain stable compression, then operational efficiency is improved, but it amplifies disturbances and becomes unstable when gas mixture composition varies
Solution Approach 1:
The control system uses feedback from suction pressure measurements to automatically adjust control signals when operating conditions are stable. When gas composition variations cause instability detected through speed fluctuations or operator intervention, the system transitions to manual mode where feedback continues but allows operator-adjusted control signals, preventing amplification of disturbances while maintaining operational efficiency during normal conditions.
3Measurement precision
If the control system uses suction pressure as the primary control parameter, then it works well under consistent gas composition, but it cannot compensate for disturbances caused by composition variations
Solution Approach 1:
The control system is designed to perform multiple functions through a single integrated controller. It automatically uses suction pressure measurements for precise control under consistent conditions, but can also operate in manual mode to handle composition variations and disturbances. This multi-functionality allows the same control system to adapt to both stable and variable operating conditions without requiring separate control systems.
Data Source
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AI summary
The control system 200 is arranged for a rotary compressor driven by a rotary engine, and comprises: a first control subsystem 210, a second control subsystem 220 and a selector 230; the first control subsystem 210 is arranged to provide a first control signal 26 as a function of the performance 21 of the compressor; the second control subsystem 220 is arranged to provide a second control signal 27 as a function of the speed 22 of the compressor; the selector 240 is arranged to select the first control signal 26 or the second control signal 27 as a third control signal 24 to be provided to a power control input of the engine.