Synthesis Loop Compressor Control for Variable Renewable Feed
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Solution Overview
Problem
Controlling a synthesis loop for chemical production, such as ammonia or methanol, is challenging when the feed rate is highly variable due to renewable energy sources, leading to unstable loop pressures and potential equipment damage.
Innovation Solution
The method involves dynamically controlling the makeup and circulation compressors to maintain loop pressure within a target deviation of 20% of the design pressure by adjusting delivery rates and rotational speeds, using mechanisms like suction valve control, clearance pockets, and bypass systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the speed of rotation of the circulation compressor is reduced to reduce the flow rate in the loop, then the flow rate is controlled to match variable feed, but the loop pressure falls below acceptable levels
Solution Approach 1:
The compressor system is divided into two independent units: a circulation compressor for maintaining loop circulation and a makeup compressor for adding fresh gas. This segmentation allows independent control of each compressor, enabling the circulation compressor speed to be reduced for variable feed rates without compromising loop pressure, as the makeup compressor can compensate by adjusting its own delivery rate.
Solution Approach 2:
The control system dynamically adjusts the operating parameters of both compressors based on real-time loop conditions and feed rate variations. The circulation compressor speed is dynamically reduced to match variable renewable energy feed, while the makeup compressor's delivery rate is dynamically adjusted through suction valve control to maintain loop pressure within target ranges despite circulation compressor speed changes.
2Stress or pressure
If the speed of rotation of the makeup compressor is controlled to maintain loop pressure, then the loop pressure remains stable, but the delivery rate cannot be adjusted to match variable feed
Solution Approach 1:
The suction valve control mechanism is applied locally at the makeup compressor's suction port to adjust its delivery rate without changing the overall compressor speed. This local control of the suction valve opening degree allows precise adjustment of the makeup gas delivery rate to match variable renewable energy feed while maintaining stable loop pressure through coordinated control with the circulation compressor.
3Stability of the object's composition
If compressors are operated at constant speed to ensure stable loop pressure, then pressure stability is maintained, but the system cannot adapt to variable renewable energy feed
Solution Approach 1:
The control system transitions from constant speed operation to dynamic speed and delivery rate control. The circulation compressor speed is dynamically adjusted to match variable renewable energy feed rates, while the makeup compressor's delivery rate is dynamically controlled through suction valve adjustment to compensate for circulation changes and maintain loop pressure stability, achieving both adaptability and stability simultaneously.
Solution Approach 2:
The control system continuously monitors loop pressure and feed rate variations, using this feedback to dynamically adjust the operating parameters of both compressors. The circulation compressor speed is adjusted based on feed rate feedback from renewable energy sources, while the makeup compressor's suction valve position is adjusted based on loop pressure feedback, creating a closed-loop control system that adapts to variable conditions while maintaining stability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach ensures stable and reliable operation, reduces mechanical stress, and optimizes production efficiency without the need for large buffer storage, effectively managing variable renewable energy inputs.
Implementation Method 1
the makeup gas is elevated to the loop pressure by a suitable makeup compressor
Implementation Method 2
A second compressor, called circulation compressor, is used to maintain circulation in the loop, i.e. to compensate for the pressure losses, due to the partial conversion of the reactants, in the items and piping of the loop
Implementation Method 3
The loop includes at least a synthesis converter, which is usually a catalytic converter, wherein the makeup gas is reacted under suitable conditions of pressure and temperature
Implementation Method 4
The effluent of the converter typically contains unconverted reagents which are separated and recycled to the converter
Data Source
AI summary
A method for controlling a synthesis loop for production of a chemical product, such as ammonia or methanol, wherein a feed rate of the loop depends on at least one source of renewable energy, the pressure of the loop and the delivery rate of a makeup compressor and of a circulation compressor are continuously controlled to follow the variable rate of the feed while maintaining the loop pressure within a target deviation from a design loop pressure.