Makeup and Circulation Compressor Control for Variable Feed
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Solution Overview
Problem
The challenge of controlling a synthesis loop for producing chemical products like ammonia or methanol is posed by the variability in feed rate due to renewable energy sources, which can cause fluctuations in loop pressure, leading to inefficiency and potential damage to equipment.
Innovation Solution
The method involves dynamically controlling the pressure and delivery rate of makeup and circulation compressors to maintain loop pressure within a 20% target deviation of the design pressure, using various control mechanisms such as suction valve unloaders, modulators, clearance pockets, bypass systems, and flow throttling valves, especially for reciprocating and centrifugal compressors, to stabilize operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the speed of rotation of compressors is varied to control flow rate, then the flow rate can follow variable feed, but the delivery pressure decreases and loop pressure falls below acceptable levels
Solution Approach 1:
The invention applies dynamics by making the compressor system adaptable through variable geometry mechanisms. The inlet guide vanes and suction valves are dynamically adjusted to maintain stable delivery pressure while allowing flow rate to vary according to renewable energy feed availability. This dynamic adjustment resolves the contradiction between variable productivity and stable pressure.
Solution Approach 2:
The invention changes operational parameters by adjusting inlet guide vane angles and suction valve timing independently of rotor speed. This allows the system to decouple flow rate control from pressure control, enabling flow rate to follow variable renewable feed while maintaining delivery pressure within acceptable ranges for loop operation.
2Adaptability or versatility
If the speed of rotation is reduced to reduce flow rate, then variable feed can be followed, but the makeup compressor and circulation compressor cannot operate independently when mounted on the same shaft
Solution Approach 1:
The invention segments the control functions by separating inlet guide vane adjustment from suction valve control, and further separating these from rotor speed control. This segmentation allows independent optimization of each compressor's operation even when mounted on the same shaft, enabling the makeup compressor and circulation compressor to be controlled independently through their respective control mechanisms.
Solution Approach 2:
The invention introduces dynamic control elements (inlet guide vanes, suction valves with independent actuation) that allow each compressor to respond independently to control signals despite sharing a common shaft. This dynamic segmentation of control functions resolves the contradiction between adaptability to variable feed and ease of independent operation.
3Adaptability or versatility
If loop pressure fluctuates to follow renewable power fluctuations, then variable feed can be accommodated, but conversion efficiency is severely affected and equipment may be damaged by fatigue stress
Solution Approach 1:
The invention implements feedback control by continuously monitoring loop pressure and delivery pressure, and using this information to adjust inlet guide vane positions and suction valve timing. This feedback mechanism ensures that loop pressure remains stable despite variations in renewable energy feed, thereby maintaining conversion efficiency and preventing equipment damage from pressure fluctuations.
Solution Approach 2:
The invention applies beforehand cushioning by using the compressor's internal volume and controlled compression process to buffer against rapid pressure changes. The suction valves and inlet guide vanes are adjusted in advance to anticipate and cushion pressure fluctuations, protecting the loop from damaging stress while accommodating variable renewable feed.
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 with reduced mechanical stress, optimized production, and minimal need for buffer storage, effectively handling rapid fluctuations in renewable energy input.
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
Data Source
Figure 1
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.