Second Expander Speed Biasing to Avoid Resonant Speed Ranges
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In gas and oil refrigeration systems with two expanders in series, manual operation to avoid undesirable speed ranges is risky, inefficient, and can lead to prolonged exposure to harmful operating conditions, distracting operators and potentially causing damage due to resonance-induced vibrations.
Innovation Solution
An automated method and device that bias the speed of the second expander based on the speed of the first expander, using a controller to adjust the speed within predetermined ranges to minimize time spent in unsafe speed ranges, ensuring the second expander operates safely and efficiently by applying positive or negative biases according to specific conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If manual operation is used to bias the speed of the second expander, then the operator can control the system to avoid undesirable speed ranges, but the operation becomes complex and distracting, increasing the risk of accidental inappropriate operation
Solution Approach 1:
The control system automatically monitors the speed of the first expander and adjusts the speed of the second expander without requiring manual intervention. The system serves itself by detecting when the first expander enters the bias application range and automatically applying the appropriate speed bias to the second expander, eliminating the need for operator attention and reducing operational complexity.
Solution Approach 2:
The control system continuously monitors the speed of the first expander and uses this feedback to automatically adjust the speed of the second expander. When the speed sensor detects that the first expander's speed enters the bias application range, the controller automatically applies the predetermined speed bias to the second expander, creating a closed-loop control system that responds dynamically to changing conditions.
2Loss of time
If the speed of the second expander is manually biased to avoid undesirable ranges, then the transition time through unsafe speed ranges can be reduced, but the operator must simultaneously monitor multiple constraints including maximum allowed running time, rate of change of speed, and speed difference between expanders
Solution Approach 1:
The automated control system independently manages all control constraints without requiring operator intervention. It automatically calculates and applies the appropriate speed bias to minimize transition time through undesirable ranges while simultaneously ensuring compliance with maximum allowed running time, rate of change of speed, and speed difference constraints between the two expanders.
Solution Approach 2:
The controller acts as an intermediary between the speed sensor and the second expander, automatically translating the speed of the first expander into an appropriate speed bias for the second expander. This intermediary automatically balances multiple competing constraints, including minimizing transition time while maintaining safe operating parameters and compliance with system limits.
3Adaptability or versatility
If manual operation is used to control the second expander speed, then the operator can adjust the speed to control the first expander indirectly, but this creates difficulty in operating the whole system in a controlled manner and may result in harmful transition states
Solution Approach 1:
The control system uses feedback from the speed sensor monitoring the first expander's speed to automatically adjust the second expander's speed. This closed-loop control ensures that the indirect control of the first expander is achieved in a controlled and reliable manner, preventing harmful transition states by automatically managing the rate of change and maintaining system stability.
Solution Approach 2:
The automated system independently manages the complex interaction between the two expanders, automatically adjusting the second expander's speed to indirectly control the first expander while maintaining system stability. The system self-regulates to prevent harmful transition states without requiring operator intervention or judgment.
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A method (1200) of controlling a transition time through a speed range that is unsafe for an integrity of a second expander (120) that receives a fluid flow from a first expander (110), by automatically biasing a speed of the second expander (120) when the current speed of the first expander is within a bias application range, is provided. The method (1200) includes setting the speed of the second expander to be smaller than a current speed of the first expander (S1210), when a current speed of the second expander increases and is smaller than a first speed value, or decreases and is smaller than a second speed value, and setting the speed of the second expander to be larger than the current speed of the first expander (S1220), when the current speed of the second expander increases and is larger than the first speed value, or decreases and is larger than the second speed value.