Optical Emission Spectrometry Gas Flow Control
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Solution Overview
Problem
Optical emission spectrometers face challenges in maintaining stable transmittance levels and optimizing gas consumption due to air leaks and absorption by oxygen and water, leading to unreliable quantitative analysis and high argon costs.
Innovation Solution
A method and apparatus using absorption spectroscopy to dynamically control the flow of purge gas by measuring transmittance and adjusting gas flow rates based on feedback, ensuring stable transmittance levels with reduced gas consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a constant argon flow is maintained during each phase of operation, then the concentration of gaseous contaminants is kept at a controlled level, but the cost of argon consumption increases significantly
Solution Approach 1:
The patent implements dynamic control of argon flow rate based on real-time transmittance measurements. The system transitions from constant flow to variable flow, adjusting the purge gas flow rate according to the measured transmittance levels and operational phase, thereby optimizing gas consumption while maintaining analysis reliability
Solution Approach 2:
The system uses transmittance measurements as feedback to control the purge gas flow rate. A controller monitors transmittance levels and adjusts the argon flow accordingly, creating a closed-loop control system that responds to actual transmittance conditions rather than operating with fixed preset flow rates
2Loss of substance
If the purge system is switched off to contain costs, then argon consumption is reduced, but air leaks penetrate and contaminate the spectrograph, causing wavelength shifts
Solution Approach 1:
The system dynamically adjusts purge gas flow based on operational state. During analysis phases, the system maintains controlled purging to prevent contamination, while during idle periods it reduces or suspends flow to minimize consumption, with automatic transitions between states based on transmittance monitoring
Solution Approach 2:
The system performs preliminary purging actions before analysis phases to ensure the spectrograph is properly conditioned, and uses real-time transmittance monitoring to determine when sufficient purging has been achieved, allowing for optimized gas usage while maintaining wavelength stability
3Reliability
If a long fixed-period purge is applied to eliminate impurities, then transmittance is restored to optimum levels, but the purge consumes excessive argon and requires long stabilization periods
Solution Approach 1:
The system uses real-time transmittance measurements to determine when purging is sufficient, replacing fixed-time purge protocols with feedback-driven control that stops purging when transmittance reaches acceptable levels, thereby reducing both gas consumption and time required
Solution Approach 2:
The system changes the flow rate parameter dynamically during the purge process, using higher initial flows to quickly remove bulk contaminants, then reducing flow as transmittance improves, optimizing the balance between purge effectiveness and resource consumption
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 rapidly stabilizes transmittance levels and minimizes argon consumption, enhancing the reliability and efficiency of quantitative analysis in optical emission spectrometry.
Implementation Method 1
transmitting light from a light source along a second path through the gas to a second detector
Implementation Method 2
detecting an intensity of the light from the light source at the second detector at one or more wavelengths of the light
Implementation Method 3
A method and an apparatus that measures the intensity of light transmitted through the purge gas within the spectrometer and thus the transmittance of the gas. The invention is based on the use of absorption spectroscopy to determine the transmittance of the gas.
Implementation Method 4
VUV radiation is absorbed by air, in particular by oxygen and water present in air
Data Source
AI summary
A method for controlling the flow of gas through a spectrometer, comprising: flowing a gas through a volume of the spectrometer, the volume being a volume through which light from a sample passes along a first path to reach a first detector and the gas being transparent to the light in a spectral region analysed by the spectrometer; transmitting light from a light source along a second path through the gas to a second detector; detecting an intensity of the light from the light source at the second detector at one or more wavelengths of the light; comparing the detected intensity of the light to a respective setpoint corresponding to a desired transmittance of the gas in the volume of the spectrometer and generating at least one error signal based on the comparison; and adjusting a flow rate of the gas through the volume of the spectrometer based on the error signal, in particular to minimise the difference between the detected intensity and setpoint.