Dual-Chamber Gas Analyzer for NOx and SO2 Measurement
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Solution Overview
Problem
Conventional gas analyzers face challenges in reliably measuring nitrogen oxides and sulfur dioxide in exhaust gases due to interference from ozone and incomplete conversion of nitrogen monoxide to nitrogen dioxide, as well as overlap in absorption bands, which affects the accuracy of sulfur dioxide measurement.
Innovation Solution
A gas analyzer with two measuring chambers and a beam splitter arrangement to separate light signals, using a narrowband light source for oxygen measurement, and an ozone generator with high-energy ultraviolet light to ensure complete conversion of nitrogen monoxide to nitrogen dioxide, while minimizing ozone interference in sulfur dioxide measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single measuring chamber is used to measure both nitrogen dioxide and sulfur dioxide, then the device complexity is reduced, but the measurement precision deteriorates due to interference from ozone and incomplete conversion of nitrogen monoxide
Solution Approach 1:
The patent divides the measurement system into two separate measuring chambers: a first measuring chamber for measuring sulfur dioxide concentration, and a second measuring chamber for measuring nitrogen dioxide concentration. This segmentation allows independent optimization of measurement conditions for each gas, eliminating mutual interference and improving measurement precision while maintaining reasonable device complexity through modular design.
Solution Approach 2:
The patent introduces an oxidation device as an intermediary component between the gas sample inlet and the second measuring chamber. This oxidation device converts nitrogen monoxide to nitrogen dioxide through controlled oxidation, ensuring complete conversion before measurement. The intermediary processing step resolves the issue of incomplete conversion that would otherwise compromise measurement accuracy.
2Productivity
If ozone is used to convert nitrogen monoxide to nitrogen dioxide, then the conversion efficiency is improved, but the measurement precision of sulfur dioxide deteriorates due to ozone interference
Solution Approach 1:
The patent separates the measurement paths for sulfur dioxide and nitrogen dioxide into different measuring chambers. The first measuring chamber measures sulfur dioxide without ozone interference, while the second measuring chamber receives oxidized nitrogen dioxide. This spatial segmentation allows ozone to be used for conversion purposes without compromising sulfur dioxide measurement accuracy.
Solution Approach 2:
The patent applies preliminary oxidation action to convert nitrogen monoxide to nitrogen dioxide before the nitrogen dioxide measurement. The oxidation device performs this conversion in advance, and the oxidized gas is then directed to the second measuring chamber. This preliminary action ensures complete conversion while preventing ozone interference in the sulfur dioxide measurement chamber.
3Device complexity
If a broad-band light source is used for measurement, then the device complexity is reduced, but the measurement precision deteriorates due to overlap in absorption bands
Solution Approach 1:
The patent applies local quality by using narrow-band light sources with specific wavelengths optimized for each measurement: a first narrow-band light source with wavelength matching the absorption band of sulfur dioxide for the first measuring chamber, and a second narrow-band light source with wavelength matching the absorption band of nitrogen dioxide for the second measuring chamber. This wavelength-specific optimization eliminates absorption band overlap interference while maintaining manageable device complexity through specialized component selection.
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
Enables accurate and reliable continuous measurement of nitrogen oxides and sulfur dioxide concentrations by distinguishing between nitrogen dioxide and nitrogen monoxide, and monitoring the conversion process, thereby improving measurement precision and reducing interference.
Implementation Method 1
a first light-emitting diode (2) radiating in the near-ultraviolet range (NUV) between 350 nm and 500 nm
Implementation Method 2
a second light-emitting diode (4) radiating in the middle-ultraviolet range (MUV) between 250 nm and 300 nm
Implementation Method 3
a first detector (14), which detects the light of both light-emitting diodes after irradiation of the measuring chamber
Implementation Method 4
an oxidation device (23) that treats the exhaust gas with ozone to convert nitrogen monoxide contained in the exhaust gas into nitrogen dioxide
Implementation Method 5
The ozone is generated from atmospheric oxygen via electrical discharging
Implementation Method 6
a beam splitter arrangement (10) that splits off part of the light of the first light-emitting diode (2) to the second detector (17)
Data Source
AI summary
A gas analyzer via which exhaust gas to be analyzed is conducted untreated through a first measurement chamber and, after treatment in an oxidation device, through a second measurement chamber, wherein ozone is produced from oxygen to thereby convert nitrogen monoxide into nitrogen dioxide, where the gas analyzer has a first light emitting diode and a second light emitting diode, light of both diodes is conducted through the first measurement chamber onto a first detector, light of the first light emitting diode is partly conducted through the second measurement chamber onto a second detector via a beam splitter arrangement, based on the first detector signal, the nitrogen dioxide concentration of the untreated gas is also measured, based on the second detector signal, the nitrogen dioxide concentration of the treated exhaust gas is measured, and the nitrogen oxide concentration of the exhaust gas is additionally determined from measured nitrogen dioxide concentrations.