Gas Analyzer UV Ozone Generation Nitrogen Oxide Measurement
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Solution Overview
Problem
Existing gas analyzers for measuring nitrogen oxides in exhaust gases face challenges in accurately determining oxygen concentration and suffer from cross-sensitivity issues with sulfur dioxide measurements, and the formation of undesirable nitric oxide compounds during ozone generation.
Innovation Solution
Incorporating an ultraviolet light source in the reaction chamber to generate ozone from residual oxygen in the exhaust gas, and using a second photometer to measure ozone concentration in the middle ultraviolet range, allowing for the calculation of oxygen concentration and computational compensation for cross-sensitivity, along with a bypass for nitrogen dioxide measurement to correct for ozone consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ozone is generated by electrical discharge from atmospheric oxygen, then nitrogen monoxide is reacted into nitrogen dioxide, but undesirable nitric oxide compounds are formed
Solution Approach 1:
The patent changes the ozone generation method from electrical discharge to ultraviolet light irradiation. This parameter change in the energy source type and wavelength (UV light at specific wavelengths) prevents the formation of undesirable nitric oxide compounds while still achieving the oxidation of nitrogen monoxide to nitrogen dioxide, thus resolving the contradiction between measurement accuracy and harmful byproduct formation
2Measurement precision
If a single photometer measures nitrogen dioxide concentration, then oxygen concentration cannot be determined, but cross-sensitivity with sulfur dioxide occurs
Solution Approach 1:
The patent segments the measurement function into two separate photometers: one dedicated to measuring nitrogen dioxide concentration and another dedicated to measuring ozone concentration (which is used to determine oxygen concentration). This segmentation eliminates cross-sensitivity interference between sulfur dioxide and oxygen measurements, as each photometer is optimized for its specific target gas, thereby resolving the contradiction between determining oxygen concentration and avoiding cross-sensitivity errors
Solution Approach 2:
The patent uses ozone as an intermediary substance. By measuring ozone concentration with a dedicated photometer and using this measurement to calculate oxygen concentration, the system avoids direct measurement of oxygen which would be interfered with by sulfur dioxide. The ozone measurement serves as an intermediary that indirectly provides oxygen information without suffering from cross-sensitivity issues
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 precise determination of oxygen concentration and reduces cross-sensitivity, providing accurate nitrogen oxide measurements by utilizing ozone generation from residual oxygen and compensating for interference, thereby improving the accuracy of gas analysis.
Implementation Method 1
an ultraviolet light source arranged in the reaction chamber and is designed to produce the ozone from the residual oxygen content of the exhaust gas
Implementation Method 2
another photometer is arranged in the exhaust path between the reaction chamber and the heating chamber, which is designed to be absorbent From light in the middle ultraviolet range between 220 nm and 300 nm in the partially treated exhaust gas to determine the ozone concentration
Implementation Method 3
in the heating chamber To decompose nitrogen oxides and excess ozone thermally into nitrogen dioxide and oxygen
Implementation Method 4
a photometer lying in the exhaust gas path behind the oxidizing device, which is adapted to the absorption of light in the nearby ultraviolet range between 350 nm and 500 nm in the treated exhaust gas To determine nitrogen dioxide concentration
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
The invention relates to a gas analyzer for measuring nitrogen oxides and at least one further component of an exhaust gas (1), comprising an oxidation device (7) for treating the exhaust gas (1), and a subsequent photometer (12) for measuring the nitrogen dioxide concentration by light absorption in the near ultraviolet range between 350 nm and 500 nm. The oxidation device (7) has a reaction chamber (9) located in an exhaust gas path, and a heating chamber (10) downstream thereof. In the reaction chamber (9), an ultraviolet light source (8) generates ozone from the residual oxygen content of the exhaust gas (1) in order to convert nitrogen monoxide into nitrogen dioxide in the exhaust gas (1). In the heating chamber (10), nitrogen oxides and excess ozone are broken down into nitrogen dioxide and oxygen. The photometer (12) outputs the measured nitrogen dioxide concentration as nitrogen oxide concentration of the untreated exhaust gas (1). In the exhaust gas path between the reaction chamber (9) and the heating chamber (10), an additional photometer (14) is located, which, by way of light absorption, measures the ozone concentration in the partially treated exhaust gas (1') in the medium ultraviolet range between 220 nm and 300 nm, and outputs the same as oxygen concentration of the untreated exhaust gas (1).