SO3 Analysis Device Using Wavelength-Controlled Laser Spectroscopy
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Solution Overview
Problem
Current methods for measuring sulfur trioxide (SO3) in flue gas are costly, time-consuming, and difficult to perform in real-time due to the need for pretreatment and interference from coexisting gases like water vapor, making it challenging to optimize ammonia injection in combustion plants.
Innovation Solution
A device using wavelength control to emit laser light in specific ranges (4.093 to 4.132 µm) for direct measurement of SO3 concentration via infrared spectroscopy, incorporating nonlinear optical crystals for difference frequency generation, and incorporating temperature and pressure measurement to calculate SO3 concentration without pretreatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional gas sampling and optical analysis with FT-IR is used, then SO3 concentration can be measured, but pretreatment steps (dust removal, H2O dilution) and reduced pressure operation are required, increasing cost and time
Solution Approach 1:
The patent changes the measurement wavelength parameter from conventional long-wavelength mid-infrared (7 μm) to short-wavelength mid-infrared (3 μm). This parameter change enables direct measurement of SO3 in flue gas without pretreatment, as the 3 μm wavelength region has unique absorption characteristics for SO3 that are not overlapped by H2O and CO2 interference
Solution Approach 2:
The patent extracts only the necessary measurement function by using a compact quantum cascade laser system that directly measures SO3 at 3 μm wavelength. This eliminates the need to extract and pretreat the gas sample, removing dust removal equipment, H2O dilution systems, and reduced pressure operation requirements
2Measurement precision
If gas sampling with pretreatment is performed, then SO3 analysis can be conducted, but real-time measurement becomes difficult
Solution Approach 1:
The patent enables continuous real-time measurement by eliminating the sampling and pretreatment process. The quantum cascade laser system continuously irradiates the flue gas at 3 μm wavelength, allowing uninterrupted SO3 concentration monitoring without the intermittent nature of sampled analysis
3Measurement precision
If long-wavelength mid-infrared (7 μm) spectroscopy is used, then SO3 can be detected, but absorption line overlap with H2O makes measurement difficult
Solution Approach 1:
The patent changes the wavelength parameter from 7 μm to 3 μm, where SO3 has strong absorption lines that do not overlap with H2O or CO2 absorption lines. This parameter change eliminates the harmful interference effect while maintaining SO3 detection capability
4Object-affected harmful factors
If ammonia injection amount is increased to reduce SO3, then H2SO4 corrosion is prevented, but ammonium sulfate production increases, clogging the dust arrester
Solution Approach 1:
The patent implements a feedback control system where real-time SO3 concentration measurements from the quantum cascade laser system are fed back to the ammonia injection control. This allows dynamic adjustment of ammonia injection amount to precisely neutralize SO3 without excessive injection, preventing both corrosion and ammonium sulfate clogging
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 in-situ, accurate, and prompt measurement of SO3 concentration in flue gas without pretreatment, reducing the need for equipment modifications and avoiding interference from coexisting gases like CO2 and H2O.
Implementation Method 1
A device using wavelength control to emit laser light in specific ranges (4.093 to 4.132 µm) for direct measurement of SO3 concentration via infrared spectroscopy
Implementation Method 2
incorporating nonlinear optical crystals for difference frequency generation
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
To provide an SO3 analysis device and analysis method capable of accurately and rapidly measuring the concentration of SO3 in exhaust gas without pre-processing. The present invention is provided with a light source (11) for radiating laser light (2) to exhaust gas (1) including SO3, CO2, and H2O, a photodetector (13) for receiving the laser light (2) radiated to the exhaust gas (1), a light source control unit (14a) of a control device (14) for controlling the wavelength of the laser light (2) radiated by the light source (11) so as to be 4. 060 µm to 4.192 µm, and a concentration calculation unit (14b) of the control device (14) for calculating the SO3 concentration by infrared spectroscopy on the basis of the output from the photodetector (13) and a reference signal from the light source control unit (14a).