| Launch：2022-05-26 |
abstract
The ultraviolet absorption measuring device is built with xs11639-180-540-25, and the concentration and emission of SO2, no, NO2, NH3 and other gases in flue gas can be detected online by combining with ultraviolet differential absorption spectroscopy.
Research background
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To build a "beautiful China", it is proposed that the cities in Beijing, Tianjin, Hebei and surrounding areas should realize the continuous improvement of air quality. By 2025, NOx and PM2 5. VOCs and SO2 emissions will be reduced by 35%, 45%, 35% and 50% compared with 2016. Therefore, the real-time and on-line monitoring of these air pollutants is particularly critical.
Flue gas measurement refers to the measurement of the concentration and emission of trace harmful gas components such as SO2, NOx, HCl and H2S emitted from fixed pollution sources such as coal-fired chimneys of power plants and industrial chimneys of iron and steel plants.
UV Differential Absorption Spectrometry
At present, the commonly used flue gas measurement method is ultraviolet differential absorption spectrometry, which is called DOAS for short. This method is a combination of UV absorption method and differential algorithm. Using the narrow-band absorption characteristics of NOx, SO2 and other gases in flue gas in UV band, the UV spectrum is differentially processed by mathematical method, and then the gas concentration to be measured is calculated by mathematical methods such as least square method or Fourier transform.
Standard review
The on-line flue gas monitoring system developed based on UV differential absorption spectroscopy has emerged at the historic moment. Many domestic manufacturers have launched a complete set of systems for on-line detection of the concentration and emission of SO2, no, NO2 and NH3 in flue gas. The system consists of sample collection and transportation unit, sample pretreatment unit, flue gas parameter monitoring unit and analysis and detection unit.
The Ministry of ecological environment has successively issued a number of standards, which have made requirements on the technical indicators of flue gas detection methods and flue gas detection equipment.
Requirements for some performance indexes of flue gas measuring equipment:
Oceanhood solution
As a professional spectrometer manufacturer, Oceanhood has a rich and complete product line in terms of optical fiber spectrometer and light source. Oceanhood provides modular solutions for the analysis and detection unit, the core of flue gas measurement equipment, and helps manufacturers in the flue gas detection industry to produce measurement equipment that meets the standard requirements.
Use Oceanhood xs11639-180-540-25 to build an ultraviolet absorption measuring device, with the following characteristics:
Wavelength range: 180-540nm
In the wavelength range of 200-220nm, the intensity of xenon lamp is significantly improved; In the wavelength range of 200-500 nm, the energy is relatively balanced.
Spectral resolution: < 0 7nm@25 μ M (maximum)
Repeatability: the spectrum collected by xenon lamp for 6 times has good consistency.
Signal to noise ratio: 2700:1
It is calculated according to signal-to-noise ratio = spectral intensity / dark noise. The integration time of the spectrometer is 5ms, and the xenon lamp flashes for 5 times, with an average of 5 times.
The dark noise of the spectrometer at different temperatures (0-50 ℃) has good consistency, which is about ± 20 counts.
Wavelength indication error: < 0.3nm (take the maximum)
1H drift
The xenon lamp has good long-term stability, and the intensity changes at 217.6 nm, 301.4 nm and 424.2 nm are within 400 counts.
Epilogue
Oceanhood xs11639-180-540 spectrometer can easily meet the requirements of flue gas monitoring equipment manufacturers for detectors. It has high signal-to-noise ratio, good stability and high resolution, and can easily measure SO2, NOx and other flue gas components. The safety supervision of atmospheric environment is urgent. For example, Oceanhood solution helps you deal with it calmly.
• The spectrometer adopts sandwich structure to isolate the circuit board and optical path, with low heat conduction and small temperature drift of the spectrometer;
• The spectrometer can directly control the xenon lamp, realize multiple flickers and average in a single frame, and improve the stability of the light source;
• The spectrometer adopts spatial filter to realize spectral equalization and ensure the consistent signal-to-noise ratio of each band;
• 11639 UV enhanced detector is used to improve the signal-to-noise ratio;
• The software provides various smoothing algorithms such as Kalman filter;
• Use USB communication to ensure the reliability and stability of signal transmission;
• The software supports andorid, windows, Linux and other operating systems;
• It has a wide range of applications and is suitable for the measurement of air pollutants and harmful gases such as industrial exhaust and automobile exhaust.
