In-situ Gas Analyzer

In-situ analysis and measurement of gas composition in the industrial process are becoming more and more important in the world industrial field.

Measuring principle of Gas Analyzer

In-situ gas analyzer is an optical instrument, which emits laser from a single-mode diode laser with stable temperature to a receiver with opposite diameter. The diode laser works near room temperature.

The traditional on-line analyzer is usually affected by the cross interference from other gas components (including dust, moisture background components, etc.), which becomes more and more serious when the detection content is very low. Compared with the traditional IR on-line analyzer using broadband spectral filtering, the laser gas on-line analyzer adopts the single line spectral technology in the near infrared spectral range.

The single line spectrum measurement technology is based on the selection of a single absorption line in the near infrared region. Through the spectral analysis of the selected absorption line, there is no other gas absorption line (no cross absorption interference) in the selected absorption line wavelength. Then, by adjusting the temperature and driving current of the diode laser, the frequency of the diode laser is adjusted to the single absorption line of the gas. The spectral width of the laser is adjusted to be narrower than that of the single absorption line. By changing the current of the diode laser, the laser wavelength including a single absorption line is scanned and emitted.




During laser scanning and emission, according to the characteristics of wavelength, the light intensity detected by the receiving unit will change, and this change only comes from the absorption of the measured gas molecules in the optical channel between the laser and the receiver. The shape and size of the detected single absorption line are used to calculate the gas content between the emitter and the receiver. The absorption line of other gases will not appear in the selected wavelength range, so it will not interfere with the single absorption line or affect the flue gas measurement.

The in-situ gas analyzer is not affected by the absorption of water, dust or pollutants on the window in the process gas. This is because the calculation of gas content is based on the unique single absorption line size and shape, which realizes more reliable measurement and reduces the need for maintenance.