High sensitivity and high-precision ultraviolet spectrometer based on fast Fourier transform (FFT)

Direct injection measurement of high temperature and high humidity gases

CEM500 is an online gas analyzer specifically designed for continuous emission monitoring. The new model of the instrument uses a 2048 pixel CCD (charge coupled device), which can provide extremely high resolution (0.1 nm) and a long bulb lifespan (3 years). Detection based on ultraviolet spectroscopy not only brings higher sensitivity than infrared, but also enables simultaneous measurement of multiple gases. By performing fast Fourier transform (FFT) on the absorption spectra of gases with periodic structures such as NH3, SO2, NO, high selectivity has been achieved. The internal gas circuit of the instrument is heated at 190 ° C, so it can directly introduce high-temperature and humid gas without condensation. CEM500 adopts IP65 wall mounted housing. According to the requirements, this model can also be equipped with a heating sampling pump.

Main testing method: UV spectroscopy

By using different wavelengths and algorithms, multiple gases can be measured simultaneously, thanks to UV spectroscopy. For gases with periodic absorption spectra, such as NH3, SO2, NO, CS2, or acetylene, a method based on FFT (Fast Fourier Transform) ensures excellent measurement selectivity. Due to the solid-state design of UV spectroscopy, the measurement system has high reliability and does not require maintenance.

UV lamp is a long-lasting xenon flash lamp that is unlikely to produce measurement drift due to thermal effects.

The gas flow cell has two quartz windows for transmitting UV light through the measured gas. The standard path length of the flow pool is 240 millimeters.

The spectrometer is based on a concave grating to miniaturize the optical components, and the spectrum is read on a 2048 pixel CCD with a resolution of 0.1nm.

Automatically adjust the zero point under clean air or nitrogen (if possible, every 2 or 4 hours, but once a day is still acceptable).

The absorption spectrum is calculated based on the reference spectrum obtained during the zeroing step.

Heating version

The analyzer is equipped with a heating system for the gas path.

The heating temperature can be adjusted to 190 ℃, and high temperature can evaporate the sediment on the detection window.Does not interfere with CO, CO2, and CH4

The main emission gases such as CO, CO2, and CH4 do not absorb ultraviolet radiation, so they will not interfere with the measured gas.

H2O has weak absorption in the ultraviolet range, but absorbs less at different wavelengths than combustion gases such as NH3, NO, NO2, or SO2.

Therefore, H2O with a concentration between 5% and 20% usually does not interfere with the measurement.

Multiple gas configurations

If the composition of the sample gas is compatible with the selected algorithm and wavelength, multiple gases can be measured in the same analyzer.

Due to the use of proprietary algorithms to identify specific UV absorption spectra of gases, this analyzer has high measurement selectivity.

For denitrification applications, such as coal-fired power plants, special algorithms can simultaneously measure NH3 concentrations ranging from 0 to 10 ppm and SO2 concentrations up to 1200 ppm.

Low maintenance and high reliability

This design is specifically designed for low maintenance and high reliability in measurement.

The specified lifespan of the ultraviolet xenon lamp is 109 flashes, so the lifespan for continuous measurement is about 3 years. If it is reduced to one measurement per minute,

The lifespan can last up to 10 years.This greatly reduces the risk of maintenance and incorrect measurements caused by replacing aging lamps.

Humanized user interface

The color touch screen facilitates users to easily browse multiple windows for setting and checking instrument operation settings.

The protective film reduces the risk of damaging the touch screen surface, especially for solvents and corrosive liquids.

Time

Due to the ultra fast electronic design based on high-speed DSP (digital signal processor), the analyzer can measure sample concentration within 200 milliseconds. However, the usual measurement of exhaust gases is completed within 5 seconds, and a special automatic averaging algorithm can be used to improve stability without affecting response time.

Gas path

The air inlet and zero air outlet are connected to a three-way electric valve. When the automatic zero calibration starts, the solenoid valve switches to the zero gas inlet. The pressure sensor compensates for the measured gas pressure and provides flow indication.

The gas circuit is located inside the heating chamber, and the temperature can be set and controlled between 60 ℃ and 190 ℃ (± 0.5 ℃).

An optional pump can be installed before the gas analysis tank to extract air when using ambient air as the zero gas.

automatic compensation

Real time measurement of sample gas temperature and pressure, applying ratio rules related to ideal gases to the measured values to compensate for the effects of temperature and pressure.

CEM500Technical Parameter

*Higher range products can be customized according to demand