Description
The CEM500-L is an extractive online gas analyser for Continuous emission monitoring (CEMS).
It is specifically dedicated to the new low level emission Regulations known as 50/30/5/3 (50 mg/Nm3 NOx, 30 mg/Nm3 SO2, 5 mg/Nm3 particles, 5 μg/Nm3 mercury) and also to chemical processes requiring low values of H2S. This new model is based on a multi-path flow cell of 1200 mm coupled to a high resolution spectrograph (0.1 nm) using an ultra-sensitive 2048 pixels CCD (charge-coupled device). It gives a high sensitivity and a longer lamp life time (3 years). The uv spectroscopy brings a higher sensitivity than Infra-red spectroscopy and also gives the possibility to measure several gases simultaneously on the same Spectrograph.
It is specifically dedicated to the new low level emission Regulations known as 50/30/5/3 (50 mg/Nm3 NOx, 30 mg/Nm3 SO2, 5 mg/Nm3 particles, 5 μg/Nm3 mercury) and also to chemical processes requiring low values of H2S. This new model is based on a multi-path flow cell of 1200 mm coupled to a high resolution spectrograph (0.1 nm) using an ultra-sensitive 2048 pixels CCD (charge-coupled device). It gives a high sensitivity and a longer lamp life time (3 years). The uv spectroscopy brings a higher sensitivity than Infra-red spectroscopy and also gives the possibility to measure several gases simultaneously on the same Spectrograph.
OPTICAL PRINCIPLE – MAIN METHOD : UV SPECTROSCOPY
- Several gases can be measured simultaneously thanks to the UV spectroscopy method by using different wavelengths and algorithms. For gases with a periodic absorption spectrum such as NH3, SO2, NO, CS2 or acetylene, an algorithm based on FFT (Fast Fourier Transform) guarantees a very good selectivity of measurement. The solid-state design due to the UV spectroscopy gives a high reliability of the measuring system with quite no maintenance.
- The UV lamp is a xenon flash lamp with a high lifetime and without thermal effect that may generate measurement drift.
- The gas flow cell has two quartz windows to transmit the UV light throught the measured gas. The standard path length of the flow cell is 1200 mm.
- The spectrograph is based on a concave grating to minimize the optical parts and the spectrum is read on a 2048 pixel CCD with a resolution of 0.1nm.
- A zero is done automatically on zero air or nitrogen with an adjustable period (if possible every 2 or 4 hours but once per day remains acceptable).
- The absorbance spectrum is calculated from the reference spectrum acquired during the zero step.
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