Emerson IM-106-5500 Manual Do Utilizador
Instruction Manual
IM-106-5500, Original Issue
August 2005
CCO 5500
1-8
Carbon Monoxide IR Absorption Spectrum
Carbon monoxide absorbs IR energy in a band between wavelengths of
approximately 4.5 and 4.9 µm. The absorption spectrum is complex and is
illustrated in Figure 1-3 below.
approximately 4.5 and 4.9 µm. The absorption spectrum is complex and is
illustrated in Figure 1-3 below.
Figure 1-3. CO IR Absorption
Spectrum
However, two other common flue gas constituents - carbon dioxide and water
vapor - also absorb energy within this wave band. Fortunately, at 4.7µm, IR
absorption by each of these gases is at a minimum. Figure 1-4 demonstrates
how the absorption spectra of CO, CO
vapor - also absorb energy within this wave band. Fortunately, at 4.7µm, IR
absorption by each of these gases is at a minimum. Figure 1-4 demonstrates
how the absorption spectra of CO, CO
2
and water vapor affect wavelengths of
between 4.5 and 4.9 µm.
Absorption Spectra of CO, CO
2
and Water Vapor
By using a narrow band pass filter which only passes IR energy at
wavelengths of around 4.7µm, correctly designed CO analyzers are able to
ignore the effects of water vapor and CO
wavelengths of around 4.7µm, correctly designed CO analyzers are able to
ignore the effects of water vapor and CO
2
. (The filter characteristics are
shown in Figure 1-4). No other flue gases absorb IR energy in this band.
Figure 1-4. Comparison of
Spectra
4.5
4.6
4.7
4.8
4.9
Wavelength (microns)
Absorption
(%)
0
4.5
4.6
4.7
4.8
4.9
Wavelength (microns)
Absorption
(%)
0
CO
2
H O
2
Filter
Limits
Limits