Extraction Gas Analyzers made by Fuji Electric
The ZRE type gas analyzer (made by Fuji Electric) is capable of measuring the concentration of up to 5 components in sample gas (including oxygen).
For most common applications the analyzer is suitable to measure SO2, NOx, CO and O2. It was designed as a main instrument for the continuous emission monitoring system of incinerators, boilers and other various industrial furnaces. The analyzer is certified with the QAL-1 according to PN-EN14181 standard.
NOx is a term commonly used to describe a group of all nitrogen oxides (NO, NO2, N2O, N2O3, N2O5). Nevertheless, acc. to IED Directive NOx stands for the sum of NO and NO2 only. Moreover, according to the current Polish and EU low concentration of NOx should be calculated and expressed as NO2.
An analyzer capable to measure all the five gases would be very expensive and complicated device. It was described and proven in may scientific papers that for most exhaust gases (coming from coal-firing power boilers) approx. 95% of NOx is NO and the rest 5% consists mainly of NO2. Therefore, the basic type of the ZRE analyzer does not really measure NO2.
If a Customer requires a real measurement of NO2, the analyzer will be adjusted for it by using a special NO2 to NO converter (made also by Fuji Electric).
Principle of operation and construction
The analyzer has a big display screen showing all measurement readings. A keyboard placed next to it allows a User to enter all configuration setups of the analyzer.
The instrument is capable of measuring 4 components in sample gas by non-dispersion infrared method (NDIR).
Principle diagram of NDIR type measurement
All the infrared measuring cells (the drawing above) consists of infrared-ray light source mounted in a rotating cylinder with a gag. The rotating cylinder ensures a modulation of the radiation beam. A detector (located opposite the source) generates a measuring signal which is then enhanced and converted to the digital form. Next, the signal is introduced to the processor, which on the basis of certain algorithms calculates the signal of the gas concentration.
Apart from oxygen the concentration of all measured gases are calculated according to the description presented above. A principle of oxygen measurement procedures (electrochemical, zirconium and paramagnetic) is described below. All three methods are acknowledged by the low and their selection depends on flue gas parameters and a customer preferences.