All Rights Reserved. Copyright © 2004, Yokogawa Electric Corporation TI 11M12A01-01E
4-19
4. Applications<Toc> <Ind>
b) Calcinating furnace
Exhaust gas oxygen concentration measurement for fluidized-bed calcination roasting furnaces,
sulfur combustion furnaces and other such furnaces which burn sulfur-containing materials or
elemental sulfur presents sample conditions such as the following, so direct-in-situ type zirconia
oxygen analyzers cannot be used for measurement.
Corrosive gas in exhaust gas: SO
2
7 to 18%
Note, however, that the Yokogawa direct in situ type zirconia oxygen analyzers are fully capable of
measurement in exhaust gases containing SO
2
concentrations up to 5000ppm.
c) Facilities with reducing gas atmospheres
The term “reducing gases” refers to those gases which react with metal oxides to reduce them
either to metal or to oxides of a lower degree of oxidation. These gases are composed of a
reducing component, of which H
2
is the primary example, and an inert gas component such as N
2
.
These reducing gases are used for purposes such as protecting metal surfaces from oxidation or
dacarbonization during heat treatment, or to improve certain properties. If an attempt is made to
use a direct in-situ type zirconia oxyen analyzer in such a metal treatment furnace, the combus-
tible gas (reducing gas) and oxygen in the sample gas will incite a combustion reaction like that
shown below in the high-temperature cell section (generally above 600°C), causing a negative
measurement error, so that measurement is generally impossible under these conditions.
2CO+O
2
➝2CO
2
2H
2
+O
2
➝2H
2
O
CH
4
+2O
2
➝CO
2
+2H
2
O
Reference
Bulletin 11M12A01-01E
GS 11M12A01-01E
May 31, 2004-00
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