Yokogawa Integral Oxygen Analyzer ZR202 - Manual (Page 121)

IM 11M13A01-04E 10-3
10. Other Functions
10.1.1 Air Ratio
“Air ratio” is defined as the ratio of (the amount of air theoretically required to com-
pletely burn all the fuel) to (the amount of air actually supplied).
For this equipment, the air ratio will be obtained in a simplified way by measuring the
oxygen concentration in the exhaust gas. The air ratio may be expressed mathematically
by:
m ={1 / (21- oxygen concentration)}
ϫ 21
If you use the air ratio data for estimating the combustion efficiency, etc., check that no
air is leaking in beforehand and that the measured value has not been affected by any
interference gas (CH
4
, CO, H
2
, etc.).
10.1.2 Cell Temperature
This indicates the cell (sensor) temperature, usually indicating 750˚C., obtainable from
the thermoelectromotive force and cold junction temperature described below.
10.1.3 C. J. Temperature
This is the internal (where the electronics is installed) temperature of equipment, which
compensates for the cold junction temperature for a thermocouple measuring the cell
temperature. If this temperature exceeds 85˚C, the electronics may fail. When the ZR202
Detector is used, the maximum C. J. temperature will be 150˚C. If the internal tempera-
ture exceeds this, take measures to reduce the temperature such as by not exposing the
equipment to radiation.
10.1.4 Amount of Water Vapor in Exhaust Gas
Calculate the water vapor in the combusted exhaust gas using parameters set in Section
8.7.3, “Setting Fuels”. Use the following equation for calculation:
Moisture (water vapor) = {(amount of water vapor per unit quantity of fuel) +
(moisture in air) }/total amount of exhaust gas = (Gw + 1.61
ϫ Z ϫ Ao ϫ m)/(X
+ Ao
ϫ m)
where,
Gw = Amount of water vapor in exhaust gas, m 3 /kg (m 3 )
Z = Atmospheric absolute humidity, kg/kg
Ao = Theoretical air amount, m
3 /kg (m 3 )
m = Air ratio
X = Fuel coefficient, Nm
3 /kg or m 3 /m 3
For details on parameters, see Section 8.7.3, “Setting Fuels” earlier in this manual.