Ametek 888 User Manual

Appendix B-2 | Model 888 ATEX IECEx Tail Gas Analyzer
The concentrations are then corrected for differences in the cell tempera-
ture and pressure recorded at the time of factory calibration.
• Temperature correction scales concentration by the ratio of the current
temperature and the factory calibration temperature.
• Pressure correction scales concentration by the ratio of the factory
calibration pressure temperature and the current pressure.
Excess H
2
S, Excess SO
2
, Ratio (H
2
S/SO
2
) and Total (H
2
S + SO
2
)
Excess H
2
S is calculated by the following equation:
Excess H
2
S= [conc]
H2S
- Excess Factor * [conc]
SO2
The default value for the Excess factor is 2.0 and the concentrations of H
2
S
and SO
2
are in percent by volume.
Excess SO
2
is calculated by the following equation:
Excess SO
2
= [conc]
SO2
-
[conc]
H2
S
Excess Factor
Ratio is calculated by the ratio of the H
2
S and SO
2
concentrations. Total is
the sum of the H
2
S and SO
2
concentrations.
Air Demand
The two-step modified Claus Process consists of a high temperature reac-
tion step followed by a low temperature catalytic reaction. The two reac-
tions, high temperature and catalyst, are shown below:
The Model 888 can provide an analog output that can be used to regulate
the amount of air needed by the reaction furnace to produce the correct
ratio of H
2
S to SO
2
.
The correct amount of process air can be estimated using the following
equation:
∆ A ≈ Plant Factor ( 2[SO
2
] - [H
2
S] )
3 H
2
S + O
2
SO
2
+ 2 H
2
S + H
2
O
3
2
yields
2 H
2
S + SO
2
S
X
+ 2 H
2
O
yields
3
X

Ametek 888 Specifications

General

Brand	Ametek
Model	888
Category	Measuring Instruments
Language	English