Galvanic Applied Sciences 943-TGXeNA, Operation Manual

Page: 46 / 149

Revision 5 46 August 2021
Figure 21: Analysis 1 Concentration Fields
The analyzer’s physical measurement range, which is determined by the length of the
measurement cell, is optimized for typical on-ratio (that is to say, non-upset) concentrations
of H
2
S and SO
2
. COS and optionally CS
2
concentrations are also displayed here. The sulfur
vapour (S
vap
) is monitored to indicate when there may be a problem with the sulfur condenser
“cold finger” at the tip of the sample probe (refer to Section 3.2.3) and to prevent sulfur
plugging inside the analyzer sample handling system.
4.3.3 Air Demand
The Air Demand field and Air Demand trend graph shown in Figure 22 show the current
calculated Air Demand (% Excess Air) and the recent trend in the Air Demand data. The Air
Demand field is read-only and cannot be edited.
Figure 22: Air Demand Value and Trend
The air demand reading is an indicator of the current process status relative to the optimal
ratio (typically a 2:1 ratio H
2
S:SO
2
). If the air demand value is negative, this indicates that
the H
2
S concentration is too high and there is insufficient air being added. If the air demand
value is positive, this indicates that the SO
2
concentration is too high and there is excess air
being added. If the air demand is zero, this indicates that the H
2
S to SO
2
ratio is at the optimal
value and the air does not need to be adjusted.