Galvanic Applied Sciences 943-TGX, Operation Manual

Page: 42 / 110

Revision 4 42 August 02, 2019
To edit a parameter, use the
Field Prev
or
Field Next
button to access the field and press
Enter. A dialog box similar to Figure 4-6 will be presented. Enter the desired value, select the
Okay button and press Enter .
When all desired changes have been made, select Save. Selecting Revert will keep the
parameter values that were used before the start of the editing process.
a)
Plant Factor
- This parameter specifies the
Plant Factor
term used in the analyzer’s
calculation of Air Demand. The
Plant Factor
is a gain term applied to the air demand
output used to adapt the process variable (Air Demand) to the plant’s front end air
adjustment capability. Plant Factor is defined as follows:
pf = -Q
tg
(100) / ([H
2
S]
ag
) (Q
ag
)
where:
Q
tg
= flow rate of the tail gas stream in moles/unit time (typical)
Q
ag
= flow rate of the acid gas feed stream in moles/unit time (typical)
[H
2
S]
ag
= molar concentration of H
2
S in the acid gas feed stream (typical)
PF
= plant factor
The value for
Plant Factor
is typically in the order of -3.0.
b) Operating Ratio - Under stoichiometric concentrations of H
2
S and SO
2
([H
2
S] / [SO
2
] =
2/1) the Air Demand output becomes zero regardless of the plant specific gain factor (F)
when the operating ratio (R
op
) is two (2). When the plant specific gain factor (F) is
established for a particular process, the units of Air Demand become ‘percent change
required in process air’. ( i.e., a computed Air Demand of +1.5% means that the process
is 1.5% excess in air.) To achieve optimum performance of the Claus Sulfur Recovery
Plant, the Air Demand should be kept near zero.
c) H2S Span - This parameter specifies the span factor utilized for the H
2
S concentration
display and output. This value should always be close to 1.0.
Any deviation of the H2S span parameter will impact the output calibration
of the analyzer.
d) SO
2
Span - This parameter specifies the span factor utilized for the SO
2
concentration
display and output. This value should always be close to 1.0.
Any deviation of the SO2 span parameter will impact the output calibration
of the analyzer .
e) COS Span - This parameter specifies the span factor utilized for the COS concentration
display and output. This parameter (when used) should always be close to 1.0.
f) SVAP Span - This parameter specifies the span factor utilized for the SVap
concentration. This parameter (when used) should always be close to 1.0.
g)
CS2 Span
- This parameter specifies the span factor utilized for the CS2 concentration.
This parameter (when used) should always be close to 1.0.