Galvanic Applied Sciences 943-TGX-CE, Руководство по эксплуатации

Страница: 16 / 151

Revision 4 16 April 2020
Figure 1: Model 943-TGX-CE
1.4 Sample Handling System
The Analyzer system utilizes a close coupled mounting arrangement of the measurement cell
block to the tail gas process sampling point to minimize the sample handling system length. The
short length allows for analyzer response times to be optimized while sample transport problems
are mitigated. A small volume of tail gas sample is drawn through the measurement cell by use
of an air-driven
aspirator where the concentrations of the various species are determined
photometrically.
The measurement sample is drawn from a central point of the process duct using a specifically
sized
sample probe . After measurement, the process sample (mixed with the aspirator drive
air) is vented to the wall of the process duct. The concentric chamber design of the sample
probe provides both the sampling and venting of the tail gas sample through a single sampling
point on the process duct.
The sample probe incorporates a mechanism for reducing the dew point of sulfur vapour in the
sampled gas stream. Instrument air can be introduced to provide an exposed cool surface to
the incoming sample gas. Excess condensed sulfur is hydrostatically returned to the process
duct. The sulfur vapour concentration is measured and displayed on the analyzer display. The
sulfur vapour concentration is useful for system troubleshooting.
Incoming sample gas is filtered to 60 micron and drawn through the measurement cell by the
aspirator. The measurement cell exposes a known length of sample to UV radiation for
spectroscopic analysis. The aspirator is integral to the measurement cell and uses instrument
air (or other inert gas) as the aspirator drive gas. The analyzer turns on the aspirator drive media
only when no analyzer faults are detected. In the event of a
fault condition, the analyzer
automatically purges the entire sample handling system with instrument air.
Analyzer zeroing is accomplished by introducing higher pressure instrument air (or other inert
gas) upstream of the measurement cell. The zero gas flushes the entire sample handling system