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SGM-9 Portable Monitor for Mercury In-Stack Gas

SGM-9 Portable Monitor for Mercury In-Stack Gas

In combination with the EMP-3 (Portable mercury survey meter) and WLE-9 (Gaseous mercury pretreatment unit) and with the high mobility achieved by its light and compact body, the SGM-9 has dramatically reduced the workload during stack gas measurement at elevated locations which was difficult in the past.



Measurement of mercury concentration in stack gas

The EMP-3’s built-in air pump directs stack gas to the WLE-9 (Gaseous mercury pretreatment unit) through a heating conduit. As a pretreatment in the WLE-9, 10% tin (II) chloride solution is added into the first gas scrubber bottle to reduce Hg2+ in the sample gas to Hg0, and acidic gases (interfering gases such as SO2, NOX, and HCl) are removed in the second gas scrubber bottle using 1 mol/L of KOH solution. Then, moisture in the gas is condensed and removed in the third gas scrubber bottle, which is cooled by an electronic cooling unit.

After that, the gas is introduced into the absorption cell of the EMP-3, and the total mercury concentration in the stack gas is measured using atomic absorption spectroscopy at absorbance of 253.7 nm wavelength.

Its measurement range is wide: 0.1–2,000 µg/Nm3, and its response time is only 1 second. Measured data is stored in the internal memory in CSV format and can be output into a USB flash drive for data analysis.

In addition, all the reagents and solutions are automatically discharged and replenished.


Expandability for speciation measurements

Real-time speciation measurements of both metal mercury and total gaseous mercury can easily be realized through combining two sets of the SGM-9.

In the WLE-9 (Gaseous mercury pretreatment unit) of the first set (SGM-9T), a sample gas is passed through 10% tin (II) chloride solution to reduce the oxidized mercury into metal mercury in order to measure the total gaseous mercury in stack gas.

On the other hand, KCl solution is fed into the WLE-9 of the second set (SGM-9E) so that only the gaseous metal mercury can be measured.

Using this system (operating two sets of the SGM-9 in parallel), you can make speciation measurements of both metal mercury and total gaseous mercury.