Teledyne 102E Theory Of Operation, Measurement Principle, TRS Conversion, TRS + O2 Æ SO2, Rev A1

M102E/M501 TRS THEORY OF OPERATION

(Addendum to M101E Manual - P/N 04740 Rev A)

9. THEORY OF OPERATION

The M102E is a modified M101E which, when used in conjunction with a M501-TRS determines the concentration of total reduced sulfur (TRS), in a sample gas drawn through the instrument In most ways the theory of operation of the M102E & M501-TRS system is identical to the M101E theory of operation as described in Chapter 10 of the M101E Manual - P/N 04740 Rev A.

This section describes those areas where differences between the M102E and the M101E exist as well as updated information made available since the publication date of the M101E Manual - P/N 04740 Rev A.

9.1. Measurement Principle

This section supercedes Section 10.1 of the M101E Manual - P/N 04740 Rev A

9.1.1. TRS Conversion

The M102E TRS analyzer is basically an SO2 analyzer with a TRS Æ SO2 converter (the M501- TRS) inserted into the gas stream before the sample gas enters the sample chamber.

The M501-TRS, receives sample gas from the M102E after it has been passed through a particulate filter and has been scrubbed of hydrocarbon interferents. Once inside the M501-TRS the sample gas is scrubbed of all naturally occurring SO2, then passed through a special quartz converter which heats the gas to a very high temperature causing it to react with the O2 present in the sample gas creating SO2 in the following manner .

TRS + O2 Æ SO2

(Equation 9-1)

The converter is most efficient when it operates at 1000°C, converting >95% of the TRS into SO2. Converter temperature is viewable via the front panel of the M501-TRS

When the converter is operating at peak efficiency there is a nearly 1:1 relationship between the amount of TRS entering the converter and the amount of SO2 leaving it. Therefore, by measuring the amount of SO2 in the gas after it leaves the converter, the amount of TRS originally present on the sample gas can be directly inferred.

9.1.2. SO2 Ultraviolet Fluorescence

The physical principle upon which the M102E’s measurement method is based is the fluorescence that occurs when sulfur dioxide (SO2) is excited by ultraviolet light with wavelengths in the range of 190 nm-230 nm. This reaction is a two-step process.

The first stage (Equation 9-2) occurs when SO2 molecules are struck by photons of the appropriate ultraviolet wavelength. In the case of the Model 102E, a band pass filter between the source of the UV light and the affected gas limits the wavelength of the light to approximately 214

05514 Rev A1 43