Case Study MEDOR Exp for sulfur compounds analysis in natural gas0 pages

Case Study N°NG1 – Natural gas monitoring – Medor Exp – updated: 09.10.15

Case Study
Natural Gas Monitoring Applications

Analysis of H2S, Mercaptans and/or THT with MEDOR Exp
Context & Challenges
Natural gas used for household consumption typically contains odorant sulfur components for safety reasons. As
natural gas is normally odorless, the sulfur components are artificially added. When natural gas is transported
between various companies, regions or countries, gas companies have to verify that the sulfur species are
present as specified.
For more than 30 years, Chromatotec® has manufactured the energyMEDOR,
based on the gas chromatography principles, to measure H2S, mercaptans and
THT in natural gas. Due to the advantages of the “MEDOR” technology, a new
guideline was defined, ASTM D7493-08 (as the Standard Test Method for Online
Measurement of Sulfur Compounds in Natural Gas and Gaseous Fuels by Gas
Chromatograph and Electrochemical Detection). The energyMEDOR by
Chromatotec® is fully compliant with this guideline.
In most cases and despite the hazards related to natural gas, the analyzers are
installed in safe areas where risks are minimized. In this particular instance,
Chromatotec® was asked to supply a system to measure H2S, mercaptans and
THT in a Class 1, div 2, group B,C&D hazardous environment.

Class 1: Flammable gases,
vapors or liquids
Division 2: where ignitable
concentrations
of
flammable gases, vapors or
liquids are not likely to exist
under normal operating
conditions
Group B, C&D: Ethylene,
propane gas group.

Chromatotec® Solutions
Instrument: Medor Exp
The energyMEDOR, normally manufactured as a 19’’ rack design, has been re-packaged
in a 3.25 cubic feet ATEX rated 316 SS enclosure. The system is wall-mounted. A Zpurge is installed and creates a constant positive flow of air inside the enclosure, thus
making a positive pressure inside enclosure. The effect of this purge is to prevent toxic
fumes from going inside the instrument in case of hazardous leakage.
A device located on the side of the analyzer with visual display (green light) senses if the
out-coming air flow supplied to the instrument is sufficient at minimum 4.8 Bars (70 psi).
To be sure that there is a positive pressure inside the analyzer, a pressure probe has
been placed inside the instrument and the pressure value is displayed at all times on the
monitor.

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