Operating instructions

8. Version for Hg determination in natural gas and other hydrocarbon gases (Tedlar®
Bag Version) page 80
Mercury Instruments UT-3000-E_V2.11.docx 31.07.12
Analytical Technologies
8. Version for Hg determination in natural gas and other
hydrocarbon gases (Tedlar® Bag Version)
A special version of the UT-3000 analyser can be used for measurement of mercury in natural
gas and derivatives. For these applications special precautions have to be made to prevent
explosion. The appropriate safety regulations have strictly to be observed. This instrument must
not be operated in hazardous areas. Customized versions are available for installation in an
hazardous area, contact the manufacturer.
F IGURES : P LANTS FOR NATURAL GAS PRODUCTION . S PECIAL UT-3000 SETUP ALLOWS TO MEASURE H G CONTINUOUSLY
OR MANUALLY .
8.1 Sampling system for mercury determination in natural gas
The Natural Gas Sampling System is dedicated for taking a sample stream from a pressurized
natural gas source. This source may be a storage tank or a pipeline containing or conducting
compressed natural gas. The sample can be filled into a special sample bag (Tedlar bag) and
carried to the analyzer. Sample bags come as accessories with the UT-3000 Mercury Ultratracer.
The Natural Gas Sampling System reduces the primary high pressure of the sample source (up
to 200 bar) to a pressure below 1 bar so that the gas can be filled into a sample bag or fed to a
continuously operating analyzer (for example the UT-3000 Mercury Ultratracer). Pressure
reduction is performed with a high precision pressure regulator. To avoid condensation due to the
Joule-Thompson effect the pressure regulator is electrically heated. Especially for mercury
analysis it is important to precondition all surfaces of the system which come into contact with
the sample. To guarantee a suitable preconditioning the sampling system has a bypass stream at
the low pressure side. The bypass flow may be adjusted with a needle valve. The bypass flow is
indicated by a flow meter. With a ball valve at Sample IN the sampling system can be isolated
from the gas source. A second ball valve allows closing the outlet sample flow. In order to avoid
ingress of water droplets or aerosols into the sample bag or analyzer a special coalescing filter is
installed in the sample stream.