Page 17 - Shimadzu Journal vol.4 Issue1

Natural Gas Analysis

Making Improvements to Today’s Natural Gas Analysis Systems

Hiroyuki Aikawa, Ryosuke Kamae, Yuki Hashi, PhD, Shimadzu (China) Co., Ltd.

1. Introduction 2–2. Shimadzu NGA system
In recent years, driven mainly by rising energy demand, many regions Table 1 shows two typical Shimadzu NGA systems. While
of the world have witnessed a resurgence in the production of “GC-2014NGA1” is a packed columns-based system and all
petrochemicals. New technologies for mining the deep shale deposits components are detected by two TCDs, “GC-2014FNGA1” is a PLOT
for natural gas have been refined in the U.S. and made extraction of columns-based system (except for He, H 2 detection) and all
these deposits economically viable. In China, new technologies for components are detected by two TCDs and one FID.
turning coal into olefins by way of methanol (CTO: Methanol to “GC-2014FNGA1” is called a Fast NGA system since the analysis time
Olefin) has fueled its economy and provided feedstocks for the is only 10 minutes, enabling high productivity. The detection range of
chemical and polymer industries. components with this system is shown in Table 2. This system consists
In every petrochemical process, measurement and quality control are of four sample loops and eight columns. O 2 , N 2 , CH 4 and CO are
essential. Processing plants must characterize the incoming raw separated by an Rt-MS-5A plot column (0.53 mmI.D., 50 µm, 30 m)
materials. Finished products must be evaluated to ensure and CO 2 , C 2 H 6 and H 2 S are separated by an Rt-Q plot column (0.53
specifications are met. Every time natural gas changes hands, an mmI.D., 20 µm, 30 m). These components are detected by TCD1. In
analysis is done to determine its energy content and thus its value. order to avoid an overlapping of eluted peaks from two columns, the
There is a need for scientific instrument manufacturers to match the Rt-Q plot column analysis is started after the Rt-MS-5A plot column
innovation shown by the petrochemical industry by producing analysis has finished. This is referred to as a “Delay injection
high-precision, accurate equipment that this industry can rely on. technique”. C 3 or higher hydrocarbons are separated by the Rtx-1
+
Shimadzu Corporation is ready to meet this challenge with a lineup of column (0.32 mmI.D., 3.0 µm. 30 m) and detected by FID. C 6
NGA systems (Natural gas analyzers). components are back-flushed as a single peak. H 2 and He are
Our NGA system can include permanent gases such as H 2 , N 2 and light separated by an MS-13X packed column (60/80 mesh, 2.1 mmI.D.,
+
hydrocarbons from C 1 to C 6 . Samples may take the form of a gas or 1.0 m) and detected by TCD2. (Fig. 2, 3)
high-pressure liquid state. Our systems can combine standard analyses One of the outstanding characteristics of this system is its short
with extended analysis of condensates. We have the tools to build the analysis time. This results from adapting a 0.32 mmI.D. capillary
systems that meet the demand of today’s petrochemical industry. In column for C 3 or higher hydrocarbons separation. Furthermore, a split
this article, improved technologies in these NGA systems will be line is placed in front of the capillary column in order to maintain
shape.
introduced. good peak shape.

2. Typical Natural Gas Analyzers (NGA)
2–1. Requirements of typical NGA Systems
Natural gas processing occurs in a number of steps. It begins with the
extraction of the raw gas at the well head. Analyses occur at this
stage to determine the water content, hydrogen sulfide and aromatic
hydrocarbon content. These parameters are important in determining
the best processing options and are closely monitored by the EPA if
there is a flare associated with the well. From the source, the gas is
transported to the processing plant by truck, train or pipeline, where
again it is analyzed to determine its chemical composition. Finally, as
the processing plant sells the finished, dry, sulfur-free natural gas to
the distributor or end user, another analysis is done to determine the
price based on the energy content of that particular lot. This is done
by taking the percent composition of that lot of gas and calculating its
BTU content. For each of these steps, Shimadzu offers a variety of
NGA systems to comply with industry-standard methods such as those
developed by ASTM, GPA, ISO and UOP. In many cases, multiple
Fig. 1 NGA System based on GC-2014
methods can be combined in a single GC to save on bench space and
optimize a lab’s budget.

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