Page 20 - Shimadzu Journal vol.4 Issue1

Natural Gas Analysis

3. NGA System using the Barrier Discharge Ionization 3–2. Ultrafast NGA system with BID
Detector (BID)
The ultrafast NGA system’s configuration consists of three sample
3–1. The barrier discharge ionization detector (BID) loops, six columns and two detectors: BID and FID. The detection
range of components is shown in Table 3. H 2 , O 2 , N 2 and CO are
The BID is a highly sensitive detector that creates ionization from
separated by an Rt-MS-5A plot column (0.53 mmI.D., 50 µm, 30 m)
dielectric barrier discharge plasma. It offers highly sensitive detection
whereas CO 2 , C 2 H 4 , C 2 H 6 , C 2 H 2 , H 2 S are separated by an Rt-Q plot
of all compounds except helium and neon. Plasma is generated by
column (0.53 mmI.D., 20 µm, 30 m). The ends of the two columns are
applying a high voltage to a quartz dielectric chamber in the presence
joined together and the components are detected by the BID (Figs. 5, 6).
of helium. Compounds that elute from the GC column are ionized by
CH 4 and C 3 or higher hydrocarbons are separated by an Rtx-1 column
this He plasma, then captured with collection electrodes and
(0.53 mmI.D., 5.0 µm. 60 m) and detected by FID.
described as peaks (Fig. 4). The BID has the advantage of providing
high-sensitivity detection of both inorganic and organic compounds at
the sub ppm level. This advantage may potentially simplify gas analysis
systems like the NGA system.
Table 3 Detection range of components of the Ultra-Fast NGA system
Concentration Range
No. Name of Compound Detector
Low Conc. High Conc.
Quartz tube He plasma He 1 H2 0.001% 10.0% BID
(dielectric substance) 2 O2 0.001% 20.0% BID
3 N2 0.001% 50.0% BID
4 CO 0.001% 5.0% BID
Column
5 CO2 0.001% 20.0% BID
6 C2H4 0.001% 10.0% BID
7 C2H6 0.001% 10.0% BID
8 C2H2 0.001% 10.0% BID
9 H2S 0.01% 30.0% BID
10 CH4 20.0% 100.0% BID
11 C3H8 0.001% 10.0% FID
12 i-C4H10 0.001% 10.0% FID
13 n-C4H10 0.001% 10.0% FID
14 i-C5H12 0.001% 2.0% FID
Fig. 4 Barrier discharge ionization detector (BID)
15 n-C5H12 0.001% 2.0% FID
16 C6 + 0.001% 0.5% FID

(CO, CH 4 ) CO 2 , C 2 and H 2 S

H 2 , O 2 , N 2 , CH 4 and CO

Fig. 5 Part of flow diagram of the Ultrafast NGA system (Channel of BID)

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