Column that suitable for natural gas analysis using GC-TCD

[Ellina]

Hi,

I have a problem regarding the column that I want to use for natural gas analysis. I am refer with the Agilent Application note 228-387 which is GC/TCD Analysis of A Natural Gas Sample on A Single HP-PLOT Q Column. My problem now, I don't have this column in my stock. I want to do the analysis urgently. Is there any column that suitable for natural gas analysis? Can I use HP-PLOT Al2O3S as my column? What is the method analysis?

TQ

[GasMan]

Ellina,

You should first ask yourself what you need to measure in natural gas. If you need to measure oxygen and nitrogen, then this column is not suitable. Do you need to go above C6. Is there H2S in the sample or even helium. Once you know what you have to measure, an analysis plan can be made up. Generally you need more than one column for a complete natural gas analysis. What GC do you have and what inlets and detectors are available on your GC.

Gasman

[chromatographer1]

To analyze natural gas, it is assumed you are measuring the following components and are able to calibrate accurately (no splitting of an injected sample as any discrimination will affect the results for the calculation of BTU values):

nitrogen

carbon dioxide

methane

ethane

propane

isobutane

butane

isopentane

pentane

hexanes through nonanes summed as a single peak or individually measured and the areas added together

methyl silicone columns using a reverse column step multidimensional valving configuration is usually chosen. One can use a porous polymer column to separate all the above components but the trace amounts of C6+ may not integrate well.

The CO2 values using an alumina PLOT may not be accurate and water may affect your analysis using that column.

Determine how accurate your analysis has to be and choose the best column you have.

Good luck,

Rod

[Ellina]

Hi,

Thank you for reply. I need to measure this components using GC/TCD:-

Mixture of: -
Isopentane 100 ppm
N-pentane 100 ppm
N-hexane 100 ppm
N-butane 300 ppm
Isobutane 500 ppm
Propane 0.25%
Nitrogen 0.42%
Carbon Dioxide 1.60%
Ethane 2.60%
Methane Balance

Is it possible to use HP-PLOT Al2O3S as my column? In this case, CO2 is not important for this analysis.

Please advice.

[Ellina]

Hi,

I don't have H2S or He in my samples. I don't have any idea which column is suitable because this is our first time to do natural gas analysis. I just have this column in my stock:-

DB-1
DB1-HT
HP-MOLSIV
HP-5
GS-Q
DB-WAXETR
DB-WAX
HP-PLOT AL203S

Please advice

TQ

[chromatographer1]

What is GS-Q ?

Is it similar to HP-PLOT Q?

If you are performing a BTU analysis can you inject without splitting?

Do you have a calibration mix to calculate against?

Have you read:

http://www.afms.org/Docs/sample/BTU_Analysis.pdf

best wishes,

Rod

[Ellina]

Hi,

I don't think GS-Q is same with HP-PLOT Q.

GS-Q:-
-Porous divinylbenzene homopolymer
-A PLOT column with polarity between Porapak-Q and Porapak-N
-Separate ethane, etylene and ethyne (acetylene)
-Not recommended for quantification of polar compounds
-Minimal conditioning time required - hour

I have buy mixture gas analysis standard. What do you mean inject without splitting and calibration mix to calculate against?

I've never read the pdf document that you give before this.

[chromatographer1]

Natural Gas analysis is one requiring great accuracy. Even a very small error (1%) can give 10 BTUs error which is well beyond any reasonable analysis requirements. Most BTU measurements have less than 1 BTU variability. A complete measurement is required so a mole percent, not an area percent, is the goal to calculate the BTU content of NG. Usually this value is around 1050 BTU, but rich gas can be 1300 BTU and lean gas 1010 BTU.

You may wish to review the GPA methods in detail before you start an analysis without a clear idea of the goal involved.

best wishes,

Rod

ps I used to work for Daniel Industries, the most popular manufacturer of pipeline analyzers for custody transfer of NG in the world. They sell over half of the BTU analyzers sold each year.