NGA vs. LPG

Chromatography Forum: GC Archives: NGA vs. LPG
Top of pagePrevious messageNext messageBottom of pageLink to this message  By Andyno on Tuesday, June 8, 2004 - 12:13 am:

Hi. Can I use the packed columns from natural gas analyzer to quantitative analysis of LPG? This is a three column set and the column are:
30% DC-200 on Chromosorb PAW 80/100
30% DC-200 on Chromosorb PAW 80/100
and ASAG 45/60
Thanks.


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Les on Thursday, June 10, 2004 - 12:28 pm:

Maintaining sample integrity of LPG makes big differences when running liquid gases. NGA components generally range from C1 to C4 with concentration of gases high C1 to low C4.
I run LPG under 600 PSI Nitrogen pressure through a Liq sampling valve. This makes big difference when many of my samples range from C1 to C6. The low boiling points of C5 & C6 would cause them to be decreased in the overhead and increased in the liquid phase if not under pressure. The preferred method involves a water pressure system. The water is forced into the peanut bomb and the hydrocarbon is removed from the top of the bomb via LSV.
If you can get a representative sample into your splitter, you should have no problem running the samples.
I prefer the plot columns for LPG, peaks resolve better at the C4 and C5 olefins.


Top of pagePrevious messageNext messageBottom of pageLink to this message  By andyno on Friday, June 11, 2004 - 12:39 am:

Thankīs. In this case I have only two options.

1: Finding the reference material and prove it.

2: Purchase the PLOT Alumina/KCl columns.

But in my region is possible, that the ref. material will cost about the price of one PLOT column. Maybe I ask differently.
Can my packet columns separate all this substances?

methane ethane ethylene propane
propylene n-butane isobutane isobutene
1-butene n-pentane isopentane 1-pentene
cis-2-butene trans-2-butene 1,3-butadiene

Only this substances will be in my samples with different composition.

Thank You.


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Bernd Mischke on Friday, June 11, 2004 - 03:40 am:

IMHO your only chance is Al2O3 PLOT,

no liquid phase is able to separate CH4 and C2...


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Andyno on Friday, June 11, 2004 - 06:55 am:

I am sorry, I donīt understand the sentence: "no liquid phase is able to separate CH4 and C2..."
Please, what does it mean, because with this columns till can I separate samples with substances: methane, ethane, propane, isobutane, n-butane.....
Do you mean isomers or homological row like ethane-ethylene-acethylene? Or?

Thank You.


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Les on Friday, June 11, 2004 - 11:56 am:

Yes, I think your system will do just fine. The sample injection problem may require modification. You will need to be certain that the samples are not discriminating between light and heavy material.
I too have packed column GC's. The system separates all the gases fine. The problem is that LPG boils at different temp and pressure. The methane thru propene are very volatile while butane thru pentane are not so volatile leading to discrimination.
There are some people who put the samples into an oven at 150C and volatilize all the components and run them as a gas. I am not that brave, heating hydrocarbon inside an oven is not safe, period.


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Andyno on Monday, June 14, 2004 - 12:13 am:

Oki. But in my apparatus (Arnel 2200) straight behind LSV is there a liquid vaporization zone. Maybe this will affect the producing an equivalent peak shapes for gaseous and liquid samples.


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