Chromatography Forum

I have a application where need to measure Natural Gas components up to c7 +, N2, CO2, H2S and Mercaptan. Can this application be done by one GC

Dear Nareshdangi,

You should contact Varian Inc in Europe ( Middelburg), chromatography division .
At the time I have worked there we had a portable natural gas analyser capable of separating all the compounds you mention. I cannot remember all details but I am sure the expertise is still there.
Just had a quick search on the internet : http://www.varianinc.com/image/vimage/d ... i-0232.pdf)

regards Philippe

I believe you can find a vendor to perform this analysis in one instrument.

Siemens AAI, ABB, Yokogawa, Daniel Industries (Emerson-Rosemount) are the primary vendors, but there are other companies as well.

I assume you mean methyl mercaptan.

Just don't expect it to be done in a short time, I would expect a time of 6 to 10 minutes. You should not be expect very low levels of sulfur containing compounds while at the same time trying to measure BTU accurately with the same instrument, but reasonable levels should not be impossible.

Remember:

One does not drive to work and fly to the moon in the same vehicle.

best wishes,

Rod

I have a application where need to measure Natural Gas components up to c7 +, N2, CO2, H2S and Mercaptan. Can this application be done by one GC

Depending on the levels of N2, CO2, H2S and methyl mercaptan you're looking for, any GC supplier should be able to build you an instrument that will do that analysis.

I've been very happy with the new Shimadzu GC-2010 we got for doing a similar analysis (sans the sulfur compounds).

Nareshdangi,

The problem, after separations, will most likely be the vastly different levels of analytes. N2, CO2, C1 to C6+ commonly done, by many vendors (probably including Yokagawa), with TCD using helium carrier. C6+ being the sum of the heavier hydrocarbons provides enough material for the TCD to effectively measure. If you want C6 as isomers and C7 you could have a problem with sufficient material on column to get good sensitivity. Literature I have seen show these as FID candidates but now you have two detectectors (which could also do the methyl mercaptan.) Still have the problem that you cannot do low level H2S with either of these detectors. Keeping in mind I have a natural bias, I would suggest TCD for high level components and either PID, PDD, or DBD in argon mode to do the C6 and above, the H2S and the methyl mercaptan. The ionization potential of said constituents is well within any of the three detectors described and, thus, you will get excellent sensitivity. Which brings me back to origional comment that separations must be sufficient to get the H2S and methyl mercaptan (in particular) away from the early high level hydrocarbons (Rod?). A heartcut for the H2S, methyl merc and C6+ to a second column/detector might be most efficient means of separation.

Sorry for the long post, best regards.