Gas analysis – the hydrogen way increases in popularity

Tag : Natural Gas Valve

Hydrogen in GC-FID applications is used to produce the flame thatconverts the sample into electrically-charged ions that produce therequired electrical signals that generate the chromatograph.
The vast majority of GC-FID applications use hydrogen for thispurpose but to date the analytical accuracy and limits of detectionachieved have been limited by the purity of the hydrogen and airthat is commercially available. For optimum analytical results itis important to use the highest grade of gas possible, with a lowtotal hydrocarbon (THC) content.
When the purity of the hydrogen or air used in the GC-FIDapplication falls short of the quality needed for such gasanalysis, it results in a phenomenon known to chemists as‘baseline noise’ – the appearance of unwantedpeaks on the chromatogram. These imperfections can make itvirtually impossible to measure the area beneath the peaksaccurately. For the oil or gas analyst, this means that it may notbe possible to detect some components in the sample at all, simplybecause they are present at very low concentrations below the limitof detection.
In the ongoing drive for improved accuracy, these imperfections areno longer acceptable and the petrochemical and natural gasindustries are demanding quality gas products that are capable ofproducing highly accurate analyses and improved limits ofdetection, time after time. Ultimately, this focus on accuracygives the process manager better control over the process and canhelp to improve overall plant efficiency.
In a bid to improve the accuracy of GC-FID applications, AirProducts has developed a new hydrogen product which uses its ownBIP technology to deliver an exceptional ultra-high purity gasproduct, with critical impurities such as oxygen, water andhydrocarbons dramatically reduced compared to conventional hydrogengrades.
Fitted with an internal purifier and patented valve system, thetechnology effectively ensures that the gas meets the higheststandard of purity at the point of use, every time it is used.
This technological development has the potential to make a bigdifference. For the analyst, using the ultra-high purity BIPhydrogen will significantly lower detection levels and provide anassurance of improved accuracy.
For some oil and gas industry customers, there could be furtherbenefits too if they consider extending their use of pure hydrogento other analytical applications.
A recent survey by LCGC Europe has revealed that 73percent of theproblems that arise in GC analysis are due to impurities in thecarrier gas. Such impurities are typically water and oxygen andthey need only be present at very low levels to affect the accuracyand reliability of analyses.
In order to eliminate this problem, petrochemical and natural gasindustry customers are increasingly using higher purity gases andcurrently, the carrier gas of choice is helium, which provides fastanalysis combined with a high level of analytical accuracy. As acarrier gas, helium compares very favourably to nitrogen, whichwhile lower in cost results in much slower analysis.
However, the arrival of the ultra-high purity BIP hydrogen presentsan opportunity for petrochemical and oil industry operators toimprove efficiency by further increasing the speed of analysis insome applications.
When hydrogen is used as a carrier gas, it is possible to completeeach analysis with a time saving that can be as high as 35percent.There is another benefit too – when using hydrogen as acarrier gas, the analytical results produced can often be even moreaccurate than when using helium.
Despite the potential improvements with hydrogen, helium is likelyto remain the carrier gas of choice for the petrochemical andnatural gas industries mainly because it is totally inert andtherefore does not react at all with any components in the sample.However, for some laboratories where there is a particularly highlevel of usage, the efficiencies that could be attained byswitching to hydrogen as a carrier gas are difficult to ignore.
In such circumstances, using hydrogen has recently become all themore viable due to the safety features that have been introduced tomodern gas chromatographs, such as flow rate monitors that willautomatically shutdown the hydrogen supply if a leak is detected.
The introduction of these safety features, combined with theavailability of the ultra-high purity BIP hydrogen gas, is encouraging a growing numberof analytical users to consider using hydrogen as a carrier gas forthe first time.