Sensitive, new age gas chromatograph

A NEW, more sensitive gas chromatograph has been released for coal mine gas analysis, giving mines a better chance of picking up spontaneous combustion events earlier.
Sensitive, new age gas chromatograph Sensitive, new age gas chromatograph Sensitive, new age gas chromatograph Sensitive, new age gas chromatograph Sensitive, new age gas chromatograph

A new gas chromatograph offers better sensitivity to detect critical mine gases at lower levels.

Angie Tomlinson

Published in September 2008 Australian Longwall Magazine

Two of the new systems have already been ordered by central Queensland mines and one system will head to India to a South Eastern Coalfields Limited (SECL) operation.

The new system – Agilent 3000 series 2 micro GC – was developed in collaboration with Simtars, a business unit of the Queensland Department of Mines and Energy, by major analytical equipment player Agilent over four years after identifying areas the older model could be improved upon.

“Agilent has continued its collaboration with Simtars on the development of the Agilent 3000 series 2 micro GC,” said Agilent Australian manager Rod Minett. “This process involved Simtars sharing their extensive expertise in mine gas analysis with the development teams in both North America and China resulting in an instrument capable of single-digit ppm detection limits. Simtars then took the latest technology to deliver a solution tailored for the rigours of mine gas analysis.”

For Simtars’ Darren Brady, manager of the Occupational Hygiene and Environmental Chemistry Centre (OHECC), the development of the new system was about getting a better product for the Australian market. The incentive for the manufacturer was being able to target bigger, developing markets such as China, with a state-of-the-art product.

One of the major areas of improvement to the gas chromatograph was the sensitivity, with the new model being able to detect gases at much lower levels. The gas chromatograph analyses helium, hydrogen, oxygen, nitrogen, methane, carbon monoxide, carbon dioxide, ethylene and ethane.

Gases that are important to detect at low quantities include carbon monoxide, ethylene and hydrogen. Catching these gases at low levels can alert the mine of a heating and potential spontaneous combustion event.

The gas chromatograph is fed via a tube bundle system or hand-collected gas samples using bags originally developed for wine casks.

Simtars has been developing, supplying and providing ongoing support and training in mine gas analysis and interpretation by gas chromatography for nearly 20 years. It was the first in the world to utilise the emerging computerisation of gas chromatographs when, in 1989, it initiated an interconnected network of chromatographs at Queensland minesites.

These had the capability to transfer data and methods from the minesite back to Simtars over a telecommunications link. Qualified gas chemists were then able to assist with any problems experienced or validate that the instrument was working correctly.

The system was dubbed Camgas (Computer Assisted Mine Gas Analysis System) and is still the name given to the complete package that Simtars offers today for mine gas analysis by gas chromatography.

“The logic behind the Camgas system was to equip the mine with a powerful analytical tool, but make it easy enough for them to use without having to employ dedicated gas chemists. This meant providing a total system including dedicated software, rather than just an instrument,” Brady said.

In another world first, Simtars adapted an ultrafast micro gas chromatograph, initially developed for NASA, for underground mine gas analysis. The first of the micro Camgas systems was installed at an Australian mine in 1997. Following that, a further 10 of these first generation micro systems have been installed at minesites in Australia and one system has been provided to the Directorate-General of Mines Safety (DGMS) in Dhanbad, India.

A second generation of micro systems based on the Agilent 3000 series 1 came a few years later and now the third generation Agilent 3000 series 2 is available.

Together with the hardware, Simtars had also developed software dedicated to mine gas analysis by gas chromatography since the initial Camgas system nearly 20 years ago. This has resulted in the current Simtars-developed software – EzGas Professional.

EzGas Professional steps the operator through the process required to analyse a mine gas sample, allocates the gas components to the peaks on the chromatogram, determines the gas component concentrations and improves reporting of results and naming of data files.

Data acquired by the gas chromatograph using EzGas Professional is transferred directly into Segas Professional – a decision support system used for gas interpretation and determining the explosibility status of a mine gas sample.

It achieves this by automatically generating Coward Triangles, Ellicott Diagrams and USBM Diagrams to indicate the explosibility and plotting graphical trends of up to eight different parameters including gas ratios to detect spontaneous combustion.

Altogether the Simtars systems are installed in nine Queensland and New South Wales mines, two Indian mines (soon to be three) and six Chinese mines.

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