Testing Natural Gases Using an Electronic Nose

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The natural gas, used by consumers is the processed one which is free from any impurity and quite different from the natural gas taken from underground up to the wellhead. Although the processing of natural gas is less complicated compared to the processing and refining of crude oil, it is equally necessary, before it reaches customers. The unrefined natural gas contains impurities like pentane, butane, propane, ethane and some higher molecular-weight hydrocarbons that are separated at refineries during the natural gas processing to generate ‘pipeline quality’ of dry natural gas. However, before the processing procedure can begin, it is essential to detect such impurities.

Testing Natural Gases Using zNose^®

EST Inc. has developed an advanced sensor technology that is capable of detecting and quantifying the unwanted elements present in the raw natural gas in a minute, providing help to the refineries by simplifying the processing procedure. The zNose^® can carry out analytical measurements of odors and volatile organic vapors in near real time with part per-trillion-sensitivity, precision and accuracy.

A testing procedure was performed to analyze the caliber of zNose^®. A one-liter Tedlar bag was used to collect a natural gas sample from a local residence. Approximately 5 milliliters of the sample was extracted and analyzed by means of zNose supplied with a one-meter db-624 column. The sample was injected into the zNose^® after an interval of 3 seconds. A further 10 second interval was maintained before the column ramping, which was performed from 40 °C to 160 °C at 5 °C per second.

Low molecular weight compounds are also detected by zNose^®. The detectability of low molecular weight compounds is dependent on the temperature of the sensor crystal. The detector temperature of 20 °C was used during the testing procedure and this temperature can be as low as 0 °C since the response for zNose^® is restricted to compounds with above 0 °C boiling points.

The lowest weight compound detected in the natural gas sample was 274 counts and it had an index of 479 or slightly below C5 (pentane).

zNose^® software allows the user to rapidly calibrate the results and to easily produce individual peak response factors and alarm levels. This software automatically displays peak readings in the preferred units for example ppm, after a peak file has been defined and scale factors have been determined. In addition, the referencing retention time to n-alkanes offers an appropriate peak naming convention in cases where the real compound is unknown.

Conclusion

Therefore, the zNose^®, EST Inc.’s advanced electronic sniffer, can cater to all the requirements of calibrating, detecting and quantifying the unwanted elements present in the raw natural gas. It skillfully carried out five replicate measurements on the natural gas sample at intervals of 1 minute, demonstrating the retention time stability and precision of the zNose^®. Henceforth, zNose^® meets the requirement for speed, accuracy and precision in the chemical analysis of all types of vapors, fragrances and odors. The ability of zNose^® to create virtual chemical sensor arrays in order to monitor these compounds makes this electronic sniffer an important process monitoring tool.

Furthermore, zNose^®’s capability to carry out hundreds of chromatographic analyses per day makes it a cost- effective solution to measure the impurities of raw natural gas. Hence, the unique features of zNose^® make it a one-stop solution and is worth investing for the quality check of natural gas.

This information has been sourced, reviewed and adapted from materials provided by Electronic Sensor Technology.

For more information on this source, please visit Electronic Sensor Technology.