SPECTRA: Scientific Validation of the Measurement Method

SPECTRA solution is the result of AUTOMA's wish to offer an alternative to the gas chromatography, traditionally used for odorant measurement in natural gas. Although gas chromatography measurement is accurate and firm, on the other hand it is also rather burdensome in terms of both initial investment and maintenance, with regard to the need for specialised personnel and consumables. It also has requirements that do not allow it to be operated continuously, autonomously and directly in situ. For these reasons, gas chromatography provides discontinuous monitoring over time, which is ineffective in the early detection of malfunctions and abnormal situations.

SPECTRA, on the other hand, which is based on UV-Visible absorption spectroscopy, is designed for on-site installation and fully automatic operation without human supervision, allowing continuous and timely monitoring of abnormal events occurring in the distribution network.

Based on the positive results obtained in the field since 2014, AUTOMA aimed at and obtained the scientific validation of the measurement method through the publication of an article describing the measurement method behind the SPECTRA solution in the prestigious journal Applied Spectroscopy.

Applied Spectroscopy: the scientific journal on spectroscopy

Applied Spectroscopy is a scientific journal that specialises in spectroscopy and its many applications. It is a peer-reviewed journal, which means that each article, in order to be published, must illustrate the data and methods with undeniable scientific rigour and must have elements of innovation compared to the rest of the scientific literature.

The article: Odorant Monitoring in Natural Gas Pipelines Using Ultraviolet–Visible Spectroscopy

The scientific article “Odorant Monitoring in Natural Gas Pipelines Using Ultraviolet–Visible Spectroscopy” was written thanks to the collaboration of various experts in the sector: Dr. Rossana Galassi (University of Camerino), Dr. Christian Contini (Automa), Engineer Matteo Pucci (Automa), Dr. Ennio Gambi (Polytechnic University of the Marche) and Dr. Gabriele Manca (Institute of Chemistry of Organometallic Compounds, Florence) and is composed of four main sections:

• Introduction
• Spectroscopic analysis 
• Computational analysis
• Experimental section

The introduction describes the state of the art of odourant concentration measurement in natural gas. An overview is given of the most common odorants and their importance in preventing explosions caused by gas leaks. A comparison of the main measurement techniques is also presented, with a focus on their desirable and undesirable characteristics. Finally, the theory behind spectroscopy is explained, with particular focus on UV and visible gas phase spectroscopy. In the section on spectroscopic analysis, the UV-Visible spectra of the two most common odorants, THT and TBM, are shown for the first time in the scientific literature. It is also shown that light hydrocarbons (mainly methane and ethane) do not interfere with the measurement of odorants, irrespective of their concentration. In the third part of the paper, concerning the computational analysis of the energy levels of the two odorants, the correspondence between the experimentally detected signals and the signals obtained mathematically from the theory of molecular orbitals is demonstrated. The simulation of the orbitals and energy levels of the two odorants has thus made it possible to assign each UV signal to a specific energy transition within the molecule, and this has made it possible to understand the nature of each absorption characteristic of the two substances. Finally, in the experimental section it is shown that the two odorants - THT and TBM - respect the Lambert-Beer law, a fundamental law of spectroscopy, even within a complex matrix such as natural gas. The variations observable in the spectra of odorised natural gas over a long period are also presented and the characteristic signals are assigned to the specific substances responsible for them, laying the foundations for measuring the concentration of other sulphur compounds (dimethyl sulphide) and aromatic hydrocarbons (benzene, toluene, xylene).

Conclusions

The SPECTRA solution is based on a scientifically rigorous measurement method, and odourant concentration measurements are totally independent of the variability of the concentration of the hydrocarbons that make up almost all natural gas. In addition, the method can also be effectively applied to the measurement of other sulphur compounds and aromatic hydrocarbons. The article is available at the following permanent link: https://doi.org/10.1177/0003702820960737. This result represents the first scientific acknowledgement of the validity of the SPECTRA measuring system in the field of natural gas odorisation measurement and joins many other successes that over the years have rewarded the continuous research of AUTOMA. It is not definitely a point of arrival, but another step in the growth path that the company has undertaken since the early years of life and that it has proposed to follow constantly in order to offer updated solutions and greater guarantees to its customers