SPECTRA: A continuous and accurate monitoring of BTXs

One success after another for our SPECTRA solution

The scientific validation of the measurement method of the SPECTRA solution dates back to a little more than one year ago, with the publication of the scientific article "Odorant Monitoring in Natural Gas Pipelines Using Ultraviolet-Visible Spectroscopy" (here) on the peer-reviewed scientific journal Applied Spectroscopy. In that occasion, AUTOMA, together with experts from different research institutions (University of Camerino, Polytechnic University of Marche and CNR-ICCOM), presented the SPECTRA solution as an alternative to gas chromatography, traditionally used for the measurement of odorant in natural gas. With SPECTRA, AUTOMA demonstrated the efficiency and accuracy of the measurement carried out by means of UV-Visible absorption spectroscopy. You can read the full article here. A few months later, the reliability of SPECTRA has been reconfirmed through the official validation of the system and of the measurement method. This was obtained following an interlaboratory test organised by Unichim, a body federated to UNI and accredited by Accredia for the execution of tests recognised by adequate operational protocols (Proficiency Testing - PT). More information about the interlaboratory test can be found here). The measurements obtained with SPECTRA during the interlaboratory test complied with the reference standards for both odorants measured, THT and TBM. In particular, the THT measurement was among the most accurate of the 12 participating laboratories (more information on the interlaboratory test can be found here).

SPECTRA under the spotlights of Sensors

These successes were an important acknowledgement of the validity of the SPECTRA measuring system in the field of natural gas odorant measurement. However, AUTOMA didn't stop at the first successes. Infact the company continued to invest in the SPECTRA solution. A few days ago, the article "Automatic Optical Measurement and Control of Benzene and Benzenoids in Natural Gas Pipelines" was published in the journal Sensors, of the MDPI group, an international peerreviewed journal on sensor science and technology. The article, born from a new collaboration between Dr. Rossana Galassi (University of Camerino), Dr. Christian Contini (Automa), Ing. Matteo Pucci (Automa), Ing. Ennio Gambi (Polytechnic University of Marche), demonstrates that the method and instrumentation behind SPECTRA for the measurement of odorants can also be used to simultaneously measure aromatic hydrocarbons, carcinogenic compounds whose detection is typically confined to laboratories and requires specialised instrumentation and personnel.

SPECTRA for continuous monitoring of aromatic hydrocarbons

Natural gas transport and distribution lines are present all over the world and, for this reason, the safety of these lines is crucial, both with regard to the risk of explosion and the air pollution caused by any gas leaks. The composition of natural gas is quite variable and, apart from the majority of light hydrocarbons (primarily methane), many undesirable components may be present. Among the minority components of natural gas are benzene, toluene and xylene (aromatic hydrocarbons referred to as BTX). These substances, particularly benzene, are notorious for their toxicity and carcinogenic properties. This makes continuous and selective monitoring of aromatic hydrocarbons absolutely essential to ensure the safety of end users and operators working directly on distribution lines. The detection of these substances has historically been entrusted to: • electrochemical sensors, which typically have measurement problems in the presence of interfering substances; • laboratory analyses, which are generally expensive and unable to monitor BTX concentration in real time and with adequate frequency. Generally, there is a lack of remote monitoring solutions on the market that can selectively measure BTX directly in-situ, such as SPECTRA does.

The experimental test SPECTRA system consists of:

• Power supply from power line (A) or from photovoltaic panel (B)
• 14V battery (C) which acts as a backup in the absence of electricity and as a buffer to balance out conditions of varying photovoltaic panel efficiency
• Deuterium UV source (D)
• Fibre optics (E) to transport light
• Solenoid valves (F1 and F2) to control the gas flow
• Steel flow cell (G) for sampling the gas to be analysed
• UV spectrometer (H)
• Wireless communication unit (H)
• Computer or remote server for data storage (L)

SPECTRA system was tested for the measurement of BTX in a standard gas cylinder (benzene + nitrogen), comparing the measurements with those obtained by independent laboratories. The results showed without a shadow of a doubt a higher accuracy in the measurement performed by SPECTRA. Specifically, with respect to a given certified concentration, the error reported by the two independent laboratories part of the trial and who used two different analytical techniques, ranged from -7.98% to -10%. For the measurement of the same sample, AUTOMA presented two SPECTRA systems that reported a relative error of 0.31% and 1.90% respectively. Therefore, considering that the universally acceptable error is 5%, it is clear and definitive that the SPECTRA solution is based on a scientifically rigorous measurement method. The results, confirm the theory on the effective application of the method to the measurement of various sulphur compounds and aromatic hydrocarbons that had been anticipated in the article 'Odorant Monitoring in Natural Gas Pipelines Using Ultraviolet-Visible Spectroscopy' (Applied Spectroscopy). As the system is designed to operate completely autonomously, SPECTRA uses control algorithms to automatically identify any unforeseen environmental or instrumental issues and to invalidate potential untrue measurements accordingly. 

SPECTRA in the detection of benzene concentration: an essential measurement

SPECTRA's recent successes come as no surprise. In fact, SPECTRA systems have been installed in various distribution networks, both inside and outside the European Union, since 2014, and have always produced positive results. In all these years, AUTOMA has observed marked differences in the composition of the various natural gases depending on the country of installation; moreover, even within a single country, significant differences in composition have emerged depending on the particular choice of installation point and the period of observation. What emerged from the careful observations of the measurements provided by SPECTRA, is that BTXs are present in all cases, including benzene, which, as is well known, is a carcinogen that in high concentrations can seriously damage the eyes, respiratory system and central nervous system, to the point of causing leukaemia. From the graph in Figure 2, one can see extremely large and rapid fluctuations in benzene concentration that appear to be unpredictable. The speed and magnitude of these fluctuations underline once again the importance of the continuous monitoring that SPECTRA system can provide.

Conclusions

AUTOMA has responded to the need for BTX monitoring with the SPECTRA system, a device designed for on-site installation and fully automatic operation without human supervision, allowing continuous and accurate monitoring of abnormal events occurring in the distribution and transportation network