FEATURE Sensors & Sensing Systems
New air sensor for safe chemical plants
Chemical plants will become safer places to work with a reduced risk of injury, chronic respiratory ailments or even death, thanks to a new air sensor being developed to detect toxic and explosive solvents using photonics
T
he number of worldwide deaths from chemical-related incidents is surprisingly common, with 681 fatalities reported in global media in 2017 alone. Recent high-profi le chemical-plant explosions include the Port Neches Chemical Plant explosion in Texas in November 2019, the La Canonja explosion in January 2020, and the surfactant unit explosion of Tarapur, Maharashtra, in April 2020. Now, scientists from the University of Navarra in Pamplona, Spain, have teamed up with the EU photonics innovation hub ACTPHAST 4R to develop a demonstrator of its breakthrough optical sensing technology that detects lethal chemicals that are both dangerous to inhale and highly explosive.
No technology currently exists to perform a real-time, automatic check in fuel tanks for Volatile Organic Compounds (VOCs) – chemicals that evaporate quickly at room temperature. Technologies that are generally used to monitor these chemicals currently use electronic sensors that need to be heated beyond 150o
C.
Emptying giant tanks fi lled with alcohols, ketones, aldehydes, chloroform and dichloromethane, chemical-plant staff have to ensure no traces of vapour or liquid remain. Having to climb inside these giant tanks, workers are under constant threat of causing an explosion from friction or static electricity. And now, with the help of ACTPHAST 4R – the EU innovation hub specialising in supporting researchers working in academia throughout Europe to advance their breakthrough scientifi c concepts into industrially-relevant demonstrators – the research team from the University of Navarra has managed to successfully develop a prototype for its innovative solution, to safely identify these toxic and explosive solvents in industrial settings. The new detector uses optical fi bres
22 April 2021 | Automation
sensors for many years but can be unsafe and slow to use in dangerous environments. Dr Aguado said: “We want to create the safest chemical plants ever made, putting workers’ lives and well-being fi rst. This technology allows instantaneous, real- time monitoring, and not having to wait days for samples to come back from a laboratory.”
Air sensor demonstrator setup
to monitor air quality, with no electrical or fl ammable components being part of the device. The optical-fi bre sensing solution is designed for dangerous places where electricity is forbidden, and could soon create safer working conditions for chemical-plant staff who handle highly toxic and explosive chemicals. “An air sensor using optical fi bres for the purpose of VOC detection is a major scientifi c breakthrough. It is currently in its prototype, demonstrator phase but has the potential to be further developed for industrial applications,” said Dr César Elosúa Aguado from the Electrical, Electronic Engineering and Communications Department at the University of Navarra and lead researcher on this project. If the demonstrator is successful,
the researchers will look at commercialisation options such as licensing or to spin-out the company from the university, to take it to the next stage of a working prototype and eventually a full commercial product.
Light versus electricity Today’s electronic sensors use metallic oxides that are capable of sensing toxic chemicals but are not safe in the shipping of chemical solvents. When exposed to VOCs, semiconductor metallic oxides show a change in electrical resistivity and have been used to develop electronic
Combining several diff erent platforms, the new sensor looks at the interaction between the cladding modes and the sensitive coating, producing a new signal when a toxic substance is present. “We still use metallic oxides but our system looks at the refractive index of the sensing material, rather than changes in electrical conductivity. The sensor surface is coated with zinc oxide as a sensing material, which reacts when harmful materials are present.” The sensor is specifi cally tuned to a toxic substance, meaning the only molecules that are captured along the sensor are dangerous gasses. The reactivity to the gas (known as “selectivity”) will depend on VOC molecular properties, such as polarity. “The reaction mechanism between the metallic oxide and the VOC is a reversible redox chemical reaction. The selectivity of these materials is low, so they react to a wide range of solvents with diff erent sensitivities. Therefore, sensors with diff erent responses combine to form a specifi c pattern for each VOC,” said Aguado.
In a nod to the future plans for this solution, he added: “The sensor response will be used to train an artifi cial intelligence system capable of identifying diff erent VOC samples.”
CONTACT:
ACTPHAST 4R
https://researcher.actphast.eu/en/regis- ter-your-interest-as-researcher
automationmagazine.co.uk
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