GAS DETECTION SYSTEMS - PROTECTING PEOPLE, ASSETS AND FACILITIES
The price tag of a medium-sized, medium-complexity refi nery in Europe is around 2 billion Euros. That’s the typical total replacement and rebuild value of the capital assets. Such a site will also be the workplace for several hundred permanent employees and many additional contract staff. With such a rich concentration of people and assets, it is essential to consider the right mix of gas detection systems for safety.
Fire and explosions rocked the Philadelphia Energy Solutions refi nery on the US east coast on the 21st of June 2019. Soon after, the incident led to the announcement that the refi nery complex would cease operations after more than 150 years of oil storage and refi ning on the site. At 335 thousand barrels per day of refi ning capacity it ranked as tenth largest refi nery in the US and was the largest on the eastern seaboard. The risks posed by fl ammable gases are more than theoretical: they present a real and present danger that must be monitored using an array of suitable gas detection techniques to protect people, assets and entire facilities.
Violent explosions, invisible killers and environmental pollutants
It is a miracle that the dramatic refi nery blaze at Philadelphia resulted in no deaths. It is equally fortunate that violent explosions and raging fi res at refi neries in Vohburg in Germany in 2018 and Sannazzaro de’Burgondi in Italy in 2016 also resulted in no fatalities. But toxic and inert gases present hazards which are equally as dangerous, but much subtler that these sensational events.
Underground miners work in a confi ned space for most of their shift, on the other hand entry into confi ned spaces generally takes place on refi neries during maintenance and turn-around events. Whether we consider refi neries or sub-surface mining, where gas detection systems are also common, hydrogen sulphide is one of the most feared toxic gases and will often be incorporated into the range of gases monitored by fi xed toxic gas detection systems.
Toxic gas leaks can present a dire health hazard, as can the accumulation of an inert gas, such as nitrogen, to displace life-giving oxygen. A toxic gas cloud is likely to be invisible. Some toxic gases are detectable by their odour, but many are not. And, nitrogen accumulation resulting in oxygen defi ciency is completely invisible and odourless – but extremely dangerous. Gas detection systems have a vital role to play in protecting people in such situations.
Hydrocarbon gas-leaks on the refi nery present a fl ammability risk on the one hand and an environmental concern on the other. The monitoring of hydrocarbon gas-leaks on refi neries is regulated by the US EPA according to Method 21 – ‘determination of volatile organic compound leaks’. It prescribes suitable distances between the potential leak point and the gas detector and proposes suitable gas detection technologies such as photoionization, infrared absorption or catalytic oxidation. All these sensor types are common in various modern chemical-based fi xed gas detection systems.
Vast spaces and high-risk point sources
Portable gas detection systems which are worn by operators as they move around between locations can be effective to warn personnel to avoid areas where toxic, fl ammable or inert gases have accumulated. Fixed systems, on the other hand are designed to detect gas leaks as they happen or soon after. However, whether they are fi xed or portable, gas detection systems based on chemical sensor technologies are limited to monitoring gases close to the location where they are situated. Open path gas detection systems, on the other hand, can detect fl ammable gases in the line of sight where they are installed and can cover a vast range.
For expansive areas, such as a tank farm or the route of a gas pipeline oven fl at terrain an open path gas detection system might be ideal to cover the long distances involved. On the other hand, in a complex refi nery process fi eld where distillation
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