Acoustic sensor system monitors underground tanks, reports on leaks
Petroleum products, such as petrol and diesel, are dangerous. For this reason, they are stored for long periods in underground tanks. Yet, these liquids are highly corrosive. They can eventually corrode tank walls, causing tanks to leak. This is very harmful to the environment. Petrol leaks can contaminate soil and groundwater. Petrol vapours can cause explosions and possibly lead to health problems. A leaking underground storage tank (UST) also costs its owner money. Tanks are therefore routinely inspected for damage. This often requires an inspector to physically enter the drained tank and manually inspect the walls. This is difficult, hazardous and time-consuming. Various automated alternatives, such as for monitoring liquid levels, reveal the presence of leaks when it is already too late.
Acoustic sensors
The EU-funded MoniTank project developed an alternative method that assesses UST walls using acoustic technologies. The team also developed algorithms that analyse the sound patterns for diagnostic and risk assessment purposes. The system allows for remote, automated inspection and scheduled maintenance. Project work mostly involved scaling up and developing the prototype, plus marketing. “MoniTank was already at technology readiness level (TRL) 6 from an earlier project,” explains Onur Yalim, project coordinator. “This means there was already a verified prototype. We developed it to TRL 9, which is a fully commercial industrial system.” Operating the system involves mounting acoustic emissions sensors at specific places on the outsides of tanks. A computer collects and analyses the data, looking for indicators of risk. “Acoustic emission is a passive technique,” continues Yalim. “It basically ‘listens’ to the structure. Once a crack or corrosion occurs, the network acquires this signal and several algorithms process it to pinpoint the damage.” Then, next-level algorithms process features of the acoustic signal to decide whether the tank wall’s condition represents significant risk.
Monitoring process
Likely customers include petrol stations and similar facilities. After a customer purchases the system, hardware and software components will be installed at their premises. Then the monitoring process starts. Where necessary, the system notifies customers of potential problems via email. This eliminates unnecessary inspections and can allow maintenance to be scheduled in advance. Clients can choose whether to share the monitoring data with company experts or keep the data in house for their own personnel. Final testing confirmed that all the project’s objectives had been achieved. The system has been shown to reliably analyse and report on UST condition. MoniTank is already marketing the fully certified system. According to Yalim, competitors are significantly more expensive and less capable. The system is initially being marketed to petrol station franchises, but this market segment could be expanded in future. After establishing the product in the EU, the MoniTank team will pursue eastern European and then central-Asian Turkic countries. The team is working to expand the system’s capabilities to include other types of tank. This will require new algorithms and further validation. The system will allow continuous monitoring of the condition of USTs. This will prevent environmental problems caused by leaks.
Keywords
MoniTank, petrol, acoustic sensor, inspection, maintenance, acoustic emission, underground storage tank, corrosion
