Can an ‘intelligent’ approach to tank cleaning finally do away with the dangerous practice of confined space entry?
Wall washing has long been the accepted procedure to ensure a tank is ready to load the next cargo, but it involves the dangerous practice of confined space entry. Speaking at the Asian Tanker Conference, tank cleaning manufacturer Kockumation’s head of sales, Johan Ljungbeck, noted: “Wall washing is the standard in the market and that is what I wish to challenge: can we do this a better way to avoid the risk of confined space entry?”
Mr Ljungbeck explained alternatives exist to the current practice of having a crew member enter the tank to conduct the wall wash test. “There are as many procedures for a wall wash test as there are chief officers,” he told delegates, adding “There is no repeatability and no one way of doing it.”
In order to be ready to load Mr Ljungbeck said there is a tendency to over-wash. “This costs energy, hot water and increases turnaround times,” he said. He then challenged the assumption that this practice necessarily produced the required results.
Mr Ljungbeck described a system where ‘intelligent’ cleaning machines are part of an integrated system that provides feedback on the washing cycle to the control centre on the bridge.
This allows full tracking of the tank cleaning process, including tracking and monitoring. The system provides information on the performance of the nozzle, the position and the location of the wall that has been cleaned and energy usage.
“Now there is transparency of the progress of the cleaning process; it is no longer a case of nozzles spraying around out of sight,” he said.
By combining this integrated, ‘smart’ approach with a spectrometer in the stripping line, the operator receives “an accurate measurement of the waste water content and can see the point when no matter how much more washing you do, [the tank] will not be any cleaner,” said Mr Ljungbeck.
The process is evidential, providing a paper and/or electronic signature that the wash water no longer has traces of the previous cargo and the tank is ready for the next cargo.
Mr Ljungbeck said that this system has demonstrated significantly reduced cleaning times and reduced fuel consumption. But most importantly, it removes the need for a human to enter the confined tank space.
This integrated cleaning process also facilitates the efficient use of detergent: “A high speed laminar flow means detergent does not stick to the [tank] wall; it just bounces off,” he said. The detergent should cling to the wall, activating the cleaning process. Kockumation has found that applying air or nitrogen to the spray greatly increases the efficiency of the process. “It is like cleaning your windows at home. A powerful spray bounces off the pane. A fine mist clings to the dirt and carries it off,” explained Mr Ljungbeck.
Mr Ljungbeck said this integrated system can reduce washing times to a third and provides a digital footprint for the charterer or the coast guard to prove the tanks are clean.