Improving efficiency for ship propulsion systems
The heavy oil fuel used in ships requires a continuous treatment prior to propulsion engine consumption. Often complicated, it is a process that usually depends upon centrifugal separators, which are both expensive to install and require expensive regular maintenance and servicing. However, compared to the high cost of light diesel oil, the cheaper heavy fuel oil combined with installation and maintenance costs provides operators with long-term economic benefits. When centrifugal fuel separators were first used they were very efficient because heavy fuel oils did not contain many chemicals, asphaltenes, waxes and other corrosive particles. However this trend has shifted, so centrifugal separators now require much finer mesh sizes to prevent impurities from entering the combustion cylinders. As a result, this has also led to the increased maintenance required, which in turn reduces the overall economic gains. A Finnish company that has built three technical innovations using ultrasonic energy, hopes to revolutionise heavy fuel oil treatment through finer filtration, homogenisation and the emulsification. The process from design to testing to implementation was a rather protracted programme, but in order for a fully functional working example, it was the only way forward. Hence three different homogenising units were designed, modelled and manufactured for 20kHz, 7kHz and 1kHz ultrasonic excitation. Two of the homogenising units have been tested at the Institut fur Schiffsbetriebsforschung, and one 5-micrometer filtration unit has also been successfully tested. All this groundbreaking work therefore led to the manufacture of a full scale homogenising unit for a ship's 10, 000KW engine, which was successfully tested ashore in a research testing facility. The unit has now been tested on board a ship and this pioneering company is now further improving ship operational cost and overall ship propulsion systems.
