These centrifuges are really cool how they work. The principle is using gravity to separate two liquids by spinning the rotating bowl at a high speed to increase the gravitational force so separation happens fast. What might take an hour to do with the liquid in a glass sitting on a desk, happens in a matter of a few seconds in the centrifuge. The disk stack is in there so the solids hit the underside of the disk above and slides towards the outside. With a large number of disks, you have a large filtering area. These machines can be set up as separators that separate two different liquids, oil/water, milk/cream, etc, or as clarifiers that clean a single density liquid, beer, wine, chemicals, etc.
The ship usually has two centrifuges for heavy fuel oil, and two for lube oil, each system running in parallel. Some ships will have centrifuges for cleaning the bilge water too. It’s designed so that only one is needed, but you can run both at the same time. For fuel oil, you will have a storage tank that feeds the centrifuges that then discharge into a day tank with clean fuel. Lube oil centrifuges are used to clean the engine oil.
At the end of this is a link to a video that describes it. The audio cuts out in the middle of it, but the animation seems clear enough, this is how the systems work. A centrifuge works as a separator by creating a separation zone of the two different density liquids. That line of separation varies based on what is being separated, so each machine is built for a specific purpose. Since the centrifuge is separating water from the fuel as well as impurities, and water is heavier than oil, the water is injected into the centrifuge to keep oil out of the water discharge section, since water is heavier than oil, the water is towards the outside of the bowl where the centrifugal force is highest. Once enough water is in the rotating bowl, it seals the water discharge from the incoming oil and oil can then be fed into it. To discharge the collected solids, there is a piston that seals the discharge ports around the perimeter of the bowl. Water is injected into ports in the bottom of the bowl to either exert a force upwards to keep the piston closed, or downwards to open it. The opening and closing happens extremely fast, usually less than a half second on the older designs and much less than that on the newer ones. If there are any questions the video doesn’t answer, let me know and I’ll try and fill in the gaps.
The ship usually has two centrifuges for heavy fuel oil, and two for lube oil, each system running in parallel. Some ships will have centrifuges for cleaning the bilge water too. It’s designed so that only one is needed, but you can run both at the same time. For fuel oil, you will have a storage tank that feeds the centrifuges that then discharge into a day tank with clean fuel. Lube oil centrifuges are used to clean the engine oil.
At the end of this is a link to a video that describes it. The audio cuts out in the middle of it, but the animation seems clear enough, this is how the systems work. A centrifuge works as a separator by creating a separation zone of the two different density liquids. That line of separation varies based on what is being separated, so each machine is built for a specific purpose. Since the centrifuge is separating water from the fuel as well as impurities, and water is heavier than oil, the water is injected into the centrifuge to keep oil out of the water discharge section, since water is heavier than oil, the water is towards the outside of the bowl where the centrifugal force is highest. Once enough water is in the rotating bowl, it seals the water discharge from the incoming oil and oil can then be fed into it. To discharge the collected solids, there is a piston that seals the discharge ports around the perimeter of the bowl. Water is injected into ports in the bottom of the bowl to either exert a force upwards to keep the piston closed, or downwards to open it. The opening and closing happens extremely fast, usually less than a half second on the older designs and much less than that on the newer ones. If there are any questions the video doesn’t answer, let me know and I’ll try and fill in the gaps.
