SKF Blohm + Voss Industries is now launching a new component, the SIMPLEX-COMPACT Oil Dryer. The unit extracts water from the sterntube seal lubrication oil – thereby maintaining the quality of the oil. The company will present the solution at the SMM 2014 trade fair in Hamburg, 9-12 September. The new SIMPLEX-COMPACT Oil Dryer facilitates reliable oil/water separation – irrespective of whether the water in the oil is in a free, emulsified or dissolved state.
Oil/water mixtures can occur frequently in oil-lubricated sterntube seal designs without an air chamber. But even in installations where the sealing rings provide a seal against oil or water, the fluids are still required to provide lubrication for the sealing rings on the sterntube bushes. This is how water, even if only in small quantities, is able to mix with the lubricating oil.
In order to maintain the quality and lubricating properties of the oil, the water content of the lubricating oil should be kept as low as possible. When water mixes with the seal’s lubrication oil there is – particularly when ester-based oils are used – a risk of the sealing ring’s performance becoming degraded and its aging process accelerating. After the Vessel General Permit 2013 entering into effect, the use of biologically degradable oils, which are mostly ester-based, for lubricating the sterntube have increased. But the risk of hydrolysis exists even with just slight water contamination in these types of oil: Water promotes the decomposition of the oil into alcohol and acids, which then attack the sealing rings.
Reliably separating water from the lubrication oil
The SIMPLEX-COMPACT Oil Dryer functions according to a simple principle: A pump permanently circulates fresh oil between the seal and the associated tank. This ensures that potential contaminants are removed from the sealing rings. Inside the oil tank the system forces air through the oil from beneath, which is simultaneously heated. This creates evenly distributed air bubbles in the fluid, on the surface of which the water can evaporate. The air bubbles transport the water vapour enclosed within them to the surface, where they burst and release the vapour into the air in the space above the oil. This air, enriched with water vapour, is now actively removed from the tank. In this manner, the SIMPLEX-COMPACT Oil Dryer is capable of removing up to 1.5 litres of water per day from the sterntube lubrication oil.
Should the electricity supply on board the vessel be interrupted, the oil dryer is equipped with a backup system which ensures that the seal still receives a stable supply of oil. A second oil line bypasses the pump and this is normally closed by a solenoid valve. If the power supply should fail, this valve automatically opens, thereby maintaining the flow between the oil tank and the seal.
Often economically viable and easy to retrofit
The SIMPLEX-COMPACT Oil Dryer is offered as a complete “plug-and-play” solution which includes the pump, tank, filter and control unit. The system can be installed or retrofitted with all types of oil-lubricated sterntube seals, provided the seal is fitted with feed and return lines for circulating the oil and that electricity and compressed air supplies are available on board.
The use of a SIMPLEX-COMPACT Oil Dryer is recommended in all situations where the water content in the lubrication oil must be kept as low as possible, for instance when ester-based oils are used. Installation is also advantageous in situations where there is increased water contamination of the lubrication oil.
An even stronger partner for the marine industry
In early 2013, SKF has acquired Blohm + Voss Industries (BVI), the German manufacturer of ship components. With this acquisition, SKF intends to strengthen its product portfolio for the marine industry. Furthermore, SKF widens its access to the market by using BVI's world-wide leading network of Sales and Service partners. Customers will benefit from SKF's expertise as a knowledge engineering company in combination with BVI's focus on shipbuilding and ship operations. The new joint organisation will be an even stronger partner for the marine industry, supplying critical components and fast and reliable services, as well as developing new applications that address future challenges in the ever changing environment of the industry.