Multifunctional marine cylinder lubricants
The IMO classifies the world’s navigable waters into Global areas and ECAs (emission control areas), with separate exhaust emission regulations governing each. In Global areas, the sulfur cap is 3.5% and high-sulfur fuels are still used. High BN (base number) cylinder oils (70BN) are used in Global areas to prevent corrosive wear that can be caused by the sulfuric acid generated through combustion of sulfur in the fuel. In ECAs, low-sulfur fuel (S < 1%) must to be used in order to meet SOx regulations. Engine manufacturers require the use of low BN cylinder oils (40BN) in ECAs, because high BN cylinder oils are not suitable for 2-stroke crosshead engines running on low-sulfur fuel. Because the list of areas designated as ECAs continues to grow, mid BN cylinder oils (55BN) were developed, which can be used with both lowsulfur and high-sulfur fuels. Meanwhile, ship owners often operate vessels in slow steaming mode to improve fuel efficiency, due both to skyrocketing bunker fuel prices and in the interest of cutting CO2 emissions. But slow steaming increases the amount of unburned materials (ex. soot) and decreases heat capacity in the combustion chambers. Therefore, the lubrication conditions in slow steaming are more severe and more corrosive than in normal load operation. Thus, the performance of mid BN cylinder oils may be insufficient to provide proper lubrication in slow steaming. If high BN cylinder oils could be modified for use with low-sulfur fuels, these problems would be solved. Therefore the authors studied the incompatibility between lowsulfur fuels and high BN cylinder oils and found two contributing factors. One is the previously-recognized problem of increased ash deposits from surplus basic additives on the cylinder top lands, and another is a decline in oil spreadability, which is linked to the formation of high-molecular weight substances traceable to the oxidation products of the base oil and surplus basic additives. The decline in oil spreadability can be inhibited by improving the oil’s oxidation stability. We developed an ash softening technology to prevent the buildup of piston ash deposits. This technology can convert what would normally be hard ash deposits into meringue-like soft deposits. The technology was developed by optimizing the detergent and dispersant system. The optimization is based on the selection of the molecular weight and quantity of the dispersant used, and combining the dispersant with a proper detergent. This technology has not only an ash softening effect but also acts to accelerate the acid neutralization rate. High BN cylinder oils formulated with this technology are suitable for 2-stroke crosshead engines running on either high-sulfur fuel or low-sulfur fuel and operating in slow steaming mode. Thus, these cylinder oils could be called multifunctional marine cylinder lubricants. In addition, 40BN cylinder oils utilizing this technology could be used in 2-stroke crosshead engines running on ultralow-sulfur fuel (S < 0.1%, distillate or LNG, etc.).
Naozumi Arimoto Shigeki Takeshima
JX Nippon Oil and Energy Corporation,Japan
国际会议
上海
英文
1-9
2013-05-13（万方平台首次上网日期，不代表论文的发表时间）