Extending Oil Life in Natural Gas Engines
The choice of oil drain interval (oil life) in engines burning natural gas fuel represents a costbenefit balance. Longer oil life lowers the costs for oil purchase, labour, and equipment downtime, the last usually being the most valuable. More frequent oil changes may extend the overall life of the engine and reduce long-term maintenance costs, as well as provide a margin of safety and psychological well-being. Somewhere in between is the optimum for a given engine make, model, fuel composition, and service. Oil drain intervals for large industrial gas engines are often determined by used oil analysis. Typical parameters, such as viscosity and acid number increase; base number decrease; oxidation and nitration by infrared; and wear metals content are compared to recommendations from the engine manufacturer, the analysis laboratory, or experience. However, oil analysis may not give a reliable indication of expected engine life or long-term engine condition. A series of field tests was conducted to determine the factors affecting oil life and engine durability. Differences among engine makes, models, and configurations that affect oil life are shown, including brake mean effective pressure (BMEP), oil sump volume, brake specific oil consumption (BSOC), and air:fuel ratio. Stoichiometric ( 1), lean burn ( 1.5), and ultra-lean burn ( 2.0) configurations are shown to give significantly different stress on the oil and therefore, different oil life. The validity of typical used oil condemning limits was explored by extending oil life beyond the recommended limits. Generally, oil drain intervals may be extended beyond common guidelines with no apparent harmful engine effects, although there may be warranty implications. In addition to used oil properties, wear and cleanliness resulting from the extension of oil drain intervals were examined. As expected, longer oil drain intervals - for constant engine model, fuel, service, and engine oil - led to increased deposits, which may or may not affect engine life. Wear was much less sensitive in these highly hydrodynamic engine designs. Based on these findings, a new engine oil formulation is demonstrated to double the oil drain interval of the previous ’best in class’ product, without sacrificing wear, cleanliness, or used oil analysis parameters. The probable limitations of extended oil drain intervals are discussed and predicted.
Fred W. Girshick
Infineum USA,L.P.,USA
国际会议
上海
英文
1-7
2013-05-13（万方平台首次上网日期，不代表论文的发表时间）