Optimizing low speed diesel cylinder oil feed rate
ExxonMobil has introduced a technically advanced program to optimize cylinder oil feed rates in low-speed (crosshead) diesel engines.
The "Feed Rate Optimization" program is designed to help minimize operating expenses by analyzing scrapedown oil as a way to detect changes in the condition of an engine1s cylinders.
The program, which is designed to help customers find a balance between the cost of cylinder oil and the expense of wear-related cylinder maintenance, analyzes scrapedown oil collected from the engine's scavenge space, a technique pioneered by ExxonMobil.
It provides comprehensive laboratory testing and analysis of the oil sample, and offers onboard testing tools that enable ship1s engineers to quickly detect substantive changes in cylinder condition.
"We have introduced this program to make it easier for ship operators to respond to recommendations from engine manufacturers to adjust feed rates," says Mark Andreotta, vice president, ExxonMobil Marine & Aviation Lubricants. "At a time when new severe engine designs are operating in high-stress environments, we have developed a way to provide our customers with the data and knowledge they need to safely optimize cylinder oil feed rates and also to take preventive measures to reduce wear-related maintenance and operating costs."
The new program features:
Signum Oil Analysis. ExxonMobil has extended its existing Signum Oil Analysis program, which can help forecast potential mechanical problems before they occur, to include scrapedown testing. This extensive laboratory analysis provides insight into engine wear via the condition of a vessel1s scrapedown oil.
Onboard testing. Onboard testing tools include a proprietary Mobilgard Scrapedown Analyzer, a portable unit that enables a ship's engineer to quickly analyze the current wear rate of each cylinder. For customers who do not want to wait for a comprehensive lab report, onboard testing provides real-time readouts on the oil1s most important properties relative to the engine's operating condition.
Quality oil. ExxonMobil recommends Mobilgard 570, a cylinder oil formulated at an optimized viscosity level with high quality base oil to provide excellent thermal and oxidation stability, and protection against engine deposit and wear. It is proven to provide low-speed, two-cycle crosshead diesel engines with these performance features even as lower feed rates are adopted.
ENGINE MANUFACTURER SUPPORT
The new Feed Rate Optimization program was developed with the support of the major engine manufacturers, including MAN B&W and Wärtsilä.
"Changes in cylinder wear due to engine operation, ambient conditions and fuel sulfur levels can be detected as they are occurring, particularly if onboard sample analysis is employed," says Kjeld E. Aabo, senior manager engineering services, MAN B&W Diesel A/S. "Advanced warning of cylinder condition, as seen through scrapedown oil analysis results, allows the operator to optimize feed rates while ensuring optimum engine performance
The Feed Rate Optimization program was designed to respond to recent changes in the marine industry and to help save customers money. The trend toward increased size and speed of general cargo ships and container vessels mandates the continued domination of this segment by low-speed (crosshead) diesel engines, which can burn less-expensive residual fuel oil more efficiently and reliably than can other types of engines. At the same time, manufacturers have changed their engines dramatically over the past 20 years, and the new higher output designs for greater efficiency have greatly increased stress on the cylinder oil. Reduced cylinder oil consumption rates made possible by new feed system designs have further stressed the oil. Environmental regulations and variations in HFO (heavy fuel oil) characteristics around the world have resulted in increasing numbers of engines operating on low-sulfur-content HFO. This can result in sudden wear if feed rates and lubricant selection are not properly balanced. A program to safely optimize cylinder oil feed rates against these variables while monitoring the condition of the engine1s cylinders can help ship owners find an acceptable balance between the cost of the cylinder oil and the expense of wear-related cylinder maintenance. Identifying that balance can reduce total operating costs.
With the use of cylinder scrapedown oil analysis (the analysis involves various tests of used oil as a way to monitor the condition of the engine and the lubricant), it is possible to reduce cylinder oil feed rates to provide the optimum balance of cylinder oil and engine component replacement cost. Shipboard personnel can monitor the condition of an engine1s cylinders and detect changes as they occur. The testing, analysis and expert interpretation of results provides information to adjust cylinder oil feed rates to optimized levels without risk to the engines.
For many years, ExxonMobil has been using Signum Oil Analysis to help customers monitor the performance and condition of lubricants, engines and equipment. The Signum program has been expanded to include analysis of scrapedown cylinder oil. A comprehensive slate of laboratory tests includes:
Inductively Coupled Plasma Emission Spectroscopy (which monitors wear metals - including iron, a primary wear indicator, and phosphorus, an indicator of system oil contamination).
Physical and/or Chemical Analysis (which measures the total base number, viscosity and water as indicators of oil degradation and contamination).
Particle Quantifier (which monitors abrasive wear)
Ferrography (which helps identify wear type and cause). Oil samples are sent from shipboard to an ExxonMobil laboratory. The program automatically reports trends and compares variables such as iron, base number, load, fuel sulfur and humidity. Findings can help identify wear indicators before problems occur. And they can be used to optimize cylinder oil feed rate, minimizing the overall cost of operations.
The Feed Rate Optimization program includes an option for onboard testing &Mac220; particularly useful for customers who do not want to wait for a comprehensive lab report.
ExxonMobil provides the onboard tools for ship personnel to test the most important properties relative to wear and optimizing feed rates. A Mobilgard Scrapedown Analyzer (MSA) instantly measures and displays the iron content of a used cylinder oil sample. A Signum Onboard Test Kit monitors lubricants for alkalinity retention (TBN), water contamination and changes in viscosity. A MSA Logbook enables crew members aboard ship to store results, graph trends and analyze relationships between variables. The tools are easy to use.
Onboard testing augments and complements the more comprehensive Signum laboratory testing with supplementary reports that are especially useful because they provide key results in a matter of seconds.
Speedy access to technical data means that shipboard personnel can make feed rate adjustment decisions quickly. If the testing equipment alerts a ship's engineer to substantive changes in cylinders, he can take immediate corrective action before any problems become serious. Speed in detecting changes is important because wear can occur rapidly in two-stroke engines.
Mobilgard 570 is a lubricant specifically formulated to protect low-speed diesel marine engines. To minimize piston ring and cylinder liner wear caused by metal-to-metal contact or by excessive corrosion, the formulators had to optimize product viscosity in response to the more severe engine designs of today and in the future. To offset higher temperatures, which tend to break down oils and form deposits, they also had to provide improved thermal and oxidation stability and improved detergency to minimize deposit formation and breakdown. Mobilgard 570 was formulated from high quality base oils to help provide high levels of thermal and oxidation stability and protection against deposits and wear. ExxonMobil data show that the lubricant protects slow-speed, two-cycle crosshead engines better than any other marine cylinder oil on the market today.
The new program was developed after cooperative testing with the major engine manufacturers. Says Matthias Amoser, manager Tribology and Material Technology, Wärtsilä Switzerland, Ltd.: "Our experience has shown that the analysis of scrapedown cylinder oil can provide many clues regarding the operation of the engine, the impact of varying fuel sulfur levels, the effect of feed rate, and also, can serve as an early warning to potential undesirable wear situations. A frequent onboard analysis program supplemented by land-based laboratory analysis provides key information for monitoring piston running experience."