Gas engine builders are continuing to push the boundaries of engine design. But not all existing lubricants can cope with these changes. Jarmo Vihersalo of ExxonMobil explains why next generation gas engines need next generation oils.
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Natural gas is one of the world’s fastest growing sources of energy. However, with fluctuating energy prices and more focus than ever on sustainability, market conditions are challenging. For owners and operators to ensure profitability, an efficient operation is critical.

In an effort to increase power efficiency and reduce cost of ownership, gas engine builders are continuing to push the boundaries of engine design. Many gas engine configurations are now larger, cleaner and more cost-effective to run, with emissions such as carbon monoxide and NOx down and power outputs up.

To achieve these results, a number of operational fundamentals have changed. Many of the new generation of gas engines operate at higher pressures (BMEP) and combustion temperatures than previous models. In order to achieve such engine yield, top land is usually shortened.

Taken together, these features can create an environment which is far more severe for a lubricating oil. Traditional lubricants can often suffer and, for many, it can trigger premature oil degradation. This can lead to shorter oil drain intervals, increased engine downtime, and reduced power output.  Given the volatile nature of the energy market, many operators cannot afford for this to happen.

It is for this reason that ExxonMobil works closely with leading equipment builders – using bench, screening and field tests – to develop next generation lubricants that meet the challenge of today’s high output gas engines.

Most recently, ExxonMobil launched Mobil Pegasus™ 1100 series, which was requested by major OEMs to cope with severe engine conditions and significantly extend oil drain intervals.

The natural gas engine series includes Mobil Pegasus™ 1105 and Mobil Pegasus™ 1107. Both lubricants have a well-balanced formulation helping to extend oil drain intervals by up to 1.5 times[1]when compared to conventional mineral oils.

Following comprehensive industry and bench testing, the lubricants exhibited excellent oxidation and thermal stability, which helps to extend oil life. The series’ outstanding anti-wear characteristics help reduce wear of engine components and scuffing of liners in highly loaded gas engines. In addition, the oil controls varnish formation and carbon deposits helping to maintain engine cleanliness.

Mobil Pegasus™ 1107 is approved by Jenbacher for use in all versions of the series 2, 3 and 6 natural gas-fuelled engines (in Fuel Class A). TI 1000-1109 carries both the ‘Extended Drain’ capability flag as well as catalyst approval.

Mobil Pegasus 1107 also received official approval from Caterpillar Energy Solutions for its use in their MWM TCG and CATERPILLAR CG gas engines.

Recent engine design innovations have placed increasing demands on the lubricants responsible for helping deliver reliable gas engine productivity around the clock.  However, next generation lubricants such as the Mobil Pegasus 1100 series are now entering the market, which are designed to support these gas engine developments and support the changing needs of the industry.

Looking to the future, ExxonMobil works with equipment builders to engineer new lubricant technologies for gas engines that will help customers further protect their businesses in the years to come

Maintenance top tips

A scheduled maintenance programme is essential for supporting the smooth running of gas engines. ExxonMobil has developed tips to help keep unscheduled downtime to a minimum, while also saving money.

Replacement of consumables, such as oil and filters, typically occurs every 1,000 – 2,000 operational hours, depending on engine type and fuel quality. Using a high performance synthetic lubricant, such as one of the Mobil Pegasus™ 1100 series, can help extend oil and filter life, reducing maintenance downtime and used oil disposal costs.

A common cause of unscheduled maintenance is fuel gas quality – natural gas is cleaner and less challenging than landfill or biogas. It is therefore important to ensure that maintenance periods are more frequent if poor quality gas is burnt.

Work in partnership with your maintenance service and lubricant suppliers to ensure you have the best possible safeguards in place to help ensure the smooth running of your gas engines.

[1] Mobil Pegasus 1105 and Mobil Pegasus 1107 are long life gas engine oils that have demonstrated up to 1.5X longer oil drain intervals versus competitor conventional mineral oils in high performance natural gas fuelled engines

Jarmo Vihersalo is Offer Advisor for Europe, Africa and the Middle East at ExxonMobil.
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The latest trends and technologies in gas engines and turbines will be explored in detail at POWERGEN Asia later this year. For details of the event, click here.