HOT TOPIC at CTOTF: Turbine lubrication

Many variables impact the condition and performance of turbine lubricants. On the subject of varnish, for example, discussion seemingly can be endless as to why a given petroleum oil operates varnish-free in one unit and wreaks havoc in another. The type of turbine, its age and service duty, the oil’s formulation and its additives package, type of filtration equipment, and experience of O&M personnel are just a few of the most obvious variables that can come into play.

Lubrication was a presentation/discussion topic at two of the roundtables attended by the editors at the CTOTF’s™ 40th Anniversary spring meeting, recently concluded at the Sanibel Harbour Marriott in Ft Myers, Fla. During the GE E/EA-Class session, an OEM lube-oil presentation generated questions and discussion on industry experience with TF-25, a synthetic polyalkylene glycol (PAG) substitute for conventional turbine oils that does not produce varnish. The fluid is distributed in North America by American Chemical Technologies Inc (ACT). At the GE F-class session, Dan McCormick of McCormick & Munson Technologies LLC presented on the identification and removal of varnish precursors as a way to avoid varnish problems associated with petroleum oils.

Just before the CTOTF meeting, Analysts Inc, one of the industry’s leading providers of lubricant analysis and testing solutions, released version 2.0 of its Lube Oil Analysis Management System (LOAMS) software, giving owner/operators the capability to compare and trend lube-oil lab results using plant historical information as well as fleet-wide data.

PAG. The OEM presenter on lubricants mentioned that GE now accepts PAG fluids as an alternative lube for its turbines but he had no first-hand experience to answer some of the questions that attendees asked. One of the first questions had to do with the number of turbines currently operating with ACT’s PAG products. ACT’s Jim Kovanda told the editors late last week that the total now is over 100.

There were several other questions related to the experiences of turbine owners with EcoSafe TF-25, and on the function and use of ACT’s UltraKlean TO and EcoSafe Revive products, which went unanswered for the most part. Much of this information is readily available in the article, PAG acceptance grows with field experience, available at CCJ ONline. However, the questions indicated there may be some confusion among users between UltraKlean and Revive. Hopefully, the following passage will clear that up:

ACT originally developed UltraKlean for the purpose of cleaning and preparing a turbine lube-oil system for conversion to TF-25. UltraKlean was designed for short-term use to allow for the circulation of approximately 10% of the cleaner into a varnished turbine-oil system to cleanse all surfaces and components that the comingled fluid would contact. Because the UltraKlean product lacks an anti-oxidant package to provide longevity, the recommendation for circulation to accomplish the objectives was 60 to 120 days.

The Revive base-oil modifier was formulated and patented for use in a varnished turbine oil to shift the polarity of the base stock, cleanse the system (much the same way as UltraKlean), and solubilize varnish. Revive is a more robust treatment than UltraKlean was and it provides a long-term solution for users concerned about high MPCs and visual varnish on last-chance filters. Key to its effective use is identification of the proper percentage of Revive necessary to shift the polarity. Note that as the fluid continues to cleanse and solubilize the oxidized solid deposits, an additional small percentage of Revive might be necessary to prolong the solution’s effectiveness.

A challenge occurred when users were forced to continue the use of UltraKlean beyond the recommended 120-day limit—as happened when an outage was postponed. ACT’s response was to discontinue the manufacture and sale of UltraKlean. Users who want to proactively cleanse and prepare a system prior to conversion to TF-25 can use Revive to accomplish the same task. It has been recommended in concentrations from 2% to 20% depending on turbine-oil condition. The PAG base stocks are identical between both products, allowing for similar cleaning while giving the user flexibility to accommodate shifts in scheduling.

Nano-particle tracking and analysis. The thrust of McCormick’s presentation was that sludge and varnish precursors and components exist in the sub-micron range before and during all varnishing events. He discussed a new particle-counting and –sizing technique and the effectiveness of a new electronic nano-filtration system for removing many of the precursors and components in the range of 40 to 1500 nanometers.

Regarding LOAMS 2.0, Analysts GM Cary Forgeron told the editors that his company’s new product “gives users more control over sample information and opens the lines of communication between management and maintenance personnel and the laboratory.” The software supports a plant-level lubricant wellness program by enabling visual presentation of lab reports and providing the ability to “mine” plant and fleet historical data and trend same.

The expectation is that LOAMS 2.0 will help O&M personnel get to the root cause of problems—such as varnishing. To illustrate, say your company has 10 7FAs at five plants. The new software enables you overlay lab data from each of those units and compare varnish results. If the oil for one of your engines has much higher varnish numbers than the units in the fleet, the next step might be to see if your oil is different from the others. If not, perhaps it’s the age of the oil, or duty cycle. Or perhaps the filtration system you have is not effective for removing varnish. It’s difficult to do this type of analysis efficiently and effectively without software designed for the purpose.

 

Posted in Best Practices |

Comments are closed.