Calpine Gas Turbines Benefit From PAG Based Lubricants

Midland, MI - May 26, 2009

The Calpine Oneta Power Plant in Broken Arrow, OK operates four General Electric 7FA gas turbines. Gas turbines operate at very high speeds and generate extremely high operating temperatures. The turbines in Broken Arrow were not operating efficiently because of severe problems with varnish and carbon build-up. These by-products of turbine oil degradation that result from high heat and friction were fouling servo valves, pencil filters, reservoir interiors and piping. The recurrence of varnish and carbon build-up was hindering proper operation of critical hydraulic components. The resulting sludge not only plays havoc in obvious places but collects in areas not so obvious like turbine piping and heat exchangers.

When mineral oil based turbine oils are subjected to the rigors of normal gas powered turbines, servos stick and filters get plugged. This means more time for maintenance personnel to work on the machinery. Significantly adding to those costs are the lost production of turbines that are off line. So the price Calpine was paying for less than ideal lubrication was quite high. "After unsuccessfully testing several methods and systems that claimed to remove and/or reduce the varnish seen, Oneta Energy Center (OEC) decided to move towards replacing the lubricant with a product that would better resist or eliminate the varnish or the mechanism causing it to form," said Mike Pankratz, Plant Manager of OEC in Broken Arrow, OK.

Lubrication is important for installations like the one in Broken Arrow, OK as gas turbines are built to run at high operating temperatures and require fine tuned hydraulic controls. Selecting the right lubricant and keeping the oil clean are two of the keys to fewer break downs, less maintenance or downtime. Localized hot spots in turbine oil can initiate oxidation, resulting in the formation of sludge, varnish, and hard carbon deposits. ECOSAFE TF-25 is a premium lubricant marketed by American Chemical Technologies, Inc. and based on advanced synthetic lubricant technology from The Dow Chemical Company, designed to remedy typical problems associated with traditional turbine lubricants.

ECOSAFE TF-25 Turbine Fluid can shrink the potential for varnish formation in gas turbines used in either base load service or high stress peaking operations. Avoiding varnish formation can improve starting reliability, help ensure reliable, long term turbine service, and extend equipment operating life with less maintenance and repair expense.

ECOSAFE TF-25 is a high viscosity index, polyalkylene glycol based fluid which provides a low coefficient of friction, exceptional thermal conductivity, and fast air release.

Performance Advantages of PAG Based Lubricants
Oxidation by-products are soluble in the base fluid and will not fall out of bulk solution to cause varnishing or sludge. PAG based lubricants contribute to long term actuator and valve cleanliness, reducing the likelihood of sticking and improving starting reliability. Unplanned maintenance costs due to forced outages can be minimized and intervals between costly scheduled maintenance events are longer.

High Temperature Stability
ECOSAFE TF-25 Turbine Fluid is very stable at high temperatures encountered in gas turbines and is resistant to thermal degradation at temperatures of 120 degrees Centigrade or 250 degrees Fahrenheit. The result is longer fluid life and increased reliability.

Solving Problems At Broken Arrow
To solve the problems of contamination Calpine was experiencing, a complete turnkey operation was performed to remove the old lubricant and by-products. A fluid system flush and cleaning was performed on the turbine at Broken Arrow. All the old varnish was removed, so too was the sludge that had accumulated during the normal operation. After thorough cleaning of the turbine, ECOSAFE TF-25 was used to replace the old lubricant. The results were immediately promising. "OEC noticed a slight drop in bearing metal temperatures by approximately 2°F - 3°F under similar operating conditions. This reduction in heat is assumed as a result of less friction/energy loss in the bearings," Pankratz stated. Installations like these from all over the world could benefit from the same type of advanced synthetic chemistry, resulting in reduced maintenance costs and leading to more efficient turbine operation.

After one year of operation, the people at Broken Arrow were satisfied with the use of ECOSAFE TF-25. Pankratz emphasized that there are no problems noted in analytical testing with regard to acids or oxidation. He further concluded that "After one year of service the lubricant appears to have no varnish related issues and OEC does not expect to see any problems based on the characteristics of a polyalkylene glycol product."

About Dow

For Editorial Information:

Harold Nicoll
The Dow Chemical Company
(989) 636-5162

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Gas turbines operate at very high speeds and generate extremely high operating temperatures. The turbines in Broken Arrow were not operating efficiently because of severe problems with varnish and carbon build-up. These by-products of turbine oil degradation that result from high heat and friction were fouling servo valves, pencil filters, reservoir interiors and piping. The recurrence of varnish and carbon build-up was hindering proper operation of critical hydraulic components. The resulting sludge not only plays havoc in obvious places but collects in areas not so obvious like turbine piping and heat exchangers. When mineral oil based turbine oils are subjected to the rigors of normal gas powered turbines, servos stick and filters get plugged. This means more time for maintenance personnel to work on the machinery. Significantly adding to those costs are the lost production of turbines that are off line. So the price Calpine was paying for less than ideal lubrication was quite high. "After unsuccessfully testing several methods and systems that claimed to remove and/or reduce the varnish seen, Oneta Energy Center (OEC) decided to move towards replacing the lubricant with a product that would better resist or eliminate the varnish or the mechanism causing it to form," said Mike Pankratz, Plant Manager of OEC in Broken Arrow, OK. Lubrication is important for installations like the one in Broken Arrow, OK as gas turbines are built to run at high operating temperatures and require fine tuned hydraulic controls. Selecting the right lubricant and keeping the oil clean are two of the keys to fewer break downs, less maintenance or downtime. Localized hot spots in turbine oil can initiate oxidation, resulting in the formation of sludge, varnish, and hard carbon deposits. ECOSAFE TF-25 is a premium lubricant marketed by American Chemical Technologies, Inc. and based on advanced synthetic lubricant technology from The Dow Chemical Company, designed to remedy typical problems associated with traditional turbine lubricants. ECOSAFE TF-25 Turbine Fluid can shrink the potential for varnish formation in gas turbines used in either base load service or high stress peaking operations. Avoiding varnish formation can improve starting reliability, help ensure reliable, long term turbine service, and extend equipment operating life with less maintenance and repair expense. ECOSAFE TF-25 is a high viscosity index, polyalkylene glycol based fluid which provides a low coefficient of friction, exceptional thermal conductivity, and fast air release. Performance Advantages of PAG Based Lubricants Oxidation by-products are soluble in the base fluid and will not fall out of bulk solution to cause varnishing or sludge. PAG based lubricants contribute to long term actuator and valve cleanliness, reducing the likelihood of sticking and improving starting reliability. Unplanned maintenance costs due to forced outages can be minimized and intervals between costly scheduled maintenance events are longer. High Temperature Stability ECOSAFE TF-25 Turbine Fluid is very stable at high temperatures encountered in gas turbines and is resistant to thermal degradation at temperatures of 120 degrees Centigrade or 250 degrees Fahrenheit. The result is longer fluid life and increased reliability. Solving Problems At Broken Arrow To solve the problems of contamination Calpine was experiencing, a complete turnkey operation was performed to remove the old lubricant and by-products. A fluid system flush and cleaning was performed on the turbine at Broken Arrow. All the old varnish was removed, so too was the sludge that had accumulated during the normal operation. After thorough cleaning of the turbine, ECOSAFE TF-25 was used to replace the old lubricant. The results were immediately promising. "OEC noticed a slight drop in bearing metal temperatures by approximately 2°F - 3°F under similar operating conditions. This reduction in heat is assumed as a result of less friction/energy loss in the bearings," Pankratz stated. Installations like these from all over the world could benefit from the same type of advanced synthetic chemistry, resulting in reduced maintenance costs and leading to more efficient turbine operation. After one year of operation, the people at Broken Arrow were satisfied with the use of ECOSAFE TF-25. Pankratz emphasized that there are no problems noted in analytical testing with regard to acids or oxidation. He further concluded that "After one year of service the lubricant appears to have no varnish related issues and OEC does not expect to see any problems based on the characteristics of a polyalkylene glycol product." About Dow For Editorial Information: Harold Nicoll The Dow Chemical Company (989) 636-5162
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