Lube oil performs many functions in turbine-generation, all of which are not only necessary for optimal production for the moment, but optimum equipment reliability for the future. Both production and reliability are essential elements of increased profits. For lube oil to do its job it must be kept clean and at the proper temperature. Lube oil coolers are an essential element in this process.

The primary purpose of lube oil coolers is to cool turbine oil. The heated oil travels a serpentine path through the shell side of the bundle. Cooling water flows through the tubes. Heat is transferred from the oil to the water through the tube wall, keeping the oil temperature within its ideal operating range. As the oil travels this serpentine path through the cooler the heat transfer itself can cause particles suspended in the oil to drop out and adhere to the outside of the tubes. This can be the beginning of a twofold problem. First, the build up on the shell side of the tubes becomes an insulator reducing the ability of heat to be transferred. Even a thin layer of varnish greatly reduces heat transfer efficiency. Oil operating temperatures rise, eventually reaching the point of being out of the recommended range. Maximum water valve settings can not bring the temperature down. Then, as the build up of contaminates continues, sections of the bundle can become plugged, restricting the flow and further reducing heat exchange. Eventually, some of this material can move through the bundle and cause premature wear on the bearings and other parts.

How does turbine oil become contaminated? The oil storage reservoirs often act as a collector of contaminants. They may also contain debris going all the way back to plant construction such as dust, chips and weld splatter. Leaking tubes in the coolers may cause water to get into the oil (or oil into the discharge water). The continuous wear of machine parts, gears, couplings or the bearings themselves provide contaminates. Cooking and chemical action in the hot spots of the unit will cause sludge and varnish to build up on the tubes, especially at the baffles. A thin coat can cause a 10% to 15% loss in heat transfer. Neither equipment failure nor decreased production is acceptable. The only solution is a proper preventative shell and tube side cleaning program. A thorough shell side cleaning at least every 3 to 5 years, coupled with intermittent tube side cleaning as needed, will not only increase the time between major outages, but will allow you to maintain the turbine at maximum load.

There are three choices in shell side cleaning. High pressure washing, which is only about 60% effective in tight triangular-pitched tube bundles, produces thousands of gallons of liquid waste and actually serves to pack contaminates more tightly into the center of the bundle. Next is bubble vat cleaning. In this method the bundle is placed into a vat of chemicals and air is circulated through the tank in an attempt to break up and dissolve the contaminates. The bundle is then removed and pressure washed. This still produces large amounts of liquid waste and is at best only about 75% effective. The only real solution is our patented state of the art MCC process, which utilizes a totally enclosed container. The tube nests are placed inside where they are rotated as they are sprayed full length with up to 1,000 gallons per minute of a cleaner that is compatible with your turbine oil. This cleaning agent is heated to 160° - 180°F. All solids are captured in a closed kidney loop filter system, so only clean solution is flushed over and through your cooler at all times. With this process we are able to wash your bundle all the way to the center restoring 92% to 98% of new efficiency.

Why National Heat Exchange Cleaning Corporation
and the MCC process?