Most turbine oil users change their fluid based on its condition rather than interval-based oil changes, such as what we do when changing the motor oil in our vehicles. There is inconsistency however in understanding what conditions justify a lube oil change. Part of this inconsistency is due to lack of knowledge; part of it is because there are often not black and white answers. Replacing turbine oil is expensive and carries risk.
Antioxidants (AO) are critical components in turbine oil formulations and largely determine the life and performance of a lubricant. Even though these sacrificial warriors make up about 1% of a turbine oil formulation, they protect the base oil from oxidation and rapid deterioration. An oil void of antioxidants fails rapidly and dramatically in a thermally stressful environment such as a turbine. Antioxidants play the same role in our bodies by protecting cells from the damaging effects of free radicals which are produced when our bodies break down food.
Proper greasing and lubrication increases turbo life span
June 9 2014 -
All rotating machinery has bearings that eliminate friction between rotor and the stationary housing (casing). These bearings also support loading of the rotor. The primary bearing types are hydrodynamic bearings that support high speed machinery with speeds over 4000 rpm, and anti-friction bearings supporting machinery with speeds below 4000 rpm.
Electrostatic Spark Discharge (ESD) is a phenomenon that occurs when oil generates sufficient static electricity to form sparks. This form of oil degradation has been studied extensively in many systems, including large frame gas turbines. Although most power plants are now aware of this form of turbine oil degradation, there is insufficient clarity on how critical of an issue ESD is.
The industry standard for determining when to change your turbine oil is when the antioxidants deplete to 25% of their original level. An accepted practice to extend the life of your turbine oil has been “bleed and feed”. Bleed and Feed is the practice of discarding a fraction of old oil and replacing it with new oil. Often 20-30% of the oil reservoir volume will be exchanged with new oil. This practice has become so widely adopted that few plants even pause to determine the economics of bleed and feed.
Fouling of the main oil tanks can cause serious problems in high speed machinery as these impurities can flow inside the bearings. This can cause rupture and friction within internal bearing parts such as the tilting pads or the journal parts of shaft, as well as damaging internal components of the lube oil pump. Oil filters are mainly used to remove these impurities and particulate.
Excessive return oil flow in a compressor train installation
October 9 2013 -
This compressor oil flow case study by Kevin D. Yates, a rotating equipment specialist at The Dow Chemical Company in Freeport, Texas, was presented at the 42nd Turbomachinery Symposium in Texas. The case study is about a new motor-gear-compressor train installation in which the lube oil pressure became an issue during commissioning and startup.