Patent Application
20120060463
The present application relates generally to gas turbine engines and more particularly relates to systems for the mitigation of lubricating oil varnish and the damage to engine components that may be caused thereby.
A significant issue in the maintenance and upkeep of known gas turbine engines is the creation of lubricating oil varnish. For example, lubricating oil in a hydraulic circuit may be in communication with a number of servos that operate inlet guide vanes, gas control valves, liquid fuel valves, etc. Varnish deposits on the oil wetted components and elsewhere may lead to the failure and/or the malfunction of these servos and other components. Such failures and malfunctions may result in the tripping of the gas turbine engine and a subsequent revenue loss caused by the downtime for required repairs.
Oil varnishing may be the result of a complex string of events. Specifically, the molecules in the oil stream may be broken via chemical, mechanical, and/or thermal processes. For example, chemical processes may include oxidation of the oil. Oxidation may be accelerated by heat and/or the presence of metal particulates therein. Mechanical processes may include “shearing,” where the oil molecules may be torn apart as they pass between moving mechanical surfaces. Thermal processes may include pressure-induced dieseling or pressure-induced thermal degradation due to the high pressures and temperatures. Electrostatic charges also may cause localized thermal-oxidative oil degradation. Turbines that are operated in a peaking or a cycling mode may be more susceptible to oil varnishing due to the effects of thermal cycling. Other processes and combinations thereof also may be present although not fully understood to date.
There is thus a desire for oil varnish mitigation systems so as to limit both the creation of oil varnish and the damage caused thereby, particularly in a hydraulic circuit with the servos therein and other components that may be susceptible to varnish damage and the like. Reducing varnish damage should improve overall system efficiency and reduce required maintenance and downtime. Such varnish mitigation systems may be retrofitted into existing gas turbine engines or may be original equipment in new systems.
The present application thus provides a lubricating oil varnish mitigation system for a turbine engine. The lubricating oil varnish mitigation system may include a lubricating oil circuit with a lubricating oil therein and a hydraulic oil circuit separate from the lubricating oil circuit with a hydraulic oil therein.
The present application further provides a lubricating oil varnish mitigation system for a turbine engine. The lubricating oil varnish mitigation system may include a lubricating oil circuit with a number of pumps and a lift oil supply and a hydraulic oil circuit separate from the lubricating oil circuit with a number of hydraulic oil pumps.
These and other features and improvements of the present application will become apparent to one of ordinary skill in the art upon review of the following detailed description when taken in conjunction with the several drawings and the appended claims.
Referring now to the drawings, in which like numerals refer to like elements throughout the several views,
The gas turbine engine 10 may use natural gas, various types of syngas, and/or other types of fuels. The gas turbine engine 10 may be one of any number of different gas turbine engines offered by General Electric Company of Schenectady, N.Y. such as the F-Class gas turbine engines. The gas turbine engine 10 may have other configurations and may use other types of components. Other types of gas turbine engines also may be used herein. Multiple gas turbine engines 10, other types of turbines, and other types of power generation equipment also may be used herein together.
As is shown, the lubricating oil tank 55 serves both the hydraulic oil supply 75 and the lift oil supply 85. The lubricating oil 60 thus will flow through the components of the turbine 40 and through other system components where it may be subject to high pressures, stresses, temperatures, wear and tear, and the like. The lubricating oil 60 further may flow through numerous filters that may cause static changes and increases in temperature that also may result in oil breakdown and varnish accumulation.
The hydraulic unit 110 may be in communication with a hydraulic supply to fuel gas system 115, a hydraulic supply to the inlet guide vane system 120, a hydraulic supply to liquid fuel system 125, and other components. The hydraulic unit 110 also may be in communication with the lift oil supply 85. One or more of these supplies may include the servos and other types of internal components that may be subject to varnish damages as is described above. Other configurations and other types of components also may be used herein.
The lubricating oil varnish mitigation system 200 also may include a hydraulic circuit 280. The hydraulic circuit 280 may include a hydraulic oil tank 290 with a volume of a hydraulic oil 300 therein. The hydraulic oil 300 may be a specialized oil such as a Group II base oil and the like. Other types of hydraulic oil 300 may be used herein. The hydraulic oil tank 290 may be in communication with a hydraulic oil pump 310. The hydraulic oil pump 310 may be in communication with a hydraulic oil supply 320 and the like. Other configurations and other types of components also may be used herein.
By separating the lubricating oil circuit 210 and the hydraulic oil circuit 280, the hydraulic oil 300 may not be subject to the high pressures, temperatures, and stresses commonly found with the lubricating oil 230. As such, the hydraulic oil 300 may not varnish and, hence, not cause varnish damage to the components within the hydraulic circuit 280 such as the servos and the like. Moreover, the hydraulic oil 300 may have a significantly longer lifetime as compared to the lubricating oil 230 as currently in use.
As compared to the lubricating oil system 95 described above, the additional hydraulic oil pump 210 may be required in the hydraulic circuit 280. This hydraulic oil pump 310, however, may be simplified in that only one pressure setting may be required as opposed to the two settings required with the hydraulic/lift pump 100. Likewise, the additional hydraulic oil tank 290 also may be required to hold the separate volume of the hydraulic oil 300. The existing lubricating oil tank 220, however, may now be smaller in size.
The hydraulic circuit 280 also may include a hydraulic manifold 340 in communication with the hydraulic oil supply 320. The hydraulic oil supply 320 or the hydraulic manifold 340 may be in communication with the, hydraulic supply to fuel gas system 115, the hydraulic supply to inlet guide vane system 120, the hydraulic supply to liquid fuel system 125, and other components herein.
The lubricating oil varnish mitigation systems 100 described herein thus improves overall gas turbine reliability while reducing required maintenance, downtime, and potential revenue loss. The use of the separate hydraulic circuit 280 with the hydraulic oil 300 therein largely eliminates issues related to oil varnishing in the components of this circuit and the like. The lubricating oil varnish mitigation system 100 may be retrofit or original equipment.
It should be apparent that the foregoing relates only to certain embodiments of the present application and that numerous changes and modifications may be made herein by one of ordinary skill in the art without departing from the general spirit and scope of the invention as defined by the following claims and the equivalents thereof.
