Homework SourseThe lubrication system maintains turbine 20 Sealing designs
Solution
17) D-Rotor: The moving part that extracts work form the motive fluid and transfers it to the
shaft.It is a part of turbine.
18) a-Availiblity
b-Demand of motive fuel
d- Reliabilty
19) a-Bearings
e- temperature
Lubrication system of Turbine: This system maintains turbine bearings lubrication and temperatures. The system usually operates independently of the rotation of the turbine, but may use a shaft driven oil pump. The system consists of the pump/spare, oil filters/spare, oil coolers, supply and return lines and oil reservoir. It may also contain an emergency pressure tank so that oil pressure can be maintained temporarily in event the oil pump stops. In larger machines to prevent damage it is imperative that oil flow starts before shaft rotation begins and also that oil flow continues for cooling after the shaft rotation stops. Oil flow, pressure and cleanliness are among the most critical factors in prevention of problems.
20) c-Pressure
Seals: The shaft sealing system functions to keep the high pressure motive fluids in the proper passages by preventing excessive leakage along the rotating/non-rotating boundaries. There are a great variety of sealing designs depending on fluids, pressures and temperatures. Typical designs use labyrinths (close fitting rotating/non-rotating discs), rotating/non-rotating carbon rings and others. Sometimes buffer fluids such as nitrogen gas are used to exclude motive fluids from oil systems. The idea here is to allow some leakage of the buffer gas in order to prevent leakage of the motive fluid in the other direction.
21) True
The safety/trip system consists of all sensors which cause shutdowns (such as high vibration, low oil pressure) and a logic controller which permits or dumps oil pressure to the Trip/throttle valve. Dumping oil pressure to this valve closes off machine steam supply.
