Post on 21-Apr-2015
INDUSTRIAL GAS TURBINE2.11 & 2.12 – Type of Thrust Bearings
2.13 & 2.14 –Gas Turbine Main Bearing Housing
2.15 – Main Bearing Examination procedure
2.18 – Bearing problem diagnosis
National Diploma Year 1
in Marine Engineering
LEARNING OBJECTIVE
Describe the type of Thrust Bearing without
reference.
Explain the purpose of Bearing Housings.
Describe the examination procedure for
Industrial Gas Turbine Bearings.
Diagnose any bearing problems.
2.11 – THRUST BEARING
It support any loads that directly parallel to the
rotor axis.
It consists of a collar or thrust runner rotating
against a mating stationary plate surface
(bearing).
THRUST BEARING OPERATION
Hydrodynamic operation.
The Oil film supports the thrust load and prevent
metal-to-metal contact of the bearing surfaces.
THRUST BEARING OPERATION
The thrust load of a rotor assembly is unidirectional.
Direction of thrust load only in reverse during the
starting-up & shutdown period.
2 thrust bearing required.
Why required 2 bearings?
o To support thrust load
imposed in either direction.
2.12 – TYPES OF THRUST BEARING
1. Tilting pad self-equalizing bearings.
2. Tilting pad non-equalizing bearings.
3. Tapered Land Bearings.
4. Flat land bearings.
TILTING PAD SELF-EQUALIZING THRUST
BEARING
Employed as “Loaded” thrust bearing.
Capable of sustaining high load.
Capable of handling shaft and housing
misalignment.
TILTING PAD NON-EQUALIZING THRUST
BEARING
Used for Inactive (unloaded) application.
Capable of carrying high thrust loads…
But less tolerant of misalignment than tilting
pad self-equalizing bearing.
TILTING PAD NON-EQUALIZING THRUST
BEARING CONTINUE…
Thick in size.
Have “Leveling Plates”.
Much thinner in the axial dimension.
TAPERED LAND THRUST BEARING
Used for loaded or unloaded thrust bearing.
Consist of a steel ring faced with Babbitt.
CONSTRUCTION OF TAPERED LAND
THRUST BEARING
Bearing surface divided by radial oil groves into a
number of individual pad.
Radial oil grooves not fully extend to the outer
periphery of bearing…
But instead, partially blocked. Why?
CONSTRUCTION OF TAPERED LAND
THRUST BEARING CONTINUE…
Each surface is tapered.
A portion of the surface near the trailing edge of
the pad left un-tapered.
FLAT LAND THRUST BEARING
Consist of a steel ring faced with white metal.
The bearing surface is divided by radial oil grooves
into a number of individual segment (pads).
2.14 - PURPOSE OF BEARING HOUSING
Incorporate the oil baffles.
Prevent excessive leakage along the shaft.
Provide passages for admitting lubricating oil to
the bearing.
Locates the bearing lobes both axially and radials
with respect to the shaft.
Key in place together with bearing lobes.
2.15 - EXAMINATION PROCEDURE FOR MAIN
BEARINGS OF GAS TURBINE:
Support the shaft.
Removes Top half housing.
Slide out the bottom half of the bearings.
Clean bearings with light oil (with clean rags).
Visual inspect the bearing and journal surface.
Inspect the conditions of the seals.
Check oil and air passages in the housing are clear.
Check & clean the sump.
Replace the lower half bearing (if necessary).
Replace top half bearings (if necessary).
Remove shaft support.
Note to remember: Take care not to damage any bearing
surfaces (avoid contact with shaft object during handling). .
2.18 - DIAGNOSIS BEARING PROBLEMS
1. Scratch or Scores
• Due to lack of lubrication and not correct viscosity(temperature) during start-up.
• Due to foreign matter (such as; grit or metal chips)comes in contact with the bearing surface (if notfiltered efficiently).
2. Uneven Wear (high/low spots)
• Due to vibration which is caused by misalignment orexcessive gap between space.
3. Discoloration and Crack of bearing surface
• Due to overheating which caused by highlubricating temperature (might cause from faultylube oil cooler).
RECAP
Describe type of Thrust Bearing.
Explain the function of Bearing Housings.
Describe the examination procedure for
Industrial Gas Turbine Bearings.
Explain Diagnose bearing problems.
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