220220en_ Lube Oil System

7/23/2019 220220en_ Lube Oil System

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Steam TurbineOperation Lube Oil System

Power Plant Training Center

CSXA220220en_ Page 29

AB C D

Exercises Operation & Routine Maintenance

Exercise Task List all major operation steps concerning lube oil system with relevant set points, i.e.above 90 % shaft speed switch-off auxiliary oil pump.

Exercise Aids • Plant specific P&ID and legend to P&ID• Set point list steam turbine• Starting and operating instructions of steam turbines

GroupTime Frame

Presentation

• Group work with max. 4 trainees per group• 20 minutes• Group presentation in front of class

Set Point (Speed, Load, etc.) Operation Step








AB C D

Exercises Routine Maintenance

Exercise Task List all major actions required for routine maintenance of the lube oil system.

Exercise Aids • Plant specific P&ID and legend to P&ID• Starting and operating instructions of steam turbines• Maintenance description of lube oil system

GroupTime FramePresentation

• Group work with max. 4 trainees per group• 20 minutes• Group presentation in front of class

Site visited with hands-on dry-exerciseGroup presentation in the field

Schedule Action Required






AB C D

Test Questions for Verification of Learning Progress

General The following points are important and shall be taken into account:• The training manual may be used (open book), but first try without looking up in

the manual.• Mark the box in front of each correct statement with a diagonal cross.• One or more or all statements may be correct.Use this section to verify your learning progress! Review subjects, which are notclearly understood.

Questions:

Question 01: The turbine lubrication system supplies oil to the following consumers:

A Journal and axial bearings of the steam turbine

B Turning gear system

C Hydraulic oil systemD Jacking oil system

E Sealing oil system of the generator

Question 02: The temperature of the lube oil is maintained to be not less than 45° Cduring normal load operation of the steam turbine by the following:

A Lube oil cooler

B Lube oil temperature control valve

C Lube oil mass flow control through the lube oil cooler

D Lube oil tank heater

E Cooling water mass flow control through the lube oil cooler

(Continued next page)






AB C D

Questions (continued):

Question 03:During operation, the shaft driven main lube oil pump supplies thesteam turbo set with the lube oil required. What happens if the pumpfails?

A The auxiliary lube oil pump is immediately added into service

B The emergency lube oil pump is automatically added into service

C The service is switched over to the auxiliary lube oil pump

D The steam turbine trips

E The pressure accumulator supplies oil while the auxiliary pump is running

Question 04: What happens in case of an AC loss?

A The pressure in the lube oil system collapses

B The steam turbine goes into a trip

C The emergency lube oil pump is automatically switched on

D The emergency lube oil pump will carry the supply of the lube oil toprevent damage to the unit from lack of lube oil during shut-down

E The pressure accumulator supplies oil while the auxiliary pump is runningup

Question 05: What happens when the lube oil temperature downstream of thetwin filter exceeds the pre-set maximum level?

A An alarm is issued. The operator has to take the action necessary toreturn the unit to normal operation

B An alarm is issued. If the temperature exceeds the pre-set max. level, thesteam turbine goes into a trip

C An alarm is issued. The operator has to investigate until the source of theproblem is found

D An alarm is issued. The operator has to investigate until the source of theproblem is found and has to take the action necessary to return the unit tonormal operation







AB C D


Question 06: What happens when the bearing metal temperature exceeds thepre-set maximum level?

A The steam turbine goes into a trip

B Sequential initiation of an alarm and a trip of the steam turbine

C Automatic change-over to standby oil cooler

Question 07:How Is operational readiness of the auxiliary and the emergencylube oil pump during normal operation of the steam turbinetested?

A The lube oil supply is switched over to the auxiliary pump

B The auxiliary and the emergency lube oil pumps are started automaticallyduring each FG start-up. When the pre-set pressure level after eachpump is reached, it is switched off

C The shaft driven main lube oil pump and the auxiliary or the emergencylube oil pump may be operated simultaneously, therefore the pump to betested shall be switched-on manually for a brief time

D TURBOTROL features a lube oil pump test program, which can beactivated during operation

Question 08: For how long has the FG lube oil supply to remain in operation after ashut-down of the steam turbine?

A For 72 hours

B Until the steam turbine metal temperature is <154° C and FGturning gear can be shut-down

C Until the FG lube oil supply is shut-off

D Until the FG jacking oil is shut-off







AB C D


Question 09: What has to be checked specially during a "once a shift" walk down onthe turbine lubrication system?

A Watch out for leaks because they will lead to fires where hot surfaces arepresent

B Proper lube oil forward and return temperature

C Lube oil level in the tank

D Pressure drop across twin filter

Question 10: What is important when switching over from the service to the stand-by side of the twin filter?

A Proper venting of the stand-by side before switchover

B Replace the dirty filter elements with new elements

C Discard the used elements

D Wash dirty filter elements for re-assembly

E Check the system for leaks after re-assembly

Question 11: Define the following process parameters:

A Lube oil pressure at the inlet to the bearings: ............ barg

B Lube oil pressure at the discharge of the shaft drivenlube oil pump: ............ barg

C Minimal lube oil temperature for steam turbinerun-up: ............ ° C

D Maximal lube oil temperature in the distributionsystem (alarm): ............

° C

E Maximal pressure drop across twin filter (alarm): ............ barg






AB C D

Lesson Test Questions Solution Key

The correct answers for each question are as follows:01: A, B, D02: B, C, E03: A, B04: B, C, D05: D06: B07: C08: B

09: A, B, C, D10: A, B, C, E11: 1.5barg, 5.5 barg, > 20° C, < 70° C, 0.8 barg






AB C D

Summary

The purpose of the lube oil system is to lubricate the bearings of the steam turbineand the generator. Additionally, the heat transferred to the rotor by the steam,which is conducted to the journals, is transferred to the lube oil together with thefriction heat generated in the bearings. The lube oil system supplies also a variety ofother systems, such as the power oil-, the jacking oil- and the turning gear system.The main lube oil pump, driven by the turbine shaft, supplies the lube oil system.The lube oil is partly passed through the lube oil cooler. The temperature ismaintained by the temperature controller, which mixes the warm oil from the tankwith the required amount of cooled oil. A pressure control valve maintains thesystem pressure under all operating conditions. The oil passes then through a twinlube oil filter, before it enters the bearings. Each bearing is equipped with anorifice, thus preventing a total pressure loss in the system in case of a system leak.

An oil vapor extractor maintains a slight vacuum in the system, thus preventing oilleaks on the bearing pedestals.

An auxiliary lube oil pump is required for start up, since the main lube oil pumpdelivers an insufficient quantity of oil during low speed operation. The auxiliary lubeoil pump, together with the emergency lube oil pump, is switched on, when the lubeoil pressure drops below a defined minimum.The electronic control system supervises pressure and temperature and provides thenecessary alarms or actions.The lube oil system requires only little maintenance during regular operation. Theoperator should always check for leaks on all components involved in the system.

Particular attention is required for the filter, since the filter in operation may clog upover a period of time.Severe damage results when changing-over the oil filter or oil coolers withoutproper filling venting!



Steam TurbineOperation Lube Oil System AB C D

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220220en_ Lube Oil System

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