The turbine wheels Axial flow compressor Front bearing

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1 The turbine wheelsAxial flow compressorFront bearing

2 EXHAUST 4COMBUSTIONCHAMBER2AIR COMPRESSOR1GAS TURBINE3

3 Maintenance Factor Effect of Fuel 4 3 2 1 RESIDUAL CRUDE DISTILLATE
NATURAL GASEffect of Fuel

6 TYPES OF INSPECTION A- INSPECTION OF UNIT “ Running”
B- INSPECTION OF UNIT “ Shutdown”C- SPECIAL INSPECTION

7 A- INSPECTION OF UNIT “ Running”
The running inspection is performed during start up and while the unit is operating.This inspection indicates the general condition of the gas turbine unit and its associated equipment.The registered information can be used to further plan of the unit maintenance

8 I- “Standby” inspections
B- INSPECTION OF UNIT “ Shutdown”Standby inspections are performed with the unit in a stand still positionThese inspections include:I- “Standby” inspectionsII- “Combustion” inspectionsIII- “Hot gas path” inspectionsIV- “Major” inspections

9 I- “Standby” inspections
“Standby” inspections regard particularly the gas turbineused for intermittent duties (peak or emergency).Routine servicing of the battery system,Changing of filters.Checking oil and water levelsCleaning relaysChecking device settings and calibrationsLubrication and other general preventive maintenancePeriodic test runs are also an essential part of good maintenance program.

10 It is recommended to operate unit at load for one hour bi-monthly.
(to dry out the moisture may accumulate inside the turbine components)If the unit is to be down for long period, weekly turn the rotors to 90 degree, And circulate lubricant to re-coat journal bearingsSpecial inspections such as borescope can be used to further plan periodic maintenance w/o interrupting availability

11 II- “Combustion” inspections
The inspection requires the disassembly of the main parts:Fuel nozzleSpark plug and flame detectorCombustion liner

12 III- “Hot gas path” inspections
Hot gas path inspection includes:Combustion inspectionsTurbine nozzlesTurbine bucketsTo perform this inspection, the upper half of the HP. Turbine and the 1st and 2nd stage must be removed.HP. Turbine buckets will be inspected on siteA complete set of turbine clearances should beTaken before removal of parts

13 As with the combustion inspection, It is recommended that the replacement of:
* Combustion liner* Fuel nozzle* Transition pieceto be available for installation at the conclusionof visual inspection.The removed parts can inspected at the turbineservice facilities and returned back to warehouse.It is recommended that the Hot Gas Path inspection to be conducted under the supervision of the GT. Producer representative.

14 IV- “Major” inspections
Major inspection involves the major flange-to-flange components of the GT.* Casing* Rotors* Bearings* Seals* Bladings* Atomizing air systemTo carry out this inspection, all the upper casinghalves and support bearings must be disassembled.

15 C- SPECIAL INSPECTION“Boroscope” inspection“Boroscope” inspection planA planned boroscope inspection is usuallycarried out only when necessary to repair orto replace parts.

17 Turbine preparation for boroscope inspection
Turbine must be standstill and the wheel spaceTemperature not exceed 80 degree centigradeAll the access holes for inspection are normallyclosed through plugs.

18 inspection intervals Combustion inspection
STARTS / FIRED HOURSFUELINSPECTION INTERVALSHOURSCONINUOUS DUTYGAS/DISTILLATE6000 TO 8000< 1/2004000 TO 5000GAS/DISTILLATE1/50 TO 1/200CYCLIC DUTY--1/50GAS/DISTILLATE3000OR 250 STARTSThe first inspection to be after 40% of the table intervals

19 inspection intervals Hot gas inspection 1/1000 1/100 1/50
STARTS / FIRED HOURSFUELINSPECTION INTERVALSHOURSCONINUOUS DUTYGASDISTILLATE16000 to 180001/1000GAS1/100DISTILLATEGAS1/50DISTILLATECYCLIC DUTYGAS/DISTILLATE8000OR 800 STARTS

20 inspection intervals Major inspection 1/1000 1/100 1/50 16000
STARTS / FIRED HOURSFUELINSPECTION INTERVALSHOURSCONINUOUS DUTYGASDISTILLATE32000 to 360001/1000GAS1/100DISTILLATEGAS1/50DISTILLATECYCLIC DUTYGAS/DISTILLATE16000OR 1600 STARTS

21 BOROSCOPE INSPECTIONINTERVALSFUELSEMI-ANNUALLY OR AT COMPBUSTION INSPECTION WHICHEVER COMES FIRSTGAS ORDISTILLATE

22 Gas Turbine Washing 1- Off Line Wash 2- On Line Wash 3- Solid Wash
a- Gas Turbine Speed crank speed % of full speedb- Liquid used for wash Detergent (wash )+ water (rinse)2- On Line Washa- Gas Turbine Speed Operating speed (under load) 100%b- Liquid used for wash waterc- Always done after Off Line or Solid wash3- Solid Washa- Gas Turbine Speed Operating speed (under load) 100%b- Material used for wash organic or inorganic substance

23 1- Off Line Wash a – Preparation
- Sealing air and atomizing air piping shall be disassembled and plugged to prevent water from entering in.Auxiliary atomizing air compressor connection shall be disconnected.Open the IGV.Make sure all drains are opened.Close the flame detector valvesWheel space temp. shall not exceed 82 c above water temp.

24 b -Wash procedureWash with Solvent as the quantities shown in table 1 (as a guide)table 1PGTMSMS 5001/l/mingpmMSMS EAMS EACranking speed push buttonApply the detergent for a period from 3-5 minutes, stop the unitContinue to inject during run downThe detergent soak the deposits for about 20 minutes.Start cranking speed and wash with water from 5-10 minutes.Check washing efficiencyThe compressor should be washed until drain water is clean.

25 2- ON Line Wash Wash procedure
ON Line Washing considered as complement of off- line washing and shall never be alone.The turbine shall be under loadWater shall be more than 10 C at compressor inlettable 2PGTMSMS 5001/l/mingpmMSMS EAMS EAminutes

26 3- Solid wash*When the fouling level is high and washing withliquid is not sufficient to remove deposits.*A large use of solid washing can result apermanent damage of machine components.*Washing with solids shall be carried out at steadyspeed and reduced load.* Nutshells is better than rice.

27 CHAPTER 7Miscellaneous

28 Gas Turbine Thrustbalance

29 Pd PdBALANCEDZONEPd PSUNBALANCEDZONEPd

30 BALANCING DRUM P4 – P0 + + + + – P0 – P1 + + – P2 – P3 P4 – P0 P4 – P0
Balancing RoomBALANCING LINEP4 P0 P1 P2 P3Balancing DrumP4 – P0P1 – P0P2 – P1+P3 – P2+P4 – P3+ P1 +– P0– P1+ P2 +– P2P3– P3P4P4 – P0P4 – P0

31 BALANCING DRUM 42 – 2 40 40 + + + + – 2 – 12 + + – 22 – 32 42 2 12 22
Balancing RoomBALANCING LINE42 2 12 22 32Balancing Drum42 – 212 – 222 – 12+32– 22+42 – 32+ 12 +– 2– 12+ 22 +– 2232– 3242 40 40

32 P4 Mechanical seal and bearings arrangement P Ps Ps Balancing Pressure
RoomP4 P Ps Ps

33 CompressorSurge Phenomenon33 33

34 But Does not Happen to Reciprocating Compressors
HAPPENSONLY TO :CENTRIFUGALCOMPRESSORSANDAXIAL FLOWCOMPRESSORSBut Does not Happen toReciprocatingCompressors34

35 It is the flow back of gases from the outlet of the
SURGE PHENOMENIt is the flow back of gasesfrom the outlet of theLast stage of the compressortowards the suction andreturn again to discharge

36 SURGE INOUT

37 Why SURGE PHENOMEN GAS PROPERTY FLOW-RATE IS NOT ENOUGH
COMPRESSOR PERFORMANCEFLATENESS OF P.C. AT LOW Q

38 FLOW-RATE IS NOT ENOUGH GAS PROPERTY This will happen at
starting and shutdown,also at abnormal conditions.GAS PROPERTYGas is compressible but liquid is not.

39 FLATENESS OF P.C. AT LOW Q COMPRESSOR PERFORMANCE
Centrifugal and Axial compressors are pumping gas continuously but reciprocating is not.FLATENESS OF P.C. AT LOW QGas pressure has the same energy athorizontal portions of the performance curve

40 NO SURGE IFINLET FLOW RATE Q IS ENOUGHINOUT

41 5 to 20 cycles per second IF INLET FLOW RATE Q IS NOT ENOUGH OUT
COMPRESSORIS SURGINGOUTIN5 to cycles per second

42 Q M³/ hr Hp A SURGE PHENOMENON B 10000 6000 COMPRESSOR SURGING
SURGE LINEHpQ M³/ hr10000600042 42

43 SURGE WILL DAMAGE THE COMPRESSOR THRUST BEARINGS
43

44 CENTRIFGAL COMPRESSOR ROTOR
EFFECT OF SURGE ONCENTRIFGAL COMPRESSOR ROTORTHRUST BEARINGSSURGE WILL DAMAGE THE COMPRESSOR THRUST BEARINGS

45 Hp B1 A BSURGE LINEQ M³/ hr- Q1000060005 to cycles per second

46 SURGE CYCLE Hp B1 A BSURGE LINE600010000- QQ M³/ hr46 46

47 1- BY PASS WITH ANTI - SURGE VALVE
IN CASE OFCOMPRESSOR SURGINGP,TFTUICFYCOMRESSORCOOLERANTI-SURGEVALVE WILL OPEN47 47

48 1- BY PASS WITH ANTI - SURGE VALVE
COMRESSORM 34000 M36000 MP,TFTUICFYCOOLERANTI-SURGEVALVE6000 M34000 M3UIC = ANTI- SURGE INTEGRATED CONTROLER48FY = TRANSDUCER48

49 Q M³/ hr GRAPHICALLY Hp BY PASS WITH ANTI - SURGE VALVE B A C
SURGE CONTROL LINERECYCLE TRIP LINESURGE LIMIT LINEQ M³/ hr49 49

50 2 –BLOW OFF VALVE Air UIC = ANTI- SURGE INTEGRATED CONTROLLER
AIR COMRESSORM 3 36000 MBLOWOFFVALVEAirFTP,TFYUICFY = TRANSDUCERUIC = ANTI- SURGE INTEGRATED CONTROLLER50 50

51 2 – BLOW OFF VALVE GRAPHICALLY Hp Q M ³/ hr B A B1 SURGE CONTROL LINE
51 51

52 IN CASE OF GAS TURBINE AIR COMPRESSOR SURGE BLEED VALVE WILL OPEN
52 52

53 Mokveld Anti-Surge Valve
Spring Loaded duringnormal operationValve SeatValve Diskmoves LHSto open

54 awebsaSection a-a

55 SurgeSurge is the point of minimum stable flow and maximum head condition for the centrifugal compressor.The surge region is to the left of the surge line.Operation in this region is highly undesirable and can be very destructive for the machine since a repeated, almost instantaneous flow reversal takes place.

56 Wrong Developing the Surge Cycle on the Compressor Curve Pd Qs, vol Pd
Compressor reaches surge point ACompressor loses its ability to make pressureSuddenly Pd drops and thus Pv > PdPlane goes to stall - Compressor surgesFrom A to B ms Drop into surgeFrom C to D ms Jump out of surgeA-B-C-D-A seconds Surge cyclePvCompressor starts to build pressureCompressor “rides” curve towards surgePoint A is reachedThe surge cycle is completeRlossesPdPd = Compressor discharge pressurePv = Vessel pressureRlosses = Resistance losses over pipeBB AADriver is startedMachine accelerates to nominal speedCompressor reaches performance curveNote: Flow goes up faster because pressure is the integral of flowBecause Pv > Pd the flow reversesCompressor operating point goes to point BPressure buildsResistance goes upCompressor “rides” the curvePd = Pv + RlossesSystem pressure is going downCompressor is again able to overcome PvCompressor “jumps” back to performance curve and goes to point DForward flow is re-establishedDResult of flow reversal is that pressure goes downPressure goes down => less negative flowOperating point goes to point CCMachine shutdownno flow, no pressureQs, vol

57 Steam Turbine

58 PRINCIPLE OF OPERATION
The two major components of a steam turbine areNozzles and Blades ( buckets).Nozzles are stationary; blades rotate. Steam contains energy in the form of pressure and temperature.Nozzles convert this energy into velocity energy.In a nozzle, the pressure drops and the velocity increases .The high-velocity jets from the nozzles strike the blades and cause them to move. In the moving blades, velocity energy is converted to mechanical work, or power.Blades are located in rows on rotating wheels.Nozzles are arranged on stationary wheels, between the rotating wheels

59 Impulse stage FIXED FIXED STATOR STATOR BLADES BLADES MOVING TURBINE

60 Reaction stage FIXED FIXED STATOR STATOR BLADES BLADES MOVING TURBINE

61 A stage contains one row of nozzles, followed by one row of blades.
Turbines may be single-stage or multistage.Curtis StageA Curtis stage is a special kind of wheel that takes a relatively high pressure drop.It is used for single-stage turbines and as the first stage in most older design multistage turbines.Present day turbine design uses a rateau stage since material and blade attachment methods allow higher blade operating stresses

62 A Curtis stage has one row of nozzles, followed by three rows of buckets. The sequence is as follows:1. Nozzles2. Rotating buckets that develop power3. Fixed buckets that turn the direction of the steam4. A second row of rotating buckets, that develop more power.All of the pressure drop takes place in the nozzles.Other Types of StagesIn a multistage turbine, each stage after the first one hasone row of nozzles (stationary) andone row of blades (rotating).These stages may be the "Rateau" type or the "reaction" type.

63 Classification of steam turbines
Turbines are divided into two classes,1- Power generation2- Mechanical drive1- Power generationGenerate electric power run at constant speed because the frequency of the generated power must be constant.As the turbine runs at constant speed, features can be designed to give a very high efficiency.Tolerances between the moving and stationary parts are very close.

64 2- Mechanical driveAre used for driving machinery such as compressors and pumps, where variable speed is usually required.Tolerances are larger, and fewer stages are used.Classifications of Mechanical Drive TurbinesA- General PurposeGeneral Purpose Turbines are used for low power applications.They are covered by API Standard 611 and are mass produced without regard to specific customer requirements. They are limited to steam supply conditions of less than 600 psig and 750°F.They also operate at speeds less than 6000 rpm.

65 General purpose turbines are usually single-stage turbines that may exhaust to a condensing system or to the atmosphere. Since they are less reliable than other turbines, their applications are limited to noncritical equipment.They are used as drivers for equipment that has a spare, such as pumps and fans. Such equipment is always has a backup.B- Special Purpose.For large power loads and covered by API Standard 612.They are manufactured to specific customer orders.These services are usually not spared; therefore, the turbine must be highly reliable.As these turbines are large machines, efficiency is important, and multistage designs are used. The most common applications are Gas compressors and Large pumps.

66 According to number of pressure stages
Used to drive Electric power generator2-Multistage TurbinesBlowersPumpsSimilar equipmentI -According to number of pressure stages1-Single stage TurbinesUsed to drive Centrifugal compressorsDouble cylindersFour cylindersSingle cylinderThree cylindersII-According to number of cylinders

67 III - According to principle of steam action
Reaction TurbinesImpulse TurbinesIV- According to Heat drop process1- Condensing Turbine with generatorsExtracting steam from stages to heat up feed water2- Condensing Turbine with extracting steamfrom stages for industrial process3- Back pressure Turbines4- Topping TurbinesThe exhaust steam is used as a feed to low pressure Turbines .

68 V- According to Steam condition at inlet
       Very high pressure Turbines(Steam P=170to225bara)Super critical pressure TurbinesSteam P >   Low pressure Turbines1 . 2Medium pressure Turbines40High pressure Turbines

69 Principle of steam turbine action

70 Three cases study L = Pu * u ( kg m/ sec) P u = G/g ( C1t – C2)
Steam Mass Flow kg/s G =L = Pu * u ( kg m/ sec)P u = G/g ( C1t – C2)If G = 1 kgP u = 1/g ( C1t – C2)L = work donePu = force ( kg)u = tangential velocity of blades m/secC1t = theoretical velocity of steam m/secC2 = velocity of steam after out m/secw1=Steam relative velocity in m/secw2 =Steam relative velocity out m/secThree cases studyP3= 34.7 kgc= 30SteamuC1tC2C1tP2= 40 kgbSteamu C2P1= 20 kgaSteamuC1t

71 a uC1tSteamP1= 20 kg

72 bC1tu C2SteamP2= 40 kg

73 c= 30SteamuC1tC2P3= 34.7 kg

74 Assume C1t = 196.2 m/sec Case (a) Case (b) Case (c)
Steam strikes a flat perpendicular surfaceP1 = /9.81 ( – 0 ) = KgCase (b)Steam strikes a 90 deg bendneglecting friction loss Then C2 = – C1tP2 = 1/9.81 ( ) = KgCase (c)Steam strikes a 30 deg bend ( blade )neglecting friction loss Then C2 = – C1tP3 = 1/9.81 ( ) Cos = Kg

75 w1= C1t cos 30 – u w2 = - w1= -C1t cos30 + u Case c
Taking into consideration the blade velocity u Relative steam velocity (w) m/secw1 = C1t – u w2 = C2 = 0If u = 98.1 m / secP1= 1/g ( w1- w2 ) = 1/g(C1t - u )P1= 1/9.81 ( ) = 10 kgCase aw1= C1t- u w2 = - w1= -C1t + uP2= 1/g ( w1- w2 ) = 1/g {(C1t-u )-(-C1t+u)}P2= 2/g {(C1t-u )}P2= 2/9.81 ( ) = 20 kgCase bw1= C1t cos 30 – u w2 = - w1= -C1t cos30 + uP3= 1/g ( w1- w2 ) = 1/g {(C1t cos30 -u )-(-C1t cos30 +u)}P3= 2/g ( C1t cos 30 –u )P3= 2/9.81 ( 196.2* ) = kgCase c

76 LEGEND C = m/sec C = m/sec C = m/sec C = m/sec w = m/sec w = m/sec w =
=STEAM VELOCITY AT NOZZLE INLETm/secC 1 = 1tACTUAL VELOCITY OF STEAMm/secC 1t =THEORITICAL STEAM VELOCITY AT NOZZLE EXITm/secC 2 =STEAM VELOCITY AT MOVING BLADE EXITm/secw 1 =RELATIVE VELOCITY STRIKING MOVING BLADESm/secw 2 =RELATIVE VELOCITY LEAVING MOVING BLADESm/secw 2t =THEORITICAL RELATIVE VELOCITY LEAVING MOVING BLADESm/sec= fVELOCITY COEFFICIENT = 0.95 TO 0.96y =VELOCITY COEFFICIENTh o =ADIABATIC HEAT DROP OF STEAMkcal/kgh i =USEFUL ADIABATIC HEAT DROP OF STEAMkcal/kgh n =kcal/kgNOZZLE LOSSES = C21t - C21 / kcal/kga 1 =NOZZLE ANGLE OF STEAM VELOCITY Ca 2 =EXIT ANGLE OF STEAM VELOCITY Cb 1 =ENTRY STEAM ANGLE OF RELATIVE VELOCITY wb 2 =EXIT STEAM ANGLE OF RELATIVE VELOCITY wA =1 / = THERMAL EQUIVALENT OF WORK ( kcal/kg )u =BLLADE ANGLEm/secv =STEAM SPECIFIC VOLUME m3/kgLa =WORK DONE BY 1kg OF STEAM (IDEAL IMPULSE ) = C21t - C22 / 2g= C2 1t+(w2t -w 1) - C/ 2g

77 The following example illustrates the calculation.
EXAMPLE CALCULATION - THEORETICAL STEAM RATE,ACTUAL STEAM RATE, AND OUTLET TEMPERATUREThe method used for predicting turbine conditions uses the Mollier Chart for steam.The following example illustrates the calculation.Given:Inlet steam pressure psiaInlet steam temperature °FOutlet steam pressure psiaTurbine efficiency %Brake horsepower required hpCalculate:• Theoretical steam rate • Actual steam rate (water rate)• Steam outlet condition + temperature

78 Solution:Use the Mollier chart for steam(Elliot Bulletin H-37B, inside back cover);Locate the Inlet Steam Temperature and Pressure on the Mollierdiagram. Read inlet enthalpy, h1 = 1350 Btu/lb2. Move vertically downward, along a line of constant entropy, to the outlet pressure of 2 psia. Read the outlet enthalpy, h2 = 923 Btu/lb3. Calculate the isentropic (ideal) ÆhÆhis = h1 - h2 = 1350 – 923 = 427 Btu/lb4. The conversion factor from heat to work is: __Btu_hp-hr

79 = 7.95 lb/hp/hr 5-Therefore, Theoretical Steam Rate, TSR = __ 2545___
Isentropic Æh2545427=5.966. Actual Steam Rate, ASR (Water Rate)ASR= ____TSR_ _____Turbine Efficiency_5.96=0.75= 7.95 lb/hp/hr

80 = 7950 lb 7. Calculate Steam Flow Rate Steam Flow Rate
= hp x Actual Steam Rate= 1000 hp x 7.95 __lb__hp- hr= lbhr8. Outlet Steam Condition:Calculate actual outlet enthalpyActual Æh= Æhis x Turbine Efficiency= 427 Btu/lb x 0.75= 320 Btu/lbActual h2 = h1 - Actual Æh == 1030 Btu/lb

81 Locate the outlet steam condition on the Mollier chart, at
h = 1030 Btu/lb and 2 psiaRead Outlet Temperature = 130 °FNOTE: Since the outlet steam is saturated, and the pressure is known, you can also obtain the temperature from a steam table

82 COMMON OPERATING PROBLEMS
STEAM TURBINESCOMMON OPERATING PROBLEMSProblem Possible CauseInsufficient PowerDeveloped• Steam pressure too low.• Backpressure too high.• Supply temperature too low.• Deposits in steam path.• Deposits in steam path.• Erosion of nozzles or blades.Low Efficiency

83 Problem Possible Cause
Erosion of Blades• Too much moisture in turbine;inlet temperature too low oroutlet pressure too low.Exhaust Too Hot• Low efficiency• Low steam flow rateVibration• Deposits• Erosion• Broken blades• Damaged bearings• Misalignment of piping

84 GLOSSARY Actual Steam Rate (ASR)
The actual steam rate required per unit of power.(Pounds per horse power hour.){Water Rate}Backpressure TurbineA steam turbine that does not exhaust into a condenser.The exhaust pressure will typically be 15 psig or higher.Curtis StageA type of steam turbine stage with one row of nozzles and one or more rows of buckets.The usual sequence of components is: nozzles, rotatingbuckets, stationary turning buckets, rotating buckets.GovernorA device that regulates the speed of a steam turbine.It may be mechanical or electronic.Hand ValveA valve used to shut off the steam supply to a portion of the inlet nozzles.

85 Impulse BladesRotating turbine blades in which only velocity decreases; pressure does not decrease.Rateau StageA steam turbine stage with one row of nozzlesand one row of blades.A relatively small pressure drop is taken in therotating blade of a Rateau stage.Reaction BladeRotating turbine blades in which pressuredrop takes place.

86 Bearings

87 RADIAL BEARINGTHRUST BEARINGball Bearingsroller BearingsTilting pad Bearings

88 Thrust Ball BearingsDRIVE ENDNON-DRIVE ENDHANGED BEAMIMPELLER

89 Non-frictional Bearings
Radial Ball BearingsThrust Ball BearingsSplash ring

90 MECHANICAL SEALBEARING HOUSING

91 Thrust LoadRadial Load

92 Thrust Pad Bearings DRIVE END NON-DRIVE END IN-BETWEEN TWO
BEARINGS IMPELLER

93 Mechanical seal and bearings arrangement
Equipment

94 THRUST PAD BEARINGTHRUST SHOESTHRUST COLLAR

95 THRUSTSHOESLEVELPLATESBASERINGCASINGSHAFTTHRUSTCOLLAR

96 WhitematerialTilting pad thrust bearing (carry axial load only)

97 Radial Tilt-Pad Bearing

98 Tilting pad radial bearing (carry radial load only)