Turbine section of gas turbine


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Turbine section of gas turbine

  2. 2. Industrial Gas Turbine, AssignmentDIP 1 Marine Engineering 2011/2012 TURBINE SECTION OF GAS TURBINE NAME: ABD AMMAR AR-RASYID BIN RAZALI COURSE: ND1 MRE ‘A’ 2|PageAbd Ammar Ar-rasyid bin RazaliND1 MRE ‘A’
  3. 3. Industrial Gas Turbine, AssignmentDIP 1 Marine Engineering 2011/2012 Table Of ContentIntro 1. Introduction Pg.4 2. Turbine definition Pg.4 3. Turbine section of Gas turbine Pg.5Turbine section part 1. Turbine Section part Pg.7 2. Turbine Section Part Pg.8Turbine Inspection 1. Turbine inspection Pg.9 2. Type of inspection Pg.10 3. Combustion inspection Pg.11 4. Borescope Pg.13Purpose of Preventive Maintenance Pg.14Procedure for Carrying Major Inspection Pg.15Conclusion pg.16References Pg.16 3|PageAbd Ammar Ar-rasyid bin RazaliND1 MRE ‘A’
  4. 4. Industrial Gas Turbine, AssignmentDIP 1 Marine Engineering 2011/2012 IntroductionThis assignment was given on the last week of school days before the end of the firstsemester of 2011/2012 season by our Industrial Gas Turbine instructor Mohd IskandarB. Hj Jani , it is to be done during the one month holiday . For me this is quite goodfor the student so that the will be able to learn on their own. In this assignment, I willtalk about the turbine section of a gas turbine. First of all what is a turbine? Turbine definition:A turbine is a rotary engine that extracts energy from a fluid flow. Claude Burdintake the term from the latin name turbinis, or Vortex (during an 1828 engineeringcompetition). The simplest turbines have one moving part, consist of a rotor assembly, which is ashaft with blades attached. Moving fluid acts on the blades or the blades react to theflow, so that they rotate and impart energy to the rotor. Early turbine examples areWindmills and Water Wheels.Gas, steam and water turbines usually have a casing around the blades that focusesand control the fluid. The casing and blades may have variable geometry that allowsefficient operation for a range of fluid-flow conditions.A device similar to a turbine but operating in reverse is a Compressor and Pump. TheAxial Compressor in many Gas Turbine engines is a common example . 4|PageAbd Ammar Ar-rasyid bin RazaliND1 MRE ‘A’
  5. 5. Industrial Gas Turbine, AssignmentDIP 1 Marine Engineering 2011/2012 TITLE: TURBINE SECTION OF GAS TURBINETurbine section of the Industrial Gas Turbine does a number of things depending onwhat type of engine its coming from, but in all engines, it extracts energy from thecombustion gasses and turns the shaft which also turns the compressor section. (diagram of a turbine section)Rotating compressor: sucks in the atmospheric air (pressurized it) and forces it intothe combustion chamber in a steady flow. Since the working fluid for the turbine isair, the expansion will be done by adding fuel to the compressed air which gives risein temperature of the mixture air and combustion product.Combustion chamber: is a rotary engine engine that extracts energy from the flow ofhot gas produced from by combustion of gas/fuel oil in a steam of compressed air. Ithas an upstream Air Compressor (radial or axial flow) mechanically coupled to adownstream Turbine and a Combustion Chamber in between.TURBINE : Is a rotary engine that extracts energy from a fluid flow.To extract theenergy from the high velocity gas flowing from the combustion chamber.The resultinggases are directed over the turbine’s blades, spinning the turbine, and, mechanically,powering the compressor.Finally, the gases are passed through a Nozzle, generatingadditional thrust by accelerating the hot exhaust gases by expansion back toatmospheric pressure. 5|PageAbd Ammar Ar-rasyid bin RazaliND1 MRE ‘A’
  6. 6. Industrial Gas Turbine, AssignmentDIP 1 Marine Engineering 2011/2012Function of the turbine sectionThe main purpose of a Turbine is to extract the energy from the high pressure and highvelocity gas flowing from the combustion chamber , these will cause the turbine blade torotate and run the compressor, if the turbine is assembled in a single shaft with thecompressor .The system goes like this, something boils water which creates steam, this being muchlarger than liquid water increases pressure, creating a movement of air through theturbine. This makes the turbine rotate, which generates electricity. It does this byrotating a magnet inside a coil. This induces an electric current in the coil. Magneticfields and electric fields are related: when one changes, the other is created. And anelectric field pretty much means voltage, which creates a current.The Turbine Section of an Industrial Gas Turbine does a number of things depending onthe type of engine from the combustion gases and turns the shaft which also turns thecompressor section. 6|PageAbd Ammar Ar-rasyid bin RazaliND1 MRE ‘A’
  7. 7. Industrial Gas Turbine, AssignmentDIP 1 Marine Engineering 2011/2012 TURBINE SECTION PARTS 1) First Stage Nozzle 2) Second Stage Nozzle 3) First Stage turbine wheel 4) Second Stage turbine wheel 5) Distance Piece 1 2 5 3 4 7|PageAbd Ammar Ar-rasyid bin RazaliND1 MRE ‘A’
  8. 8. Industrial Gas Turbine, AssignmentDIP 1 Marine Engineering 2011/2012 First Stage NozzleThe nozzle accelerate the gas stream and direct it onto the first row mobbing bladeswhere the pressure energy and kinetic energy of the gas stream is converted into aforce on the blade which in turn produce a torque at the shaft in which the movingblades are attached. The hot gas stream leaving the moving blades is directed intothe next stage where the process is repeated. Second Stage NozzleThe general concept with two-shaft GE-design heavy duty gas turbines is: Fuel controlis used to control the low pressure shaft speed (torque), and nozzle control is used tocontrol high performance shaft speed. Fuel is increased to increase or decrease Lowpressure speed (torque) and the second stage nozzles are used to "split" the powerbetween that required to turn the HP shaft, and control its speed, and that requiredto turn the LP shaft. FIRST STAGE TURBINE WHEELThe first stage turbine wheel is a component of the hot section of the auxiliary powersection which converts gas energy to a rotational energy to the processor. Second Stage Turbine WheelThe second stage turbine wheel is use to drive the air compressor or water pump.Main reason for multi stage of turbine is to increase the i.e the more the stages thehigher is the power produce by engine Distance PieceThe distance piece is a structural member connecting the compressor frame. Thedistance Piece are designed to contain the gas within the cylinder, but with the highpressure it is possible that some of the compressed gas will leak. 8|PageAbd Ammar Ar-rasyid bin RazaliND1 MRE ‘A’
  9. 9. Industrial Gas Turbine, AssignmentDIP 1 Marine Engineering 2011/2012 Turbine InspectionOperation of the combustion gas turbine, as of any rotating power equipment, mustinclude a planned program of periodic inspection, with accompanying repair andreplacement of parts as necessary, to ensure the maximum availability and reliabilityof the unit. Benefits, it is best to repair the turbine parts than spending more moneybuying new parts for it.Things to be inspected are such as; Check all lubrication tube (check for any leakage and deformation) Check lubricating oil level (from sight glass) Take reading of oil pressure and temperature (for comparison and monitoring) Take reading of oil pressure and temperature (for comparison and monitoring) Take reading of engine working hours meter (for record and maintenance purposes) i.e maintenance of lube oil carried out every 1000hrs of engine operation Check and record ahead and astern bearing clearances (to check for shaft misalignment) Monitor the fuel oil consumption ( record daily fuel tank and make comparison) for any pipeline leakage and fuel nozzle breakdown Check for pump and motor condition for any un-usual noise, vibration and high temperature (may indicate of bearing failure etc) Check tank for peeling paint(indicate of overheating/rusting due to moisture) ,present of sludge and unusual foreign matter in the bottom of the tank by draining some of the oil from the drain valve Check lube oil properties by doing lube oil viscosity test ( to check the viscosity of oil) Check heat exchanger for any leak(only possible if fin type heat exchanger) Maintenance  Replacement of oil filter(clean the filter or change with new one if necessary)  Check for oil contamination by doing the lube oil test(change lube oil if necessary)  Check for loose fitting/connection/pipe etc.  Check oil cooler(for accumulation of dirt, grime, foreign material etc)Cleaning of air inlet filter for diesel and compressor(change if necessary) 9|PageAbd Ammar Ar-rasyid bin RazaliND1 MRE ‘A’
  10. 10. Industrial Gas Turbine, AssignmentDIP 1 Marine Engineering 2011/2012 Types of Turbine InspectionThe types of inspections may be broadly classified in;1. 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 itsassociate equipment.2. Shutdown Inspection is performed while the unit is at standstill. The shutdowninspections include Combustion inspection, Hot gas path inspection and Majorinspections. 10 | P a g eAbd Ammar Ar-rasyid bin RazaliND1 MRE ‘A’
  11. 11. Industrial Gas Turbine, AssignmentDIP 1 Marine Engineering 2011/2012 Combustion InspectionA short shutdown inspection is required to change out fuel nozzle and to check thecombustion liners, transition pieces and cross fire tubes. These parts require the mostfrequent attention since continued operation with a deteriorated combustion systemand can result a much shortened life of the downstream parts, such as turbine nozzleand buckets.Things that need to be inspects are: 1. The nozzle 2. Combustion liners 3. Transition pieces 4. Cross fire tubeBelow is a list of a typical combustion inspection and things to be inspected• Inspect and identify combustion chamber components.• Inspect and identify each crossfire tube, retainer and combustion liner.• Inspect combustion liner for TBC spalling, wear and cracks. Inspect combustion system anddischarge casing for debris and foreign objects.• Inspect flow sleeve welds for cracking.• Inspect transition piece for wear and cracks.• Inspect fuel nozzles for plugging at tips, erosion of tip holes and safety lock of tips.• Inspect all fluid, air, and gas passages in nozzle assembly for plugging, erosion, burning, etc.• Inspect spark plug assembly for freedom from binding; check condition of electrodes andinsulators.• Replace all consumables and normal wear-and-tear items such as seals, lockplates, nuts,bolts, gaskets, etc.• Perform visual inspection of first-stage turbine nozzle partitions and borescope inspectturbine buckets to mark the progress of wear and deterioration of these parts. This inspectionwill help establish the schedule for the hot gas path inspection.• Perform bores cope inspection of compressor.• Enter the combustion wrapper and observe the condition of blading in the aft end of axial-flow compressor with a bores cope.• Visually inspect the compressor inlet, checking the condition ofthe IGVs, IGV bushings, and first stage rotating blades.• Check the condition of IGV actuators and rack-and-pinion gearing.• Visually inspect compressor discharge case struts for signs of cracking.• Visually inspect compressor discharge case inner barrel if accessible.• Visually inspect the last-stage buckets and shrouds. 11 | P a g eAbd Ammar Ar-rasyid bin RazaliND1 MRE ‘A’
  12. 12. Industrial Gas Turbine, AssignmentDIP 1 Marine Engineering 2011/2012• Visually inspect the exhaust diffuser for any cracks in flow path surfaces. Inspect insulatedsurfaces for loose or missing insulation and/or attachment hardware in internal and externallocations. In E-class machines, inspect the insulation on the radial diffuser and inside theexhaust plenum as well.• Inspect exhaust frame flex seals, L-seals, and horizontal joint gaskets for any signs of wear ordamage.• Verify proper operation of purge and check valves. Confirm proper setting and calibration ofthe combustion controlsAfter the combustion inspection is complete and the unit is returned to service, the removedcombustion hardware can be inspected by a qualified field service representative and, ifnecessary, sent to a qualified Service Center for repairs. The removed fuel nozzles can becleaned on-site and flow tested on-site, if suitable test facilities are available. For F Class gasturbines it is recommended that repairs and fuel nozzle flow testing be performed at qualifiedService Centers. 12 | P a g eAbd Ammar Ar-rasyid bin RazaliND1 MRE ‘A’
  13. 13. Industrial Gas Turbine, AssignmentDIP 1 Marine Engineering 2011/2012 BorescopeA Borescope is an optical device consisting of a rigid or flexible tube with an eyepieceon the end, an objective lens on the other linked together by a relay optical system inbetween. The optical system is usually surrounded by optical fibers used forillumination of the remote object and a rigid or flexible protective outer sheath.Borescopes are used for inspection work where the area to be inspected isinaccessible by other means. Commonly used in the visual inspection of turbineengines and to a lesser extent conventional engines. . A flexible borescope includes abundle of optical fibers which divide the image into pixels and can be used to accesscavities which are around a bend, such as a combustion chamber or "burner can", inorder to view the condition of the compressed air inlets, turbine blades and sealswithout disassembling the engine . It lets you know what to expect when youdismantle the parts to be maintained. 13 | P a g eAbd Ammar Ar-rasyid bin RazaliND1 MRE ‘A’
  14. 14. Industrial Gas Turbine, AssignmentDIP 1 Marine Engineering 2011/2012 The Purpose of Preventive Maintenance 1. The care and servicing by personnel for the purpose of maintaining equipment and facilities in satisfactory operating condition by providing for systematic inspection, detection, and correction of incipient failures either before they occur or before they develop into major defects. 2. Maintenance, including tests, measurements, adjustments, and parts replacement, performed specifically to prevent faults from occurring.The primary goal of maintenance is to avoid or mitigate the consequences of failureof equipment. This may be by preventing the failure before it actually occurs whichPlanned Maintenance and Condition Based Maintenance help to achieve. It is designedto preserve and restore equipment reliability by replacing worn components beforethey actually fail. Preventive maintenance activities include partial or completeoverhauls at specified periods, oil changes, lubrication and so on. In addition, workerscan record equipment deterioration so they know to replace or repair worn partsbefore they cause system failure. The ideal preventive maintenance program wouldprevent all equipment failure before it occurs.Advantage of Preventive maintenance are: Extends the useful lifecycle of assets decreasing the need for capital replacements. Enhances the efficiency of equipment keeping them running more efficiently and lowering power expenses. Enhances the performance of assets by increasing uptime. Enhances customer (internal or external) service because maintenance teams have less unplanned maintenance and can respond quicker to new problems. Contributes positively to the reputation of companies. 14 | P a g eAbd Ammar Ar-rasyid bin RazaliND1 MRE ‘A’
  15. 15. Industrial Gas Turbine, AssignmentDIP 1 Marine Engineering 2011/2012 Procedure for Carrying Out Major InspectionA major inspection is primarily a mechanical outage in which the gas turbine (andsometimes the generator if conditions warrant) are disassembled and inspected.Major mechanical and hot gas components are refurbished, replaced or repaired.Whilst the machine is shut down, very often the operation of control devices (pressureswitches and -transmitters, temperature switches, etc.) are confirmed (incorrectlycalled "calibrations"). Quite often LVDTs are unnecessarily "calibrated".Typical Major inspection requirements for all machines are :• All radial and axial clearances are checked against their original values (opening andclosing).• Casings, shells and frames/diffusers are inspected for cracks and erosion.• Compressor inlet and compressor flow-path are inspected for fouling, erosion,corrosion and leakage.• Visually inspect the compressor inlet, checking the condition of the IGVs, IGVbushings, and first stage rotating blades.• Check the condition of IGV actuators and rack-and-pinion gearing.• Rotor and stator compressor blades are checked for tip clearance, rubs, impactdamage, corrosion pitting, bowing and cracking.• Turbine stationary shrouds are checked for clearance, erosion,rubbing, cracking,and build-up.• Seals and hook fits of turbine nozzles and diaphragms are inspected for rubs,erosion, fretting or thermal deterioration.• Turbine buckets are removed and a nondestructive check of buckets and wheeldovetails is performed (first stage bucket protective coating should be evaluated forremaining coating life). Buckets that were not recoated at the hot gas path inspectionshould be replaced. Wheel dovetail fillets, pressure faces, edges, and intersectingfeatures must be closely examined for conditions of wear, galling, cracking orfretting.• Rotor inspections recommended in the maintenance and inspection manual or byTechnical Information Letters should be performed.• Bearing liners and seals are inspected for clearance and wear.• Inlet systems are inspected for corrosion, cracked silencers andloose parts.• Visually inspect compressor and compressor discharge casehooks for signs of wear.• Visually inspect compressor discharge case struts for signs ofcracking.• Visually inspect compressor discharge case inner barrel ifaccessible.• Visually inspect the turbine shell shroud hooks for sign of 15 | P a g eAbd Ammar Ar-rasyid bin RazaliND1 MRE ‘A’
  16. 16. Industrial Gas Turbine, AssignmentDIP 1 Marine Engineering 2011/2012cracking CONCLUSIONThe parts are quite confusing for the first time, but with a help of a reference andthe internet I’ve able to distinguish parts of the turbine. Also, it happens to show thatgreat machine have their problems needed to be taken care of. Overall, I gain someknowledge about gas turbine section parts which will help me to go through my coursemuch simpler and easier. Referenceshttps://www.google.com.bn/search?q=procedure+for+major+inspection&hl=en&safe=off&tbo=d&source=lnms&tbm=isch&sa=X&ei=aGHiUIPcBqeziQev14BQ&ved=0CA cQ_AUoAA&biw=1366&bih=662http://en.wikipedia.org/wiki/Preventive_maintenancehttp://www.proscopehr.co.za/hawkeye-borescopes/hawkeye-product-range/flexible-borescopes/pro-flexible-borescopes.htmlhttps://www.google.com.bn/#hl=en&safe=off&tbo=d&tbm=dsc&sclient=psy-ab&q=distane+piece&oq=distane+piece&gs_l=serp.3..0i13l4.227912.232939.11.233989.,or.r_gc.r_pw.r_qf.&bvm=bv.1355534169,d.aGc&fp=c43b932bc261b565&bpcl=40096503&biw=1366&bih=705https://www.google.com.bn/search?q=honeywell+second+stage+turbine+wheel+turbine+section&hl=en&safe=off&tbo=d&noj=1&source=lnms&sa=X&ei=15_hUM2kKcufiAeG9IH4DA&ved=0CAkQ_AUoAA&biw=1366&bih=705https://www.google.com.bn/#hl=en&safe=off&tbo=d&sclient=psy-ab&q=how+second+stage+turbine+wheels+works&oq=how+second+stage+turbine+wheels+works&gs_l=hp.3...4478.7891.2.8216.,or.r_gc.r_pw.r_qf.&bvm=bv.1355534169,d.aGc&fp=ecbdd52f22bc6188&bpcl=40096503&biw=1366&bih=705 16 | P a g eAbd Ammar Ar-rasyid bin RazaliND1 MRE ‘A’