Failure Analysis of Belt Conveyor system in a Thermal Power ... - ijater

International Journal of Advanced Technology & Engineering Research (IJATER)Failure Analysis of Belt Conveyor system in a ThermalPower PlantAbstractDr. Pratesh jayashwal*, Mr.Raghvendra Singh gurjar1, Mr.Arvind yadav2,*HOD of Mechanical department, MITS COLLEGE GWALIOR (M.P.) 474005, INDIA1&2 Student of Mechanical department, MITS COLLEGE GWALIOR (M.P.) 474005, INDIAE-mail: raghvendra.gurjar354@gmail.com,arvind yadav647@yahoo.inCompared with actual situation of the thermal powerplant, this paper studies typical failure the belt conveyorand maintenance of coal handling system in thermalpower plant. Analyze technical characteristics of coalhandling system and operating characteristics of relevantmachinery and equipment and describes the maintenancemethod of prevention and elimination failure to ensure theoperation of belt conveyor. Then the safe operation ofcoal handling system and the proper method of theequipment maintenance are summed up. Analysis thecause of failure, proposed some effective methods tosolve the problem.Keywords: belt conveyor; failure analysis; solutions.IntroductionBelt conveyor is a commonly used equipment ofcontinuous transport; it has a high efficiency and largeconveying capacity, simpler construction, small amountof maintenance. Can be achieved at different distances,different materials transportation. It is widely used inmining coal handling system in thermal power plant andother projects. Belt conveyor will often occur sometypical problems in the course, this paper based onresearch common typical failure of belt conveyor duringuse, analysis the cause of failure, proposed some effectivemethods to solve the problems.Belt Conveyor SystemThe belt conveyor system (BCS) consists of Drive unit (electric motor, coupling multistagegearbox ), pulleys (drive pulley and other), idlers, belts (textile or with steel cords) with their joints,Figure 1 simple belt conveyor systemType of Failures in Conveyor BeltSystemAppears in belt conveyor system with reference toconveyor components. It will be focused mainly to driveunits, pulley, idlers and belts as the most significantcomponents. It should be noted that there are nearly noinvestigation in this area.Drive UnitThe drive unit consist of electric motor, dampingcoupling, two or three stage gearbox and coupling thatconnect output shaft with pulley (fig). A crucial object inthis subsystem is gearbox. According to Matuszewski [5]in a considered lignite open coal handling system even 14% of gear boxes may be replaced each year due tounexpected failures. These failures are related to thegeared wheel wear or damages (broken tooth) and bearing(mainly over limit backlash due to environmental impact,also typical failures like outer/inner race, rolling element).ISSN NO: 2250-3536 VOLUME 2, ISSUE 3, MAY 2012 195

199319941995199619971998199920002001200220032004International Journal of Advanced Technology & Engineering Research (IJATER)Figure 2 scheme of drive unit in belt conveyor systemIt is easy to notice the significant decreasing number offailure for 2004-2006 one of possible reason is that coalhandling system using condition monitoring techniques.In this section will be consider the types of fault that35Figure 4 Percentage of failure for gearboxes used in coalhandling system30252015105totalnumberoffailuregearedwheelbearing0Figure 3 Number of failure of drive unit gearbox used inbelt conveyor systemAnalysis for drive units used in coal handling systemdone by [6]show that over 50% problems are related toinput stage that is a bevel stage.PulleysFigure 5 Example of damaged geared wheelThe pulley consists of two bearing, shaft, shell andcoating (special material in order to improve belt-pulleycontact), figFigure 6- pulleyISSN NO: 2250-3536 VOLUME 2, ISSUE 3, MAY 2012 196

199319941995199619971998199920002001200220032004MainDepartmentAs it is shown on fig. (The number of failures dependingon pulley type) especially drives are very sensitiveelements.International Journal of Advanced Technology & Engineering Research (IJATER)Figure 7 Number of failure for different types of pulleysused in coal handling machinesAs Matuszewski [5] shown number of pulley failures mayreach over 60 per year that is 12% of used pulleys, fig.one may notice two sources of primary problems, namely:bearing, shell and coating.70605040302010035302520151050KWK1500sKWK800MRs 560SchRs900droppingotherdrivetotalnumberoffailurebearingFig. 9 Examples of pulley faultsMotor-Coupling-Gearbox-Pulley in CoalHandling SystemBased on data obtained from maintenance department(data from period January- November 2008) in one coalhandling system a simple analysis have been performed inorder to get the convince that many breakdown situationscould be omitted if CM is used. In fig. we show that forso called department /flat BCS (MBCS) number ofbreakdowns is much higher than that for smaller, so calleddepartment/flat BCS (DBCS). The reason of this is thatMBCS is heavier loaded than DBCS (SEE FIG.)6050403020100Number of failure vs type ofbelt conveyorNumber offailure vs typeof beltconveyorIn fig.8 one may see examples of damaged pulley coatingand bearingFigure-10 Number of failure related to MBCS and DBCSIn fig.9 the number of failure related to elements of driveunit is presented. As one may see the number of failure ismore or less similar for each element, however thenumber of failures of gearboxes is in the highest value.ISSN NO: 2250-3536 VOLUME 2, ISSUE 3, MAY 2012 197

International Journal of Advanced Technology & Engineering Research (IJATER)3020100number of failure of driveunitcouplinggearbox motorpulleynumberoffailureof driveunitbelt (tear, puncture, cut of belt and abrasion of bottom/topcovers) and its joints (connected using glue, vulcanized ormechanical joint) [10, 11]. Because of dimension andweight of a belt it needs to be transported in rolls, piecesup to 100-400 m long, depends on a belt type. In order toreplace damaged a gearbox or pulley heavy machinery isrequired. In some cases due to environment impact (forexample rain) it takes a few times longer time.Typical faults of beltConveyor belt deviationFigure 11 Number of failure related to elements of drive unit(motor-coupling-gearbox-pulley)IDLERSThe failure analysis of idlers and belts are a bit differentissue [7, 8, and 11]. Idler are used for supporting belt withtransport materials. In some sense idlers are similar topulleys and consist of bearing and shell. One may expectsimilar types of failures. The support system for beltconsists of three idlers. Because of different load of eachidler usually side idlers are more subjected to damage.Worn Bearing in idlers will significantly increase externalload for drive units so power consumption will increase.Damaged idlers and pulleys may be reason of damage forbelts.Figure 12 - Distribution of load along belt - idler contact areaIf one consider the impact of damaged idlers it is anotherstory. The idlers are quite small in comparison to pulley;however, number of idlers is huge. Damaged idlers maycause failure of belt (the cut of a belt ) or even may startfire (belt slipping on damaged idler may increasetemperature up to 400 o C, 450 o C is the limit for so called“difficult-to-burn” belt ) and as it was mentioned energyconsumption is a rising dramatically.BeltDepends on application, belt used in conveyor systemmay be divided into two groups: textile belts and steelcords belts. In coal handling thermal plant usually textilebelts are used. Expected problems for belts are related toIn the belt conveyor, as the conveyor belt is tractioncomponents, transmit power and motion, and also iscarrying components, support material load. Workingmore complex, so at work often happen belt deviation.Deviation is the conveyor belt during operation, the centerline of belt deviation the center line of conveyor. as theconveyor belt deviation may cause between the belt edgeand rack wear, cause belt edge premature damage,ranging impact the life of conveyor, affect the throughputof material, weight is caused by withdrawal material, evenhappen stop occurrence, direct impact on production. Asthe conveyor belt is more important, the most expensiveparts. Its price about 25%-50% to the conveyor. Soanalysis the reason of belt deviation, reduce and eliminatebelt deviation, it is an important part of ensure belt towork, extent equipment life. Cause the belt occursdeviation because of the following factors.In the device itselfa. Rack rigid is poor, large deformation under load,causing the belt deviation.b. The larger error of roller outer cylindrical,caused deviation when the conveyor belt runningc. The supporting roller rotation is not flexible,because the conveyor belt both sides stress to beuneven, because the conveyor belt deviation.d. The parallelism error cylindrical axis and rolleraxis is too big \, causes the conveyor beltdeviation.e. Conveyor belt itself is questionable quality, thinand thick uneven, caused a shock lead runningconveyor belt deviation.f. Not parallel with belt connector, connection erroris too big, cause belt deviation.Installation adjustmenta. Drive change roller axis and conveyor centerlinevertical error is too big; make conveyor andhorizontal line have a bigger inclination, causebelt deviation.b. Roller axis and conveyor centerline vertical erroris big will cause belt deviation also.ISSN NO: 2250-3536 VOLUME 2, ISSUE 3, MAY 2012 198

International Journal of Advanced Technology & Engineering Research (IJATER)c. The connection strength between rack andground is not enough, the rack unstable, causingbelt deviation.d. The feeding plate of discharge through andimproperly located, both sides of the conveyorbelt uneven force cause belt deviation.With maintenancea. The cleaning performance of sweeper is poor;make the roller cylindrical diameter localincreases.b. Feeding mouth location is wrong, so that thematerial partial load on the conveyor belt, causebelt deviation.c. Poor maintenance and improper adjustment,resulting in the conveyor belt deviation.d. For the steel cord belt, as the manufacture ofsteel cord is uneven force, so that a deviationoccurs in the operation, or a strong difference ofbelt, large elongation under load, causing thevibration, the belt will deviation.e. Also, the vibration of running conveyor beltsystem can cause the deviation.f. In addition, when conveying some viscousmaterial, make the roller, etc. bonding material;make the cylindrical diameter of roller partincreases, causing conveyor belt deviation.Measures to prevent the beltdeviation1. Due to equipment in the manufacture ofconveyor belt causes the deviation, primarilythrough improved design, manufacture precisionto prevent and reduce the occurrence of conveyorbelt deviation.2. For installation adjust improper and daily usecauses deviation, mainly the following aspectsshould be considered:Conveyor belt in drive roller or on rear rollersdeviation, usually by adjusting the position of rollerbearing ways to eliminate,a. The longitudinal centerline of the roller rotationaxis and conveyor is not perpendicular, resultingin the conveyor belt one side loose and othertight, belt move from the tight side to the looseside, occurs deviation phenomenon. Should beadjusted bearing position of tighten deviationside. Make horizontal pull of belt equal,eliminate deviation. When tail roller device bothsides screw rod are not equal, resulting in causedby imbalance.b. Cylindrical axis is not horizontal, at both endsbearing of height difference is cause anotherreason of head or tail deviation. At this point, atboth ends roller bearing should add subtractshims way to leveling roller axis, to eliminateconveyor belt deviation.c. Roller surface adhesion material, equivalent toincreasing the roller local diameter, will causethe conveyor belt deviation, should strengthenempty segment cleaning of conveyor belt toreduce the adhesive material or dustaccumulation on the conveyor belt. In addition,the conveyor belt between the nose and tail partsdeviation, called central or local deviation. Suchdeviation reasons are more complex, it is withthe conveyor belt along device exposure to arelationship. Need a detailed analysis for specificissues. Using the following method can resolvethese issues.A. Load or no- load branch roller axis with theconveyor belt running centerline is notperpendicular, causing tape at the rollerdeviation. Deviation ends should adjustmentto the conveyor belt running direction. Atthis often need to adjust the adjacent groupsof order to achieve the purpose ofeliminating deviation; adjusting deviationangle should not be too big.B. Conveyor belt joint with the tape centerline(trumpet) is not perpendicular, to cause thedeviation, should improved installationconnection accuracy to eliminate deviation.C. If material loaded on the conveyer belt isstraight; make the material block and weightdistribution along bandwidth directiondistribution serious inequality, causedeviation, through adjustment blanking tubeand skirt plate location method to beeliminated.Recently, it was suggested that the method ofapplication film for transfer partial conveyor beltbecause of high manufacturing costs and sometechnical problems not well solved, makes thismethod very difficult to promote the use.Solutionsa. In the roller manufacturing process guarantee theaccuracy requirements, for example, pressing bearingbore to achieve three precision, tubes at both ends ofdimensional tolerances, concentricity and ovality mustmeet national standards. The products have strictquality inspection to ensure that all products qualified.Sealed lubrication, in addition to manufacturing qualityassurance, go with good lubricating materials. Such asuse of lithium-based grease, can improve thelubrication of bearing which extend the life of theroller is necessary.ISSN NO: 2250-3536 VOLUME 2, ISSUE 3, MAY 2012 199

International Journal of Advanced Technology & Engineering Research (IJATER)b. Bearing used to ball bearing support, plasticsealing ring labyrinth seal structure, this canensure roller worked reasonable force, whileensuring dust effect good, resistance small, easyassembly and disassembly, easy to maintain,reduce conveyor operating costs.c. For gearboxes (geared wheel and bearing) andpulleys (bearings) may use a vibration measurebased techniques [2] and temperaturemeasurement for bearing.d. For idler condition thermography measurementor noise may be used [13].e. For belt with steel cords nondestructivetechniques may be applied(measurement ofmagnetic field of steel cords)[14].for belt jointfor condition measurement some magnetic fieldsource may be placed in a joint area and by themeasurement of magnetic field the distancebetween these points may be easily calculated[15]. In order to detect cut of cover it wasproposed by one of belt produce to place kind ofelectromagnetic field transmitter. If belt is cut,electric circuit will be damaged and transmitterwill stop working [16, 17].ConclusionWide ranges applications of belt conveyors, and the workenvironment is generally more difficult, to keepequipment running in good working condition, extendequipment life, improve the quality of operation, reduceoperating costs has been the goal of engineering andtechnical personnel. Analyze and resolve the impactnormal operation of the main problems, to ensure thegood functioning of device, it is an important work ofequipment maintenance. This paper analyzes the proposedmethod. Helpful improve site maintenance staff levels tosolve practical problems, for practical project hasimportant significance.REFERENCES[1] Belt conveyor for bulk materials, fifth edition. Theconveyor Equipment Manufacturers Association, CEMAPress, USA, 1997.[2] BARTELMUS W., Condition Monitoring.OpencastMining Machinery, Published by Śląsk,Katowice, 1998.[3] Internal Materials from KWB Bełchatów Mine.[4] KOSTANSKI D., Failure analysis of belt Conveyorsystems in KWB Konin mine, Diploma Thesis, MiningFaculty (Supervisor Dr. R. Zimroz), Wroclaw 2008.[5] MATUSZEWSKI P., Condition Monitoring inBOT KWB Belchatow mine. Diploma thesis Mining,Faculty (supervisor prof. W. Bartelmus), Wroclaw 2007.[6] SKOC A., Dynamics of bevel gears in miningMachines, Mining, No. 226, Silesian University OfTechnology, Gliwice 1996.[7] GLADYSIEWICZ L, KROL R.,ConditionMonitoring of idlers. 1st Conference on Mechanization ofMining Industry, Institute of Mining MechanizationsSilesian University of Technology, 2002.[8] KROL R., JURDZIAK L., GŁADYSIEWICZ L.,Economy of Belt Conveyor Idlers Renovation Based OnResults of Laboratory Tests. Industrial Transport, nr2(2)/2008, Wroclaw 2008.[9] GŁADYSIEWICZ L., Belts Conveyor – theoryAnd calculation, WUT Press, Wroclaw 2003.270 R.ZIMROZ, R. KRÓL[10] HARDYGÓRA M., WACHOWICZ J.,CZAPLICKA-KOLARZ K., MARKUSIK S.,Conveyor Belts, publ. by WNT Warszawa 1999, ISBN83-204-2402-X.[11] JURDZIAK L:, Failure analysis of textile andSteel cords belt used in KWB “Turów mine”,Industrial, Transport, 2002.[12] Effectiveness analysis of KWB Konin for periodJanuary–September 2007, unpublished Internal materials[13] DUDEK D., FALKOWSKI M., SZTORCH S.,Termography for condition monitoring – Experience fromKWB “Konin”. ExperimentalTechniques in machineoperation, 3 rd Conference, Szklarska Poręba, 1997,Wroclaw,Institute of Design and operation WUT, 1997, s.219 233.[14] KWASNIEWSKI J., MACHULA T.,Diagnostics of steel cords belts Industrial, Transport,2006, Nr 4 (26), s. 22–24.[15] MAZURKIEWICZ D., Monitoring theCondition of adhesive-sealed belt conveyors inOperation, Eksploatacja i Niezawodność, nr 3,2005, p.41–49a.[16] The system for damage detection for belts,Becker Mining System.[17] SZCZYGIELSKA M., MRÓZ J., BROJA A.,AUGUSTOWSKI W., The system for damageDetection For belts. Mechanizacja I AutomatyzacjaGórnictwa, 09(369), 2001.[18] BARTELMUS W., Root cause analysis. Insight,Journal of British Institute of Nondestructive Testing,2006.[19] Failure analysis of belt conveyor system byRadoslaw ZIMROZ and Robert KROL[20] Yixiang Lang. Transportation machineryEquipment in thermal power plant.[M]NortheastDianli university book; 1998.08.[21] Lihua Zhao. Operation and Maintenance of CoalHandling System in Thermal Power Plant,[J].Colliery Machine; 2011, NO. 02.[22] Lihua Zhao. Typical failure analysis andProcessing of belt conveyor [J].Hoisting andConveying Machinery; 2003, NO 10.[23] Lihua Zhao. The adjustment method of conveyorBelt deviation [J]. Colliery Machine. 2001. No.05.ISSN NO: 2250-3536 VOLUME 2, ISSUE 3, MAY 2012 200