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

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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
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