Development of Air Compressor Lubrication

Development of line of business Compressor LubricationIn this project, the mission which needs to be pull throughed is to investigate the relentless root cause of such misery and to give useful recommendations which can help to avoid such failures in the reciprocating compressor under study in the future. An engine driven addendum demeanor compressor failed, the ancestrywave compressor is located in the Hawke workshop. The first tier give be to establish details about the compressor, the manufacturer and how the compressor works. Classification of compressors and casings give be besides discussed and of die hard the theory of unconscious process. Collecting components failed in order to be examined subsequently for the failure cause or causes this eitherow be held employ a variety of methods. NDE (non-distractive examination) or NDT (non-destructive rivuleting) is valuable way to use for preliminary inspection of the failed digresss without damaging it. DT (destr uctive test) is another way to instruct and inspect part entirely this inspection method appears from its pass water it lead do destructive ravish the tested parts which bequeath be no longer able to be used. Fatigue principles too will be showed. Studying all the above will gave a clear subject about the cause of the damage.Discussion of the probable causes for the failure hale be performed in the following chapters as well as the conclusion obtained from study conducted.1.1 Int celestial pole celluctionAir compressor producing is return for long metre past. The main idea of compressing reapingion line travel and discharge it used by the ancient in deferent ways. The first usage for the air compressor is increasing the combustion of furnace.The air compressor is upb abuting the heat of the furnace by bellowed nasty air to it. Moreover, the main products got from these furnaces are metals and weapons.Muscles were the main power source for the air compressor. The belo w call for a line shows the old air compressor. That large-minded of old air compressors still used in different productions.This project will investigate and analysis a failure happened in an air compressor. This investigating will be through in several(prenominal) ways to figure out the cause of the failure. Air compressor is a machine has the ability to compress the air and release it to convert the electrical power to kinetic energy to use it in several industrials and usages. Air compressor is consisting of many components. These components are electrical motor, plungers, air pump, air receiver, air drier, filters, air pressure level regulator and pressure switch.all(a) of these components will be discussed in details in the next chapters. on that point are withal faces of air compressor will be discussed later.1.2 BackgroundThe illustration which had here is a failure in an air compressor. From the first sight on the damage happened in it, it seems to be that the fail ure happened in the connecting rod and its obvious from the below figure number 3. This figure shows that the failure happened in the connecting rod from the ring part which affiliated to a crank guesswork. But the reason for this failure is unknown as there are several scenarios could be adopted. The first scenario is the fatigue is the reason for this failure. The secondment scenario is a very heavy pressure loaded to the compressor which led to that failure. These are the near expected scenarios which will be investigated later in this project to figure out the reason of the failure.1.3 Amis and objectivesAimsThe main aim of this graduation project is to investigate and discover the cause or the causes of failure of diesel engine driven auxiliary reciprocating air compressor made by Knorr-Bremse, rooml number is LP 4865. This will be achieved by carrying out the below objectives, once its achieved, the main aim of the project will be achieved.Project objectivesCollecting val uable knowledge about, model number is LP 4, this will include design of compressor, design of each part, construction materials of each part, proceeding principles, working theory, production ambit..etc. collecting data will help to recognize main failure cause, and accordingly to prepare new procedure to eliminate the problem, to come down the opportunity of failure occurrence in the future, use greater safety factor and to recognize the person or the entity answerable for failure and to make slue proofing for future avoidance of the failure. Collecting this background information is not limited to numbers only but it is should be extended to every deoxidiseg such as pictures, charts and graphs and samples. canvas operational parameters, history of operation, nature of operation..etc in order to be able to determine precisely the root cause of such failure and which failure mode it follows.Physical investigation or macroscopic inspection should be carried out. This mission i ncludes photo capturing, code of the product, model number, lot number, batch number and serial number. do compressor disassembly in order to dismantle each component, part, assemblies and sub-assemblies to perform through investigation and inspection of each. Its should be mentioned that necessary tests and analyses should be performed mainly the manufacturer normally has his own procedures and tests for test and inspection.2.0 Air CompressorWhat is the air compressor?Air compressor is a machine that converts electric power to kinetic energy (motion). This energy comes from pressurizing and compressing air. aft(prenominal) that, the compressed air goes into a chamber, and the air kept in the chamber by unidirectional valve. there are many types of compressors these types are reciprocating compressor, orbitual get it on compressor and outward- travel compressor. These types will be explained in details below.2.1 Reciprocating compressorReciprocating air compressor is positive d isplacement compressor. This compressor sucks a volume of air and presses it with postgraduate pressure. This pressure through by using a piston and cylinder as movement part and displacement part. The compressor could be wizard acting or double acting according to its accomplish by using one side or both side. When the pressure difference between the cylinder and the receiver became straight-laced, the valves open. Inlet valves open when the pressure in the cylinder is roughly below the intake pressure. Discharge valves open when the pressure in the cylinder is slightly above the discharge pressure. The compressor could be a single stage when the compression process done parallel.AdvantagesSimple design.Lower initial cost.Easy to install.High efficiency with 2 stages.No need for lubrication.Large range of horsepower.DisadvantagesMaintenance cost is racy.Many moving parts.Vibration problems.Foundation possibly requisite.Not running at full capacity all the time.2.2 Rotary scr ew compressorAlso Rotary air compressor is a positive displacement compressor. Single stage helical or spiral lobe oil flooded screw is the most common in rotary air compressor. This compressor is consisting of 2 rotors located in a case where the air is compressed internally without any valves. The cooling for these compressors done by oil. As the cooling for the working parts happened inside the compressor, this type of compressor will not experience over heat imputable to operation, so it could hold up without stop. Due to the simple design of the rotary screw compressor and its parts it can be keeped easily and installed any where could handle its static weight. The 2 stages rotary air compressor uses 2 rotors with a combined air end. This 2 rotors installed in series to share the compression. This raise up the efficiency with 50%. This 2 stage rotary compressor combined the maximum profit from the rotary screw with its simplicity and flexibility and the reciprocating compres sor with its effective energy when it works 2 stages with double acting. The 2 stages of this compressor could be cooled by water, air or oil. The cooling system for this compressor could be oil, air and water.AdvantagesSimple design.Low initial cost.Low maintenance cost.Good efficiency at 2 stages.Easy to install.Few moving parts.Common in use.DisadvantagesLimited liveliness for airend.Service for airend couldnt be done at field.High rotational speeds. essential be oil lubricated.Single stage has low efficiency.2.3 Centrifugal compressorThe centrifugal air compressor is a dynamic compressor that depends on transfer of energy from a rotating impeller to the air. This done by changing the airs momentum and pressure. By slowing the air in stationary diffuser the momentum converted to pressure. This compressor is oil free compressor. There is a separation between the lubricated oil and air by shaft seals and atmospheric vents. Where the high volume of dry air is required a centrifugal compressor is the proper compressor as it has a few moving parts and could operate continuously.2.4 Rotary Sliding Vane CompressorsRotary sliding Vane Compressor is in like manner a positive displacement compressor. This type of compressor is consisting of rotor and stator and eight blades. Between the intake and exhouset valves a cresent shape formed by the location of the rotor and stator. The compression achieved by one complete rotation as the volume changed from the maximum to minimum. Vanes are pushed outward against the stator walls. Injecting oil from the intake valve and along the stator wall to cool the air and make a sealing between the stator wall and vans and also to lubricate bearings. So that a filtration system must(prenominal)(prenominal) be installed to separates the oil from the compressed air.AdvantagesSimple design.Easy to install.Low cost.Maintenance cost is low.Reliable.Few moving parts.DisadvantagesSingle stage.Low efficiency.Must lubricate with oil. tro uble nigh with over pressure.2.5 Main Component of Air compressor in generalThe system could be installed in 2 methods. The first method is where air drier onward receiver tank. The second method is where the air drier after the receiver tank. These components will explained in details in the below paragraph.Receiver tank From its name receiver tank is a tank that receives the discharged air. It helps to forestall rapid compressor cycling by providing a storage capacity. The advantage for the receiver tank is cut down the wear and tear in motor, inlet control system and compression module. It also eliminate the flow pulsing.Air Dryers there are 3 types of air bone dry(predicate). The main objective for air sunbakeds is to dry the air to prevent rust and wearing in the air compressor components and discharge line. These types areRefrigerated air dryers This dryer used a mechanical technique to remove moisture from compressed air and cooling it and condense water.Desiccant dryers This dryer is absorbing water desiccation by using utilizes chemical drops called desiccant. The common desiccants used in this dryer are silica gel, molecular sieve and activated alumina.Deliquescent air dryers This type of dryer using desiccant to dry compressed air. The wetness in the compressed air reacted with the absorption material and turned into liquid which drained from the dryer. This process could be corrosive so the corrosion check has to be done.Filters Filters are installed to remove the lubricants and water from the compressed air. It could be installed downstream at refrigerated air dryer or upstream at desiccant dryer. The most common in filters is coalescing filter.But this filter it only can remove liquid and water which contribute been previously condensed.Piping Distribution systems Piping distribution system is controlling in how the compressed air go out to the tools and also determined the required energy for the air compressor.2.6 The reciprocating air c ompressor (knorr-bremse, model lp 4865)The main study object in this project as said before is to study the reciprocating air compressor (knorr-bremse lp 4865). By searching the internet and try to get information about the air compressor which needed to complete this study but unfortunately the required information couldnt be found except its maximum pressure 12 bar and volume 460 . So the general information about the reciprocating air compressor will be mentioned kinda of the specific air compressor.There are 9 main parts for the reciprocating air compressor these parts areCrank case Crank case is a close rigid body where the crank shaft and the bearing house where located. This body could by rectangular or square shape. Mainly crank case formed by using cast iron.Crank Shaft Crank shaft in one of the most important parts in air compressor. It is a motion transferor. It intentional as one piece has balance in its dynamics and tries to avoid any twisting. To ensure a long life sentence for bearings, the polishing and crank pin will be done. Generally crank shafts have a fly wheel. This crank shaft manufactured mainly of high grade S.G iron.Connecting rod This part is responsible of transfer the motion from the crank shaft to the piston and changing the direction from the rotating motion come from the crank shaft into reciprocating motion in piston. This part is mainly forged of alloy steel.Bearings Bearings are made to provide the rotating gear with rigidity. Its mainly manufactured of copper lead alloy. hybridizing slide to get a perfect running for cross head, this part is responsible for reduce the inertia. This part is commonly manufactured of high grade S.G. iron. cylinder This part is where the air flow passes and compressed. Cylinders are manufactured with water jacket to reduce the generated heat from the compression process. This cylinder mainly made of cast iron. plumbers helpers Piston is the main part in the compression process, which move for ward to compress the air and backward to intake a new air amount to compress. There are 2 types of piston according to its lubrication system, the first type is non-lubricated which made from atomic number 13 alloy, and the second type which is lubricated is made from cast iron. Due to moving of piston in the cylinder, so there must a space exist between them, to ensure there is no leak happened for air a piston rings located on piston.Piston rod Piston rod is this rod which connects the piston to the connecting rod. The piston rod is manufactured of alloy steel. using up and discharge valves These valves are responsible for the amount of air sucked or discharged. When the piston in the retraction position the suction valve open to allow the air to get in. when the piston move forward and reach the maximum pressure the discharge valve open. These 2 valves are adjusted to be opened and closed according to the pressure difference between inside the cylinder and the outside. These val ves are made from stainless steel even a plate type or spring type.2.7 Air Compressor LubricationDue to the operation of the air compressors which have different moving parts, a friction must be occurring. This friction generates heat and not just that it leads to part wearing which probably lead to a failure. And some time a kind of sealing need to be installed to prevent the compressed air from leaking. All of these reasons lead to using lubrication. Oil lubrication is a must in air compressors to overcome all above problems. The lubrication method could be different from type to another, but the main idea is to prevent the friction between moving parts like lubricate the bearings, or at the same time in some cases like reciprocating air compressor it also works like sealing between the cylinder wall and the piston. The problem in lubricate the air compressor is the selection of the proper oil. The selected oil must be industrial oil with high quality and matching the operation re quirements. The surround of where the compressor will be installed is one of the parameter of selecting the lubrication oil, if the environment is too cold and the temperature is low the frizzing point, an anti-frizz oil must be use. If the environment is too hot oil with high viscosity and ability to heat opponent must be used. All of these restrictions must be considered while selecting the lubricant.These are the main idea of lubrications but the implementation is different according to each type of air compressor. The lubrication system changes from one type of air compressor to another according to the operation theory of it.3.0 Quality assurance for the manufacturing processAir compressors are designed to work in both the industrial and the privet fields, it designed to press gas or pressured air. During the air compressor operations leak or failure maybe happened and this will lead to a serious damage. The quality assurance purpose is to guarantee if the production is safe a nd ready to use or if rejected and have defects. This operation done by two methods the first one is the destructive test which meaning that the tested object will be destructed and no longer could be used and this type used in the initial design and on the first production to be sure of it. The second test is called the non-destructive test (NDT) which means we can make our test and be sure if the production is good to use or not without destructing the production. This type (NDT) what we are going to focus on because its the most common method in inspection.The definition of the NDT is its a test methods used to examine an object without impairing its future usefulness. There are a several methods in NDT used likeVisualMicrowaveThermographTap testingX-rayMagnetic particlesAcoustic MicroscopyAcoustic emissionMagnetic measurements fluent penetrateUltrasonicFlux LeakageEddy currentReplicationLaser interferometerAll of the above methods are used in NDT, but in our case we will go to use the common methods and try to clarify its operation and how to use.Visual inspection It the most common and basic inspection method. In this method we can use fiberscope, bore scopes, magnifying glasses and mirrors. Another technology could be used as electronic microscopes have the ability to enter the undertake places inside the air compressor.Magnetic Particle Inspection This inspection could be done by magnetize the inspection part. After that coloured particles of iron cover the inspection area. These particles of iron will spread to the magnetic flux and show the discontinuity area. By applying the proper light this inspection could be checked by visual.splinedflour skiagraphy To perform this check a shot waves with high energy is used. Radioactive source or X-ray machine could generate such waves. The part which will be tested will be located between the radiation source and a film. This part will prevent some of the radiation. Thick areas will stop more waves. This will lead to variation on the film darkness the thick part will be less dark and the thin or cracked part will be more darker.RAD1CastingCastingRadEddy Current Testing This type of test is used to discover the crakes on the surfaces. It also could be used to test the thickness of coating of the surfaces.eddy.PNGUltrasonic Inspection To use this test a high frequency sound wave is apply to the surface of the part. These waves are reflected waves which will be reflected from any crack inside the material. This sound wave are reflected into the device which will show the reflection time on a gage this gage could show the depth of the crack by time of reflection. It could also be connecting to a computer by using a computer program which will draw a diagram of the part and the crack location.Liquid Penetrate Inspection To apply this type of test a liquid with high moistening spread over the tested part and gave time to leak into the crakes. After that the rest of liquid is removed from the surface. After that a special powder spread over the surface to get the stuck liquid out from the crack. The crack will appear and could be discovers by eye. To gain the sensitivity and accuracy of this test it could be done under ultra violet light.For the above types of NDT there is some common application where they also could be usedInspection of Raw ProductsForgings.Castings.Extrusions.Inspection Following Secondary ProcessingMachining.Welding.Grinding.Heat treating.Plating.In-Services Damage InspectionCracking.Corrosion.Erosion/Wear.Heat Damage.3.1 FatigueThe metier of the product is the most important safety factor. To be sure that the product will be safe and could stand the applied loads safety factor must be added to the design. During the operation, parts experience a non-constant loads which lead failure along with time.Fatigue could be defined as a failure happened cod to a rapid variation in loads, but without any of this load variations exceed the maximum load. Th is type of failure happened commonly in metallic materials not only but also in different materials. There are 3 stagers for Fatigue, these stages are1. Initial crack.2. Propagation of crack.3. Final fracture.3.2 How to analysis fatigue to prevent itComponent material and stress field are the main 2 principals that govern the amount of time needed for crack to start and spread criminate a failure. There are 3 main methods to calculate the fatigue time, these method areSN manner To predict a fatigue life for a part stress life approach could be used. This method gave the fatigue life for the object. This method is depending on the calculation of varying elastic strength so it couldnt be applied to low fatigue cycle. But this type of test is very accurate at high fatigue cycles.EN Method This method is using plastic stress to calculate not only the fatigue life but also the crack penetration. The advantage of this method is that it could be used for calculating the fatigue in low li fe cycle and plastic life cycle also.LEFM Method Linear Elastic Fracture mechanism is used to calculate crack growth rates. This approach assumes that a crack is already present and predicts crack growth with respect to the stress intensity at the crack tip.3.3 Fatigues in AluminiumFrom previous fatigue studies done on aluminium, it seems to be that aluminium is a very good material with high resistance to fatigue. These studies which done on a certain alloy of aluminium, but in general the heat treatment for aluminium lead to a world-shattering in the fatigue life. Heat treatment also give aluminium high strength, excellent toughness and reasonable ductile. The crack initial behaviour of aluminium took place from the surface just like many metals and alloys.3.4 Aluminium PropertiesTo be familiar with Aluminium some properties must be considered and known, these properties areYoungs Modulus 70 GPa. ductileness Malleability High.Hardness 420 MPa.Density Low 2700 kg / cubic metre.Me lting Point 660.32 C Boiling Point 2519 C.Electrical Resistivity Low 2.65 x 10-8 Ohm metres.Reflectivity High 71% unpolished and when polished 97% .All of these properties gave a clue that Aluminium is the metal of the modern world. With its strong, lightweight, ductile and reflective it could be used for several industries and accomplish a great results.4.0 Problem AnalysisThe first problem in this study is that damage which happened in the connecting rod from ring which connected with crack shaft. As said in the background, there are 2 scenarios leads to this damage. The first scenario is a fatigue accrues in the connecting rod with lead to this damage as it couldnt stand the motion and the pressure any more. The second scenario is an excessive pressure more than the maximum pressure which could be hold by the compressor. At the same time a malfunction in the discharge happened, and this could be taken in consider as it must opened at slightly below the maximum pressure. In both s cenarios, the damage in the connecting rod lead to another greater damage in the piston and the cylinder, as the piston start to move in non-liner motion and burgeon forthting the cylinder wall. This leads to a serious damage in the compressors piston and cylinder.The second problem is gathering the information about the air compressor Knorr-Bremse Lp 4865. This problem happened as the manufactured company keep the information about this compressor not listed and its material and properties to figure out the reason of the damage, maybe by knowing its maximum pressure or material type to check the fatigue on it.4.1 Problem SolutionAfter studying all sercomestances and what happened during the failure happened, it seems that the failure happened due to a serious fatigue which is not noticed in a previous time. This fatigue happened to the aluminium alloy which connecting rod made from. An analysis done for the particles and it shows that the particles is consist of 88% aluminium. Thi s gave a thought about how serious was the fatigue in this movable part. As the connecting rod is responsible for transfer the power and motion from crank shaft to the piston, it experiences a load variation all the operation time. A crack must happened time ago on the surface of the connecting rod and it start to spread and choose the weakest area which is the ring where the crank shaft is hinged. This particular area is the weakest area in connecting rod as the thickness reduced to attach the crank shaft.To overcome the second problem a deeply internet search is made with trying to tactual sensation with the manufactured company through their website www.knorr-bremse.com, but with no result. So another technique implemented, which is gathering common information about reciprocating air compressor and its common parts and materials. This could be useful but not accoutre. There are 2 appendices attached to the project which have some data about the parts and how to maintain it gath ered from the company itself.4.2 ResultsAs a final result of this project, the damage which happened in the connecting rod accusing damage on the rest of parts is happened due to a fatigue. After the fatigue weak the connecting rod it reached a phase that the connecting rod couldnt stand any load. Just after the failure the piston starts to hit the cylinder wall, which accuses the obvious damage on the piston and the piston rings. To prevent such a failure in the future a regular check must be done for the concerning parts as scheduled in the producers manual. A life time calculation for all parts must also be done and make the replacement in its time. These procedures are going to prevent such a failure to happen again.