Engineering Systems and Components of Centrifuge

Engineering Systems and Components of extractorDescriptionThe important job of the horizontal decanter centrifuge is to sepa prize poppycocks of different densities. In this system, the centrifuge is require to separate the olive oil from water and either other solids such as stones.The decanter centrifuge ( image 1) is part of the olive pressers fiction line make up of four main machines de-leafing washing, olive crushing mill, horizontal malaxer, and the centrifuge. Figure 1 shows briefly what the assembly line consists of.The commentarys into the centrifuge atomic number 18 olives which have undergone a number of processes by the other main machines of the olive presser assembly line. These processed olives are referred to as streak. This cake is the input of the decanter centrifuge and contains stone, water, other chemical additives, and oil.The centrifuge uses the concept of sedimentation to separate the cake into heavy liquid and light liquid, the lighter liquid b eing the olive oil, which is the output required from the system. canonically, collect to the difference in densities the cake and oil leave separate naturally given enough time (the oil floats on top of the cake). The centrifuge speeds up this process using high rotational speeds, exerting up to 4000G on the cake. This is useful since a process that would take hours to achieve could happen in a amour of seconds. The centrifuge rotates at high speeds, resulting in the insulation of the contents inside the centrifuge according to their density, allowing the olive oil to be retrieved from the system 1.ADD SCREENSHOT OF separatorOverview of OperationThe cake is input to the system through a small inlet tube encased in a wider irradiation. This sweep has an Archimedean spiral, i.e. the rolling wave, welded to it. The shaft together with the scroll is called the conveyor, and it is encased in a perplex. The shaft, and thus also the scroll is turned by a motor pulley system. T he cake immixs into the scroll area where separation of the olive oil from the cake occurs due to the high Gs generated by rotation and the angle at one curiosity of the scroll. The olive oil and waste are output through nozzles at opposite expirys of the centrifuge drum.The centrifuge is attached to the frame using a pillow block head. The frame supports the entirety of the system.Basic Sizing RequirementsBy comparing to existing centrifuges, the optimal drum diameter and rotational speed are 425 mm, and 3800 RPM respectively. A 14 be after ratio (drum diameter compared to the drum length) is adopted, resulting in a centrifuge length of 1700 mm 2. A beach angle of 200 is taken, as explained in accessory 1.Specification SheetCentrifuge SpecificationsCentrifuge TypeTwo-phase HorizontalMaximum Overall Length3 mMaximum Overall Width1.5 mMaximum Overall Height1.5 mInput Rate450 kg/hCentrifuge RPM3800Centrifuge Beach lean200Centrifuge drum diameter425 mmCentrifuge diameter to l ength ratio14Centrifuge Length1700 mmCentrifuge shaft outside diameter120 mmTree DiagramThe following tree diagram is a graphical representation of the centrifuge and its sub-systems. Please turn over to find the higher up mentioned tree diagram.Block DiagramThe following block diagram is a graphical representation of how the centrifuge works in set up to extract the oil from the olives. This graphical representation will provide a better understanding of how the sub-systems interact with one another. Please turn over for the above mentioned block diagram.Brief explanation of the elect componentsDrive Frame (Figure 2) A tray to which the motor is bolted down to stay in position. It is attached to the legs of the centrifuge lower casing. It determines the outgo amid the shaft of the motor and shaft of the centrifuge.Figure 2 Drive FrameCentrifuge Frame (Figure 3) The overall frame of the decanter, this supports the entire structure of the centrifuge.Figure 3 Centrifuge FrameUpp er Casing (Figure 4) The Upper casing covers the drum of the centrifuge. It blocks contaminants from making assemble with the drum and restricts the user of the machine from making run into with moving parts, providing better safety.Figure 4 Upper Casing Lower Casing (Figure 5) The lower casing acts as a collector for the products fulfill from the rotating assembly and transports them to receivers for onward handling. The casing has to keep these separated entities apart. So it can be concluded that the casing as an oil collector at one end and a cake discharge collector at the conical side.Figure 5 Lower CasingFeed Tube (Figure 6) A tube that the cake is transported to the centrifuge from the malaxer. This is also the input of the centrifuge. Its inner diameter is determined by its required input devolve rate.Figure 6 Feed Tube3-phase locomote (Figure 7) The motor provides the initial torque required to rotate the sing. The motor chosen is the AEG AM 132M ZA4*3, a 3-phase mot or which provides 7.5kW of power, with the possibility of increasing the power up to 9.2kW through a small modification, making this a flexible choice.Figure 7 3-Phase motorBelt (Figure 8) The Flat overhead connects the pulley of the 3-phase motor and the centrifuge drum together, transferring power. The chosen Flat- tap is a Polyamide A-3c overhead since it provides the appropriate thickness, allowable tension, and coefficient of friction, while also being appropriate for the minimum pulley diameter.Pulley (Figure 8) The pulley is apply to modify the speed of the drum and is connected to the motor.Key A 8 x 10 mm rectangular key 70 mm foresightful is added to the motor pulley in order to make sure that the pulley spins together with the motor shaft in such a way that in that location is no relative motion between the two.Figure 8 Belt and PulleyBelt Guard (Figure 9) The purpose of the bang guard is to protect the belt and pulley system from any accidents. It foresees contac t of the belt with any foreign objects by stopping them from entering the belt area without removing the guard first. This whitethorn prevent injuries and breakages.The guard also keeps the belt area clean from any residual debris generated during the process. It can be easily removed for maintenance and cleaning.Figure 9 Belt GuardFigure 10 Drum shell with Archimedes screw insideDrum The drum (Figure 10) is a cylindrical tube with flanges at twain ends. At one end, the liquid discharge drum hub, this is where liquids are discharged from the centrifuge, while on the other side the cake discharge hub is connected, this is where solids are discharged from the centrifuge. The separation medium reaches its maximum speed in the decanter drum. This causes the solids to settle on the wall of the drums inner diameter. This is all a result of the high outward-moving wedge, which acts on the particles.One distinctive feature of the drum is its tapered figure out. This tapered shape is ref erred to as the beach. The beach is a conical section at the end of drum. It has this conical shape to exert additional force on the solids, hence squeezing out the last drops of liquid. In this part of the process the centrifugal force push the solids uphill. This design avails to elevate the solids above the waterline in the discharge chamber.Figure 11 Bearing Setup 2Front hub bearings This horizontal setup (Figure 11) is back up by the use of bearings which are cased in a pillow block. Bearings are used to reduce friction and the effects brought on the component through wear and tear. This bearing used in this assembly is a roller bearing. The roller bearing is a bearing in which the main load is transferred through elements in rolling contact.Pillow Block The fundamental application of the pillow block is to mount the bearing safely, which enables the bearings outer ring to be stationary, while the bearing inner ring to rotate. The bearing is supported in a housing and sealed with a non-contacting flinger. This non-contacting flinger is a seal, as the name implies it does not come into contact with the shaft. Its main application is to keep lubricants and grease from escaping, while at the same time it helps keep water, dust and other contaminants that could be harmful, out of the bearing assembly. It does this with the help of the centrifugal force.Rear hub Bearings The rear hub bearing assembly is similar to that of the front hub. Its main job is to support one side of the conveyer. This bearing also resists the axile thrust of the scroll.Figure 12 Generated 3D Representation of Conveyor.Conveyer The conveyer (Figure 12) is a central hub with a continuous helix welded to it. The conveyer is in the shape of an Archimedes screw fitting inside the drum, between the 2 end hubs. This conveyer will have a small clearance in relation to the drum. It main job is to carry solids which have settled against the walls of the drum, then pushing these solids toward s the beach where they can be discharged. Its main functions are to convey the solids after they form a cake, accept the feed and accelerates it up to the drum speed. The material used is EN 1.4571 which is a form of high speed steel (HSS). The conveyer is the transport calamus in a decanter centrifuge. The conveyer rotates with a different speed in relation to the drum, subsequently transporting the settled solids towards the conical shape of the drum. Also, the speed at which the conveyer rotates in relation to the drum defines how long a solid spends in the drum. The pitch of the conveyer is related to the transport performance of the centrifuge 2.This conveyor is comprised of two main sub-components the scroll, and the shaft. The scroll is welded to the shaft, which rotates. While the two obviously need to be machined separately and welded together for economic reasons, they will be considered as a single part the conveyor.Calculations Nomenclature multivariate (Motor)Descripti onPPowerTTorqueAngular velocityVariable (Flow)DescriptionV intensivenessACross-Sectional Area of segmentLLength of segmentcakeDensity of cakeVariable (Belt)DescriptionDDriver/Motor pulley diameterdDriven/Shaft diametern1RPM of shaftn2RPM of motor pulleydAngle of contact for shaftDAngle of contact for motor pulleyCDistance between centrestThickness of beltbWirth of beltlLength of beltSpecific weight of beltDensity of beltVVolume of beltmMass per unit length of beltrRadius of pulleyRotational VelocityFCCentrifugal force on beltF1Tension in tight side of beltF2Tension in loose side of beltFiInitial force required to overcome frictionCoefficient of frictionFRResultant force of belt on shaftVariable (Deflection)DescriptionEYoungs modulus of materialIMoment of Inertia of shaftyDeflection in shaftVariable (Bearings)DescriptionP1Weight of conveyorP2Force exerted on shaft by beltRA reply at bearing ARBReaction at bearing BVariable (Shaft)DescriptionBending StressShear StressMMaximum Bending Momentc satellite radius of shaftIMoment of Inertia of shatTTorque appliedJPolar Moment of InertiarouterOuter radius of shaftrinnerInner radius of shaftCalculations and SizingMaterial SelectionSince the machine will make contact with biological materials, certain characteristics and requirements have to be met in order to ensure that the parts making up the centrifuge will not chemically alter or affect the product in anyway. A list of materials suitable for food processing has been compiled by the FDA, based in the US. The 6th iteration of this code, released in 2013, gives specific requirements with regards to materials used in food-contact surfaces of equipment in chapter 4, subpart 4-101.11. Among these requirements are corrosion resistance and durability. Considering this, the material chosen for all the parts that will come into contact with the product namely the centrifuge and its casing the chosen material is EN 1.4571 Stainless Steel, which suitably fits all relevant requi rements. 4REF FDA?Calculations to find motor required Aim To find the torque required to turn the shaft at a speed of 3800 RPM, which has been determined to be optimal for this machine (Figure 13) and thus find the power needed and an appropriate motor.DiagramFigure 13 3D diagram of power transmission systemDue to the complex effects of fluid flow on the resistance to turning, the required torque for surgical process will be found by reverse engineering a similar system.HAUS Centrifuge Technologies produce a horizontal decanter centrifuge that has a maximum RPM of 5400, and utilizes a motor with a power output of 11 kW that can process up to around 1 m3/hr of material 5. This is sufficiently similar to the system being discussed in this report and can thus be used to reverse engineer the torque requirements during becalm state.Using the compare Pdrum = Tdrum, the required torque may be found.Thus, the required power for the system will beSince the reverse engineered system accou nts for power losses due to inefficiencies and other factors, as well as the fact that that system has an overall bigger processing capacity, the required power value obtained can be assumed to slightly larger than the true minimum requirement. However, this will account for any power losses during transmission as well as any potential extra power demands.ConclusionsThe chosen motor is the AEG AM 132M ZA4*. This has a maximum of 1440 RPM and 9.2 kW of power, with an efficiency of 87% when operating at light speed% RPM, and a weight of 56kg. This is a modification of the AM 132M ZA4 motor, which only produces 7.5 kW of power 3.The AM 132M ZA4* is a 4-pole, 3-phase motor, single-speed become. The motor has a single drive and is an asynchronous type motor with an Aluminium frame. It also has an IP 55 rating, making it somewhat resistant to dirt, debris, and water a useful property for this use case, where spillages and leakages may occur.The motor manufacturer also specifies that th e chosen motor has a shaft diameter of 38 mm, and a key of 10 x 8 mm should be used for any pulleys, with the keyway being 5 mm deep and 10 mm wide. The key should have a length of 70 mm 3.Calculations for the sizing of the inlet tubeAim To find the required dimension of the inlet tube so that an appropriate amount of material will be input at an appropriate speed.DiagramFigure 14 Diagram of flow in inlet pipeIt must first be ensured that the flow rate in the inlet tube (Figure 14) will be sufficient to allow for the design specifications. In this case, the design is specified as having an input rate of 450 kg/hr.It is assumed that the cake will have a density, cake of approximately 2000 kg m-3. Thus, the appropriate inner radius may be found.Converting the input rate to m3/hr m3/hr. This results in 6.22510-5 m3 s-1 flow rate.For a system of this kind, the flow velocity is generally in the range of 0.5 to 2 ms-1. For the sake of calculations, it will be assumed that an appropriate velocity for this specific system will be 1ms-1.ThusCross Sectional Pipe Area = Area = r2, therefore = 4.46 x 10-3 m.Thus, an inner radius of 5mm can be chosen. This will result in a slight decrease in flow velocity, (down to 0.8 ms-1), however this is well inwardly the ideal range. Seeing as this pipe will undergo no torque and very little forces, a standard 2mm thickness can be taken.Power Transmission The centrifuge shaft is required to be turned at a constant speed. The load is determined mainly by flow and amount of cake in the system, which are controlled through a process done by another system. Thus, the load on the system may be assumed to be largely unchanging. The torque required is also relatively low.As such, a belt and pulley system is an appropriate choice for drive transmission. This is cheaper than a gear train, and is also easier to maintain and replace if required. This also reduces the size of the entire assembly, as the motor may be placed laterally, with the s hafts being latitude to each other.A flat belt is chosen over a V-belt. While the wedging action of a V-belt means that more power can be transmitted, flat belts are more efficient, having a 98% efficiency. Flat belts also generally have a longer work life. Most importantly, flat belts may be used across large centre distances, unlike V-belts. Thus, due to the nature of the setup a flat belt system is more appropriate. 6The larger pulley must also be crowned (curved slightly) so the belt may be kept tracking centred on the pulley 7.Flat-Belt CalculationsAim To take the forces acting upon the belt, determining friction and tension due to transmitted torque, in order to find forces and stresses on the shafts.Assumption A polyamide A-3 flat belt with thickness 3.3mm is used to calculate the forces present 8.Figure 15 Diagram of belt and pulley systemThe outer diameter of the centrifuge shaft has been chosen to be 120 mm. To find the corresponding motor pulley diameter, D (Figure 15) required in order to spin the centrifuge at the required 3800 RPM, assumptive the motor will turn at its rated speed of 1440 RPM, the following relationship is used.dn1 = Dn2Where n1 and n2 are the RPMs of the respective shaft0.123800 = D1440D = 315.57 mmThis will be approximated to 0.316 m (or 12.5 inches), the closest standard pulley size. For this size, the crown of the pulley should be 1 mm high 9.Determining the angles indicated 8 = sin-1() = 0.197where C = 500mmd = 2sin-1() = 2.747D = + 2sin-1() = 3.536Length of belt, L = = 1.704mThickness and width of belt, t = 3.3mmb = 75mm (standard belt width chosen arbitrarily)specific weight of belt, = 0.042lbf/in3 = 1162.56kg/m3Volume of belt = t x b x l= 75 x 3.3 x 1704= 421.74 x 103 mm3Mass of belt = V = 1162.56 x 4.2174 x 10-4m3 = 0.49kgMass per unit length of belt, m = = 0.2877kgm-1It can be shown thatFrom dS = mr2 d where dS, is the force due to centrifugal force= FC dThis implies FC = mr22= = 163.34NThe difference in tens ion between the 2 sides of the belt is given byF = F1 F2 = = 109.3NFor initial tension Fi,Equating Fi with the force required to overcome frictionFi = T2 e from friction equation T1 = T2 eThe negative sign indicates that this is the force that must be overcome.To find F1 and F2 , Tension in the belt where T1 is the largest tension, to be FI = 0.8D = 3.536CT2 = F2Since, F2 = Fi + FC F2 = -F2 e0.8 x 3.356 + FC F2 = F2 e0.8 x 3.356 + 163.34 1 e0.8 x 3.356 F2 = 163.34 Therefore, F2 = F = F1 F2109.3 = F1 6.06Therefore, F1 = 115.36NFinding the radial resultant force on the shaft,It can be assumed that the force will act approximately radially for the sake of calculations.By geometry = sin-1 = 0.197c = 11.3oFigure 16 Diagram showing forces acting on driver pulley result horizontally (Figure 16)(115.36 cos 11.3) + (163.34) + (6.06 cos 11.3) = 282.40NSolving vertically(6.06 sin 11.3) (115.3 sin 11.3) = -21.42NFR = = 283.45N = tan-1 = 4.34oCalculating FC for the smaller pulley using the equation FC = mr22= FC = = 164NSince FC for the bigger pulley = 163.3N, the resultant force FR will be approximately the same as previously found for bigger pulley.The chosen belt has an allowable tension per unit width of 31 N/mm, thus the chosen belt may withstand a tension up to 2325 N. Thus, the chosen belt is appropriately sized to