Waste Cooking Oil to Biodiesel Automated Fuel Pump Project

AbbeyGireNateJeffery

JessicaSchulteJaredSnowRossVanDyk

ME450

Winter2007Section006KazuhiroSaitou

4/17/2007

TABLE OF CONTENTS ABSTRACT ..................................................................................................................... 1 INTRODUCTION............................................................................................................. 1 INFORMATION SEARCH ............................................................................................... 1 CUSTOMER REQUIREMENTS AND ENGINEERING SPECIFICATIONS..................... 5

CUSTOMER REQUIREMENTS................................................................................................5 ENGINEERING SPECIFICATIONS..........................................................................................5

DESIGNING A REDUCED SCALE PROTOTYPE .......................................................... 7 CONCEPT GENERATION.............................................................................................. 7

INPUT OF REACTANTS...........................................................................................................8 Gravity Transportation...........................................................................................................9 Pump Transportation.............................................................................................................9 Time Sensor for Grease Input...............................................................................................9 Level Sensor .........................................................................................................................9 Flow Meter Sensor ................................................................................................................9

FILTRATION METHODS ........................................................................................................10 Screen Filter........................................................................................................................10 Cartridge Filter ....................................................................................................................10 Bag Filter.............................................................................................................................10 Strainer................................................................................................................................10

MIXING METHODS ................................................................................................................11 Mixing Unit Inside Tank.......................................................................................................11 Pump Recirculation .............................................................................................................11

SEPARATION METHODS......................................................................................................11 Gravity.................................................................................................................................11 Centrifuge............................................................................................................................11

CONCEPT EVALUATION............................................................................................. 11 REACTANT INPUT CONCEPTS............................................................................................12

Gravity-fed Intermediate Tanks...........................................................................................12 Piston-operated Vacuum Cylinders.....................................................................................12 Oil Pumped to Set Level .....................................................................................................13 Oil Pumped through Flow Meter .........................................................................................13 Selection: Reactant Input ....................................................................................................13

FILTRATION CONCEPTS ......................................................................................................14 Self-cleaning Coarse Screen Filter .....................................................................................14 Removable Coarse Screen Filter ........................................................................................14 Open Coarse Screen Filter .................................................................................................15 Coarse Strainer & Fine Cartridge Filter...............................................................................15 Selection: Filtration..............................................................................................................15

MIXING CONCEPTS ..............................................................................................................15 Motor-powered Shaft with Mixing Vanes.............................................................................15 Motor-powered Planetary Gear System, Dual Shafts with Vanes.......................................16 Belt-driven Paddles .............................................................................................................16 Pump Recirculation .............................................................................................................16 Selection: Mixing .................................................................................................................16

SEPARATION CONCEPTS....................................................................................................17 Centrifuge with Rotating Valves ..........................................................................................17 Centrifuge with Stationary Valve .........................................................................................17 Selection: Separation ..........................................................................................................18

OVERALL SYSTEM CONCEPTS...........................................................................................18 CONCEPT SELECTION ............................................................................................... 20

AUTOMATION AND CONTROL.............................................................................................20 Digital Input/Output Box ......................................................................................................20 Solenoid Valves ..................................................................................................................20 Check Valves ......................................................................................................................20 Flowmeter ...........................................................................................................................21

FILTRATION, TRANSPORT, MIXING, AND SEPARATION ..................................................21 Strainer and Cartridge Filter................................................................................................21 Grease Transportation Pump..............................................................................................22 Mixing Recirculation Pump..................................................................................................22 Separation Motor.................................................................................................................22 Offset Gear Drive ................................................................................................................22

CONTAINMENT AND PIPING................................................................................................23 ENGINEERING ANALYSIS........................................................................................... 23

METERING .............................................................................................................................23 MOTOR ANALYSIS ................................................................................................................24 TANK FRAME STRUCTURE..................................................................................................25

Support Bars Stress Analysis..............................................................................................26 Vertical Legs Buckling Analysis ..........................................................................................27

MECHANICAL ANALYSIS OF MAIN TANK ...........................................................................28 Bending Failure Due to Static Fluid Pressure .....................................................................28 Circumferential Stress When Rotating ................................................................................29

CENTER OF MASS AND TIPPING ANALYSIS......................................................................30 FAILURE MODE EFFECTS AND ANALYSIS.........................................................................33 DESIGN FOR MANUFACTURING AND ASSEMBLY ............................................................33

Permit Assembly in Open Spaces.......................................................................................33 Standardize to Reduce Part Variety....................................................................................33 Maximize Part Symmetry ....................................................................................................34 Eliminate Fasteners ............................................................................................................34 Allow Access of Tools .........................................................................................................34

DESIGN FOR THE ENVIRONMENT......................................................................................34 Optimize Material Use.........................................................................................................34 Optimize Production Techniques ........................................................................................34 Optimize Distribution ...........................................................................................................34 Reduce Impact During Use .................................................................................................34 Optimize End-of-Life Systems.............................................................................................35

FINAL PROTOTYPE DESIGN ...................................................................................... 35 FILTERING .............................................................................................................................36 METERING .............................................................................................................................37 MIXING ...................................................................................................................................38 SEPARATION.........................................................................................................................39 SUPPORT STRUCTURE........................................................................................................39 FULL SCALE TO PROTOTYPE COMPARISON....................................................................40

System Layout ....................................................................................................................40 Automation ..........................................................................................................................40 Prototype Scaling Justification ............................................................................................41

PROTOTYPE MANUFACTURING AND TESTING PLAN ............................................ 43 MANUFACTURING PLAN ......................................................................................................43

Separation Tank..................................................................................................................44

ASSEMBLY.............................................................................................................................45 TESTING PLAN ......................................................................................................................45

PROJECT PLAN ........................................................................................................... 46 TESTING....................................................................................................................... 47 FUTURE IMPROVEMENTS.......................................................................................... 51

STRENGTHS..........................................................................................................................51 WEAKNESSES.......................................................................................................................51

CONCLUSIONS............................................................................................................ 53 ACKNOWLEDGEMENTS ............................................................................................. 54 REFERENCES.............................................................................................................. 55 TEAM MEMBER BIOGRAPHIES.................................................................................. 57 APPENDICES ............................................................................................................... 60

APPENDIX A: QFD DIAGRAM ...............................................................................................60 APPENDIX B: GANTT CHART...............................................................................................61 APPENDIX C.1: PUGH CHART - METERING .......................................................................62 APPENDIX C.2: PUGH CHART - FILTRATION .....................................................................63 APPENDIX C.3: PUGH CHART - MIXING..............................................................................64 APPENDIX C.4: PUGH CHART - SEPARATION ...................................................................65 APPENDIX D: FMEA DIAGRAM............................................................................................66 APPENDIX E.1: MANUFACTURING PLAN FILTER COUPLING .......................................68 APPENDIX E.2: MANUFACTURING PLAN METHANOL METERING................................68 APPENDIX E.3: MANUFACTURING PLAN NAOH METERING .........................................69 APPENDIX E.4: MANUFACTURING PLAN SUPPORT STRUCTURE ...............................69 APPENDIX F.1 OIL FILTER COUPLING ENGINEERING DRAWING ..................................70 APPENDIX F.2 METHANOL METERING TANK ENGINEERING DRAWING.......................71 APPENDIX F.3: TANK ASSEMBLY ENGINEERING DRAWING ..........................................72 APPENDIX F.4: SUPPORT STRUCTURE ENGINEERING DRAWING................................73 APPENDIX G.1: ASSEMBLY INSTRUCTIONS......................................................................74 APPENDIX G.2: ASSEMBLY SCHEMATIC............................................................................75

ABSTRACT Biodieselhaspotentialtoreduceourdependenceonpetroleum,butisnotwidelyusedduetoitshighcost.Traditionally,biodieselcomesfromvirginvegetableoil,butitispossibletoconvertwastecookingoilintobiodiesel.Usingwastecookingoiloffsetstheneedforvirgincropsandrecycleswhatwouldbediscarded.Applyingtheresultsofpastseniordesignprojectsonthechemicalreactionandseparationprocess;wewillpackagetheentiresystemintoanautomated,usableprototype.Ourfocusisonproducingasafe,clean,easytooperatesystem,andestimatingitscostofmassproductionanddistribution.

INTRODUCTION TheU.S.DepartmentofEnergyestimatesthatbiodieselaccountsforapproximately0.07%ofthenationstotaldieselconsumption[1];thishamperedcommercialviabilityarisesprimarilyfromthefuelshighcostat$23/gallon[2].Factorscontributingmosttothispriceincludefeedstockandproductioncosts[2].CurrentU.S.biodieselproductionusesprimarilysoybeanoil,afeedstockabouttwiceasexpensiveasthecleanestgrease,yellowgrease[3].Contaminatedwastegrease,likethatproducedbyrestaurants,isessentiallyfreebutobviouslyrequirespurificationbeforefuelproduction[4].Asystemdesignedspecificallyforthisrestaurantgreasealleviatestheprimaryfactorinbiodieselcost,feedstockprice[5].IncooperationwithoursponsorJohnDeere,weareresearchingandconstructingasystemengineeredspecificallyforthisrestaurantgreasescenario.ApotentialcustomerforourproductistheUniversityofMichigangroundscrew,whichcouldusethesystemtofuelsomeorpossiblyalloftheirdieselvehicles.Theuniversityresidencehallcafeteriaswouldbetheprimarysourceofwastegrease.Usingwastegreasefromtheresidencehallwouldeliminatethecosttheuniversityfacesfortheremovalofthecookingoil;inadditiontothesavingsassociatedwithproducingfuelinhousemakesourproductdesirableforboththeUofMgroundscrewandtheresidencehallcafeterias.AnotherpossibleuseforbiodieselproducedfromwastegreaseisheatingUniversitybuildings.Thebiodieselcouldbeusedtoheatthebuildingsinwhichthewastegreaseisproduced.PreviousUniversityofMichiganSeniorDesignprojectresultsonthisprojecthassuppliedusthechemicalreactionrequirementsandproceduresnecessaryforgreasetofuelconversion,sowemayfocusonthesystempackaging,function,andautomation.Ourbiodieselproductionprototypewillsafelyandquicklyconvertwastegreasetobiodieselinanenclosedsystemwhilerequiringverylittlemanuallabor.

INFORMATION SEARCH TheU.S.uses178milliontonsofpetroleumbaseddieselfuelannually,creatingamajorsourceofgreenhousegases[5].Usingfuelsfromrenewablebiomasssources,suchasbiodiesel,will

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reducethereleaseofCO2,particulates,andgreenhousegasesintotheatmosphere[5].Unlikepetroleumfuels,carbondioxideproducedbycombustionofbiodieselwillberecycledbyphotosynthesis[7].Biodiesel,chemicallydescribedasafattyacidmethylester(FAME),canbeproducedfromavarietyofanimalorvegetablefats(triglycerides)throughachemicalprocessknownastransesterification[3].Usingrawvegetableoilsindieselenginescancauseproblemssuchasinjectorcoking,deposits,andpistonringsticking.Transesterification,asshowninFigure1,isusedtoreduceandsometimeseliminatetheseeffects[6].

Triglycerides(Waste Cooking Oil,

Animal Fats,Vegetable Oil)

Alcohol(Methanol)

Base Catalyst(NaOH, KOH)

TRANSESTERIFICATION PROCESS

Biodiesel(FAME)

Glycerin

NaOH+CH3OH+WasteCookingOilBiodiesel+CrudeGlycerin

Figure 1. Transesterification process inputs and outputs Thetriglycerideconsistsofthreefattyacidsattachedtoaglycerinmolecule[3].Analcohol(usuallymethanol),inthepresenceofacatalyst,isthenaddedtoreactwiththefattyacidtoproducebiodieselandcrudeglycerin[3].Theresultingbiodieselcanbeusedasfuelindieselengineswithlittleornomodification[6].Inaddition,biodieselislessvolatileandsafertohandlethanpetroleumdieselanditslubricatingpropertiescanreduceenginewear[7].Semirefinedandrefinedvegetableoilsarethemostcommonfeedstockforbiodieselproduction[9].IntheUnitedStatessoybeanoilisthepredominantfeedstock,whereasinEuroperapeseedoiliscommonlyused[9].InBrazil,wherebiodieselproductionhasbeenafocusforover20years,productionalsoreliesmainlyonsoybeanoil[14].CrudesoybeanoilintheU.S.hasbeenpricedintherangeof$0.40$0.48fortheoilusedtocreate1literofbiodiesel[9].U.S.pricesforpetroleumdieselhaverecentlybeenintherangeof$0.21$0.24perliter,abouthalfthepriceofthebiodieselfeedstock[9].NoordamandWitherfoundthatrawmaterialisoneofthemost

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crucialvariablesthataffectthecostofbiodiesel[5];biodieselproducedwithvirginoilscannotcompeteeconomicallywithpetroleumbaseddiesel,afactthatcontributestothelackofproductionintheU.S.Tomakebiodieselaneconomicallyviablealternativefuel,thefeedstockusedforproductionmustberelativelycheap.Wastecookingoilshavethepotentialtoreducetherawmaterialcostconsiderably.Yellowgrease,whichhasafreefattyacidcontentoflessthan15%andisthemostexpensive,rangesinpricefromabout$0.14$0.32perliter[3,5].Therefore,bothyellowandbrown(FFA>15%)greasebothhavethepotentialtoprovideabiodieselfeedstockthatislessexpensivethanthefinishedpetroleumproduct.From1995to2000,theUSDAestimatesthattheU.S.producedanaverageof2.6billionpoundsofyellowgreaseperyear[3].350milliongallonsofbiodieselcouldbeproducedperyearfromthisgrease.Inaddition,usingwasteoileliminatestheneedfordisposal[7].Theglycerinbyproductcanalsobesoldfor$0.50$1.00perpound(19992002),increasingtheeconomicviabilityofbiodiesel[3].However,producinghighqualitybiodieselfromusedoilsprovidesanengineeringchallengeinpartbecauseofthevariabilityinthefeedstockquality.TheresultingbiodieselmustmeettherequirementsestablishedinASTMStandardD6751,SpecificationforBiodieselFuel(B100)BlendStockforDistillateFuels[3].Manyresearchershavedevelopedprocessesforconvertingwasteoilsintousablebiodieselfuel.Thebasicprocessconsistsofareactionbetweenanalcoholandthelongchainfattyacidsintheoil.Foraneffectivereaction,theoilmustbeproperlyfilteredtoremoveallcontaminants.IntheworkofZhangetal.,anacidcatalyzedsystemwasusedtopretreatthewasteoil.Methanolisthemostcommonlyusedalcoholbecauseofitsrelativelylowcost[7].Thereactionproducesfattyacidmethylesters(biodiesel)andaglycerinbyproduct.Theseproductscanthenbeseparatedfromeachotherusingavarietyoftechniques.Zhangetal.usedpumpstoprovidethemixinginthereactionchamberandthenusedawaterwashingcolumntoseparatethemixture[7].Figure2belowshowsthegeneralconversionprocessusedbybothpreviousresearchteams.Weplantoutilizetheirworkbyusingthesamebasicsetup.

Mixing SystemFiltration and Metering

System(all reactants individually )

Separation System(biodiesel from glycerin)

Biodiesel

Glycerin

Methanol

NaOH

Waste Oil

Figure 2. General waste cooking oil conversion process Themainreactionbetweenthetriglycerideandthealcoholarecatalyzedeitherwithanalkalioranacid[7].Wewillignoretheenzymecatalyzedsolutionsinceitrequiresamuchlongerreactiontime[7].Freedmanetal.foundthatusinganalkalicatalystwaslessdamagingto

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processequipmentthantheacidcatalyst[7].TheME450groupfromWinter2005designedanalkalicatalyzedprocessusingsodiumhydroxide,whichhasbeenusedextensivelyinresearchonthetransesterificationofwasteoilinthepast[5].Oneofthelimitationsofthealkalisystemisitssensitivitytowaterandthefreefattyacidcontentofthewasteoil[7].AccordingtoJerominetal.,theoilmusthavelessthan0.5wt.%freefattyacidcontenttobeaviablecommercialsolution[7].Inmostwastecookingoil,theleveloffreefattyacidsisabove2wt.%[7].IntheworkofZhangetal.theypretreatedthewasteoiltoobtainanacceptableacidlevel[7],buttheME450Fall2006groupdidnotaddressthisconcern.Wealsowillnotaddressthisconcernbecausewearefocusingontheautomationandsafetyoftheprocess.Werealizethatfutureworkwillbeneededtooptimizethequalityofthebiodieselproduct.Inourprocessreaction,wewillcontinueusingthechemicalformulationdevelopedbytheoriginalME450Winter2005team.TheresultsofFelizardoetal.suggestthatamethanol/oilratioof4.8andacatalyst/oilweightratioof0.6%givethehighestyieldofmethylesters[8].TheproportionusedbyME450Fall2006wasquiteclosetothesevalues.Theyusedamethanol/oilratioof5andacatalyst/oilweightratioof0.4%[10].Thereareanumberofsystemscurrentlyonthemarketforconvertingwastecookingoiltobiodiesel.Wewillnowdiscussthreeofthecompetitivesystems.

TheFreedomFueler,showntotheleft,costsapproximately$2,200andproduces40gallonbatchesin24hours.Itisavailablewitheitherhoseorsteelplumbing.Theusermustbepresentatdifferenttimesduringtheprocess,asallvalvesandpumpsmustbemanuallyactuated;however,theyclaimthata40gallonbatchwillonlyrequire30totalminutesofmanuallabor.Ithasconeshapedcontainerstoensurecompletefluidtransfers.Italsofeaturesanexplosionproofmethanolpump.Therearemanyavailableadd

onsforthesystemrangingfromanoilbarrelheatertoafuelingnozzle.

TheFuelMeisterIIhasmanyofthesamefeaturesastheFreedomFueler.However,itproducesthesamebatchsizeinhalfthetime(12hours).Thisunitisquitecompact,havingafootprintofonly6.25ft2.TheFuelMeistercosts$3,000forthedomestic110voltversion.Thedesignconsistsofasingletankinwhichthereactionprocessesoccur.Itsrelativelysimpledesignonlyusesthreesteelvalves.Thissystemusesapumptomixthereactantsinthemainchamberbyrecyclingthefluid.

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TheDeepthort100B,designedbyaProfessorinThailand,wasproducedforlessthan$2,000.Itiscapableofbatchsizesuptoabout26gallons.SincepalmoilisabundantinThailand,thesystemwasdesignedtousethisitasthefeedstock.Itiscapableofperformingothertasksbesidesbasicbiodieselproduction,suchasprewashingtheoil,dryingtheoil,andrecoveringmethanol.

CUSTOMER REQUIREMENTS AND ENGINEERING SPECIFICATIONS Wespokewithoursponsorandcustomerstodevelopasetofcustomerrequirementsthatareweightedaccordingtoimportancetothecustomers[12,13].Weusedthosedesiredattributestoformulateasetofengineeringspecificationsbywhichtodesignourproduct.UsingaQualityFunctionDeployment(QFD)diagram,wedeterminedtheengineeringspecificationsthatweremostimportanttoachievingthecustomerrequirements.CUSTOMER REQUIREMENTS Thecustomerrequirementsarecenteredonthreemajorareas:safetyofoperation,efficiencyofprocess,andautomationofsystem.Themethodofinputtingthereactants,thesystemoperation,andthemethodofdispensingtheproductsmustallbesafefortheuser.Thecustomerwouldliketheprototypetobesafeduringapowerloss,whenleftunused,onadryrun,andabletobeshutdowninanemergency.ThesecustomerrequirementsarerepresentedintheQFDdiagraminAppendixA.Theproductionofbiodieselshouldbeasfastaspossible.Theprocessshouldbeautomatedasmuchaspossibletoensureconsistentresults,increasethecleanlinessoftheprocess,andrequireaslittleoperatorinvolvementaspossible.Specifically,ourdesignwillminimizetheneedformanuallychangingfiltersorcleaningcomponents.Thecustomergaveustherequirementswithnumericalvaluesassignedtodenotetheirimportance.ThesevaluesrangefromonetotenandareshownintheQFDdiagraminAppendixA.Weassignedvaluesbasedonthemajorfocusesofthepreviousparagraph.ENGINEERING SPECIFICATIONS Fromthecustomerrequirements,wedevelopedasetofengineeringspecifications.WeassessedtherelationshipbetweeneachengineeringspecificationandeachcustomerrequirementandassignedvaluesintherelationshipmatrixintheQFDdiagram.Weusedthevaluesone,three,andnineintherelationshipmatrixtoincreasetheimpactofthestrongerrelationships.Forexample,thetemperatureofthegreasewillgreatlyimpactusersafety(9),yetitwillhelpthespeedofthefiltration/reactantinputprocess(3).Wemultipliedthecustomerimportanceweightbytherelationshipmatrixvalueandsummedthosevaluesforeachengineeringspecificationtodeterminethetotalpointvalue.Withthesevalueswedecidedonappropriateengineeringtargetswhichwouldbestsuitthecustomersneeds.ThesetargetsareshowninTable1below.

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Table 1. Engineering Targets Parameters PrototypeTargetValue FullScaleTargetValueBatchSize 5gal 25galBatchTime 4hrs 4hrsNumberofUncontainedElements 0 0FiltrationQuality 2550micron 2550micronFiltrationSpeed 5.5GPM 25GPMLevelofAutomation 1useraction/batch 1useraction/batchMixingTime 1hr 1hrSeparationMotorDecibelLevel 60dB 60dBOverallUnitSize 20ft3 35ft3PowerConsumption 900W 4100WPumpPower 420W 2000WNaOH,CH3OHResistance PVC,steel,stainlesssteel StainlesssteelSeparationTime 3hrs 3hrsStrengthofMixing/SeparationContainerMaterial

E=200GPawall thickness 1/8

E=200GPawall thickness 1/8

GreaseTemperature 25C 25CSystemWeight 200lbs 1000lbs

Wedecidedthata1/5thscalevolumeprototypewouldadequatelydemonstratefunctionalityofitsfullscale25galcounterpart,andthuschosea5galbatchsize.Our4hrtotalbatchtimeisverycompetitivewithcurrentdesignsandwasthesmallesttimeachievablebaseduponourmetering,mixing,andseparationtimeestimates.Literaturesearchesgaveappropriatechoicesforgreasefiltration(1025micron)andreactantresistantmaterials(stainlesssteel).Mass,inertia,andtorquecalculationsyieldedanecessarystrengthvalueforthatsteel,aswellasatargetsystemweight.Ourprimaryautomationgoalasclosetouserindependentaspossibleinvolvesasingleaction,simplypressingastartbuttontobeginconversion.Uponresearchintotypicalgreasepumps,wedecidedthata350W,5.5GPMmodel(420Wconsumption)wouldquicklysupplygreasetothemixingcontainerandalsoconsumesanacceptableamountofpower.Fromthis,solenoidvalves,theseparationmotor,andLabVIEWsoftwarenecessaryforautomation,wearrivedatanappropriatetotalsystempowerconsumption.Forusercomfortworkinginthevicinityofthesystem,60dBwasdeemedthemaximumvolumeallowedtotheseparationmotorandpumps(slightlyquieterthanabusyintersection).Lastly,greasetemperaturewasregulatedto25C(roomtemperature)inlightofusersafetyissuesandtheaddedenergyandmonetarycostofabarrelheater.Iftestingshowsthegreaseistooviscousforproperflowratesandfiltering,thisdecisionwillbereconsidered.Wealsoanalyzedtheinteractionamongtheengineeringspecifications.Inthecorrelationmatrixabovetherelationshipmatrix,weusedasystemofplusesandminusestodenoteapositiveornegativeinteractionamongtheengineeringspecifications.Ifoptimizingonespecificationaidsinoptimizinganother,thosetwohaveapositiverelationshipandviceversa.

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Forexample,increasingthelevelofautomationofthesystemwillgreatlyreducethetimerequiredforproducingabatchofbiodiesel(++).However,thisintroducesincreasedweightandsize().

DESIGNING A REDUCED SCALE PROTOTYPE Givencostandtimerestrictions,manufacturingafullscalebiodieselsystemisimpossibleandwehavethusdecidedonthepreviouslymentioned1/5thscaleversion.WewilladdressthetargetsinTable1attheconclusionofourfullreportandgiveourfindingsfromprototypetesting.Our1/5thscalesystemislargeenoughsuchthatwecannotneglectthelargemasses,momentsofinertia,andstressesinherenttoa5galbatchsize,similartoa25galsetupwhichwillrequiresimilarengineering.Theprototypeshouldbelargeenoughthatweseeproblemswhichwouldlikelybeevenworseinalargesystem.Fromthispointforwardinconceptgeneration,evaluation,selection,design,andmanufacturing,wewillfocusontheprototype.Uponconclusionofreducedscaletesting,formalrecommendationscanbemadeforafullscalesystem.

CONCEPT GENERATION TheFunctionalAnalysisSystemTechnique(FAST)Diagram(seeFigure3)breaksupthebasicandsecondaryfunctionsoftheoverallsystemdesign.TheFASTstartswiththeoverallsystemandthetaskofconvertingwastecookingoilintobiodieselfuelandthenbreaksoffintobranchesforeachsubsystem.Thesubsystemsaremethodsofinputofproducts,filtrationofcookingoil,mixing,separation,andtheoutputofthereactants.Eachofthesesmallercategoriesbreaksupintothefunctionsthatneedtobeperformedbeforethenextsubsystem.

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Pleasesenses

Mixingunit

Separationunit

Assuredependability

OutputSystem

ConvertWasteGreaseintoBiodieselFuel

Assureconvenience

Enhanceproduct

Multiplefilterstoeliminatelargeandsmallparticles

FullyEnclosedSystem

Measurequantityofeachinputforonebatch

Mixcontentsquicklyandthuroughly

Smartsystemtodetectandreacttoallpossibleerrors

Safetytouseandforoperators

Orderofrelease:MethanolthenSodiumHydroxide

Pumpgreasefromholdingtankthroughfilters

Fullycontainsinputsfortransporttotank

Meteringunit

Filtrationunit

Fromthemeteringunit,mixintheproperorder

CentrifugesecparatesandpushesGlycerintotankwall

Mustproduceveryhighqualitybiodiesel

Fullyautomatedsystemwithlimitedmanuallabor

Easycleaningandmaintenance

Gravitythensettlestankintwolayers

Productdispensingiscleanandsafe

Contentsarefullycontainedthroughoutprocess

Automationwillshutoffiferrorsaredetected

MethanolandSodiumHydroxidemixedfirst

Addfilteredwastecookingoiltomixture

Figure 3. FAST diagram INPUT OF REACTANTSThereactantsareloadedintoinitialholdingtanksbytheoperator.Oncethesystemisstartedtheprocessbeginsbyusingamethodtotransporttheliquidsfromtheholdingtanksintothemixingunit.Thecorrectproportionsofeachreactant,methanol,sodiumhydroxide,andwastecookingoilmustbetransportedintothemixingtank.Designingacompletelyautomatedsystemrequiresthesystemtohavesensorstodeterminewhenthecorrectamounthasenteredthesystem.Methanolandsodiumhydroxidewillbedispensedintothemixingunitintheproperordertogeneratethecorrectproducts.Theinputprocesschosenforthewastegreasewillincorporatethefiltrationunittocleantheoilbeforethewasteoilentersthemixingunit.

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Gravity Transportation Fromtheinitialholdingtanksgravitywillbeusedtodrawthecontentsfromtheholdingtanksandintothemixing/separationtank.Theamountofeachreactanttransportedfromthetankwillbetheexactamountrequiredtocompletethereaction.Usinggravityfortransportationisinexpensivebutitalsocreatessomedesignchallenges.Theholdingtanksforallthreeliquids,grease,methanol,andsodiumhydroxidewouldneedtobehigherthanthemixingtank.Thegreasecomesin50gallonbarrelssothisbarrelwouldneedtobehigherthanthemixingtankinordertousegravityasthefeedingintothesystem.Theamountofrequiredmethanolandsodiumhydroxideisnotaslargesogravityseemstobeapracticalwaytoinputbothliquids. Pump Transportation Apumpcanbeusedtotransportthereactantsfromtheinitialtanksintothemixingtank.Oncethedesiredamountofliquidisinsidethetank,thepumpcanbeturnedoff.Althoughthisisnotverypracticalforthemethanolandsodiumhydroxidetanksbecauseofthesmallamountsrequiredperbatch,usingapumpforthewastegreasewouldbeverybeneficial.Thewastegreasebarrel,sittingonthegroundnexttothesystem,employsapumptocarrythegreaseupandintothemixingtank.Thedifficultywithusingapumpforthewastegreaseistoachievetheappropriateamountinthemixingchamber.Thewastegreaseusedinthesystemwouldbeofvariablepropertiesincludingtemperatureandparticlecontent.Foranautomatedsystem,asensorwouldneedtobeusedtoshutthepumpoffafterthecorrectamountofgreaseismeasuredout.Thesensorsusedinthiscasecouldbeatimesensor,levelsensor,orflowmeter. Time Sensor for Grease Input Everytimethesystemwastorunasinglebatchthepumpwouldoperateforasetlengthoftimebeforeshuttingoff.Thelengthoftimewouldbebasedonhowlongittakestogetthegreasepumpedthroughafilterandthedesiredamountintothemixingchamber.Themainproblemsforusingatimesensoristhatthegreasefrombatchtobatchwillhaveavaryingnumberofparticlestoberemovedwiththefiltrationsystem.Thetimerequiredtogettheamountofgreaseintothesystemwouldvaryperbatchbecauseverycleangreasewouldmovethroughthefiltersquickerthanthedirtiergreasewithlargeparticles.Theuseofatimesensorwouldnotbeaveryaccuratewayofgettingthecorrectamountofgreaseintothetank. Level Sensor Alevelsensorisapieceofequipmentthatwouldbelocatedatacertainheightinsidethemixingtank.Thesensorworksbydetectingchangesinthedensityfromitsinitialstate.Inoursystem,thesensorwouldbesurroundedbyairinitiallybutasthetankfilleduptheliquidlevelwouldreachthepointofthelevelsensor.Atthisdetectionofthechangeindensityfromairtoaliquid,thesensorwouldsendasignaltoinformthesystemthatthegreasehadreachedthedesiredlevelinsidethemixingchamber,andthepumpwouldbeturnedoff.Thelevelsensormustbelocatedinsidethemixingchamberwhichmustbeconsideredinthemixingdesign.Flow Meter Sensor Aflowmetersensorworksbymeasuringtheamountofflowthroughagivenpipe.Aflowmetercouldbeusedtodeterminehowmuchliquidhaspassedthrougha

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pipe.Theamountofdesiredwastegreasecanbecalculatedtodeterminehowmuchgreaseneedstoflowthroughthedesiredtube.Afterthecalculatedamountoffluidhasbeendetectedbytheflowmeterthesystemcanbeprogrammedtostopthepump. FILTRATION METHODS Thewastecookingoilobtainedfromthecafeteriasisprefilteredtoremovetheextralargeparticlesfromthegrease.Abetterfiltrationsystemisrequiredtoproducepureproductswithoutparticlesfloatinginside.Thefiltrationsystemwillbecoordinatedwiththeinputsystemtofilterthewastecookingoilbeforeitreachesthemixingchamber.Adesignchallengeofcreatingafullyautomatedsystemischallengedbycreatingafiltrationsystemthatrequireslittletonochangingofthefilter.Thegoalistoensurethatfiltermaintenancedoesnotbecomeanuisance.Thefiltrationunitcouldincludeanautomatedcleaningsystemtoreducetheamountofmanualworkoritcouldbeamanualcleaningsetoffilters.Screen Filter Ascreenfilterisawirescreenthatisplacedinatubetocollectlargeparticleslocatedinsidethewasteoil.Theparticlesarecollectedastheliquidpassesthroughthepipebecausetheyarenotsmallenoughtopassthroughtheholesonthescreen.Thisisasimplefilterbutifitbecomesblockedbecausetheparticlesbuildupbecausetheycannotpassthroughandthentheliquidflowisstoppedthesystemwillnotfunction.Itcouldcauseasafetyhazardaswellasamaintenanceissuetounclogtheblockedpipe. Cartridge Filter Theliquidentersthroughaninlettubeandisforcefedthroughthechamber,whichcollectstheparticles,andthenthefilteredliquidexitsthroughanoutlettube.Cartridgefiltersworkverywellwithastrongforcefeedlikeonegeneratedfromapump.Theyalsocomeinmanydifferentsizesandfiltrationrangesallowingalargevarietytobeusedinthesystem. Bag Filter Abagfilterismadeofasyntheticmaterialthatallowstheliquidtoenterthroughanopenendandthencontinuethroughthematerialandcanbeusedwithgravityfeed.Theparticlesarecaughtinthematerialbecausetheyaretoolargetomakeitbetweenthefibers.Bagfiltersarebeneficialtouseinsuchasystembecauseastheparticlesbuildupthebaggetsfilledbutthesidesarealsomadeofthesyntheticmaterial.Theentirebagwouldhavetofillupbeforethefilterwouldbecomeblockedandliquidcouldnotpassthrough.Thebagfilterscomeindifferentmaterialswhichallowfordifferentsizedparticlestobecaughtinthebags.Itisunclearhowwellthematerialwouldholdupwhenpairedwithapumpandastrongflowpassingthroughthefilter. Strainer Astrainerisacombinationofascreenfilterandabagfilter.Thestrainerusesthedesignofabagfilterwheretheparticlesareallowedtobuildupinaportionofthefilterandtheliquidcanstillpassthroughthesides.Althoughratherthanbeingmadeofmaterialthestrainerismadeoutofmetallikethescreenfilter.Themetaliswoventoallowapatternthatonlyliquidandparticlessmallerthantheholesareallowedtopassthrough.Thestrainergivesthestrengthofthescreenfilterbutintheshapeofabagfilter.Thisallowsthestrainertobeusedwithapumpsystem.

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MIXING METHODS Theinputsystemdispensesmethanol,sodiumhydroxide,andthewastecookingoilinthecorrectproportionsintothemixingunit.Themixingunitmustfirstmixthemethanolandthesodiumhydroxidetoproducesodiummethoxide.Thenthewasteoilisaddedintothemixingunitandmixedthoroughlytocreateahomogenousmixture.Themethodofmixingtheliquidsmustbereliableandfasttoreducetheamountoftimerequiredforthebatchtobecomplete.Oncethemixtureiscompletetheliquidcanbegintheseparationprocess.Thedesignchallengeistocreateamixingunitthatwillbecompatiblewiththeseparationunittooccurinthesametanktoreducethesizeoftheoverallsystem. Mixing Unit Inside Tank Amotorwithabeltsystemorgearsystemcouldbeusedtodesignamixingsysteminsidethetank.Thismixingunitcouldincorporateindividualpaddlesoracentralrotatingshaftwithbladesthatforcemotionofthefluid.Thisunitmustbecompatiblewiththeseparationunitchosen. Pump Recirculation Apumpwouldtakethemixturefromthebottomofthetankandrecirculatetheliquidbackintothemixingchamber.Themotionoftheliquidbeingsuckedfromthebottomandbacktothetopandhavingtheliquidfallbackintothemixingtankwouldprovidepropermixingofthereactants.SEPARATION METHODSThemixingprocessformsacompletelyhomogenousmixture.Thismixtureisthenseparatedintotwoproducts,glycerinandbiodiesel,whichisafattyacidmethylester(FAME).OncetheseparationprocessiscompletedthebottomlayerwillbeglycerinandthetopwillbeFAME.ThebottomwillbedrainedoutintoawastecontainerandtheFAMEwillbedrainedintoacontainertobeusedasbiodiesel.GravitySeparationcanoccurbyallowingthemixturetosetinatankforanextendedperiodoftime.Unfortunately,thisisaverytimeconsumingprocess.Usinggravitydoesnotrequireanymovingpartstoreducepossibleproblemswiththesystemandtheresultingproductscanbeachievedatlowcost.CentrifugeApplyingcentrifugalforcestothefluiddecreasestheamountoftimerequiredfortheseparationprocesstooccur.Agearsystemandmotorisusedtospintheentireseparationtanktocreatethecentrifugalforcesontheliquid.Theliquidisspunathighspeedsandcreatestwodistinctlayersintheseparationunit.Thecentrifugeseparationunitiscostlybecauseitrequiresamotorandgearstospintheentireseparationtank.Thecentrifugealsoneedstobedesignedsothatitissafeforthelargecontainertobespunathighspeeds.

CONCEPT EVALUATION Foreachofthemainsubsystems(reactantinput,filtration,mixing,separation)weevaluatedtheconceptsbasedonourmajordesignobjectives.Manyofthedesignsoutlinedinthissectionwerecreatedundertheassumptionthatthemixingandseparationtanksweretwoseparate

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units.Forourfinaldesignweincorporatedthesetwofunctionsintoonecontainer,whichgreatlyinfluencedthedesignandselectionprocess.Thefollowingsectiondescribesourevaluationofeachconceptandthereasonsbehindourfinalselection.REACTANT INPUT CONCEPTSThefirstgoalofoursystemistotransferspecificamountsofthethreereactantstoacommonlocation,wheretheywillbemixed.Ourconceptsforachievingthisgoalareshownbelow.

Gravity-fed Intermediate Tanks Ourfirstconceptforreactantinputinvolvedsuspendingopencontainersofwasteoil,methanol,andsodiumhydroxideaboveintermediatetanks,whichinturnaresuspendedabovethemixingchamber.Withbothvalvesineachlineclosed,theuserwouldfillthereactantcontainersandthenopentheuppervalves.Gravitywouldforcethefluidsintotheintermediatetanks,whichcouldonlyholdtheamountofrespectivereactantneededforonebatch.Whenthefillingiscomplete,thelowervalvesopenandreleasethereactantsintothemixingchamber.Ifnecessary,thetimingcouldalsobemodifiedtoreleasethemethanol

andsodiumhydroxidetobemixedbeforetheoilenters.Whilethisdesigndoesnotrequireapumporanytypeofsensor,thesuspendedoiltankpresentsalargesafetyhazard.Thetechnicalfeasibilityofsuspendingsuchalargetankwouldalsobequestionable,nottomentionthenearlyimpossibleusertaskoffillingtheinitialcontainer.

Piston-operated Vacuum Cylinders Weconsideredusingavacuumasamethodforintroducingthereactantsintothemixingchamber.Asshowninthedrawing,theconceptconsistsofapistoninsideofacylinderconnectedbothtothesourcetank(sideconnectionassumedtobeat1atm)foreachreactantandtothemixingtank(bottom).Thepistonisconnectedtoarackandpiniongearsystem,whichispoweredbyanelectricmotor.Attheappropriatetime,themotorwillturnthepinion,therebyliftingthepistoninsidethecylinder.Asthevolumeofthecylinderincreasesthepressureoftheairwilldecrease,therebycreatingadifferentialpressurebetweenthecylinderandtheatmosphericpressureonthesourcetank.Whenthecorrectamountoffluidhasentered,the

valvetothemixingtankwillopenandreleasethecontents.Thisdesigneliminatestheneedforpumpsorthesupplytanksplacedabovethemixingtankforagravityfeed.However,thisconceptwouldcreateotherdesignproblems.Thecylinder,aswellasthepiston/cylinderinterface,wouldneedtobeairtighttofunction.Toobtainthenecessarypressuretomovethefluids,thisconceptmayrequirealargevolumetricexpansionoftheair,whichwouldnecessitatealargevolumecontainer.Althoughweeliminatetheneedforpumps,themotornecessarytodrivethissystemwouldlikelybemoreexpensivethanapump.

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Oil Pumped to Set Level Thisconceptusesthegravityfeedprocessforthemethanolandsodiumhydroxideassumingthatthesystemheightisstillreasonablewiththesetanks.Afteropeningthevalvesforthesetanks,theoilwouldthenbepumpedintothemixingtankuntilthetotalfluidlevelachievesthecorrectvolumeofoilmeasuredbywhenitreachesthecorrectheightinthetank.Alevelsensorwouldprovidethefeedbacktothecontrolunitto

shutdownthepumpandpossiblycloseavalve.Thisdesignallowstheusertosimplyinserttheoilinputhoseintothebarrelofwasteoilandstarttheprocess.Sincethemethodofmeasurementisrelativelysimple,thisconceptwouldallowforaccurateproportionsofreactantinput.Althoughlevelsensorsarefairlycheap,thisdesigndoesintroduceextracost.Inourlatersystemdesigns,weincorporatethemixingandseparationprocessesintoasingletank,soanyattachedapparatusmustbecompatiblewiththetankrotationfortheseparationprocess.Withaspinningtank,slevelsensorpresentsmanyengineeringchallenges,suchaswhattodowiththesignalcableattachedtothesensor.Thecablewillbecomewrappedaroundthetankandifthetankspinsforseveralminutesat500rotationsperminute,thisintroducesalargeamountofcabletocontrol.

Oil Pumped through Flow Meter Aflowmeterlocatedintheoillinecanbeusedtodeterminethevelocityofthefluid.Thevelocityofthefluidmultipliedbythecrosssectionalareaofthepiperesultsinthevolumeflowrate.Byperformingatimeintegrationofthevolumeflowrateinourcontrolsoftware,wewillshutthepumpoffwhenonebatchsworthofoilentersthetank.This

solutioneliminatestheneedforanysensorattachmentsonthemixing/separationtankandtheengineeringchallengesthatpresents.However,flowmetersaremoreexpensivethanlevelsensorsandwillincreasethecostofthedesign.Thecontrolmethodandsoftwareprogrammaybemorecomplicatedaswell. Selection: Reactant Input Forourdesign,themethanolandsodiumhydroxidewillenterfromintermediatetanksfedbygravity.Thecookingoilwillbepumpedfromthestoragecontainerintothemixingtankwithaflowsensorinsidetheoillinetoachievethecorrectvolumeforasinglebatch.AschematicofourbasicreactantdeliverymethodisshowninFigure4,below.

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Figure 4. Reactant input concept selection (not showing other components)

FILTRATION CONCEPTSThewastecookingoilmostlikelycontainsunknownparticulatematerialsthatmayaffectthequalityofthereactionprocess.Toreducethisrisk,wehavedevelopedthefollowingfiltrationconceptsdesignedtoprovideahomogeneous,puresupplyofoil.Workbypreviousgroupshasshownthatfiltrationismosteffectivebyusingacoarsefilterandafinerfilterinseries.Wewillusethissameapproach.

Self-cleaning Coarse Screen Filter Toreducetheamountofmanualmaintenance,wedevelopedanideaforaselfcleaningcoarsefiltrationunit.Thewastegreaseentersandflowsthroughametalscreen,whichcatchesthelargeparticles.Abladesystem,attachedbyashafttoalowcostmotor,barelyscrapesthesurfaceofthescreen.Thebladesareshapedinawaythatpushestheaccumulatingparticulatematterintoawasteoutletline.Thisdesignwouldnotrequiretheusertochangethefilterbyhand.Theuserwouldonlyperiodicallyemptythewastereceptacle.Whilethisdoescutdownonusereffort,itinceasesthecomplexityofthedesignandaddsequipmentandmanufacturingcosts. Removable Coarse Screen FilterAcoarsefilterthatrequiresmanualcleaningiscomposedoftwocylindersjoinedbyahingeononeside.Thelipsofeachcylinderarecoveredinrubbertoobtainatightseal.Theinputlineisaflexiblehosetoallowtheuppercylindertomovefreelyonthehinge.Thescreenissupportedontabsinsidethebottomcylinderandithasahandleforeasyremoval.Thisdesignwouldallowforrelativelyeasycleaningandremovalofthescreen,althoughitmaybemessytoremovethescreenfromthecylinder.

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Open Coarse Screen Filter Anotherideawasacoarsescreenfilterthatisopentotheatmosphere.Thefluidentersatankandflowsoutthroughascreeneddraininthebottom.Thescreenhaseitherataborahandleattachedforeasyremovalandcleaning.Thisdesignwouldviolateourobjectiveofenclosingallsystemcomponentsforsafetyandcleanliness.Apictureoftheconceptfromthetopandalsodirectlyfromthesideareshowntotheright.

Coarse Strainer & Fine Cartridge Filter Wewereconcernedthatfilteringdownstreamofthepumpmaydamageorclogthepump.However,wewereworriedthatfilteringupstreamofthepumpmaymakeprimingdifficultandpossiblypreventproperflow.Toalleviatebothoftheseconcernswedecidedtoincludeacoarsefilterupstreamandafinefilterdownstream.Thiswaywellgreatlyreducetheparticulatesthroughthepumpwithoutcreatingtoolargeaflowrestrictionontheinletofthepump.Wewillincorporateanautomotiveoilfilteroranequivalentcartridgefilterasthefineparticlefilterfollowingthepump.

Selection: Filtration Wewilluseatwostagefiltrationmethodwithacoarsestrainerupstreamofthepumpandafinercartridgefilterdownstream.Thiswillprotectthepumpfromlargedebriswithoutcreatinganexcessivelylargeflowrestrictioninthepumpinletline. MIXING CONCEPTSOncethereactantshaveenteredacommontank,theymustthenbemixedthoroughlytoensurethebestpossiblereactionefficiency.Ourconceptsformixingaredescribedandevaluatedinthefollowingsection.

Motor-powered Shaft with Mixing Vanes ThebasisforourinitialconceptformixingwasinspiredbytheworkoftheFall2006group.Thedesignconsistsofrotatingshaftpoweredbyamotor.Mixingvanesarerigidlyattachedtothecentralshaftandphysicallymixthereactants.Wehadvariousconceptsonthemanufacturingoftheshaft/vaneassemblyandthevanegeometry.Themostfeasiblesolutionwediscussedwastomillslotsintotheshaftandtoinsertstripsofsheetmetaltoserveasvanes.Wewouldthenjustboltthevanestotheshaftwithtwobolts.Onedrawbacktothisdesignisthatsomefluidatthebottomofthetankandintheoutlettubewouldnotbemixed.Wecouldplacetheoutletvalveascloseaspossibletothebottomofthetank,buttherewillalwaysbesomeunmixedfluidthatenterstheseparationtank.

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Motor-powered Planetary Gear System, Dual Shafts with Vanes Ournextconceptisverysimilartotheonejustdiscussed,butwebelieveitwouldprovidemoreeffectivemixing.Inthisdesign,weattachasungeartothedriveshaftwhichmateswithaplanetgearconnectedtoitsowndriveshaft.Mixingvanesareattachedtobothshafts.Thedriveshaftrotatesinplaceandthesecondaryshaftrotatesarounditsaxisandcirclesaroundthedriveshaft.Thisaddedrotarymotionwouldlikelyspeedupthemixingprocessbyintroducingaddedturbulenceintothefluid.Alongwiththesamedisadvantagesdiscussedforthesingleshaftdesignabove,thisdesignalsorequiresanothercutoutinthetopofthecontainerforthesecondaryshaft.Thismayposeasafetyhazardifthemixingprocesssendsreactantsorproductsoutofthecutout.

Belt-driven Paddles Wealsoconsideredadesignwhichreliesonbeltdrivenpaddlesformixing.Theendsofthepaddles,attachedtobeltsheaves,wouldprotrudeoutofthesidesofthetank.Amotorwoulddriveabeltconnectedtotheendsofeithertwoorthreepaddles.Therotationofthepaddleswouldmovethefluid.Thepaddlecouldcontainanynumberofholesorslotstohelpintroduceextraturbulence.Thisdesignwouldrequireverygoodsealswherethepaddleendsprotrudefromthecontainer.Itmaybedifficulttokeepthesefourtosixloadbearingsealsfromleaking.

Pump Recirculation Ourgroupdevelopedaconceptformixingwhichreliesonrecirculatingthereactantfluidsusingapump.Thereactantswillenterthetank,exitoutthebottomofthetank,enterthetubeandbepumpedbackinthroughthetopofthetank.Theentranceintothetopofthetankcouldbethroughasprayerorthroughmultipleentrypointstohelpmixthefluid.Ourgroupanticipatesthatsendingthefluidthroughthiscentrifugalpumpwillalsogreatlyaidinthemixingprocess.Thisdesignapproachisusedinanumberofthecompetitiveproductscurrentlyonthemarket,suchastheFuelMeisterII.

Selection: Mixing Wewilluseapumptorecirculateandmixthefluidinthetankbecausethiswillbesufficientformixingandistheeasiestdesignconcepttopairwiththeseparationmethods.

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SEPARATION CONCEPTS Thewasteoil,methanol,andsodiumhydroxidereactinthemixingchamber,formingglycerinandbiodieselasproducts.Theseproductsmustthenbeseparatedfromeachother.Mostcomparablesystemssimplyrelyongravitytoseparatetheproducts,whichcantakeupto24hours.Timeeffectivenessisoneofourmajordesignconcernssowedevelopedthefollowingconceptstodecreasetheseparationtime.Centrifuge with Rotating Valves MuchoftheworkofthepreviousME450designteamswasfocusedonseparationbyapplyingcentrifugalforcestothefluid.Sincewewishtoutilizetheapplicablepastresearchasmuchaspossible,themajorityofourfocushasbeenonthismethod.TheprototypefromFall2006usedacentrifugewithtwooutletvalves,oneonthebottomdrainlineandoneonthesideofthetanktodraintheglycerinthatisforcedtotheouterwallsduringspinning.Whilethisprovidedadequatefunctionalityformanuallyoperatedvalves,solenoidvalvespresentaproblembecauseoftheirelectricalcables.Ifweallowthevalvestorotatethecableswilltangleandtwist.Therefore,ourdesignmustkeepthevalvesstationary.

Centrifuge with Stationary Valve Inordertokeepthevalvesstationarywedecidedthattheseparationtankinletandoutletlineswillbeontheaxisofthetank.Wewilldrillholesinthetopandbottomofthetankandattachbearingstoguidethefluidtransferlines.Bothbearingsandpipeswillbereinforcedbyadditionalstructuralsupports.Thisdesignallowsthevalvestobeplacedonthestationarypipelines.Sincetheoutletpipeisonthecentralaxis,weneedawaytooffsetthemotoraxiswhilestillprovidingtorquetothetank.Weconsideredbothagearandbeltsystemforperformthistask.Abeltsystemmayprovideacheapwayoftransmittingtheenergy,butthehightorquerequiredmaynecessitatemorecostlyVbelts(aswellasappropriatesheaves).

Abeltwouldalsorequireatensioningsystem,whichmayintroduceextramaintenanceeffortintheeventthatthebeltslipsoffthesheave.Usingagearsystemwillallowustotransmithightorquewithoutworryingabouttensioningorslipping.

Water-washing Column AsintheresearchofZhangetal.,weconsideredusingawaterwashingcolumntoseparatethereactionproducts.Waterispipedintothecolumnfromaboveandbiodieselandglycerinfrombelow.Biodieselislessdensethanbothwaterandglycerinsoitrisestothetopofthecylinder.Theglycerinandwaterarethenremovedoutthelowerdrain.Thebiodieselthatproducedbythisprocessisnotcompletelypure.Zhangetal.foundthatthebiodiesel(FAME)containedlessthan6%unconvertedoil,methanol,andwater.Thisstreammustundergoanexpensiveandcomplicatedpurificationprocesstoremovethecontaminants.Thisadded

expenseisnotfeasibleforourprototypeorourrecommendedsystemdesign.

Water

FAME + Glycerin

Glycerin + Water

FAME

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Selection: Separation Wewillseparatethebiodieselfromtheglycerinusingcentrifugalforcesandastationaryvalvesystem.Thetankcontainingtheproductswillberotatedbyagearsystemconnectedtoamotor.Thevalvesfortheinputandoutputlineswillbeonthetopandbottomofthetankandremainstationaryduringrotationtoallowforcableconnections.Figure5,below,showsamoredetailedsketchofthebearing,gear,andsupportsystem.

Figure 5. Detailed view of main separation tank support and bearing system OVERALL SYSTEM CONCEPTS Forthemixingunitweoriginallyplannedonusingthevane/motorassembly,butsoonrealizedthatusingtwotankswouldnecessitateapumpbetweenthemtoreducetheoverallheightoftheunit.Wethenrealizedthatapumpcouldbeusedforbothtransferringbetweentanksandforrecirculatingflowformixingpurposes.Withthisdesigninmind,wedecidedtosimplycombinethemixingandseparationprocessesintothesametank.Thisallowsustoeliminatethecostlymotorrequiredfortheoriginalmixingsolutionandtogreatlyreducethemanufacturingcostsofthesystem.ThetotalsystemschematicdiagramisshownonthenextpageasFigure6.AllofourfinaldesignchoicesaresupportedbythePughchartsinAppendixC.Theseallowedustoroughlyquantifytheadvantagesanddisadvantagesofeachconceptandselectaccordingly.

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Figure 6. Waste cooking oil conversion system schematic diagram

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CONCEPT SELECTION Ouronetanksystemcanbedividedintothreefunctionalcomponentsubsystems:automationandcontrol;filtration,transport,mixing,andseparation;andcontainmentandpiping.Thefollowingsectionswilldiscusstheircharacteristicsandourreasonsforchoosingthem.AUTOMATION AND CONTROL TheheartofourcontrolschemewouldbeacomputerrunningLabVIEWinconjunctionwithaUSBboxwhichsendssignalstosolenoidvalves,thetwopumps,andtheseparationmotor,aswellasreceivesignalsfromaflowmeterandseveralshutdownsensors.Digital Input/Output BoxThisinterfacepossessesmultipledigitalinputsandoutputs,iscapableofinterfacingwithLabVIEW,andservesasthelinkbetweencomputercommandsandmechanicalfunction.Thisbox,aswellasLabVIEW,willbesuppliedtousbytheUniversityofMichigansowearenotsureofitsexactspecificationsatthepresenttime.Setupslikethisarethecommonsolutionfortherelativelysimpleautomationwerequire.Solenoid ValvesElectricallyactuatedvalveswereseenasthemosteconomical,feasible,andaccuratemethodforcontrollingliquidmovement.Theirsimpledesigneasilyincorporatesthemintoourautomationplan.Twodiametersofelectricallyactuatedvalveswillbeused,0.25inand1.00in(seeFigure7,below).Tosavecost,onlyonelargediametervalvewillbeusedintheentiresystem,asseeninFigure6.Thoughusingsmallervalveselsewhereinthesystemwillslowdowntheprocess,weestimatethatourprocesstimestarttofinishwillstillfallbelowthatofcompetitiveproducts.

a. b. Figure 7. (a) 0.25 and (b) 1.00 solenoid valves

Check ValvesAttwotimesinthesystemprocess,pumpsareshutoffandfurtherflowfromtheiroutletpipesisnotdesired.Additionally,theseoutletpipesmustbesectionedofffromotherpipeslaterintheprocesstopreventbatchcontamination.Checkvalvessuitedtheseobjectives,aspositivepressuredownstofthevalveduringpumpingensurestheystayopen,butclos

uponpumpshutoff.Specifically,thereistimebetweenthepumpselectricalshutoffandthetimeitsimpellerstopsspinning;checkvalvespreventthepressurebuildupatypicalactuated

reame

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valvewouldcause,stayingopenuntilfluidstopsflowing.Wewillutilizetwo1.00PVCcheckvalvesinthesystem(seeFigure6),oneafterthegreasepumpandtheotherfollowingthemixingpump.PVCisagoodprototypechoice,asitisacheaperbutlessdurablealternativetostainlesssteel,withthesameNaOHresistance.

FlowmeterSummingindividualoutputvalueswithLabVIEW,aflowmetergivesusanaccuratewayofmeasuringhowmuchgreasehasbeenpumpedintothemixingtank.Paddlewheelflowmetersareusefulforviscousfluidswhereextremeaccuracyisnotrequired,andarelessexpensivethanultrasonicorpositivedisplacementmeters.OurflowmeterwillsnapfitintoaPVCfitting,asseentotheleft.ThismaybesuppliedbytheUniversity,sowearenotsureofitsexactspecificationsatthepresenttime.

FILTRATION, TRANSPORT, MIXING, AND SEPARATION Filtrationwasdesignedwithpumpinginmind,assignificantpressuredropsupstreamofcentrifugalpumpshurtstheirperformancesignificantly.Also,combiningmixingandseparationrequiredspaceconsiderationswiththeelectricmotorworkingincloseproximitytothemixingpump.Strainer and Cartridge FilterThoughthewastegreaseisprefiltered,wedecidedtouseacoarsestrainertoensurethatnolargeparticlesenterthepump.The400micronstrainer(showninFigure8(a),below)has0.75NPTfittings,isdesignedforroomtemperaturegrease,andwillfunctionwellwithapumpunlikeconventionalbagfilters.Basedontheviscosityofourgrease,commonautomobileoilfilterswillworkwellwithourpump,astheyareacartridgestyleandrangefrom1550micronfiltrationquality.Additionally,ourchoiceofasyntheticmediaoilfilter(Figure8(b))improvesfiltrationandflow.Wewilllikelyremovetheoutershellasshowninthefigureandfabricateourowninterfacesystembetweenthefilterandpiping.

a. b. Figure 8. (a) Pre-pump strainer and (b) Cartridge oil filter

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Grease Transportation PumpBasedonourtargettimesfortransportationofthecookingoil,wechosean11GPMpump.Thisflowratefillsthemixingtankinaboutaminutewiththecorrectvolumenecessaryforafivegallonbatch.Thepump(showninFigure9(a)below)iscastironandpossessesmountablefeetforpermanentapplicationslikeoursystem.Mixing Recirculation PumpTheinitialmixingprocessisjustofmethanolandsodiumhydroxidetoproducesodiummethoxide.Thisrequiresthepropermaterialssothatthechemicalsdonteatthroughthepumpmaterial.Themixingprocedurealsoneedstorecirculatetheentirefivegallonbatchatleast10times,soahigherGPMthanthegreasetransportationpumpisdesired.Thestainlesssteelpumpwechoseoperatesat11GPM.

a. b. Figure 9. (a) Grease Transport Pump (b) Mixing Recirculation Pump Separation MotorTosizetheelectricmotorthatwillturnthemixing/separationtank,wecalculatedthenecessarytorquerequirementsforafivegallonbatchsizeandanangularspeedof500rpm.Thesecalculationsareshownintheengineeringanalysissection.TheBison32framepermanentmagnet12VDCmotor,showninFigure10(a),willbeusedinourprototype.Offset Gear DriveRotationofthemixing/separationtankrequiresthatallinletandoutletpipingbeonitscentralaxis,butamotordrivingthisaxisdirectlyfromthebottominterfereswithanycoaxialoutlettube.Anoffsetgearsystem,asshowninFigure10(b),solvesthisproblem,allowingthetransferofrotationbetweenfromthemotortotankaxis.Alongwiththemotorcalculationsintheengineeringanalysissection,arethecalculationsforthenecessarygearsrequired.Thegearswillbea15/8inchgearanda6inchgear.Thetankgearwillemployataperedrollerbearingaroundtheoutlettube,necessarybecausebothradialandthrustloadswillactuponit.

a. b. Figure 10. (a) separation motor (b) Offset gear drive illustration

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CONTAINMENT AND PIPING Thematerialsselectedforthecontainmentandpipingcannotbereactivewithsodiumhydroxide,methanol,orwastegrease;ideally,allcomponentswouldbestainlesssteel.However,costdictatesthatwecompromisewithPVCandsteel.PVCischeapandnonreactivewithmethanolandsodiumhydroxide;steelisalsononreactivewithsodiumhydroxidebutdoescorrodeincontactwithmethanol.AllofthepipingwillbemadeofPVCpiecesandfromthepumpswewilluseaclearvinylthickwalledhose.ThemethanolandsodiumhydroxidemeteringtankswereconstructedofPVCtubingenclosedbyvalves.Thesizeofthesetanksiscalculatedintheengineeringanalysisbelow.

ENGINEERING ANALYSIS METERINGThemeteringsystemmeasuresouttheexactamountofsodiumhydroxideandmethanoltoaddtothebatchtomakeacompletereaction.Thereactantswillbeheldinalargecontainerandusingapipewithvalvesonbothends,thecorrectamountwillbemeasuredintothepipetomakeasinglebatch.Ratiosfoundfromthepreviousseniordesignprojects,wereusedtodeterminehowmuchofeachreactantwasneededperbatch.TheresultsareshowninTable2.Table 2. Reactant ratios for a single batch Variables Value UnitsTotal Liquid Volume of tank 5.00 galCooking Oil 4.08 galMethanol 0.82 galSodium Hydroxide 0.10 gal Usingthevolumeofeachreactantnecessarytocompletethereaction,themeteringsystemcontainersmadefromdifferentsizesandattachmentsofPVCcouldbedesigned.Thevolumeofliquidlocatedineachpipeconnectingthevalvesandintheendcapsorfittingsforthetankwerecalculatedfirst.Thensubtractingthisvolumefromthetotalvolumeofthereactantrequiredgivestheamountofliquidthathastobelocatedinthemeteringcontainer.Thevolumetobeenclosedinthetankwasdividedbytheareaofthetankusingtheareaofacircleandthediameterofthepipetobeusedforeachcontainer.Thisleftuswiththelengthofthemeteringtanknecessarytoenclosethecorrectamountofvolume,asshowninTable3.FindingthelengthsofeachtubeisnecessaryforpurchasingthecorrectamountofPVCandalsofordesigningthemeteringsystem.SeeAppendixF.2forafulldetaileddrawingofthemethanolmeteringtank.

23

Table 3. Metering container calculations MethanolMeteringContainer SodiumHydroxideMeteringContainerVariables Value Units Variables Value UnitsVolumeofMethanol 0.82 gal VolumeofSodiumHydroxide 0.10 galDiameterofpipe 4.00 in Diameterofpipe 2.00 inRadiusofendcaps 2.00 in Lengthoffitting 1.00 inLengthofinletvalvepipe 1.50 in Lengthofinletvalvepipe 1.50 inLengthofexitvalvepipe 1.50 in Lengthofexitvalvepipe 1.50 inDiameterof1valvepipe 1.00 in Diameterof1valvepipe 1.00 in

TotalVolumeofMethanol 188.57 in3 TotalVolumeofSodiumHydroxide 23.57 in3

VolumeofFluidinEndcaps(x2) 33.51 in3 VolumeofFluidinFittings(x2) 1.13 in3

VolumeofFluidinValvepipes(x2) 2.36 in3 VolumeofFluidinValvepipes(x2) 2.36 in3

VolumeofFluidinPipe 152.70 in3 VolumeofFluidinPipe 20.09 in3

LengthofMethanolPipe 12.15 in LengthofSodiumHydroxidePipe 6.39 in MOTOR ANALYSIS To determine the correct motor, calculations for speed and torque had to be performed. The analysis started by finding the average angular acceleration,, calculated from the target angular speed of 500 RPM. Using geometric properties and material properties the inertia, I, for both the tank and the liquid inside the tank were found and added to get the total inertia. =Itotal Eq.1 Using Eq. 1, the amount of desired torque, ,wascalculated.AsshowninTable4,thetorqueneededwasaround252ozin.ThemotorselectedfortheoperationistheBison32model.Usingthespecificationsofthemotorthespeedwasusedtofindthegearratio.Oncethegearratiowasfoundtheamountoftorquegeneratedfromthemotorthroughthegearswascalculatedtoensurethatenoughtorquewouldbeproducedtospinthelargeseparationtank.Usingthegearratiothesizeofthegearlocatedonthemotorshaftandthegearmountedtothebottomofthetankcouldbedetermined.Ofcoursewewillhavetobuystandardsizegears,butthisanalysiswillatleastgiveusareferencepointsoweknowwhatapproximateratiowedliketouse.Thespinuptimeofthetankisnottooimportanttoourselection,sincethemotorwillbespinningforapproximately30minutesintotalandweareonlyconcernedwiththesteadystatespeed. Table 4. Motor Specifications Required and Motor Selected Properties MotorCalculations Bison32MotorSelectedCharacteristics Value Units Characteristics Value UnitsAngularSpeed(500rpm) 52.3599 rad/sec MotorSpeed 1948 rpmAverageAcceleration 3.4907 rad/s2 MotorTorque 93.4 inozMomentofInertiaofLiquid 0.1625 kg/m2 GearRatio(motorspeed/500rpm) 3.896 MomentofInertiaofContainer 0.3479 kg/m2 GearonTank(setbydesignspecs) 6 inTotalMomentofInertia 0.5104 kg/m2 GearforMotor 1.54 inAverageTorqueNeeded 1.7817 Nm TorqueonTank(motortorque*gearratio) 363.886 inozAverageTorqueNeeded 252.3136 ozin

24

Figure 11. Tank Support Structure TANK FRAME STRUCTURE Priortoconstruction,weneededtochecksupportstructuremechanicsandensureitsintegrityunderthetankandfluidloads.Stresscalculationswereperformedforthecrossingmembersthatdirectlysupportthetank,aswellthesquarepiecesthatsupportthosemembers.Bucklingcalculationswereperformedforthefourmaincornersupports(seeFigure12forillustrationofthesepieces).OrthographicdrawingswithoverallstructuredimensionsareinAppendixF.4.

Outside Leg

Bar 1

Bar 2

Bar 3

Center Leg

Bar 4

Figure 12. Tank support structure

25

Support Bars Stress Analysis Basicfreebodydiagramscanbedrawnfortheprinciplecrossingmembers(labeledinFigure12),asshownbelowinFigure13.CalculationassumptionsandprocessareshowninTable5;Table6givesmaterialparametersandresults.Table 5. Stress calculation approach

Assumption/Process Step Algebraic Result1.Force/Momentbalance 1additionalequationrequiredtodetermineforces

2.MomentDeflectionrelation3.Isotropicsteel E=constant

5.Additionalequationfromdeflectionanalysis6.Bendingmomentdiagram Pointoflargestmomentvisible

7.Evaluatestressatx

4.Zerodeflectionatsupportforces Bar1example:

Solveforsupportforces

EIM

dxvd =2

2

0)2()()0( 11 === vvv

IyxMyx )(),( =

FA FBFCENTER

1/3 FTANK 1/3 FTANKd2 d2

d1 d1

FC FDFCENTER

1/3 FTANKd5

d3 d4

2.00"

0.25"

Bar 1

Bar 2

x

x

y

y

FE FF

d6

d7

Bar 3 x

y FA

FG FH

d8

Bar 4 x

y FD

d8

1.00"

1.00"

0.1875"

Figure 13. Support beam free body diagrams

26

Table 6. Maximum stress in bars 1, 2, 3, and 4

Bar Maximum Stress1 819psi2 5494psi3 136psi4 70psi

ASTMA36SteelPropertiesYIELD=36260psiE=30x106lbf/in2

*Note:maxcompressiveandtensilestressesequalduetocentrallylocatedneutralaxis

Bar2experiencesthelargeststressand,asexpected,thesquaresupportbars3and4experiencethesmalleststresses.Allfourcalculatedstressesfallwellbelowsteelsyieldstrength,sowecanconcludethatthesupportbarsforthetankstructureareamechanicallysounddesignandwillwithstandtheirrespectiveloads.Werealizethatanydeflectionofthebeamsmayintroducesomemisalignmentofthetanksrotationalaxis.However,theresultingdeflectionwillbeminisculecomparedwiththeuncertaintyintroducedbythemanufacturingprocessesusedtoalignthetank.Forthisreason,wearenotconcernedaboutthesesmalldisplacements.Vertical Legs Buckling Analysis Bucklinganalysiswasperformedoneofthefouroutsideverticallegsaswellasthecentersquareleg,accordingtotheprocessgivenbyTable7.ResultsareshowninTable8.

FE + FG

FR1

2.00" 2.00"

0.25"

Outside Leg

FCENTER

FR2

Center Leg

2.00"2.25"

Figure 14. Vertical beams for support structure

27

Table 7. Buckling calculation approach

Assumption/ProcessStep Algebraicresults

1.ForceBalanceexample:FE andFG frompreviousstresscalculations

2.EulerBucklingLoad3.IsotropicSteel E=constant

AP YIELDMAX =

able 8. Force present in outside and center legs T

Leg Force BucklingForceOutside 6.39lbf 3.4x104 lbfInside 23.14lbf 6.8x104 lbf

ASTMA36SteelProperties YIELD =36260psi sbothcenterandoutsidelegloadsarefarlessthantheirrespectivebucklingloads,theoutside

ECHANICAL ANALYSIS OF MAIN TANKUsingthesamecalculationmethodsasusedforthe

d

ending Failure Due to Static Fluid Pressure Beforeandaftertheseparationprocessthetank

Aandcentersupportsareinnodangeroffailure.Mprototypethetwopossiblefailuremodesforthemixingtankarecalculatedasbendingfailureandcircumferentialstress.Toensurethatthescalingmethodsareacceptablethecalculationsareveryimportanttoensurethatasystem5timesbigger.Forthestationarytanksupportingaround150lbsofweightfromthefluid,thebendingfailurestressisfound.Wefirstconsiderethepossibilityforbendingfailureinthebottomofthetankwhenthefullfivegallonsoffluidisstationary.Wethenconsideredthepossibilityforexcessivecircumferentialstressinthewallsofthetankduringrotation.Forbothofthesecaseswemadesurethatthedesignhasasignificantmarginagainstfailure.Bwillneedtosupportroughly40lbsofstationaryfluid.Themostlikelyfailuremodewillbethebendingofthebottomlayerofmaterial.Assumingthatthetankisonlysupportedbytherollersonthebottom,thediagramofthissituationisshownbelowinFigure15.

28

Figure 15. Free body diagram of the tank supporting 40 lbs. of fluid. Thepressureatthebottomofthetankisequaltogh,whichequals3.4kPa.Wetreatthebottompartofthetankasacircularplatewhichissubjecttoauniformpressure.Sincetheendsaresimplysupportedfrombelowandattachedtothecylindricalportionofthetank,weconsidertheedgeofthecircularplatetobebuiltin(nodeflectionorchangeinangle).Inthissituationthebendingmomentisequaltothefollowing: ( )2 20 (1 ) (3 )( )

16rrv a v r

M r + + = Eq.2

Themaximumbendingmomentoccursattheoutsideoftheplate(r=a)andisequalto8.8Nm.Theresultingstressintheplateisdescribedbelow. max

max 2

6 Mt

= Eq.3Themaximumstress(tensileandcompressive)inthetankis8.3kPa.Theyieldstrengthofmediumdensitypolyethyleneis19.3MPaandthefracturetoughnessis3.8MPa m .Thisdesigndoesntcomeclosetofailinginthismode.Table9belowshowstherelevantparametersusedincalculations. Table 9. Values used for calculations

Parameter Value 1000kg/m3

h 0.35mv 0.44a 0.143mt 0.00635m

Circumferential Stress When Rotating Whilethetankisrotatingduringtheseparationprocessthecentrifugalforcesfromthefluidwillputpressureonthesidewallsofthetank.AdiagramofthissituationisshownbelowinFigure16.

P

a

h

t

Possible Failure

r

29

P

ar

t

Figure 16: Free body diagram of the tank walls retaining rotating fluid. Tocalculatethepressurethewaterexertsonthetankwalls,wetreatthewaterasanelasticplasticmaterialwhichyieldsatzeroshearstress.Wealsoassumethatthetankiscompletelyfullofwaterwheninfactitisonlybe5/6thsfull.Thepressuredistributioninthewaterwillbe: 2

2 2( )2aP r r = Eq.4

Thepressureattheinnersurfaceofthetankwallwillbe27.6kPa.Assumingthatthetankcanbetreatedasathinwalledcylinder,thecircumferentialstresswillbe: P a

t = Eq.5

Thestresswillbe0.62MPainthetankwall.SincetheyieldstrengthofMDPEis19.3MPa,thereisasafetyfactorofover30againstyield.Inaddition,thecriticalflawsizeneededtoinitiateacrack(modeIconditions)willbeextremelylarge.Table10belowshowsthevaluesoftheparametersusedincalculations.

Table 10. Values used for calculations

Parameter Value 1000kg/m3

52rad/sa 0.143mt 0.00635m

CENTER OF MASS AND TIPPING ANALYSIS ThefullsystemwasreducedintomajorcomponentsasseeninFigure16,eachwithitsrespectivexCMandyCMlocationandmass.Duetonearperfectzaxissymmetrythroughthebasecenterline,zCMwasassumedtobezero.ThexandycentersofmasswerethencalculatedusingEq.6,below.

n

nnCM mmm

xmxmxmx ++++++=

......

21

2211 Eq.6

30

34.00

7.00

68.00

28.00

70.00

78.00

6.00

72.00

Steel 120 lbs

Tank & Liquids 45 lbs

Mixing Pump 20 lbs

12.00 6.00

7.00

Grease Pump 15 lbs

Methanol Metering 6.4 lbs

NaOH Metering 0.8 lbs

NaOH Tank 1.6 lbs

3.50

Methanol Tank 8 lbs

3.50

GROUNDCL

CL

3.00 Base 40 lbs

3.25

25.25

System CG 256.8 lbs

y

xz

Note: all measurements in inches

Figure 16: Center of masses for individual components and final COM for system

31

Becausethebaseis5ftlongandyCMisslightlyover2ft,tippingishighlyunlikely.Onewouldneedtoapplyaforceatthetopofthestructurewhilesimultaneouslykeepingthecasterslockedagainstrolling,therebypushingthesystemtoanangleof49.9,asseeninFigure17.Thisextremeangleyieldsveryminimaldangeroftippinginthexyplane.

25.25

30.00

AT REST TIPPING OCCURS

49.9

ForceNote: all measurements in inches

Figure 17: Tipping in x-y plane Thebaseissignificantlynarrowerthanitislongat2.5ftwide,sotippingwasinvestigatedfurtherintheyzplane.Figure18showsthesmallertippingangleincomparisontothexyplanecase.

25.25

15.00

AT REST TIPPING OCCURS

30.7

Force

?

Note: all measurements in inches

Figure 18: Tipping in y-z plane Tocalculatetheforcenecessarytoachievethistippingangle,amomentbalanceisfirstusedtofindthemomentactingtokeeptheCOMatitstippingpoint.ThoughthepictureshowsaforceactingontheCOM,weassumethelargestmomentarmavailabletotheuser(thusminimizingtheforcerequiredfortipping),sotheforceisactuallyappliedatthetopofthestructure,80fromtheground.Withthecalculatedtippingmoment,onecandeterminetheuserappliedforcerequiredfortipping.ThisprocessissummarizedinEqs.7and8.

32

15cos = mgM TIP Eq.7

80TIPMForce = Eq.8

Thisprocessyieldsauserforceof41.42lbf.Theonlylikelyscenariofortippinginvolvessuddenlyhittingabumpthatstopsthecasters,andthisinvolvesanimpulseforce,nottheconstantforcejustcalculated.Ultimately,thelikelihoodofausermaintainingaforcegreaterthan41.42lbftothetopofthestructureforthetimenecessarytotipthebase30.7isextremelysmall.Thefullsystemisthusdeterminedtobestableinbothplanesofinterest. FAILURE MODE EFFECTS AND ANALYSISOncewedeterminedthegenerallayoutofourdesignwecreatedafailuremodeeffectsandanalysistoidentifythegreatestfailurerisksandwaystomitigatethem.Foreachofthemaincomponentsofthesystemwedeterminedthemostlikelypossibilitiesforfailureanddeterminedtheeffectontheprocessasawhole.Weusedascalingfromonetotentoquantifytherelativeseverity,cause,andsubtletyofeachmodeoffailure.ThemultiplicationofthesethreeparametersgivestheRiskPriorityNumber(RPN),whichquantifiestherelativedetrimenttothesystem.ForthosefailureswitheitheralargeRPNoracheaporsimplesolution,wedeterminedpossiblecorrectiveactionstohelpmitigatetherisk.WethenrecalculatedtheRPNconsideringthatthechangeshadbeenimplementedandalsocalculatedthepercentreductioninRPNtoquantifytheeffectiveness.Fromouranalysiswefoundaneedforfluidsensorsdownstreamofthereactantvalves,downstreamofthebiodieseloutletvalve,andafterthemixingpump.Wealsodeterminedthataflowmeterontheinputoillineandatachometeronthemotorwouldhelpdecreasethesubtletyandseverityofpossiblefailures.Thesefeaturesareincorporatedintothefinaldesign,butduetobudgetconsiderationsweareunabletoincludethemintheprototype.ThefullFMEAspreadsheetisshowninAppendixD.DESIGN FOR MANUFACTURING AND ASSEMBLY We designed our prototype with ease of manufacturing and assembly in mind. We took several guidelines into account which are explained next along with how we applied them to our design. Permit Assembly in Open SpacesOurdesignprovidesadequatespaceforassembly.Allfoursidesofthesupportstructureareopensothereisntanyspacewheretoolscannotreach.Themountingbracketsforthesupportwheelsareeasilyaccessibleandthereforeallowthewheelstobeattached.Also,thesupportbarsonthetopandbottomofthetankareboltedontothesidebarsinareaswithadequateclearanceallaround. Standardize to Reduce Part Variety Allboltsusedforagivensetofattachmentsarethesamesize.Thisincludestheboltsformountingthesupportstructuretothebase,mountingthesupportwheelsinthebrackets,andattachingthetanksupportbeamstothesidesupport

33

beams.However,thesesetsofboltsarenotthesamesizebecauseeachapplicationrequiresadifferentlengthbolt. Maximize Part Symmetry Allofthesteelpartsusedinourprototypearesymmetric,whichsimplifiesassemblyproceduresbecauseorientationisnotafactor.Thisincludesthesupportlegsandallsupportbeamsandsupportwheelbrackets,thebracketsusedtoattachthesupportlegstothebaseboardaresymmetricsincenomatterwhichwaytheyareorientedtheholeslineupthesameway.Eliminate Fasteners Weeliminatedalotoffastenersbyallowingmostofthesupportstructuretobeweldedtogether.Therearenotanysuperfluousfastenersusedinourprototypeandsomeparts,includingthemixingpump,werenotattachedbecauseitwasunnecessary. Allow Access of Tools Goingalongwithpermittingassemblyinopenspaces,wemadesuretherewasadequateroomforthetoolsneededforassembly.Forfastenersthatincorporateanutandaboltweensuredtherewasaccessfortoolsatbothends. DESIGN FOR THE ENVIRONMENTTherewereseveralguidelineswhichweconsideredinourprototypedesign.Althoughwewereabletomeetmostoftheguidelines,somewerenotpossibletomeetduetobudgetconstraints.Optimize Material Use Wemadeasupportstructuretohouseallofourcomponentsratherthanusingalargeboard,thusreducingtheamountofmaterialused.However,duetobudgetconstraintswewereunabletoavoidusingPVCinourfinalprototype.Usuallythisisamaterialtoavoidsowewouldhaveusedstainlesssteelinsteadhaditbeenfeasible.Optimize Production Techniques Whenconsideringproductiontechniqueswedeterminedourproductcaneitherbeassembledbyhandorusingrobotics.Anautomatedassemblyplantwouldresultinmuchlargerproductionwaste,butwouldalsogreatlyincreasethespeedandvolumeofproduction.Optimize Distribution Ourentireproductcanbeseparatedfromthebaseboard,thusreducingthesizeofcontainerneededtotransportit.Thisallowsourproducttobebyawiderrangeoftransports,includingbyair.Reduce Impact During UseOurproductrunsoffatypicalwalloutlet,requiringamaximumof15ampsofcurrent.Nootherenergysourcesarerequiredduringuse.Theinputstothesystemareeasilyacquiredsodiumhydroxideandmethanolandbyusingwastecookinggreaseourproducttakesalreadywastedmaterialsandmakesthemusable.Nothingharmfulisproducedfromtheoperationofthisproduct,andinadditiontobiodiesel,glycerinisproduced,whichcanbeusedtomakesoap.

34

Optimize End-of-Life Systems Thefourmainmaterialsusedinourprototypearerecyclable,whichincludessteel,PVC,Polyethylene,andwood.Unfortunatelyourdesignrequiredthatmuchofthesteelbeweldedtogetherwhichresultsingreaterdifficultyindisassembly.Theotherrecyclablematerialscanbeeasilyremovedandprocessed.

FINAL PROTOTYPE DESIGN ThefinalprototypedesignisshowninFigure19.WeusesixmanualPVCvalvestoreplacethesolenoidvalvesweinitiallyplannedonusing.Oncewerealizedthatcostconsiderationswouldlimitusfromusingalargenumberofsolenoidvalves,wethenredesignedthesystemtouseonlytwosolenoidvalves.Wewouldhaveimplementedastainlesssteel2wayvalveandabrass3way,inadditiontothefourmanualvalvesforthereactantmetering.EvenafterworkingextensivelywithKundingerControls,alocalprocesscontroldistributor,wewereunabletofindsolenoidvalvesthatwouldfitwithinourbudget.

35

Biodiesel Glycerin / Waste

Waste Grease

Methanol

SodiumHydroxide

Filter

Gear Drive

Mixing Pump

Oil Pump

Motor

PVC

Mixing / SeparationTank

Mixing Return Line

1" PVC

Strain er

PVC Check valve

1" PVC

1" PVC

" hose

1" PVC

1" PVC

1" PVC

1" PVC

1" PVC

PVC

PVC

" hose

hose hose

hose

hose hose

hose

Figure 19. Final prototype design schematic Wechosetousemainly1PVCpipestoallowthefluidstomovequicklythroughthesystem.Bothontheinletandoutletofbothpumpsweusedflexiblevinylhose.Weusedonallconnectionsexceptfortheoutletoftheoilpump,whichwas. FILTERING A400micronstrainer(Figure8)willbeincorporatedbeforetheoilpumpandaWix57251automotiveoilfilterwillbelocatedafterthepump.Thestrainerisaselfcontainedunitwhichwillbepurchasedfromwww.biodieselwarehouse.com.Locatingthestrainerintheoillinebeforethepumpwillstoplargeparticlesfromenteringthepump,preventingpossibledamagetothepump.

36

TheWIXoilfilterhasa19micronratingwhichissufficientforthewasteoilenteringthesystem.Thisunitislocatedafterthepumpandhasamaximumflowrateof1215GPM,whichislargerthantheflowrateofthepumpsoitwillnotcauseabackup.Thecoupling(Figure20)allowsthefiltertobeconnectedintheinletoillineandcanbechangedeasily.SeeAppendixF1fortheengineeringdrawing.

a. b. c. Figure 20. Oil filter with coupling (a) connected together (b,c) exploded to show connection METERING Wedesignedspecificmethodsformeteringinordertoachievetheproperproportionsofeachofthethreereactants.Forthewastegreasetheoilpumpwillbetimedtodeterminehowlongittakestopump4gallonsintothemixing/separationtank.Formethanolmeteringanintermediateonegallontankwillbeincorporatedbelowthemethanolstoragetankwithvalvesonthetopandbottom(Figure21(a)).ThistankwillbemadewithafourinchdiameterlengthofPVCpipewithendcaps.Aoneinchinlettubeisconnectedtothetopandasimilartubeforexitingoutthebottom.Manualvalveswillcontroltheflowofmethanolinandoutofthetank.Thebottomvalvestartsoutclosedandthetopvalveopensuntilthetankisfull.Thenthetopvalveisclosedandthebottomvalveisopeneduntilthetankempties.The0.102gallonsofNaOHneededissmallenoughsothetwoinchPVCpipingcanbeusedtometeritwithvalveslocatedaspecificdistanceapart,asshowninFigure21(b).Thiswilloperateinthesamewayasthemethanolmeteringtank,onlyonamuchsmallerscale.

37

a. b. Figure 21. (a) Methanol intermediate metering tank and (b) NaOH metering pipe

MIXINGWehavedecidedonapumptocirculatethereactantsinthemixingtanktoachievethedesiredlevelofmixing.Figure22(a)showsthesetupforthemixingpumpandtank.Thepumpwewilluseforthisisan11GPMstainlesssteelunitpurchasedfromBiodieselWarehouse.Thestainlesssteelconstructionwillensurethattheinternalmaterialswillnotcorrodewhenexposedtothereactants.The11GPMpumpwillcompletelyrecirculatethereactantsonceaboutevery30secondsandwefeelthatthiswilloffersufficientmixing.Themixingwillrelyonthelevelofturbulentflowandrelativemotionofthefluid.Thepumpwilltakethereactantsfromthebottomofthetankthroughthetankoutlettubeandwillpumpthembacktotheinlettubeatthetopofthetank.Thisprocesscontinuesuntilthedesiredlevelofmixingisachieved.

a.

Mixing Pump

PVC

Mixing / SeparationTank

Mixing Return Line

" hose

PVC

" hose

b. Motor

PVC

Mixing / SeparationTank

PVC

" PVC

2-way SS valve

Figure 22. (a) Mixing pump setup and (b) Separation setup

38

SEPARATION Theseparationtankisthesametankwhichisusedinthemixingstep.Formixingtheentiretankwillspinonitsaxisatapproximately500rpm.Weusedtheworkofpreviousgroupsbytakingtheirrecommendationforrotationalspeed.Toaccomplishthiswechoseamotorandwilltranslatethetorqueusinggears.Figure20(b)showstheseparationsetup.

A6.5diametergearwillbeattachedtothetankanda1.625diametergearwillbeattachedtothemotorshaft.Thiswilldecreasetherotationalspeedbutincreasethetorque.TheVXBballbearingkit7358(Figure23(a))willbeusedatboththetopandbottomofthetanktomakesurethetankspinssmoothly.Thebearingswillbeattachedtotheinletandoutletpipes,whichwillnotspin.ThemotortobeusedisaBison32DCmotor(Figure23(b)).

a. b. Figure 23 (a) Ball bearing kit and (b) Separation motor Tofurthersupportthetankwhilespinning,rubberwheelsonballbearingaxiswillbelocatedaroundthetankbothonthebottomandthesides. SUPPORT STRUCTURE Themixing/separation,methanol,andsodiumhydroxidetanksareeachheldinplacebytheprimarysupportstructure,asseeninFigure24.Thestructureuses2Ltypesteelstockatitsfourcorners,bracedwith1squaretypesteelbetweeneachleg.Attachedtothesebracesaretwocrossingmembersthatcollectivelysupportthemixing/separationtankatthreepointswithmediumhardnessrollerbladewheels.Becauseofthesignificantloadonthesetwocrossingmembers,alarge2x2centersupportwasaddedattheirintersection.Thistypeofwheelisalsousedaroundthesidesofthetanktokeepitspinningsymmetrically;basedonpossibleinaccuraciesduringconstruction,wemadethesewheelsadjustabletoenablethepropercenteringofthetank.Thetwomethanoltankscombineforsubstantialweighttoonesideofthesupportstructure,sothemixingpumpwasplacedoppositethemforcounterbalancing.Basedonobservedstabilityduringtesting,additionalstructurebracingatthegroundmayormaynotberequired.

39

Figure 24. Support Structure FULL SCALE TO PROTOTYPE COMPARISON Wewillnotmanufacturethefullscalemodelofthesystembecausethecostofallthecomponentswouldexceedourbudget,andbecausewehavealimitedmanufacturingschedulethatwouldnotaccommodatealargersystem.Theprototyperepresentsascaledmodelofthefullscaledesignwitharatioof1:5,or5gallonbatchsizetothefullscale25gallonbatchsize.System LayoutThefullscalemodelwillbeorientedhorizontallytoensuresafetyandconveniencefortheoperator.Thefluidflowthroughthesystemwillbeachievedmainlythroughtheuseofpumps.Duetobudgetlimitations,theprototypedoesnotutilizeasmanypumps,butusesgravitytomovethefluidsthroughthesystem.Thefullscalemodelwillhaveinletpumpsforthemethanolandsodiumhydroxideaswellthewastegrease.AutomationCostlimitationsforcedustoeliminateautomationintheprototype;thefullscaledesignwillbeentirelyautomatedfromstarttofinish.LabVIEWsoftwarewillbeusedtoturn

40

eachsystemcomponentonandoff,withoutadditionaluserinput.Thethreereactantscanbemeteredusingflowmetersorbytimingtheinletpumps.Duetotheconstantviscosityofthemethanolandsodiumhydroxide,timingthepumpsforthesetworeactantswouldbeequallyaccurateandlessexpensivethanflowsensors.Usingpumpstoinputthereactantsdecreasesthenumberofvalvesrequiredinthedesign,becauseiteliminatesthemeteringtanks.Eachremainingvalvewillbeasolenoidvalvethatcanbetimedpreciselytothereaction.Theoutletvalveswillbetimedbasedonthemixingandseparationtimesandthepredictedvolumesoftheproducts.Theboundarylayerwillbeincludedwiththewastelayerofglycerintoensurethepurityofthebiodiesel. Prototype Scaling JustificationThescalingfactorof5:1issmallenoughtoallowforaccuratecomparisonstobemadefromtheprototypetothefullscaledesigninengineeringcalculationsaswellaspracticalapplication.Bydecreasingthebatchsizethegroupcouldsavemoneybypurchasinglessmethanolandsodiumhydroxide,Table10.Theamountofreactantsneededforthe5gallonbatchare4.08gallonsofcookingoil,0.82gallonsofmethanol,andalso0.10gallonsofNaOH,perbatch.Thefullscalemodelwouldrequire16.33gallonsofcookingoil,3.27gallonsofmethanol,and0.41gallonsofNaOH,foreachbatch.Italsoreducestheoverallprototypeconstructioncostsbecauselessmaterialisneededtoassembletheprototypesystem.Thesizeoftherequiredtankisreducedfroma30gallontanktoa6gallontank.Theamountofrequiredmaterialforthesupportstructureislessforamuchsmallertank,althoughtheexactsamedesignwillbeusedforthefullsystem.Table 11. Comparisons for reactant ratios for prototype and full scale model Variables Prototype

5.004.080.820.10

Fullscale UnitsTotalLiquidVolumeoftank 25.00 galCookingOil 20.41 galMethanol 4.08 galSodiumHydroxide 0.51 gal Table 12. Comparison of methanol and sodium hydroxide containers for prototype and

full scale model MethanolMeteringContainer SodiumHydroxideMeteringContainerVariables Prototype Prototype

0.82 0.104.00 2.002.00 1.001.50 1.501.50 1.501.00 1.00

188.57 23.5733.51 1.132.36 2.36

152.70 20.0912.15 6.39

Fullscale Units Variables Fullscale UnitsVolumeofMethanol 4.08 gal VolumeofSodiumHydroxide 0.51 galDiameterofpipe 8.00 in Diameterofpipe 4.00 inRadiusofendcaps 4.00 in Lengthoffitting 1.00 inLengthofinletvalvepipe 1.50 in Lengthofinletvalvepipe 1.50 inLengthofexitvalvepipe 1.50 in Lengthofexitvalvepipe 1.50 inDiameterof1valvepipe 1.00 in Diameterof1valvepipe 1.00 in

TotalVolumeofMethanol 942.86 in3 TotalVolumeofSodiumHydroxide 117.86 in3

VolumeofFluidinEndcaps(x2) 268.08 in3 VolumeofFluidinFittings(x2) 3.13 in3

VolumeofFluidinValvepipes(x2) 2.36 in3 VolumeofFluidinValvepipes(x2) 2.36 in3

VolumeofFluidinPipe 672.42 in3 VolumeofFluidinPipe 112.38 in3

LengthofMethanolPipe 13.38 in LengthofSodiumHydroxidePipe 8.94 in

41

Theprototypewillnotbeusingaflowmeterlikethedesignofthefullscalemodel.Insteadtheprototypewillhavealinemarkedontheoutsideofthetankatthecorrectvolumeforthegreaseinput.Theflowmetersensorisveryexpensiveandusingalengthoftimetoautomatethepumpdoesnotchangethefunctionalityofthesystem.Havinganautomatedsensorwouldbeamoreaccuratewayofmeasuringtheamountofcookingoilinthetank,butlettingtheuserturnoffthegreasepumpwhenthecorrectvolumeisreachedwillbesufficientfortheprototype.Thenumberofsolenoidvalveswasalsodecreasedintheprototypetocutthecostsandthesevalveswillbereplacedwithmanualvalves.Althoughtheprototypeisnotautomated,thedesigncanbeautomatedsimplybysubstitutingtheautomatedcomponentsforthemanualones.MassProductionManycostfactorsneedtobeconsideredwhenplanningtomassproducethefullscalemodel.Table13belowshowsthecostofallthepiecesforthefullscalemodelwhenpurchasingthemfromthirdpartysuppliers.Thetotalcostforproducingonesystemisaround$1400.Thisestimatedoesnotincludethematerialsforthesupportstructure,labor,orothersmallcostsintubingandPVCconnectors.Theestimatefortheitemsshownishighbecausetheseproductsarenotalldiscountedforpurchasinglargequantitiesandalsotheyarenotfromawholesalemarket.Whentakingintoaccountthecostsnotincludedinthetableitisexpectedthattheoverallcostwillbearound$2000persystem.Whencomparedtootherbiodieselconversionsystems,thisisaverycompetitivepriceforafullyautomatedsystemthatwillworkquicklybyusingcentrifugalseparationTable 13. Mass production for full scale design Items Price Per1000Units Price DiscountLengthofmethanolmetering8pipe $14.60 /ft 1166.67 ft $14,478.37 15%for120ft+Lengthofmethanolmeter