英文文献年产万吨的苹果汁工厂设计.docx
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英文文献年产万吨的苹果汁工厂设计.docx
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英文文献年产万吨的苹果汁工厂设计
英文文献
2.5.3.Designandconstructionofthebuilding
Roofsandceilings
Walls
Windowsanddoors
Floors
Lightingandpower
Watersupplyandsanitation
Layoutofequipmentandfacilities
Ingeneral,abuildingshouldhaveenoughspaceforallproductionprocessestotakeplacewithoutcongestionandforstorageofrawmaterials,packagingmaterialsandfinishedproducts.However,theinvestmentshouldbeappropriatetothesizeandexpectedprofitabilityoftheenterprisetoreducestart-upcapital,thesizeofanyloanstakenoutanddepreciationandmaintenancecharges.
Roofsandceilings
Intropicalclimates,overhangingroofskeepdirectsunlightoffthewallsandoutofthebuilding.Thisisparticularlyimportantwhenprocessinginvolvesheating,tomakeworkingconditionsmorecomfortable.Fiber-cementtilesoffergreaterinsulationagainstheatfromthesunthangalvanizedironsheetsdo.Highlevelventsinroofsbothallowheatandsteamtoescapeandencourageaflowoffreshairthroughtheprocessingroom.Theventsmustbescreenedwithmeshtopreventinsects,rodentsandbirdsfromenteringtheroom.Ifheatisaseriousproblem,theentrepreneurcouldconsiderfittingelectricfansorextractors,althoughthisclearlyincreasescapitalandoperatingcosts.
Raftersorroofbeamswithintheprocessingandstorageroomsareunacceptable.Theyallowdusttoaccumulate,whichcanfalloffinlumpstocausegrosscontaminationofproducts.Similarly,insectscanfallfromthemintoproducts.Theyalsoallowpathsforrodentsandbirds,withconsequentrisksofcontaminationfromhairs,feathersorexcreta.Itisthereforeessentialtohaveapaneledceilingfittedtoanyprocessingorstore-oom,withcarefulattentionwhenfittingthemtoensurethattherearenoholesinthepaneling.Careshouldalsobetakentopreventbirds,rodentsandflyinginsectsgainingaccesstotheprocessingroomthroughgapsintheroofstructureorwheretheroofjoinsthewalls.
Walls
Asaminimumrequirement,allinternalwallsshouldberenderedorplasteredwithagoodqualityplastertopreventdustformingintheprocessingroom.Anexperiencedplasterershouldbeusedtoensurethatnocracksorledgesremaininthesurfacefinish,whichcouldaccumulatedirtandinsects.Thelowerareaofwalls,toatleast1.08metres(fourfeet)abovethefloor,ismostlikelytogetdirtyfromwashingequipment,fromproductsplashingetc.andspecialattentionshouldbepaidtoensurethatthisareaiseasilycleaned.Higherareasofwallsshouldbepaintedwithagoodqualityemulsion.Thelowerpartsofwallsshouldbeeitherpaintedwithawaterproofglosspaint,preferablywhite,toallowthemtobethoroughlycleaned,orideallytheyshouldbetiledwithglazedtiles.Iftilingaprocessroomistooexpensive,itispossibletoselectparticularareassuchasbehindsinksormachineryandonlytiletheseparts.InsomecountriesthereisalegalrequirementforspecifiedinternalfinishesandthisshouldbecheckedwiththeMinistryofHealthorotherappropriateauthority(seealsoSection2.4.2)
Windowsanddoors
Windowsillsshouldbemadetoslopefortworeasons:
topreventdustfromaccumulatingandtopreventoperatorsfromleavingclothsorotheritemslyingthere,whichinturncanattractinsects.Windowsallowstafftoworkinnaturaldaylight,whichispreferabletoandcheaperthanelectriclighting.However,intropicalclimatesthereisanaturalinclinationforworkerstoopenwindowstoallowgreatercirculationoffreshair.Thisprovideseasyaccessforflyinginsects,whichcanreadilycontaminatetheproduct.Windowsshouldthereforebefittedwithmosquitomeshtoallowthemtobeleftopen.
Normallydoorsshouldbekeptclosed,butiftheyareusedregularlythereisagainatendencyforthemtobeleftopenwithsimilarconsequencesofanimalsandinsectsenteringtheplant.Inthiscase,thinmetalchainsorstripsofmaterialthatarehungverticallyfromthedoorlintelmaydeterinsectsandsomeanimals,whileallowingeasyaccessforstaff.Alternativelymeshdoorscreenscanbeused.Doorsshouldbefittedaccuratelysothattherearenogapsbeneaththemandallstoreroomdoorsshouldbekeptclosedtopreventinsectsandrodentsfromdestroyingstockoringredients.
Floors
Itisessentialtoensurethatthefloorsofprocessingroomsandstoreroomsareconstructedofgoodqualityconcrete,smoothfinishedandwithoutcracks.Insomedevelopingcountries,itispossibletobuyproprietaryfloorpaintsorvinylbasedcoatings,buttheseareusuallyveryexpensive.Generally,itisnotadequatetousetheredwaxfloorpolishesthatarecommonlyfoundinhouseholds,asthesewearawayeasilyandcouldcontaminateeitherproductsorpackages.Overtime,spillagesofacidicfruitproductsreactwithconcreteandcauseittoerode.Attentionshouldthereforebepaidtocleaningupspillagesastheyoccurandtoregularlymonitortheconditionofthefloor.
Thecomerswherethefloorandthewallsjoinareplacesfordirttocollect.Duringconstructionofthefloor,itshouldthereforebecurveduptomeetthewall.Itispossibletoplacefilletsofconcrete(or'coving')inthecomersofanexistingfloortofilluptherightangle,butcareisneededtoensurethatnewgapsarenotcreatedwhichwouldharbourdirtandinsects.
Thefloorshouldslopeatanangleofapproximately1in8toacentraldrainagechannel.Attheendofaday'sproduction,thefloorcanbethoroughlywashedanddrained.Properdrainagepreventspoolsofstagnantwaterforming,whichwouldinturnriskcontaminationofequipmentandfoods.Thedrainagechannelshouldbefittedwithaneasilyremovedsteelgratingsothatthedraincanbecleaned.Wherethedrainexitsthebuilding,thereisapotentialentrypointforrodentsandcrawlinginsectsunlesswiremeshisfittedoverthedrainopening.Thistooshouldbeeasilyremovedforcleaning.
Lightingandpower
Generalroomlightingshouldbeminimizedwhereverpossible.Fulluseshouldbemadeofnaturaldaylight,whichisbothfreeandbetterqualitylight,especiallyforintricatework.Whereadditionallightingisneeded,florescenttubesarecheapertooperatethanincandescentbulbs.However,ifmachineryisusedthathasfastmovingexposedparts,theseshouldbelitwithincandescentbulbsandnottubes.Thisisbecauseeventhoughthepartsshouldhaveguardsfitted,arotatingmachinecanappeartostandstillifitsspeedmatchesthenumberofcyclesofthemainselectricitythatpowersfluorescenttubes-withobviousdangerstooperators.
Allelectricpowerpointsshouldbeplacedatasufficientlyhighlevelabovethefloorthatthereisnoriskofwaterenteringthemduringwashingthefloororequipment.Ideally,waterproofsocketsshouldbeused.Itisimportanttouseeachpowerpointforoneapplicationandnotusemultiplesocketswhichriskoverloadingacircuitandcausingafire.Ifthereareinsufficientpowerpointsfortheneedsofaprocess,additionalpointsshouldbeinstalled,eventhoughthisismoreexpensive.Allplugsshouldbefittedwithfusesthatareappropriateforthepowerratingoftheequipmentandideallythemainssupplyshouldhaveanearthleakagetripswitch.Ifthree-phasepowerisneededforlargermachinesorforheavyloadsfromelectricheating,itisimportantthatthewiringisinstalledbyaqualifiedelectriciantobalancethesupplyacrossthethreephases.
Watersupplyandsanitation
Waterisessentialinnearlyallfruitandvegetableprocessing,bothasacomponentofproductsandforcleaning.Anadequatesupplyofpotablewatershouldthereforebeavailablefromtapsaroundtheprocessingarea.Inmanycountries,themainssupplyisunreliableorperiodicallycontaminatedanditisthereforenecessaryfortheentrepreneurtomakearrangementstosecurearegularsupplyofgoodqualitywatereachday.Thiscanbedonebyinstallingtwohighlevel,coveredstoragetankseitherintheroof-spaceoronpillarsoutsidethebuilding.Theycanbefilledalternatelywhenmainswaterisavailableandwhileonetankisbeingused,anysedimentinwaterintheothertankissettlingout.Assedimentationtakesseveralhours,thecapacityofeachtankshouldbesufficientforoneday'sproduction.Thetanksshouldhaveaslopingbaseandbefittedwithdrainvalvesabovetheslopeandatthelowestpoint.Inuse,wateristakenfromtheuppervalveandwhenthetankisalmostempty,thelowervalveisopenedtoflushoutanysedimentthathasaccumulated.
Waterthatisincludedinaproductshouldbecarefullytreatedtoremovealltracesofsedimentandifnecessary,itshouldbesterilised.Thisisparticularlyimportantiftheproductisnotheatedafterwaterhasbeenmixedinasaningredient.
Therearefourwaysoftreatingwateratasmallscale:
byfiltration;byheating;byultra-violetlightandbychemicalsterilants,suchashypochlorite(alsonamed'chlorinesolution'or'bleach').Otherwatertreatmentmethodsaregenerallytooexpensiveatasmallscaleofoperation.
Filtrationthroughdomesticwaterfiltersisslow,buthavingmadethecapitalexpenditure,itisrelativelycheap.Largerindustrialfiltersareavailableinsomecountries.Heatingwatertoboilingandholdingitatthattemperaturefor10-15minutesissimpleandhaslowcapitalcosts,butitisexpensivebecauseoffuelcostsanditistimeconsumingtodoroutinely.Heatingsterilisesthewaterbutdoesnotremovesedimentandboiledwatermaythereforerequirefilteringorstandingtoremovesediment.
Ultra-violetlightdestroysmicro-organismsinwaterandcommercialwatertreatmentunitsthatusethisprinciple(Figure38)arecomingdowninpricetothepointthat
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