Separating solids from liquids - PDF document

PCD00002EN 0909 Separating solids from liquids Alfa Laval is a leading global provider of specialized products and engineeredare dedicated to helping customers to optimize the performance of theirprocesses. Time and time again.We help our customers to heat, cool,separate and transport products suchas oil, water, chemicals, beverages,foodstuff, starch and pharmaceuticals.to help them stay ahead.Up-to-date Alfa Laval contact details for all countries are always available on our website at www.alfalaval.com Separating solids from liquids plays a key role in countless industrial processes.Decanter centrifuges from Alfa Laval perform this Accelerating the processHowever, such clarification is anextremely slow process and was notable to meet industry’s needs for morerapid, controllable results.the decanter centrifuge was thereforeto provide the continuous mechanicalseparation of liquids from solids, tokeep pace with modern industrialwhose base is wrapped around a4 Alfa Laval – decanter centrifuge technologyWorking principlesVirtually all branches of industry needto separate solids from liquids at somepoint in their manufacturing processes.Alfa Laval has more than fifty years ofexperience in meeting this requirementusing decanter centrifuge technology.to the force of gravity.centre line. Rotating this unit rapidlymeans that the effect of gravity isreplaced by a centrifugal force – theeffect of which can be up to 4000times greater.This force is then used to separatesolids from liquids efficiently in amanner that is easy to control.configuration and surroundingdifferent solids from one or two liquid Outlet for clarified liquidScrew conveyor VFD-controlled motor for screw conveyor particles is continuously removed bythe screw conveyor, which rotates at adifferent speed than the bowl. As aresult, the solids are graduallyThe centrifugal force compacts theThe dried solids then discharge frombowl. Baffles within the centrifugecasing direct the separated phases intothe correct flow path and prevent anyrisk of cross-contamination. Alfa Laval – decanter centrifuge technology 5 Erosion-protected Inlet tube How a decanter centrifuge worksfrom one or two liquid phases in onesingle continuous process. This is doneusing centrifugal forces that can bewell beyond 3000 times greater thangravity.When subject to such forces, thedenser solid particles are pressedoutwards against the rotating bowlforms a concentric inner layer. Differentdam plates are used to vary the depthrequired. Weirs Side walldepth compaction Surface area Cake removal The speed of the screw conveyor mayvariable frequency drive (VFD) in order to exceptional performance In specifying a decanter centrifuge for a•the pitch of the conveyor•feed zone design•beach angle•bowl surface•abrasion resistance•materials used in construction.Alfa Laval decanter centrifuges featurefour main sections, each optimized forproperly designed inlet zone keeps any6 Alfa Laval – decanter centrifuge technology Alfa Laval decanter centrifuges provideseparating solids from liquids, andmake it possible to do so continuously,efficiently and controllably.Decanters are invariably the first choicevirtue of their high reliability, continuousAlfa Laval decanter centrifuges aresolid particles with diameters from 5mm to a few microns.with a solid content from as low as0.1% w/w to more than 65% w/w.variations in the feed more effectivelyperformance of decanter centrifuges:•the centrifugal force required for •the clarification area necessary to “capture” the solids•the differential speed required to •the hydrodynamic design, which •the turbulence•the design of the conveyor and beach sections, which are important for efficient solids transportation. Alfa Laval – decanter centrifuge technology 7 A number of feed zone specificationsare available for Alfa Laval decantercentrifuges, each designed to ensurewith a specific process.Screw conveyorlies in the efficient, effective scrolling ofthe screw conveyor is therefore crucial.industrial processes with specificconfigurations of flight pitch, lead angleand differential speed, in order tosecure the best possible results.can vary from a dry powder to a paste.zone is therefore chosen to enablesuch “cakes” to exit as effectively asInnovative Alfa Laval design enableserosion-prone components used in thesolids discharge zone to be replacedon site at low cost and with a minimumof disturbance to production.In a two-phase decanter, the liquidlevel is regulated by dam plates.When operating in a three-phaseset of dam plates into separate baffledcompartments in the casing.In certain applications, a centripetalpressure head developed by therotating liquid phase is used to pumpthe liquid from the decanter. Three-phase designParing disc design 8 Alfa Laval – decanter centrifuge technology Benefits and features The Alfa Laval differencecomplex, high-value processingstreams – and to do so with meticulouscontrol, low cost and high reliability –requires decanter centrifuge technologyWhen the profitability of an entireprocess is at stake, it is important thatrelied on to meet the highly complexdemands associated with modernAlfa Laval has more than fifty years ofand manufacture of high performancedecanter centrifuges.translate customer requirements intoefficient, reliable machine design and Alfa Laval is in a position to providecustomers with superior products,superior service and superior results atResearch and developmentOur know-how and specialist processcustomer and each particularsteel for all parts that come intocontact with the process, in order toavoid any risk of the corrosionsteel. Corrosion leads to product Alfa Laval – decanter centrifuge technology 9 down time are important for users ofcentrifuges exposed to high stress aretherefore machined from high-strengthensures castings with a uniform grainstructure free from flaws and defectsas well as a completely weld-freefinished component. The results aremaximum strength, unparalleledreliability and a long service life.Abrasion resistanceWear caused by the abrasive action ofsolids affects both the performanceas the result of low stress scratchingabrasion and were therefore able todevelop ways of eliminating its effects.All wear-prone areas of Alfa Lavaldischarge output zone, bowl and scroll– are therefore protected by abrasion-resistant material, selected to matchthe pattern of wear in each particularindustrial process. with pressure differentials are requiredwherever the processing involvesdesign, depend on the requirementsprocess. Continual refinement of theseal technology used in Alfa Lavaldecanter centrifuges is ensured by ourtechnological resources. This is an areawhere Alfa Laval expertise andexperience make a key difference. After fifty years of experience with decanter centrifuges, Alfa Laval has referenceinstallations that are second to none, across a wide range of industries.10 Alfa Laval – decanter centrifuge technology Process industry applicationsMineral processing industryKaolin clay and calcium carbonate processing, bentonite and titanium dioxide manufacturersOil/gas exploration and petrochemical industryOil and gas exploration, oil refineries and related industries, lubricating oil additives and waste oil stream recyclingOrganic intermediate and end productsThermoplastics including PVC, polypropylene, polystyrene, synthetic rubber and fibresBleaching agents, acids, silica products and fertilizersEthanol productionProcessing of grain alcohol spent wash and molasses fermenter residuesStarch processingWaste recyclingRecovery and recycling of waste streams from the sectors listed above Benefits pay off Alfa Laval – decanter centrifuge technology 11 Animal proteinFish and meat by-product processingSurimi processingEdible protein recoveryBreweryCoffee and teaExtraction of instant coffee and teaRecovery of casein, lactose, whey fines and cheese finesClarification of palm oil, olive oil and pressed seed oilExtraction from fruit, berries and vegetablesVegetable proteinExtraction from soybeans, oil seeds and leguminous crops 12 Alfa Laval – decanter centrifuge technology In modern industrial processes,efficient, well-planned service plays animportant part in maintaining profitable Full controlAlfa Laval operates with a highlyspare parts distribution centres in morethan fifty countries throughout Service counts Alfa Laval – decanter centrifuge technology 13 Alfa Laval has full control over the entiresupply chain, which means that we canprovide customers with response times,availability and lead times that areThe service requirements for Alfa Lavaldecanter centrifuges are minimal, andplanned preventive maintenance is thekey to making sure this always remainsAlfa Laval’s worldwide serviceof decanter centrifuges ensure that anyservice work required involves the 14 Alfa Laval – decanter centrifuge technology Separating solids from liquids plays a key role in countless industrial processes.Decanter centrifuges from Alfa Laval perform this PCD00002EN 0909 Separating solids from liquids Alfa Laval is a leading global provider of specialized products and engineeredare dedicated to helping customers to optimize the performance of theirprocesses. Time and time again.We help our customers to heat, cool,separate and transport products suchas oil, water, chemicals, beverages,foodstuff, starch and pharmaceuticals.to help them stay ahead.Up-to-date Alfa Laval contact details for all countries are always available on our website at www.alfalaval.com