Centrifugal Separators

CENTRIFUGAL SEPARATORS

for industrial use

SEPARATORI_CENTR_GB_Luglio_2013:Layout 1 19-07-2013 16:19 Pagina 3

Sedimentation is one of the mostversatile separation processes.Pieralisi Vertical Separators (Disc-Stack Separators) are ideally suited toseparation processes where thephysical characteristics ofsedimentation can be applied thanks to density difference.

Centrifugal sedimentation is often avery good and economical alternative to other separation processes such as:• Filtration: based on particle size,• Micro-Filtration: based on particlesize in the sub-micron range,

But what can we do if we do not haveenough time or if we want to increasecapacity? Going back to Stokes’ Law,to obtain an higher settling velocityand consequently to accelerate thesedimentation process, we canreplace gravitational acceleration “g”by centrifugal acceleration “ˆ2 r”.The centrifugal acceleration “ˆ2 r”produced in a Pieralisi VerticalSeparator is up to ten thousand timeshigher than the ordinary force ofgravity “g”. As a consequence, settlingvelocity is up to ten thousand timesfaster, and separation can beachieved in a very short time and/orusing very small volumes.

SEDIMENTATION

The most common advantages ofcentrifugal sedimentation, betterknown as Centrifugal Separationare:• compact size of equipment,• low capital investment,• versatility,• ease of use,• low operating costs,• high performance.

The basic principle of separation bysedimentation allows for thesimultaneous separation of two orthree different, immisciblesubstances. PIERALISI VerticalSeparators that make use of thislatter separation regime are calledthree-phase separators. None of thealternative principles mentionedabove can achieve this result.Sedimentation is the physicalprocess whereby suspensions andemulsions (or a combination of both)are exposed to gravitational force,either the earth’s gravity or by usinga centrifuge. By applying g-force, thedroplets and/or particles acquiresettling velocity (vg) and are sent tothe bottom/wall of thecontainer/centrifuge bowl.

Settling velocity (vg) increases with:• bigger particle diameter,• higher density difference,• lower dynamic viscosity of the fluid

environment.

Settling velocity can be estimated via awell-known equation known as Stokes’Law:

Sedimentation is used in manyindustrial processes where it isnecessary to separate substancesthat are mixed together (dispersion).With a suitable recipient and the timeneeded to complete the sedimentationprocess, the two or more substanceswith different densities will be

separated (stratified) within therecipient, the lightest going to thesurface, the heaviest to the bottom.(See illustration below)

ADVANTAGES

INCREASING CAPACITY

ofThe Principles

Separator FPC18technical drawing

Separator S300technical drawing

Modified Stokes’ Law

N.B. Stokes’ Law can of course only be used whenthe settling process takes place under conditionswhen the Reynolds-No. is below 0,25. For higherReynolds-No., the Grassmann system has to beused, which takes advantage of two dimension-lessparameters: the Archimedes number and theOmega number.

• Flotation: based on physical-chemical behaviour, i.e. surfacetension. In many cases centrifugalsedimentation and anothercomplementary technology arecombined to achieve the requiredprocess results.

Separation


Pieralisi Vertical Separators combine very high rotational speed, a unique design and special materials. They generate a very highcentrifugal force which, when used for sedimentation purposes, ensures extremely efficient equipment. The mixture to beseparated is forced through a conical disc stack, where multi-layer sedimentation takes place. The separation happens very quicklyas the mixture passes through the parallel thin channels of the disc stack. A medium-sized Disc-Stack Separator, when using highcentrifugal force, can be compared to the efficiency of a sedimentation tank with a surface area of 60,000 m2, the same size as10 football fields. In technical terms, this separator hosts an “equivalent settling area” of 60,000 m2 .

Construction materialsThe structural parts of the bowl aremade of special stainless steel, theinside parts in contact with theproduct are made of suitablematerials for the processingenvironment: stainless steel, brassor bronze. The housing of theVertical Separator is in stainlesssteel or aluminium and cast iron. The gearbox is made of paintedcast iron or cast iron coated withstainless steel. The gasket materialis always selected according to theprocess media.

TransmissionThe movement is always generatedby an electric motor and istransmitted by means of:

• clutch and worm gear,• flexible coupling worm gear,• set of pulleys and flat belt.A special transmission version makesuse of a high-speed motor coupleddirectly to the vertical shaft.

Feeding and discharge of process liquidsThe mixture generally is fed in througha stationary feed pipe in the centre ofthe bowl. The separated liquid may bedischarged from the Vertical Separatorby an overflow or by one or two built-incentripetal pumps.

DESIGN FEATURES

SPECIAL VERSIONS

HOW DOES IT WORK?

Thousands of “g”s are produced in thebowl of the Disc Stack Separator, thecentrifugal force being the product ofthe high rotational speed and the largesize of the bowl. The rotation isgenerated by an electric motorconnected to the horizontal shaft bymeans of an elastic coupling or clutch.Thanks to the gear ratio produced byspecially-designed gears, the movementis transferred to the vertical shaft. The bowl is assembled on the conicaltop-end of the vertical shaft. The processing liquid is fed into thecentre of the bowl through thestationary feed pipe. Subsequently theinflow is accelerated by means ofspecially-designed accelerators, forced

PieralisiVertical

Separators

in the first instance to the periphery ofthe bowl, and then through the discswhere multi-layer separation takesplace. The separated liquid(s) flow to thetop of the bowl where they are

discharged by overflow or by centripetalpumps. The solids captured via thedescribed settling process are collectedat the periphery of the bowl, and thendischarged intermittently. This discharge

is activated by ahydraulic systemlocated underneaththe separation area.In essence, thesolids aredischarged viaopenings at theperiphery of thebowl which areopened and closedby the down- andupwards movementof either a slidingpiston or bowlbottom (see picture).

SECTIONOF A BOWL

Sanitary versionSpecially-designed all-stainless-steelSeparators, designed to be usedwith a CIP cycle for cleaning

purposes. This version is designedfor the easy sanitization of all partsin contact with the product andrequires with no manual operation.

ATEX versionSpecially-designed and certifiedVertical Separators, designed to beinstalled in hazardous areas and forthe treatment of potentiallyinflammable products, i.e.Separators complying with II2G EExcp IIB TB4. These separators areinactivated by means of nitrogen gasto minimise the risk of ignition and tofulfil ATEX requirements.

Hermetic versionHydro-hermetic device installed insidethe bowl, designed to ensure thatcontact with the surroundingenvironment is avoided, and toprevent oxidation and gas leaks.


Vertical Disc-Stack Separators are normally designed for one type of separation only, but in some cases, more versatileversions are available that can carry out two different types of separation. Below is a list of the range of disc stacks and bowldesigns used for different types of separation.

PIERALISI Disc-Stack Separators are able to simultaneously process dispersions of two liquids and one solid. The Pieralisi productrange offers three main equipment solutions: one with solids retention (requiring manual cleaning) known as the S-Type, oneequipped with nozzles that allow continuous solids discharge, known as the SU Type, and the other with automatic, intermittentsolids discharge, known as the FPC-Type. The tables below show types and sizes, with some general indications of dimensions.

Applicationsand Technical

Features

Environmental Processes� treatment and disposal processes of sludge from municipal and industrial waste water � drying of animal slurry � drying of biomass � thermal sludge dryingChemical Processes� production processes involving intermediate or end products and integrated recycling and recovery processes � processes within HDPE, PVC and PP polymer production � production processes for thepharmaceutical and biotech sector � minerals and ores production processes� production processes for non-fossil fuels,such as biodiesel and ethanol

Recycling� treatment processes for drilling mud � treatment and recovery processes forindustrial fluids � recycling of polymers and their respective recyclables � recyclingof service water in industrial processesOleo-chemistry� production processes for oleo-chemistryderivates � refining processes for ediblevegetable oils, excluding olive oilMineral- Fuel and Lube Oils Processes� purification and conditioning of fuels� purification of lube oils � treatment and recovery of mineral andfuel oils � treatment of slop-oils fromrefineries and lagoons, of slops from lube

AREAS OF APPLICATION FOR PIERALISI SEPARATION SOLUTIONS

oils, of bilge waterAnimal-Based Products� treatment of by-products from the fish-processing and meat-processingindustriesFood and Beverage Production� processing and recovery of non-liquid foodproducts � wine and sugar processing � processing of fruit and vegetable juices � recycling of food-related productsDairy Products� production processes of dairy and cheese products � recycling of relatedwaste materials

CLARIFICATION PURIFICATION (SEPARATION) CONCENTRATION (SKIMMING)

Separation of suspended particles from aliquid (e.g. fruit juices, cell biomass).

Concentration of a light liquid dispersedthroughout a heavy liquid (e.g. skimming ofcream from milk).Simultaneous separation of solids is also possible.

Separation of a heavy liquid from a main lightliquid (e.g. separation of water fromlubricating oil).Simultaneous separation of solids is also possible.

SOLIDS RETAINING BOWL NOZZLES AUTOMATIC DISCHARGE

SEPARATORS WITH SEPARATORS WITH

5

S200

11

S250

25

S300

36

SU400

9

FPC 6

14

FPC 12

24

FPC 18

38

2 6 8 11 4 7 12 16

9100 6900 6400 4800 7100 6500 6400 5800

5000 8000 30000 100000 8000 16000 30000 50000

1,0 x 0,7 x 1,2 1,2 x 0,8 x 1,4 1,5 x 0,8 x 1,7 1,7 x 1,0 x 1,7 1,3 x 0,9 x 1,4 1,6 x 1,2 x 1,4 1,7 x 1,3 x 1,7 1,8 x 1,4 x 1,9

300 500 950 1900 1100 1400 2000 2600

FPC 24Type

Bowl Volume [l]

Sludge Space Volume [l]

Bowl Speed [rpm] max.

Hydraulic Capacity [l/h]

Dimension L x W x H [m]

Mass [kg]


worldwideApplications

Chemical industry

Chemical industry

Bioethanolindustry

Biotech industry

Slop oils separation Recycling industry

Lube oil treatmentMilk treatmentBiodiesel glycerin separation

Vegetable oils separation Fuel oil purification


SolutionsSeparation

Division

Via Don Battistoni, 1 - 60035 JESI (AN) - Italy - Phone +39-0731-231.1 - Fax +39-0731-231.239www.pieralisi.com - [email protected]

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Original Spare PartsThe same attention we pay to design andconstruction of our machines, is alsodedicated to the production of spare parts,so that each machine is able to ensure themaximum reliability and excellentperformance over time, without altering theproperties of the processed products. All Pieralisi original spare parts are builtaccording to the highest standards of qualityand coverei by warranty. They can bepurchased directly by our service network orthrough the dedicated web portal:www.ricambioriginalipieralisi.com

Planned MaintenanceA proper maintenance plan makes it possibleto prevent and solve the problems related tothe normal machine wear, to ensure ongoinghigh performance and to maintain the value ofthe investment unchanged over time. Pieralisihas two solutions for planned maintenance: LIGHT is the standard option ideal for 2 to 4inspections at a fixed price; HEAVY is the special option that proposesthe replacement of the worn parts in additionto the 4 inspections.

SERVICE

Pieralisi Planned Maintenance is: CHEAPER, because it always offers a discounton the original spare parts used for allmaintenance operations and labor costs arereduced and protected from any rise; MORE EFFICIENT, because the prior checksand the related operations allow you tooptimize performance in terms of extractionyields and energy consumption; SAFER, because our maintenance operationsare conducted in compliance with the locallaws on safety. Moreover our specializedtechnicians always provides all necessaryinformation for the proper running of themachines; MORE FLEXIBLE, because our worldwideservice network is highly specialized andensures a qualified maintenance wherever themachines are located.

Extra MaintenanceIn order to maintain over time machines value,reliability and performance, we offer three typesof action, GOLD, SILVER and BRONZE,depending, on the machine conditions. All operations are performed in Pieralisiproduction plant and covered by warranty.


Centrifugal Separators

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