1ConthermScraped Surface Heat Exchangers

More than the package

2Today convenience food plays an important role inpeoples lifestyles as it frees them from many tedi-ous, time-consuming tasks. However, the modernconsumer still wants the desirable qualities found innumerous traditional home-made foods, especiallyfresh flavour and pleasing texture. Premium food ataffordable price is also expected. This presents achallenge to food manufacturers, particularly with pre-pared foods made from delicate raw materials orwhose consistency demands special processing.

Optimizing thermal efficiencyContinuous production is a prerequisite for modernfood processing because it promotes high through-put, uniform heat transfer and better economy. Toachieve the rapid product heating and cooling requiredby continuous production, heat exchangers are usu-ally included in the processing line. These incorpo-rate various features to optimize thermal efficiencyand to eliminate product burn-on and discoloration.Such features include optimal design for specific ap-plications, thin high-conductivity metal, product agi-tation and countercurrent media flow.

Why a scraped-surface heat exchanger(SSHE)?Many prepared foods prevent optimal heat transferbecause of their consistency. For example, food con-taining large particles, viscous, sticky and crystallineproducts can quickly block or foul certain types of heatexchanger.Scraped-surface heat exchangers incorporate spe-cial design features which make them ideal for heat-ing and cooling products that impair good heat trans-

Heating Cooling Evaporation

As processing difficulty increases, so does the complexity and price ofthe equipment required. Plate heat exchangers are inexpensive and canhandle materials that have low viscosities, and a limited amount of fibresand particles. Tubular heat exchangers are more expensive and are usedfor more difficult-to-process products. Scraped surface heat exchangersare more expensive still, but can handle high viscosity and particulateladen products. Contherm units can handle particles, or chunks, up to25-30 mm3.

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Contherm The superior SSHE for heating andcooling viscous products

fer. As the product is pumped through the SSHE cyl-inder, even temperature distribution is ensured by arotor and blade assembly which continually and gen-tly blends the product while simultaneously removingit from the heat-transfer surface.Versatility also sets SSHEs apart. They fit readily intonon-dedicated lines where short production runs andfast product changeover are routine. They can evenbe modified to concentrate appropriate products. And,of course, SSHE design complies with strict interna-tional standards of hygiene.

Contherm is the most effectiveContherm is a vertically-mounted, scraped-surfaceheat exchanger, a design that has proven to be themost effective in providing a comprehensive range ofbenefits, including:

Saving valuable floor space Maximizing product recovery Optimizing cleaning-in-place (CIP) and

reducing the risk of contamination Facilitating rapid removal of the rotor

assembly for inspection and maintenance Allowing simple, labour-saving maintenance Providing effective air purging

Low Viscosity High ViscosityLow Fouling FoulingLow Particles Particles

3Motor

Contherm Scraped-Surface Heat Exchanger

Product Outlet

Heating/Cooling Media Port (in)(Refrigerant - out)

RotorInsulationBlade

Heat Transfer Surface

Media Channel

Media Coil

Heating/Cooling Media Port (out)(Refrigerant - in)

Product InletRotor Lifting Device

Blade

Heat TransferSurface

Rotor

4Contherm, supplied by Alfa Laval, embodies morethan 30 years of efficiency and reliability. Units installedworldwide are fulfilling the demand for a premium,uniform product quality.As Contherm is designed on aseptic technology andfollows good manufacturing practice (GMP), it com-plies with the strict standards of hygiene expected inthe food industry. Moreover, Contherm is designed toheat and cool products that can generally be pumped,especially those which traditional heat exchangers justcannot handle.

How it worksProduct enters the cylinder through the lower tangen-tial port and continuously flows upwards through thecylinder. Simultaneously, media travels in a counter-current flow through the narrow annular channel. Ro-tating blades continually remove the product from thecylinder wall to ensure uniform heat transfer to theproduct. A coil in the annulus increases media veloc-ity and hence adds to the heat transfer efficiency. Theproduct exits the cylinder via the upper tangential port.Product flow and rotor speed are varied to suit theproperties of the product flowing through the cylinder.Two or more Contherm units can be linked in seriesor parallel to give a greater heat-transfer surface areadepending on the processing capacity required.

Features that optimize performanceThe rotors and tangential inlet/outlet ports are spe-cially designed to improve food processing. Rotor di-ameter and pin/blade configuration vary to suit differ-ent applications. Smaller diameter rotors allow largerparticles to pass through the cylinder, while larger di-ameter rotors result in shorter residence times andimproved thermal performance.As a general rule, a 90 blade configuration is best forheat-sensitive products, whereas, a 180 blade con-figuration suits less viscous products. Staggeredblades are used for viscous products with or withoutparticles.Better product integrity and quality are maintained bytangential inlet/outlet ports that allow the product toenter and exit the cylinder in the same direction as theturning rotor. The resulting gentler handling is a mustfor such products as pie fillings, fruit preserves, andsoups and stews.

Vertical benefitsThe upright design of Contherm contributes signifi-cantly to everyday processing efficiency and cost re-ductions. At process start-up, all the air is completelypurged ahead of the product thereby allowing the heattransfer chamber to fill completely with product. At proc-ess shutdown, product recovery is maximized by theability to chase the product with water. Following this,complete drainage facilitates CIP/product changeover.Moreover, when steam is used as the heating mediumthe resulting condensate is removed rapidly from theannulus by gravity thereby maintaining high heat trans-fer efficiency.

Typical products that benefit fromContherm processing*

Over 30 years of successful processing

ParticulateChicken pieces, fish meal, jams andpreserves, pet food, rice pudding,yogurt fruit.

StickyCaramel, cheese sauces, lecithin,process cheese, confectionery andstarch.

* Individual types of applications may possess more than one of these properties.

ViscousKetchup, mayonnaise, chocolate,fruit pie filling, gravy and sauces,peanut butter, pizza sauce, pudding,salad dressing, salsa and taco fill-ings, sandwich spreads, debonedchicken (MDM), gelatin, scrambledeggs, baby food, ointment, lotions,mascara and candle gels.

Crystallizing/Phase ChangeCoffee/tea extracts, cookie cream,confectionery topping, lard, sugarconcentrates, margarine, shorten-ing, spreads, beer and wine.

5PRODUCT IN

CONTHERMPREHEATER

CONTHERMCONCENTRATOR

PRODUCTOUT TOFILLING

STEAM STEAMSTEAM

CONTHERMCOOLER

COOLANT

CONTHERMHEATER

Typical Cooking andCooling LineFor sauces, gravies, soups, marma-lade, preserves, jams, and dressings.A Contherm-based system for cost-effective continuous processing thatresults in premium quality products.

Typical Contherm applications

CONTHERMHEATER

CONTHERMHEATER

CONTHERMCOOLER

CONTHERMCOOLER

PRODUCTOUT TOFILLING

STEAM COOLANTSTEAM

INGREDIENTSIN

INGREDIENTSIN

COOLANT

CONTHERMSTERILIZER

CONTHERMSTERILIZER

CONTHERMCOOLER

CONTHERMCOOLER

CONTHERMCOOLER

PRODUCTOUT TOFILLING

STEAM COOLANTSTEAM

PRODUCTIN

COOLANT COOLANT

Fruit and VegetableProcessingFor pures, mashes, pulps, concen-trates, and pastes.The integrity of fruit and vegetableproducts is retained better in aContherm system than in traditionalheat exchangers because they areexposed to heat for shorter periods.

Aseptic ProcessingFor soups, sauces, jams, yogurt fruit,pures, and juices.Aseptic processing preserves producttaste, colour and texture, and prolongsshelf life. A Tetra Pak aseptic packag-ing system can be integrated tocomplete this type of processing line.

6CONTHERMCOOKER

CONTHERMCOOLER

PRODUCTOUT TO

PACKAGING

MILK &ADDITIVES DRY

RICE

STEAM WATER

PLATE HEATEXCHANGER

HOTWATER

PRODUCTIN

DEBONER PUMPRIBBON

BLENDER FILLING

CONTHERMCHILLER

Caramel ProcessingThe caramel mixture (condensed milk,corn syrup, HFCS, caramel, sugar andflavouring) is heated and agitated in aprocess vessel and then pumped to aContherm to further heat the product.It is then flashed into a caramel tankfor colour development. The mixture isthen pumped to a Contherm for finalcooling, as temperature control iscritical to the production of a consist-ent product.

Typical Contherm applications

SUGAR, MILK, ETC.

PREMIX TANKS

STEAM WATER

VAPOR

PRODUCTOUT

CONTHERMCOOKER

CONTHERMCOOLER

CARAMELTANK

MDM Cooling LineThe Contherm scraped surface heatexchanger is used for batch orcontinuous cooling of mechanicallydeboned meat (MDM). The Conthermsystem improves product quality com-pared to other methods of cooling.

Continuous RicePudding ProductionThe pudding ingredients (milk, salt,sugar and thickener) are mixed andpreheated before dry rice or grain ismetered into the mixture. The mixtureis then pumped to a Conthermscraped surface heat exchanger forheating (scalding). It then resides ina holding cell before being cooled in aContherm to the required fillingtemperature, which determines theconsistency of the end product.

7removal of blades.

Next, after the rotor has beenlowered using the hydraulic lift, itcan be held in position by aspecial retainer to facilitateinspection, maintenance andThen, lower the rotor automatically

by means of the hydraulic lift.

Only a few simple steps arerequired to lower the rotor for rapidinspection and maintenance. First,remove the clamp.

Numerous Contherm design features and options en-sure reliability, flexibility and maximum runtime. Theseall add up to increased lifetime economy.

Hydraulic lift systemA unique feature is the hydraulic rotor lift system. Thisrequires just one person to rapidly lower and raise therotor assembly thereby facilitating inspections andmaintenance procedures, and reducing manpowerexpenditure. It minimizes system downtime by speed-ing up the inspection and replacement of seals andbearings when required.

Vertical cost-effectivenessThe vertical design of Contherm contributes to cost-effective installation, operation and maintenance. Its0.33 m2 footprint saves valuable floor space. As costsper square area for new construction rise, or whenfloor space is limited in existing facilities, a small foot-print can mean big savings. During short-run process-ing, costs are saved from minimal mixing of productand purging water during product changeover.

Automatic Maintain Status for coolingunitsThis is a major feature of the Contherm refrigerationpackage incorporating cooling with ammonia. If theproduct flow is interrupted for any reason, the refriger-ant is instantly purged from the annulus and replacedby hot gas. After a predetermined time the flow of hot

gas is halted to ensure that the cylinder temperatureis slightly higher than the products freezing point. Thisaction protects drive motors and contributes to rapidproduction restart.

Aseptically-sealed unitsA Contherm model is available for aseptic processingto minimize the risk of microbial contamination. Dur-ing production, steam is fed to the area between thetwo seals. These seals withstand the high pressuresand temperatures found in aseptic processing.

Cylinders, rotors, blades and sealsDepending on the application, either nickel, chromednickel, stainless steel, chromed stainless steel, or mul-tiplex cylinders can be supplied.A choice of rotors is available to optimize product ve-locity, retention time and particulate handling. An ec-centric rotor may be supplied as an option for verysticky products. Stainless steel and nonmetallic bladesare available. A full range of seals are stocked to suitdiverse products and applications.

Fast service and spare partsA processing line out of operation means lost revenue.We provide immediate response worldwide, should aContherm unit require attention. Moreover, a compre-hensive range of parts is always kept in stock for im-mediate delivery.

Features and options that mean lifetime economy

8Fair system paybackThe return on investment depends on several ope-rational factors including production run times, utilitycosts and the price of raw materials. When such fac-tors are taken into consideration, and from the exten-sive experience already gained from customizedContherm systems worldwide, the payback periodsfor Contherm have proved more than satisfactory.

Compared to batch processing, continuous process-ing offers better profitability primarily because it em-braces economy of scale. Higher throughput com-bined with reduced labour costs sharpens competi-tive edge. This is where Contherm comes in.Not only is Contherm an economic processing mod-ule, it is specially designed to maintain the quality offood ingredients. A breakdown of the costs involvedin running a typical Contherm unit compared with atypical batch processing system is presented in thetable on this page to show how Contherm cuts thecosts of everyday processing.

Contherm continuous process systemFigures based on continuous run of 2,270 kg/hr, once a day clean up.

UTILITY CONSUMPTION UNIT COST $ COST $/2,270 kgSteam 331 kg/h 13.23/1,000 kg 4.38Electrical Power

Motors 32 HP = 23 kwh 0.07/kwh 1.61Controls, alarms, displays 6 kwh 0.07/kwh 0.42

Air 5 kwh 0.07/kwh 0.35Manpower 1 14.00/hr* 14.00Water 11,355 m3/h 0.132/m3 1.50CIP 145 kg/day 4.41/1,000 kg 0.11Total 22.37

Batch system using jacketed kettlesFigures based on batch processing of 2,270 kg/hr using 6 kettles.

UTILITY CONSUMPTION UNIT COST $ COST $/2,270 kgSteam 1,135 kg/h 13.00/1,000 kg 15.00Electrical Power

Motors 9 HP = 7 kwh 0.07/kwh 0.49Controls, alarms, displays 2 kwh 0.07/kwh 0.14

Air Manpower 6 14.00/hr* 84.00Water Cleaning 145 kg/day 4.41/1,000 kg 0.64Total 100.27

Underlying assumptions: Six batches of 2,270 kg food/batch produced each day, 5 days per week for 52 weeks (1,560 batches per year). All continuous process motors operate at full rating. Continuous system cooling and heating are 95% efficient. Batch system heating is 30% efficient (conservative estimate).

How Contherm cuts the costs of everyday processing

One man operates the continuous system, six men (conservativeestimate) operate the batch system.

The continuous system involves CIP, the batch system does not. Costs for poorer product quality and recovery for batch processing

are not considered.

* In many European countries $ 35

* In many European countries $ 35

9Technical information

Working temperature range: -35C to +150C.

Maximum working pressure: 20 bar on product side.17 bar on media side.

Connections - product side: 51 mm (2), union.

Connections - media side: 48 mm (2), upper.37 mm (11/2), lower.

Options Alternative drive systems are available. Tachometer. Nickel, chromed nickel, stainless steel,

chromed stainless steel, or multiplex cylinders. Mounting column. Stainless steel and nonmetallic blades. Flush and hard face seals. Rotors: 76, 102, 114, and 127 mm. Eccentric rotor. Staggered blades to prevent channelling of

product. Connections with a larger diameter. A horizontal Contherm option is available for use in

facilities having limited ceiling height. Cryogenic units.

Particulars required for quotationTo enable our representative to tailor a Contherm sys-tem to your exact requirements, inquiries should be ac-companied by the following information: Flow rates required. Temperature program. Physical properties of your product(s) or a

description. Type of heating and/or cooling media preferred.

Model Heating A B C D E Net* FloorSurface mm mm mm mm mm Weight Spacem2 kg m2

6x3 0.279 854 2502 864 933 717 140 0.336x6 0.557 1387 3645 864 933 1326 234 0.336x9 0.836 1997 4864 864 933 1936 274 0.33*Excluding motor

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From initial contact to system operation, there aremany ways in which we can help you get the best outof your investment in Contherm. Our customer sup-port program includes application advice, test units,process development and configuration, and servicecontracts. By listening to your views and followingprocessing trends at source, we can fine-tune oursystems to satisfy your demands.To enable your staff to run and maintain your Conthermduring everyday production, we offer training coursesand seminars covering all aspects of their use. And,of course, because we provide local support on aworldwide basis, we can respond rapidly to your emer-gency situations.

Maintenance and serviceTetra Pak offers service and maintenance agreementstailored to your individual requirements. We can alsohelp you to optimize the performance of your plant toachieve better efficiency and utilization.

Food Development Centres at yourdisposalThe R&D Assistance option enables you to put theContherm and your product to the test. We have fullyequipped Food Development Centres, which are avail-able for the cost effective development and definitionof process conditions prior to scale-up. Whether youwant to test processing methods or plant efficiency,we have the facilities and application knowledge tohelp your decision-making.

Rental units are also availableFor reasons of confidentiality, if you prefer to carryout processing trials using Contherm in your own plantand with your own personnel, we can offer you aContherm test unit on a rental basis along with quali-fied Contherm personnel during start-up.

Convap evaporation moduleThe Contherm SSHE can be modified to form theConvap evaporator, which is particularly suited to con-centrating viscous products. The system normallyoperates under vacuum. The entrainment separatorconnected to the SSHE by means of a specially de-signed vapour head allows the separation of the con-centrate from the vapour phase.

Customer support andinnovative technology that never ends

Our Food Development Centers are at your disposal to allow you to de-velop and define process conditions using Contherm units prior to scale-up.

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Convap, a continuous single-effect scraped surface evaporator whichincorporates a Contherm SSHE, is the ideal system for concentratingviscous products.

We maintain close contact with our customers to help them get thebest out of their Contherm equipment.

We offer very short delivery times on standard units and nearly 100%of all spare parts are shipped the same day.

Modular Contherm and Convap test units are readily available on arental basis to facilitate your in-house research and development.

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PB 63423 E2 / 0012 Alfa

Laval, Lund, Sweden