Drying Technology

Buss-SMS-Canzler

2

Buss-SMS-CanzlerCore Competence Drying

More than 500 dryers worldwideFor more than 50 years we have sup-plied different types of dryers, adap-ted to a large variety of applicationsthroughout the world, currently morethan 500 dryers. Based on our long-standing experience and supportedby lab and pilot tests, the specialistsat Buss-SMS-Canzler select the mostsuitable drying technology for yourapplication. Lab tests in our labequipment show general feasibility.Tests in our pilot plants provide thebasis for the design of our dryers.These studies are not only carried outupon our customers’ request, but alsoto investigate new applications onour own development projects, as forexample the TDI recovery in the CFTdryer (page 12).

Buss-SMS-Canzler is a leading inter-national supplier of thermal separa-tion solutions for difficult productsand mixtures.We are the world’s leading supplierof thin film evaporation technology,this is due to the long-standing expe-rience of the three former companiesLuwa, SMS, Buss and Canzler. Thislong experience and expertise is nowincorporated into Buss-SMS-Canzler.For our customers around the worldwe develop and manufacture machi-nes and plants for evaporation, pro-cessing of highly viscous materials,membrane filtration and drying. Ourexperience and our test centre allowus to develop customer specific pro-cess solutions by applying tailor-madeequipment and complete systems. Buss-SMS-Canzler partners you asconsultant, designer and manufactu-rer through all project stages: fromprocess layout, pilot tests, enginee-ring, mechanical design, manufactu-ring and documentation, to instal-lation, start up and after sales service.

CP dryer in outdoor test stand

Four horizontal thin film dryers for a Chinese customer

3

Drying Technologyat a Glance

The Buss-SMS-Canzler range of dry-ers carries out the following processsteps: drying, cooling, heating, calci-ning, reacting, mixing, sublimationand sterilisation.The product range covers heating tem-peratures of -20°C to 400°C, processpressures of 0,01 to 30 bar and resi-dence times from seconds up to seve-ral hours.

Buss-SMS-Canzler offers a program ofdryers using different operating prin-ciples tailored to meet the individualprocess requirements when treatingproducts with particular characteris-tics and specific drying behaviour.

Vertical and horizontal thin film dryerswith thin product layers on the heatexchange surface, the ROVACTOR®with specific paddles to convey lumpywet feed, the REACTOTHERM® withself-cleaning hooks for sticky productsas well as the CFT dryer with its me-chanically agitated fluid bed are tech-nically mature solutions for a largevariety of different drying applicati-ons.

VerticaldryerCDC

V, A, Psec•–––•–––••––––––• ••–•••••

Horizontaldryer

CDC

V, A, Pmin••••••–•–•••••–•• ••–•••••

CombidryerCDC

V, A, Pmin••––––––••––––––• ••–•••••

Poss

ible

pro

cess

es

Wet

pro

duc

t fo

rmDry

ing b

ehavi

our

REACTOTHERM® CFT dryer

CDB, C

V, A, P(min), hrs

••••••••••••••–•• ••••••••

CDC

V, A, P(min), hrs

••••••••••••••–•• ••••••••

• suitable/applicable • fairy suitable/case-to-case evaluation– not suitable/not used/not applicable

CD = ConductionC = Continuous operationB = Batch operation

V = VacuumA = AtmosphericP = Overpressure

ROVACTOR®

CDC

V, A, P(min), hrs

••••–•–•––••••••– •–––••••

Heat transfer byOperation modePressure on process sideProduct residence timeDryingHeating, CoolingMixingSublimationDesublimationMeltingSolidifyingReactionsSuspension, SolutionThixotropic pasteSludge, hardly pumpableFilter cakeWet powderGranular (mm)Very coarse (cm)FibrousCrystallising„Breaks up“ in particlesPasty phaseSticky/viscous phaseCrust formingTemperature sensitiveCombustible, explosion riskToxicAbrasive

4

Vertical Thin Film Dryers

Thin film dryers are characterised bya mechanically agitated thin productlayer. The film thickness is normally inthe range of less than one up to a fewmillimetres.In vertical thin film dryers the wet feedis distributed over the heated wall bya distributing ring and evenly appliedto it in a thin film by hinged pendulumblades. Running downward the pro-

duct passes typically through an eva-poration zone, then a slurry or crystal-lisation zone and finally a powderzone. Most of the liquid is removed inthe evaporation and slurry zone whilein the powder zone the surface mois-ture from the solid particles and someof the internal moisture is driven off.

The volatile components driven out ofthe product by heat, pass upwardthrough the dryer counter-current tothe product flow and are then conden-sed in an external condenser. Thepowder obtained at the bottom isdischarged continuously via a suitablegaslock system. The total residencetime of the product is between 30 and60 seconds.

Applications• Agrochemicals (Atrozine etc.)• Waste water and spent liquors• Chlorides, bromides, sulfates• Silane recovery• Benzosulfonic acid• Chemical intermediates• Solvent recovery from waste• Carbonates, phosphates• Silicon, silicon carbide• Xanthates• Dyes and pigments• Glycerine• Sodium formiate• Baron carbide, baron nitride• Caffeine, condiments

Process Features• Continuous processing of liquid and pumpable products to get dry solids in one step• Gentle treatment of products thanks to short residence time and – if necessary – operation under vacuum• Fully enclosed design to treat explosive, toxic and hazardous substances• Complete recovery of solvents• Contact drying to ensure optimal energy utilization• Self-cleaning of heat exchange surface, hence a constant high heat transfer

Manufacturing of CP rotor

Assembly of CP dryer

5

Horizontal Thin Film Dryers

Process Features• Continuous, fully enclosed processing• Short residence time, small product hold-up• Low energy consumption• Superior mixing efficiency• Flexible through exchangeable rotor elements• Self-cleaning of heat exchange surface• Easy access• High heat transfer coefficient

Applications• DRYING of slurries, sludges, pastes, filter cakes, wet powders•HEATING and COOLING of solids•MELTING (Urea etc.)•REACTION•MIXING of solids with liquids and subsequent thermal processes

Vapours pass counter-currently to theproduct flow and leave the dryer closeto the feed nozzle. Entrained particlesare removed in the wet zone. Moisture levels of a few tenth of apercent up to 5% and more can beachieved. The residence time of theproduct is typically between 5 and15 minutes.

Thin Film Dryer with pulled rotor

Horizontal thin film dryers are continu-ously operated contact dryers andused for a broad range of applicationsunder vacuum, atmospheric pressureand overpressure. They consist of a ho-rizontal externally heated shell withend covers, the inlet and outlet nozzlesfor feed, vapour and final product,nozzles for the heating medium and arotor with screwed on elements suppor-ted in external bearings. The wet pro-duct fed through the inlet nozzle isconveyed steadily by the rotor ele-ments along the heated dryer wall ina thin film, allowing an optimum heattransfer and a high evaporation per-formance.

Transport of thin film dryer for food industry

6

Combi-Dryer

the high speed rotor. The pre-driedproduct falls from the drying zone ofthe vertical dryer directly onto therotor of the horizontal dryer. This rotorconveys the product in horizontal di-rection to the product outlet on the op-posite side of the dryer.The vapours of both dryers flow incounter-current direction to the pro-duct, and then through the vapournozzle of the vertical dryer into thenext process stage.

Advantages of the Combi-Dryer• Entrained fine particles from the horizontal dryer are removed in thetop wet zone of the vertical dryer

• Product loss is minimized due to thecompact arrangement

• No intermediate storage or conveying device is required between first and second drying stage

• Different heating media as well as different temperature profiles can beapplied

ApplicationsThe dryers are widely used throughoutthe process industries to convert li-quids, slurries and pastes to free flo-wing solids in continuous, single passoperation.

The Combi-Dryer is applied forprocessing of• Dyes and pigments• Optical whitener• Polypropylene suspensions• Organic and inorganic salts• Polyethylene slurry• Zeolites

Industrial use of Combi-Dryer Combi-Dryer

The Combi-Dryer from Buss-SMS-Canzler consists of a combination of avertical dryer and a horizontal thin filmdryer. Special features of thin film con-tact drying technology:• Gentle treatment of heat sensitive products due to a short residence time

• Fully enclosed design to treat explosive, toxic and hazardous substances

• Continuous operation• Small hold-up

Operating methodThe wet product is fed into the verticaldryer directly above the heating zoneand evenly spread as thin turbulentfilm on the heat exchange surface by

7

ROVACTOR®

The ROVACTOR® is an efficient con-tact processor which provides a highlocal mixing effect for the treatment offilter cakes, powders and pellets. TheROVACTOR® consists of a cylindricalor trough shaped body and a hollowagitator shaft fitted with specialpaddles in form of segmental discs. Heating or cooling is provided indi-rectly by means of steam or a transferfluid via the segmented rotor discsand the jacketed body.Continuous or batch processes undervacuum, atmospheric pressure oroverpressure are possible. Product re-sidence times can be adjusted in alarge range. The processor can beeasily protected against wear andtear.

Process Features• Continuous enclosed processing of toxic, inflammable and explosive products• Uniform product temperature, processing of heat sensitive products• Contact drying with low energy consumption• Low rotor speed: minimum dust production, minimal particle size reduction, suitable for abrasive products• High heat transfer coefficient: high throughput rates per unit

ApplicationsCHEMICALS:• Catalysts• Carbon, carbon black• Limestone• Gypsum• Sodium chloride• Detergent additives• Detergent intermediates• Uranium oxidePOLYMERS:• Polyproylene• Polyethylene• Polyvinyloxide• Terephthalic acidFOOD:• Cocoa• Flour• Sweets• PectinENVIRONMENT:• Industrial sludge• Refinery sludge• Oil drilling sludge• Contaminated soil

Large ROVACTOR®for drying solvent moist synthetics

Rotor of a ROVACTOR®

8

REACTOTHERM®

The REACTOTHERM® is used for ther-mal processing of a wide variety ofpasty, viscous, fouling and lumpingproducts. It consists of a cylindrical,horizontal shell and a rotor with seg-mented discs and mixing bars. Statio-nary mixing hooks are attached tothe inside of the shell. The close clea-rance between the mixing hooks, thesegmented discs and the rotor resultsin a high mixing and kneading effectand largely self-cleaning properties ofthe rotor.The inside of the shell is cleaned bymixing bars avoiding the fouling ofheat exchange surfaces and the for-mation of agglomerates. Shell, shaftand discs can be heated or cooled.Continuous or batch operation undervacuum, atmospheric pressure andoverpressure is possible.

Rotor of a REACTOTHERM®

REACTOTHERM® for continuous operation

ApplicationsDRYING:• Polymers• Pharmaceutical intermediates• Fine chemicals• Food• Dyes, optical brighteners• Antioxidants• Phosphate salts• Surfactants• Paint and varnish sludgeREACTIONS:• Resorcinol• Salicylic acid• Benzoic acid• Sodium cyanateRESIDUE TREATMENT:• Chemical waste with organic solvents• Radioactive waste

Process Features• Self-cleaning heat exchange surfaces• Constant heat transfer with fouling products• Intensive mixing and kneading effect• Optimal heat/mass transfer with pasty and sticky products• Universal use for liquid, pasty and solid products• Several process steps in one machine

9

CFT – Combi Fluidization Technology

CFT lab dryer

Combi Fluidization Technology twin pack

Many of the slurries and sludges oc-curing in the field of environmentalprotection, as e. g. paint and varnishsludges, can be processed under at-mospheric pressure. The Combi Fluidization Technologyalso offers a very interesting alterna-tive with regard to cost and energydemand compared to the spray dry-ing of products with sticky phases, ifno specific properties and conditionsof the dry product are required.

This technology can be used for manydifferent applications, as various hea-ting methods are available and tem-peratures up to approx. 600°C canbe reached. The CFT dryer can beoperated under vacuum or overpres-sure.

The main component of the CombiFluidization Technology is the CFTdryer. This dryer is filled with dry pro-duct, which is fluidized by the rotor.The wet product is fed into the hotfluid bed and due to the movement ofthe bed it is evenly distributed throug-hout the dry product and dried effi-ciently.The formation of sticky/viscous pha-ses, the direct contact of the wet feedwith the heat exchange surface andthe consequential formation of crustsare avoided to a large extent.The whole process is comparable toconventional drying with external re-flux system, but with the Combi Fluidi-zation Technology the externalmechanical work is no longer neces-sary. The vapour cleaning is integrated intothe drying room of the CFT dryer, sothat the vapours can be easily proces-sed in a condenser or rectifier.

10

Salt Drying:Efficiency by Combination

A very common drying application isthe drying of salts and salt mixtures,which occur:• in natural sources• in down gradients of chemical

processes• as product from the neutralization

plant of the flue gas scrubber• as residue from membrane proces-

ses for drinking water abstraction

The composition of salt mixtures maylead to operational malfunctions dueto the formation of crusts. In particu-lar, if salt mixtures contain compo-nents like sodium sulphate, hardcrusts may form on the heat ex-change surface. At best these crustsonly reduce the performance of thedryer, but if the worst comes to theworst the whole system may shutdown.

By combining dryers with differentoperating principles, such salt soluti-ons can be processed very efficiently,e.g. a salty solution from the flue gasscrubber can be largely dehydratedin a vertical CP dryer. The residualmoisture of the product from the firststep is removed in the CFT dryer, thuscombining a dryer with a very highevaporation performance with adryer, which safely avoids the forma-tion of crusts. This reduces the designsize and improves the operational re-liability.

CFT for salt drying

11

Environmental Protection Worldwide:Sludge Drying Process

Municipal sludge is increasingly ap-plied as valuable product, as the di-rect agricultural use will be morerestrictive in the future. Industrial slud-ges have to be incinerated in mostcases, so that the pre-drying or fulldrying of sludges from municipal aswell as industrial plants is a manda-tory process step in many cases. Thefollowing drying degrees can be clas-sified:

Pre-drying to• 35 to 50% dry solid content prior to incineration in fluidized bed incinerators

• 65 to 75% dry solid content priorto composting or incineration with garbage

Full drying to 85 to 95% dry solid content• prior to using as solid fuel for cement kilns or coal fired power stations, for pyrolisis, gasification or other conversion processes

• prior to composting, agricultural useand soil reclamation

These are typical applications, wherethe Buss-SMS-Canzler drying processcan show its advantages with an eva-poration performance between 0.2and 8 tons of water per hour. The thinfilm dryer is characterized by:• Single pass operation over the sticky or pasty phase; hence no back mixing of dried product

• Low energy consumption• Self-cleaning heat exchange surface• Self-inertisation by evaporated water

• Low operating and maintenance costs

These advantages resulted in morethan 100 sludge drying installationsworldwide, with some being in ope-ration for more than 25 years.

Sludge drying plant in USA

Transport of sludge dryer

Sludge dryer with pulled rotor

12

TDI Recovery:CFT Dryer for Economic Processes

Toluolene-2, 4-diisocyanate is thebasis for a large variety of productslike glue, soft foams for upholsteryand mattresses, shoe soles, varnishesfor the automotive industry, planesand trains. 90% of the worldwide pro-duction of TDI is used in the pro-duction of polyurethane, a foamedsynthetics used in many applications.During the TDI production process alarge amount of distillation residue,which contains 30 to 70% free TDI, isgenerated. Therefore it is crucial forthe overall profitability of the TDI pro-duction process to recover the TDIfrom this residue. As the TDI recoveryis a comparably complex processstep, different processes have beendeveloped for the TDI recovery:

• Chemical/physical separation withliquid-liquid extraction

•Chemical transformation with reaction to toluene diamine

• Thermal separation by evaporationand/or drying

The thermal separation by evapora-tion including drying allows a 100%recovery of the TDI from the residueand therefore is accepted as state-of-the-art technology.

However, the realization of this reco-very process is a demanding applica-tion. As soon as the content of free TDIin the residue reduces to approx.17%, the concentrated residue beco-mes highly viscous and sticky and sud-denly solidifies. Therefore a processorused for the TDI recovery must avoidthe blocking of the system with solids.Fluidized bed dryers, which dispersethe residue into the fluid bed or con-tact dryers in robust design with highdrive torque for the conveying ele-ments are possible solutions, but resultin high operating and/or investmentcosts. Therefore Buss-SMS-CanzlerGmbH developed the TDI recovery inthe Combi Fluidization Technology(CFT) dryer.

In the CFT dryer with its mechanicallyagitated fluid bed the wet product isevenly dispersed so that materials,which pass viscous, pasty, sticky, crustforming or crystallizing phases duringdrying, can be processed. The opera-ting principle of the CFT dryer offersa simple and economic treatment ofthe TDI residue, which could be de-monstrated in our pilot test centre inPratteln, Switzerland. The treated re-sidue was continuously dis- chargedby gravitation into a cooler. The over-all mass balance confirms – 100%TDI recovery.

Final product TDI recovery process

13

Drying of Terephthalic Acid:ROVACTOR® in Long-term Failure Free Operation

Terephthalic acid is the feed productfor the manufacturing of PET, which isused in large quantities to producebottles, foils and textile fibres. The an-nual production worldwide is morethan 40 million tons of PET, producedfrom the monomers ethylene glycoland terephthalic acid. This shows theimportance of PET as a material,which is used in large quantities formany different applications.

For the industrial production of tereph-thalic acid various processes havebeen established. The different pro-cesses have in common that the reac-tion to produce the terephthalic acidis realized in a solution, which meansthe terephthalic acid needs to bedried to obtain the final product, a

transparent, free flowing powder. Thisdrying application is very demandingfor the process equipment, due to re-latively high process temperatures bet-ween 180°C and 200°C and thelarge size of the processors. The highmechanical strain causes fatiguecracks in the welding seams, whichare one of the main reasons for ope-rational malfunctions. Based on a de-tailed analysis of the causes for thedamages on terephthalic acid dryers,Buss-SMS-Canzler adjusted the designof its segmented disc dryer RO-VACTOR®, so that the welding seamscan permanently cope with suchstrain. As a result our dryers havebeen in continuous operation for al-most ten years without any damage.

Transport of ROVACTOR® for drying terephthalic acid

Rotor for terephthalic acid dryer

14

Pharmaceutical Industry:CONTIVAC for Unchanged Product Quality

The CONTIVAC NDP processor wasdeveloped by Buss-SMS-Canzler foruse in production processes with spe-cial hygienic requirements. This proces-sor combines the advantages of con-tinuous thin film drying with a specialrotating spray nozzle that allows forCIP cleaning. The individually adjusta-ble heating and cooling zones in thethin film dryer open up new opportuni-ties for thin film drying technology to beused in complex processes.The basic operations of mixing, re-acting, flashing and drying can be car-ried out in the same machine, withseveral different substance streamsbeing fed into the processor simultane-ously.The CONTIVAC NDP processor offersmanufacturers in the pharmaceutical,fine chemical industries and in the foodand pet food industries new possibili-ties for improvement, which are notavailable with conventional batch ma-chines.

Applications• Pharmaceutical intermediates• Food• Pet food

Process Features• Combination of different basic operations in one machine (no transport problems, no contamination of product)• Very short residence time (minimum thermal damage to product, high flow rates)• Very low hold-up (little waste with product changes)

Batch operated dryers have problemswith products, which pass through a sti-cky, viscous phase during drying.Such cases require very long residencetimes, which can cause unwanted side-reactions, thermal damage to the pro-duct, and/or colour changes. Experience has proven that the resi-dence time in the CONTIVAC NDP pro-cessor can be reduced up to 500 times.Further advantages compared to batchsystems result from the low investmentand operating costs.The design of the CONTIVAC NDP pro-cessor complies with the relevant GMPrequirements.Shaft sealing and bearings are con-structed compatible with pharmaceuti-cal requirements (e.g. cartridge con-struction).

Assembly of CONTIVAC

Rotor detail

15

Lab dryer

Low Risk Investment Decision:Your test centre for new developments

We make the process, instrumenta-tion and control design for plant sta-ges and individual components aswell as the machine design for thecore components, which are mainlymanufactured in-house.

Complete service qualityWe take care of the delivery to thesite of destination, the installation orthe supervision of the installation onsite as well as the final inspection.Our process engineers plan and su-pervise start up, test run, optimizationof your plant as well as training of theoperating personnel. We also offerservice and maintenance contractsfor preventive maintenance.Spare parts are available on shortcall and are shipped once they havepassed our quality control.We offer the automation, optimiza-tion or modification of our equipmentand plants throughout their entireoperating life.

Analytics

•Drying• Physical definition• Ionic chemical analysis• Spectroscopy

•Calcination• Liquid determination• Inorganic chemical analysis

•Gas-liquid-reaction•Chromatography

Pilot tests are the best way to find the right investmentdecision.In Pratteln, Switzerland, we operatea well equipped pilot plant. Processconditions can be easily modified toreach optimized test results. With theparameters from the test results theprocess and plant engineering canstart, all under the responsibility ofone project manager.To find a suitable dryer for your ap-plication the following procedureshave proven their value:•General examination of drying behaviour of product

• Drying tests with small product samples in lab dryers to examine general feasibility of our dryers

• Drying tests in our pilot plants to obtain engineering parameters

These procedures provide the neces-sary information depending on theproject stage.

Our test report provides ourcustomers with:•Documentation of the test assembly

• Description of the test results• Analysis of the product samples

Professional project realizationfrom one sourceWe accompany and consult you fromthe product idea to the optimizedquality production. We develop cus-tomized process solutions for the ther-mal separation or concentration ofsubstance mixtures.

We operate worldwide and areactive in the most important markets.Your local contacts guarantee the fasthandling of your inquiry and arrangeshort-term competent advice.

Buss-SMS-Canzler

Head Office & WorkshopBuss-SMS-Canzler GmbHKaiserstraße 13-15D-35510 ButzbachPhone: +49 60 33 - 85 - 0Fax: +49 60 33 - 85 - 249

Branch Office & Test CenterBuss-SMS-Canzler GmbHHohenrainstraße 10CH-4133 Pratteln 1Phone: +41 61 82 - 56 - 869Fax: +41 61 82 - 56 - 766

email: info@sms-vt.com www.sms-vt.com

Branch OfficeBuss-SMS-Canzler GmbHAm Langen Graben 7D-52353 DürenPhone: +49 24 21 - 705 -1Fax: +49 24 21 - 705 - 80

© 2

012

•wer

beag

entur-n

ow.d

e