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Process control in spray drying FrieslandCampina, young company ...

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<strong>Process</strong> <strong>control</strong> <strong>in</strong> <strong>spray</strong> dry<strong>in</strong>gJohn Niederer, Frank JeurissenDecember 3 rd 2009FrieslandCamp<strong>in</strong>a, <strong>young</strong> <strong>company</strong> long history


Our membersBus<strong>in</strong>ess GroupsDefend andexpand coreactivitiesExpand <strong>in</strong>growth marketsDefend andexpand coreactivitiesCreate newopportunities


FrieslandCamp<strong>in</strong>a DomoIngredients Bus<strong>in</strong>ess Group Royal FrieslandCamp<strong>in</strong>aMarkets:Infant nutritionInfant formula:0 – 6 monthsFollow on formula:6 – 12 monthsGrow<strong>in</strong>g Up Milk :1 – 6 yearsProducts• Ingredients• Base powders• Total formulation


Markets:Medical nutritionProducts• MPC’s• Specialty prote<strong>in</strong>blends powder• Case<strong>in</strong>ates• Hydrolysates• Base powders• Total formulationMarkets:Cell cultureCell culture media forproduction ofbiopharmaceutical drugsMicrobialdiagnosticsMicrobial test<strong>in</strong>g formedical diagnosesProducts• Hydrolysates


Markets:PharmaceuticalexipientsB<strong>in</strong>ders and fillers forpharma applicationsProducts• Direct CompressionLactose• Wet GranulationLactose• Inhalation LactoseWhey process<strong>in</strong>gWhey storageEvaporatorCrystalliserCentrifugeFluid beddry<strong>in</strong>gPackag<strong>in</strong>gLactoseFeedSpray towerPackag<strong>in</strong>gUltra filtrationEvaporatorWhey Prote<strong>in</strong>ConcentratesMa<strong>in</strong>ly water removal…Spray towerPackag<strong>in</strong>g


Spray Dry<strong>in</strong>g: some typical problems• Different products, different recipes, same tower;• Clean<strong>in</strong>g In Place (microbiology, crosscontam<strong>in</strong>ation);• Energy expensive/relatively <strong>in</strong>efficient (ca. 10 timeshigher than evaporation);• Powder moisture content, its standard deviation andspecification;• Dry matter content variation <strong>in</strong> substrate;• Throughput;• (Manual) <strong>control</strong>;• …Concentrateflow rateFICOperator ManipulatedVariablesOperator MonitoredVariablesDryer <strong>in</strong>let airtemperatureDITICTICDryer outlettemperatureFB <strong>in</strong>let airtemperatureTICAIPowdermoisture


Some disadvantages current tower <strong>control</strong>:• Moisture measurements by hand, every few hours;• Control changes slow and by hand;• t delay moisture content from residence time bed;• Operation strongly dependent on operatorexperience;• Operator runs safe (i.e. not too close to spec);• Operator has to react on variations ambient (e.g.approach<strong>in</strong>g hail storm);• …Hence: operation usually not optimal!Actual powder moisture of a WPC:5.04.54.0product vochtigheid (%)3.53.02.52.01.51.00.50.0okt-06 jan-07 apr-07 aug-07 nov-07 feb-08 jun-08 sep-08 dec-08


Advanced <strong>Process</strong> ControlUse of a statistical multivariable model to predictprocess behaviour to reduce process variation.Subsequently, move closer to process limits:SPECIFICATION OR LIMITBEFORE APCWITH APCWITHOPTIMIZATIONModel development APCDevelop multivariate dynamic model from statisticalanalysis step changes.Model predicts direction, shape and size of response.


Expected results Advanced <strong>Process</strong> Control• Decrease <strong>in</strong> standard deviation moisture;• More constant product quality;• Higher average moisture content powder (sellexpensive water);• Decrease <strong>in</strong> specific energy consumption;• Increase <strong>in</strong> throughput (shorter batch time);• Possible <strong>in</strong>crease <strong>in</strong> production capacity (if extracapacity can be sold).APC trial with Connoisseur (Invensys)Three stages with go/no go decision:• Benefit study; based on analysis production data(few weeks);• Implementation trial; develop <strong>control</strong> and proveresults Benefit study (5-6 weeks);• F<strong>in</strong>al implementation (4-5 weeks).


APC: Benefit studyBased on high frequency production data:• Typical average moisture content ca. 1-1.5% belowspecification (product dependent);• Typical standard deviation moisture content ca.0.3%.Prediction results APC:• 5% reduction <strong>in</strong> specific energy consumption;• 5-10% <strong>in</strong>crease <strong>in</strong> throughput (product dependent).APC: Implementation trialDevelopment of two models:• Steady state model of optimisation function;• Dynamic model for the predictive <strong>control</strong> function.Reason 2 models: moisture content too <strong>in</strong>frequent(e.g. 2 h).Moisture can therefore not be part of a dynamic<strong>control</strong>ler.


Feed pump speedT outletT <strong>in</strong>letSteady state OptimiserPowder moistureAir HumidityOutlet air humidityCalculated setpo<strong>in</strong>ts for:- outlet air temperature;- humidity.Feed pump speedT outletT <strong>in</strong>letDynamic MPV <strong>control</strong>lerAir HumidityOutlet air humidityExample step change:


Some key relationships:Feedrate vs. T outlet :T <strong>in</strong>let vs. T outlet :Feedrate vs. RH outlet :Implementation trial: without APC


Implementation trial: turn APC onResults implementation trialRun 1Run 2∆ moisture (%)+ 0.9%+ 0.5%∆ feedrate (l/h)∆ T outlet(°C)+ 10.2%- 13°C+ 14.0%- 10°CHowever: runs <strong>in</strong> December, ambient below 0°C!


Conclusions• APC trial performed on dairy <strong>spray</strong> dryer;• Increase <strong>in</strong> powder moisture of ca. 0.7%;• Increase <strong>in</strong> throughput exceed<strong>in</strong>g 10% (with idealdry<strong>in</strong>g conditions, i.e. cold outside);• Increase <strong>in</strong> throughput comparable to expectationsBenefit study;• No significant <strong>in</strong>crease <strong>in</strong> steam consumption;• Operators happy with the system!Control Challenges• Start up / shut down optimisation / CIP• Inl<strong>in</strong>e QC (Soft sensors)• Incorporation first pr<strong>in</strong>ciple models• Proces <strong>control</strong> for batch systems- L<strong>in</strong>e <strong>control</strong>, e.g. evaporator/dryer orevaporator/crystalliser/dryer- L<strong>in</strong>e optimisation• Plann<strong>in</strong>g & scenario development- site wide- <strong>in</strong>ter site

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