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

Process control in spray dryingJohn Niederer, Frank JeurissenDecember 3 rd 2009FrieslandCampina, young company long history

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FrieslandCampina DomoIngredients Business Group Royal FrieslandCampinaMarkets:Infant nutritionInfant formula:0 – 6 monthsFollow on formula:6 – 12 monthsGrowing Up Milk :1 – 6 yearsProducts• Ingredients• Base powders• Total formulation

Markets:Medical nutritionProducts• MPC’s• Specialty proteinblends powder• Caseinates• Hydrolysates• Base powders• Total formulationMarkets:Cell cultureCell culture media forproduction ofbiopharmaceutical drugsMicrobialdiagnosticsMicrobial testing formedical diagnosesProducts• Hydrolysates

Markets:PharmaceuticalexipientsBinders and fillers forpharma applicationsProducts• Direct CompressionLactose• Wet GranulationLactose• Inhalation LactoseWhey processingWhey storageEvaporatorCrystalliserCentrifugeFluid beddryingPackagingLactoseFeedSpray towerPackagingUltra filtrationEvaporatorWhey ProteinConcentratesMainly water removal…Spray towerPackaging

Spray Drying: some typical problems• Different products, different recipes, same tower;• Cleaning In Place (microbiology, crosscontamination);• Energy expensive/relatively inefficient (ca. 10 timeshigher than evaporation);• Powder moisture content, its standard deviation andspecification;• Dry matter content variation in substrate;• Throughput;• (Manual) control;• …Concentrateflow rateFICOperator ManipulatedVariablesOperator MonitoredVariablesDryer inlet airtemperatureDITICTICDryer outlettemperatureFB inlet airtemperatureTICAIPowdermoisture

Some disadvantages current tower control:• 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.approaching 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 Process 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 Process Control• Decrease in standard deviation moisture;• More constant product quality;• Higher average moisture content powder (sellexpensive water);• Decrease in specific energy consumption;• Increase in throughput (shorter batch time);• Possible increase in 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 control and proveresults Benefit study (5-6 weeks);• Final 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 in specific energy consumption;• 5-10% increase in throughput (product dependent).APC: Implementation trialDevelopment of two models:• Steady state model of optimisation function;• Dynamic model for the predictive control function.Reason 2 models: moisture content too infrequent(e.g. 2 h).Moisture can therefore not be part of a dynamiccontroller.

Feed pump speedT outletT inletSteady state OptimiserPowder moistureAir HumidityOutlet air humidityCalculated setpoints for:- outlet air temperature;- humidity.Feed pump speedT outletT inletDynamic MPV controllerAir HumidityOutlet air humidityExample step change:

Some key relationships:Feedrate vs. T outlet :T inlet 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 in December, ambient below 0°C!

Conclusions• APC trial performed on dairy spray dryer;• Increase in powder moisture of ca. 0.7%;• Increase in throughput exceeding 10% (with idealdrying conditions, i.e. cold outside);• Increase in throughput comparable to expectationsBenefit study;• No significant increase in steam consumption;• Operators happy with the system!Control Challenges• Start up / shut down optimisation / CIP• Inline QC (Soft sensors)• Incorporation first principle models• Proces control for batch systems- Line control, e.g. evaporator/dryer orevaporator/crystalliser/dryer- Line optimisation• Planning & scenario development- site wide- inter site