in tanksin breweries. Theyhave also usedUV illuminationto detectdeposits,
Fuchsinstainingto detectproteinsand Lugol's iodinesolutionto detectstarch.
According to Paezet al. (2003)a commercialATP-bioluminescence system can
be usedto evaluate the cleanliness of milkingequipment,bulktanksand milk
transport tankers. The outletof the platecooler,the outletpipeof the bulktank
and the internal surface of the manholelid in the milktransporttanks werethe
mostcritical points.Results indicatedthat bioluminescenceresults werenot
reliablefor testingrinsewater, and thereforeswabbingwas needed to complete
the hygienic assessment. Odebrechtet al. (2000)studied the applicability of
bioluminescence methods for testing hygiene in beer fermentation and
maturation tanks and yeasttanks in breweries. Results indicated that the
bioluminescence method was not suitable for the detection of microbial
contamination, as the results did not correlate with those obtained by
conventionalmicrobial culturing techniques.It may, however, be useful as a
methodfor monitoringthe efficiency of cleaningand disinfection of tanks,
pipelinesand other brewery equipment.
30.5 Usingcomputationalfluiddynamics (CFD)to assess
cleanabilityof closedprocesslines
CFDis usedin manyapplicationsto modelthe bulkparameters of fluidflows.
Recentlymodel developments havemade it possible to resolvewhathappens in
specificpositionson and nearwalls,whichis of interest in the studyof cleaning
processes (Jensen, 2003).CFDmodelsof tanks existfor purposes of optimising
the operationof processes suchas mixing, heatingand cooling.The CFDmodel
developedby Tresset al. (2004) predicts mixingpatternsin silo tanks.It
providesinformation aboutthe behaviourof two-phase flowsstirred withtwo
pitchedbladeturbinesplaceddifferently.The results of the studiesare applied to
reducethe energyrequirements for mixingand optimisemixingefficiency. The
extension applies to combiningthe models for the prediction of the hygienic
designof valves, pipes,etc. madeby Jensen (2003)withconventionaltankflow
modelsand the establishmentof moreinformation on the connectionsbetween
surfacecharacteristics and the cleaningeffectof fluidflow. Thisis believedto
result in a tool suitable for the evaluation of the efficiency of cleaning
procedures in tanks.Thehypothesisis thatbothvalidation of the cleaning
procedure and the designof a proper cleaning system can be supported and
improved using CFDmodels. Theaim is to evaluate the suitability of CFD
simulations for estimating and improvingtankcleaningand to performcleaning
testsin a pilotplant in orderto establisha correlationwith the resultsof CFD
simulations.Preliminaryresultsof the CFDsimulationsyieldinformation about
wallshearstresses in the tank and the flowratesin differentparts of the system.
Somestudieshavebeencarriedout on the flow simulationsuitablefor the
accurate evaluationof the hygienic state of tanksduring and afterspray-ball
cleaning.
Improvingthe cleaningof tanks 503