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8/2/2019 Presentation Drying Parameters(1)
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D I E T
A G R I C U L T U R E
E N V I R O N M E N T1
Drying by desorption: a toolto determine spray-drying parameters
Pierre SCHUCK1*, Eric BLANCHARD2,Evelyne ONILLON2, Anne DOLIVET1, Serge
MJEAN1, Radwan JALAM1 & Romain JEANTET1
1: UMR 1253 Joint Research Unit on Science and Technologyof Milk and Egg (INRA, Agrocampus Rennes),
65 rue de Saint-Brieuc, 35042 Rennes Cedex, France.2: Laiterie de Montaigu, 85600 Montaigu, France.3: Food Technology, AgrocampusRennes, France.
D I E T
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Introduction (1) Spray drying is useful a technique for water evaporation using hot air, butvery black box in nature
The only way to determine a priori& precisely the parameters of spray drying
for food products consists in pilot / plant experiments
expensive, timeconsuming, empirical & sometimes unreliable
?
To date, there are no available method in order to determine precisely theparameters of spray drying for food products before drying
Why ?
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Air in contact with thedroplet T=45C ; p=9 583 Pa
Drying airT=200C ; p=1554 Pa
Introduction (2)
DROPLET
ENERGY TRANSFER
WATER TRANSFER
POWDERAIR
D I E T
A G R I C U L T U R E
E N V I R O N M E N T4
Introduction (3)
DROPLET
ENERGY TRANSFER
WATER TRANSFER
AIR
2500 kJ.kg-1 DA
Free water
n x 2500 kJ.kg-1 DA
Bound water
Inlet air
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E N V I R O N M E N T5
?
Why?
Water availability &drying behavior needsextra energy to overcomebinding of water
Kinetic of mass / heattransfer phenomena determination of boundary /local conditions ( & watercontent)
Introduction (4)
Watertransfer
Boundary
layer
Droplet
Drying hot air = 200C; P e = 1554 Pa
Heattransfer
Surface of the dropleth = 45C; P e = 9853 Pa
D I E T
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Alternative spray drying modeling, based on drying physics (mass & heattransfer laws / balance). 2 levels :
Overall mass and energy balanceestablished over the entire spraydryer
Running (settings) and control ofthe drying plant for (weatherconditions) Schuck et al. IFCET (2005), Schuck et al. DairySci. &Technol. (2008)
Air inlet, H2O
Air outlet, H2O
Global level INRA
Local mass (drying rate) and energybalance established at the droplet
Management and control of theproduct quality / functionality Chen & Lin AIChEJournal (2005)
dropletd, H2O = (t)
Micro level REA / Monash
One difficulty remaining taking into account water availability = (product)
Introduction (5)
Droplet
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E N V I R O N M E N T7
Inlet air
Fluid bed
Chamber
CyclonesConcentrate
Powder
0
AH
RH
210
2
Outlet air
2 AH
Hot air 1
1
AH2 : Dryer capacity / free water evaporation
RH2 aw x 100
?
?
Isenthalpic drying 1 & RH1
No energy losses and only free water
Spray drying water New method
Introduction (6)
0
D I E T
A G R I C U L T U R E
E N V I R O N M E N T8
PRODUCT
PRODUCT
H2o H2o
9600 Pa
Step: Concentrate desorption
by aw-metry
ZEOLITE
ZEOLITESENSORmRH (%) T (C)
SENSOR
96 Pa96 Pa
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1 2 3 4 5 6 7
0
5
10
15
20
25
30
35
40
0
Time (h)
mRH(%)
Step: Desorption curve vs. time
WATER
CONCENTRATE
Drying
kinetics
Constant rate :
free water
Falling rate :
bounded water
Energy = Lev + E
D I E T
A G R I C U L T U R E
E N V I R O N M E N T10
1
2
1
0
1 2 3 4 5 6 70
5
10
15
20
25
30
35
40
0
Time (h)
Dryingkinetics
E
Plotting temperature / humidity
pathway considering non
isenthalpic behavior
Step
: Desorptioncurve vs. time
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Step : Calculation by INRA Software
integrating the ratio of bound andunbound water.
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Concentrate
Powder
Step : View of certain
drying parameters onthe Enthalpic MollierDiagram
Inlet air afterheating1
1
Inlet air beforeheating0
0
InletAirOutlet air
after drying
22
Outlet Air
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Step : Spray drying parameterscalculated with INRA Software
D I E T
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E N V I R O N M E N T14
Materials
BB
II
OO
NN
OOVV
Pilot workshop : Researchand development forevaporation / drying
MSD type drying tower80 kg of water evaporated
per hour
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y = 0.9917x
R2
= 0.97
100
140
180
220
260
300
100 120 140 160 180 200 220 240 260 280 300
Measured inlet air temperature (C)
Calculatedinletairtemperature(C
)
Results (1)
D I E T
A G R I C U L T U R E
E N V I R O N M E N T16
10
100
1000
10000
100000
10 100 1000 10000 100000
Measured parameters
Calculatedparameters
[C] and Powder flow rate
Air TC
Outlet air AH
r2 0.99
r2 0.95
r2 0.93
Results (2)
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Conclusions (1)
? With this method, it is possible to predict
optimal drying air temperatures ( 1 -5%) for food products in relation to theirdesorption behavior
(, TS, , Cp) [C]
kWh
Air (chamber, FB)m
H2OPowder (RH2)
% drying FB
Current weather conditions (0)
Desorptioncurve analysis
(, H, RH) air 1 (chamber, FB)
ESC
Yield
Cost ($ . t-1 water / powder)
Powder, [C]m
OutputsInputs
D I E T
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E N V I R O N M E N T18
Conclusions (2)
Validation tests (> 30 products) indicate that this method could be applied to a largerange of food products & spray dryer types.
For reasons of calculation speed and reliability, the method has been computerizedand can already be used in the determination of parameters of spray drying for foodproducts. Spray Drying Parameters Simulation & Determination Software(SD2P)
NIDDN.FR.001.480002.002.R.P.2005.000.30100
? With this method, it is possible to predict
optimal drying air temperatures ( 1 -5%) for food products in relation to theirdesorption behavior
The experimental device differs from drying installation in term of duration of drying,temperature of drying, ratio surface / volume etc. We have developed somecomputational tool by taking it into account to improve the method.
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0
20
40
60
80
100
120
140
160
180
200
220
240
260
280
300
0 0,01 0,02 0,03 0,04 0,05 0,06
0
2
10
1
2
Concentrate
InletAir
Powder
Outlet Air
Inlet air afterheating
Inlet air beforeheating
Outlet airafter drying
Prospects
1
Particletemperature
Glass transitiontemperature
(T-Tg)
Temps / Position
Axe Z
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Demonstration
SD2P
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15 210 24 2Whey
40 230 220 2MPC/I WPC/I
20 215 28 2Skimmilk
Multi stagespray-dryer
Compactspray-dryer
Pilot plantspray-dryer
Powders
D I E T
A G R I C U L T U R E
E N V I R O N M E N T28
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Humid Air Chart of Inlet Air
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Humid Air Chart of Integrated Fluid Bed Inlet Air
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Desorption curves analysis
Kind of bound water
Approaching Tg
Couchman-Karasz equation extended in tertiary mixtures
332211
g333g222g111g
CpWCpWCpW
TCpWTCpWTCpWT
++
++=
Critical outlet air Tg + (40) C
tightly bound to constituents, solvent
Whey, UF/MF permeate, mono & disaccharides,
polyols, hydrolyzed compounds, minerals
Low Tg / stickiness
High Tg / High outlet compatible
trapped in a hydrophobic network, capillary
Micellar casein, maltodextrins
Inlet & flow rate
Outlet air & AH
Droplet & PowderSD2P AH2
Tg DSC
Critical powder Tg + (20) C
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Examples (1)
MDDE 33
MDDE 7
InletC
OutletC
AHg.kg-1DA
[C]kg.h-1
/ton Water
/ton Powder
Powderkg.h-1
215 4,646 74.9 38.789 41 3,146
237 4,646 86.7 44.589 41 3,146
UFPC
UFPNC (1)
213 3,204 88. 3 69.489 41 1,835
237 3,204 94.9 74.589 41 1,835
Bound and free waterSD
2
P
INRA
UFPNC (2) 153 1,751 116.0 91.180 27 1,003
Spray Drying Parameters Simulation & Determination Software
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A G R I C U L T U R E
E N V I R O N M E N T36
Standardization
SMP 1
SMP 2
InletC
OutletC
AHg.kg-1DA
[C]kg.h-1
/ton Water
/ton Powder
Powderkg.h-1
209.4 4,083 68.2 65.678.7 50.3 2,547
218.8 4,083 71.2 69.577.3 50.3 2,547
Examples (2)
SD2PINRA
Spray Drying Parameters Simulation & Determination Software
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E N V I R O N M E N T37
MERCI THANKYOU