Coupled population, mass and heat balances for liquid sprayed gas/solid fluidized beds

Size: px

Start display at page:

Download "Coupled population, mass and heat balances for liquid sprayed gas/solid fluidized beds"

Cora Webster
5 years ago
Views:

1 Working Party on Drying / ECE Technical and Business Meeting April 11 th -12 th, 2002, Magdeburg, Germany 1 Coupled population, mass and heat balances for liquid sprayed gas/solid fluidized beds Peglow, M.* / Henneberg, M. / Ihlow, M. / Heinrich, S. / Mörl, L. Otto-von-Guericke-Universität Magdeburg Institut für Apparate- und Umwelttechnik Lehrstuhl Chemischer Apparatebau Universitätsplatz 2, Magdeburg *mirko.peglow@vst.uni-magdeburg.de

2 Overview 2 1. Motivation 2. Modeling 3. Simulation results 4. Experimental validation 5. Conclusions and further prospects

3 1. Motivation 3 Coupled calculation of particle size distribution, heat and mass transfer for fluidized bed spray granulation Combination of different models to describe the subprocesses in a complex model Simulation of unsteady processes Analysis of influence of different process parameters Prediction of pneumatic and thermodynamic stability

4 2. Modeling: Structure of model 4 Population balance model Calculation of PSD and essential fluidized bed parameters for different process designs mechanistic model Time domain: hours Particle surface Particle diameter C O U P L I N G Injected mass flow Temperature Heat and mass transfer model Calculation of degree of wetting;, liquid and particle temperature and humidity Monodispers, unchangeable particle system Time domain: seconds

5 2. Modeling: population balance 5 nd ( P, t) Gd ( P) nd ( P, t) = + n& dust ( dp ) + n& nuclei ( dp ) + n& ci ( dp ) + n& r ( dp ) n& bed ( dp ) t d P overspray abrasion pension (1 overspray m & pension (1 x water x water ) ) overspray n& A, q 0,A cyclon n& dust, q 0,dust dust,in granulator n& bed, q 0,bed n& r, q 0,r separator n& T, q 0,T apparatusgeometry particleproperty dust,out n&, nuclei q 0, nuclei n& ci, q 0,ci

6 2. Modeling: population balance 6 Selected submodels for the calculation of PSD Granulation model (Mörl) Pneumatic behavior (Goroschko) Attrition (Rangelova, Werther) Overspray Classifying with turbulence and circulation time model (Molerus, Mörl) Mörl, L.: Growth of granules in fluidized-bed drying, taking into account the formation of nuclei, International Chemical Engineering, Vol. 26 (1986), Nr. 2 (April 1986), S Goroschko, W.D., Rozenbaum, R.B., & Todes, O.M. (1958): Neft i Gaz, 1, 125. Molerus, O, & Hoffmann, H. (1969): Darstellung von Windsichterkurven durch ein stochastisches Modell, Chem.-Ing.-Tech., 41 (5/6), Rangelova, J., Dalichau, J., Heinrich, S., Mörl, L.: Zerfallsverhalten von Partikeln in Wirbelschichten Anwendung eines konstanten massenbezogenen Abriebskoeffizienten, Chem.-Ing.-Tech. 73 (2001) 9, S Mörl, L., Mittelstraß, M., & Sachse, J. (1978): Berechnung der Verteilungsspektren von eststoffgranulatteilchen in Wirbelschichtapparaten mit klassierendem Abzug. Chem. Techn., 30 (5),

7 2. Modeling: heat and mass transfer 7 Differential volume element with wetted particle

8 2. Modeling: heat and mass transfer 8 Selected parameters for heat and mass transfer Heat transfer gas-particle (Tsotsas) Heat transfer gas-wall (Baskakov) Heat transfer wall-particle (Martin) Heat transfer particle-liquid film (Reppmann) Mass transfer gas-particle (Tsotsas) Degree of wetting (Mörl) Groenewold, H., Tsotsas, E.: Predicting Apparent Sherwood Numbers or luidized Beds, Proceedings of the 11th International Drying Symposium (IDS'98), Halkidiki, Greece, august 19-22, 1998, vol. A. pp Martin, H.: Wärmeübergang in Wirbelschichten.VDI-Wärmeatlas, 7. Auflage 1994, S. Mf1/Mf8 Reppmann, D: Experimentelle und theoretische Untersuchungen zur Eindüsung von lüssigkeiten in eine Wirbelschicht, Dissertation, TU Magdeburg, 1990 Heinrich, S., Mörl, L.: Description of the temperature, humidity and concentration distribution in gas-liquid-solid fluidized beds, Chem. Eng. Technol. 22 (1999) 2, pp

9 3. Simulation results 9 Selected process parameters: mbed = 20kg ρ = 1500 kg / m bed 3 nuc = 1 kg/ h = 20 kg/ h x = 0.3 T = 350 kg/ h = 150 C Start-up process Determination of resulting PSD Determination of values regarding heat- and mass transfer Aim: steady state

10 3. Simulation results: start up 600 minutes 10 mbed = 20kg nuc 3 ρ = 1500 kg / m bed = 1 kg/ h = 20 kg/ h x = 0.3 T = 350 kg/ h = 150 C

11 3. Simulation results: Variation of parameters 11 Start up to steady state Deflection from steady state Aim: coarse particle spectrum Reduction of nuclei at t = 600 min = 1 kg/ h 0.5 kg/ h nuc Raising of pension mass flow at t = 600 min = 20 kg/ h 30 kg/ h Raising of supply temperature at t = 600 min T = 150 C 200 C

12 3. Simulation results: Variation of parameters 12 = 1 kg/ h 0.5 kg/ h = 20 kg/ h 30 kg/ h T = 150 C 200 C nuc

4. Experimental validation: B DN400 13 exhaust hold-up internal nuclei external nuclei filter

13 4. Experimental validation: B DN exhaust hold-up internal nuclei external nuclei filter dust M cyclone dust bed of atomization inlet (classifying ) el. el. el. inlet (fluidizing ) product

14 4. Experimental validation 14 Holdup und nuclei material : glass Suspension: limestone with binder dis = 60 kg/ h = 0,05 kg / s m bed nuc = 30 kg = 0,8 kg / h Granulate with Nuclei = 0, 43 kg/ s ϑ = 120 C t = 430 min Holdup Granulate Nuclei

15 4. Experimental validation: PSD bed material 15 dis = 60 kg/ h = 0,05 kg / s m bed nuc = 30 kg = 0,8 kg / h = 0, 43 kg/ s ϑ = 120 C t = 430 min

16 4. Experimental validation: PSD bed material 16 dis = 60 kg/ h = 0,05 kg / s m bed nuc = 30 kg = 0,8 kg / h = 0, 43 kg/ s ϑ = 120 C t = 430 min

17 dp = 3, 05 Luftaustrittsfeuchte moisture outlet [kg/kg] 4. Experimental validation: moisture outlet 17 0,035 0,030 0,025 0,020 0,015 0,010 0,005 mm ϑ = 127 C mbed = 30 = 18,5 kg/h = 13,6 kg/h = 8,64 kg/h kg ϑ = 15 C ρ = 2400 kg / m P = 23,4 kg/h Messung measurement Simulation simulation time Zeit [s] 3 =18,6 kg/h Y in = 13,8 kg/h = 0 kg/h = kg/ kg * 2 = 2.2 / = 8,76 kg/h kg m s

18 4. Experimental validation: temperature outlet 18 dp = 3, 05 mm m = 30 bed kg ϑ = 127 C ϑ = 15 C ρ = P 2400 kg / m 3 Y in = kg/ kg * 2 = 2.2 / kg m s Luftaustrittstemperatur temperature outlet [ C] = 8,64 kg/h = 13,6 kg/h = 23,4 kg/h Messung measurement = 18,5 kg/h simulation Simulation time Zeit [s] = 18,6 kg/h = 0 kg/h =13,8 kg/h = 8,76 kg/h

19 5. Conclusions and further prospects 19 Conclusions irst coupling of heat and mass transfer with population balance model for fluidized bed spray granulation Simulation of unsteady processes urther prospects Coupling of models over the entire diameter range Solving of heat and mass transfer model for entire diameter range Implementation of agglomeration model

20 4. Experimental Validation: PSD bed / product 20 bed bed product product

INVESTIGATION OF COALESCENCE KINETICS OF MICROCRISTALLINE CELLULOSE IN FLUIDISED BED SPRAY AGGLOMERATION EXPERIMENTAL STUDIES AND MODELLING APPROACH

Brazilian Journal of Chemical Engineering ISSN 14-663 Printed in Brazil www.abeq.org.br/bjche Vol., No., pp. 165-17, April - June, 5 INVESTIGATION OF COALESCENCE KINETICS OF MICROCRISTALLINE CELLULOSE