3-D CFD SIMULATION OF A CFB CARBONATOR COLD MODEL

Transcription

1 Centre for Reearch & Technology Hella (CERTH) Intitute for Solid Fuel Technology & Application (ISFTA) 3-D CFD SIMULATION OF A CFB CARBONATOR COLD MODEL Nikolopoulo A., Nikolopoulo N. Grammeli P., Kakara Em. Contact: , Fax : , a.nikolopoulo@certh.gr, grammeli@certh.gr 64 th ΙΕΑ FBC meeting. June 2012 Naple

2 Preentation overview Motivation CFD modeling EMMS Full loop imulation Reult Concluion

3 Preentation overview Motivation CFD modeling EMMS Full loop Reult Concluion

4 Motivation Calcium looping i an attractive pot combution CO 2 capture technology epecially for retrofitting power plant. clean flue ga CO 2 Carbonation fuel Power plant flue ga F CO2 carbonator 650 o C fuel F R purge dryer calciner 900 o C CaCO 3 F 0 O 2 N 2 ASU air CaO CO2 CaCO3 eat Calcination CaCO3 eat CaO CO2 The effectivene of thi proce mainly relay on the deign and operating parameter of the two interconnected Circulating Fluidized bed reactor (Carbonator - Calciner). Epecially, carbonator i a novel reactor and there i no data available for large cale. Proper comprehenive CFD modeling i important for deign optimization.

5 Preentation overview Motivation CFD modeling EMMS Full loop imulation Reult Concluion

6 CFD modeling Iothermal CFD modeling of plexi-gla cold model (Carbonator) of USTUTT Operating condition received om USTUTT (PSD, TSI 1.5 Kg, Superficial ga velocity 2.89 m/). 3-D tranient full loop (CFB loop) TFM CFD imulation of the plexi gla CFB cold model. Dene Grid applied (~287,000 cell, equivalent cell length to particle diameter ratio : ~ 21) The EMMS cheme wa applied for the hydrodynamic imulation of USTUTT CFB cold model iothermal flow. For the returning ytem, a new tre model for the inter particle iction force wa developed.

7 Preentation overview Motivation CFD modeling EMMS Full loop imulation Reult Concluion

8 CFD modeling EMMS formulation - CERTH/ISFTA developed an advanced EMMS model for the operating condition of the plexi gla carbonator cold model of USTUTT Computational domain u c u i u i - EMMS cheme. Dene (cluter) and dilute phae - (dipered particle) in each Control Volume (C.V.). u pf u pf u c u pc u pf u f u pc u pc u pc g u f Slip vel. definition u f = u f u pf u c = u c u pc

9 EMMS formulation CFD modeling EMMS cheme i formulated incorporating: Ma and momentum conervation equation for (Dene and dilute, C.V.) Semi empirical equation (Cluter diameter and bulk denity) Contraint Objective function: Minimum energy interexchange between ga and olid Particle - ga propertie for USTUTT cold model tet Particle Diameter 142 μm Particle Denity 5700 kg/m 3 Ga Denity kg/m 3 Ga Vicoity kg/(m) ε mf The governing equation(emms model) were obtained for the operating condition of USTUTT cold model, and olved for all poible combination of voidage and u lip prior to their CFD implementation and numerical run. - The non-linear optimization EMMS problem wa olved with GAMS oftware and the reult were integrated in Fluent package with C++ UDF (Uer Defined Function) coding

10 EMMS equation 1 N t mf Ff U f mc Fc Uc mi Fi U f 1 f 1 g min imum Momentum conervation 3 f 1c 3 f C U U C U U f ga 4 d 4 d FEMMS = g f 1c gac 1 f 1 f gaf g H d F Wen, Yu F Emm 1 dc g c c di i i c g c p cl g 1 f 1 f 3 C U U f ga 4 d 1 1 df g f f f g f p 1 f 1 f g g c g C U U C U U C U U d 1 f d d df f f di i i dc c c p cl p Objective function Reult CFD modeling Effective drag coef. Standard drag coef. Reynold number U 1 1 pf f U pc f u g U 1 f U f u f c g g c g n Ma conervation f 1 f g c f Semi empirical equation 6 d d d 32 cl p p Cloure equation Dene phae Dilute Phae Inter-phae C C 4.65 dc d 0 c d0c Rec Rec C C 4.65 df d 0 f f C C (1 f ) C Cd0 f Cd0i Re Re Re Re gd p Rec U g c Re f gd Slip c U pc Uc U f U pf c Uf U f velocity Drag force dp g F C U U 4 2 Number of particle or cluter c dc c c f 1c mc 3 d p 6 c f g p f U d F C U U p g f df f f m f 1 f 1 f f Di Doi gd Rei i 10 g cl i U 4.65 f Upc Ui 1 f U f 1c d F C U U cl g i di i i f 3 i 3 d d p cl 6 m f 6 i

11 EMMS formulation CFD modeling The reult (H d index) of the optimization problem, were interpolated in order to be efficiently introduced in the Fluent CFD package (via UDF). F EMMS = F Wen,Yu / H d H d ( ) The Heterogeneity H d (ε g ) function index for u lip =2 m/ec ε g ( ) - 18 interpolation polynomial H f u, d lip g for lip velocity: 0.25, 0.5, 0.75, 1, , 1.75, 2, 2.25, 2.5, 2.75, 3, 3.25, 3.5, 4, 5, 6, 8

12 Preentation overview Motivation CFD modeling EMMS Full loop imulation Reult Concluion

13 Full loop imulation Inter-particle ictional force In the CFB recirculation ytem the flow i dene and inter particle iction force prevail. CFB flow i imulated with the Euler Euler (TFM) approach Solid are conidered a a Peudo - fluid Dilute flow (ε < 0.5) Dene flow (ε > 0.5) Dilute flow Dene flow Kinetic theory (Gidapow) Platic theory (Drucker - Prager) 13

14 Model development / State-of-the-art Platic theory The rate of energy lo during platic deformation i zero (W = D i σ i = 0) Only dilatancy and NOT conolidation in a control volume i properly modeled Full loop imulation Yield criterion (Treca, von Mie, Drucker-Prager, Gray Stile) Y IIdT Flow rule aociated flow rule Drucker-Prager 2 2 in 0 Εxtended von Mie, Drucker-Prager 14

15 Inter-particle ictional force Model development / new model Yield criterion: Pitman - Schaeffer - Gray Stile Critical point The rate of energy lo during platic deformation i not zero (W = D i σ i 0) Both dilatancy and conolidation in a control volume are properly modeled Diadvantage: Numerical tiffne Pu 15

16 Inter-particle ictional force Contitutive equation TFM equation Stre Model μ hear μ bulk P kin col kin col kin P kin P kin col kin P kin P P kin kin col Conventional model 10d 4 [1 go (1 e)] 96 (1 e ) g 5 o 4 dg(1 e ) 5 o 2 New model go e e d g 1 e 3 e o 45 g 1 6gd o 1e3e 1 4 g e d 5 kin 1 o g o max 1 max max 2.5 P in 2 0 II dd 2 P in 4in ( u ) 2 2 dd P 4in II ( u ) 2 2 dd 16

17 Inter-particle ictional force Stre Model Validation Model validation through 2D CFD imulation of a repoe angle (φ exp =36.03 o ) meaurement experiment (Geldart B) The new model through appropriate UDF wa implemented in Fluent 13 Batch of particle at T=0 Two CFD model were applied: - Conventional one (Ext. von Mie) - New one (Pitman - Schaeffer - Gray Stile) Free fall φ exp =36.03 ο Tranient imulation: ΔT T = 40μ 17

18 Inter-particle ictional force Conventional model Stre Model Validation 1.1 ec 1.4 ec 1.82 ec φ<4 ο φ exp =36.03 ο New model 1.2 ec 1.8 ec 2.2 ec t1.20 ec φ=21 ο 18

19 Preentation overview Motivation CFD modeling EMMS Full loop imulation Reult Concluion

20 continuity equation momentum equation New tre model developed for the inter particle iction force in the recirculation ytem Vicou Stre tenor granular temperature TFM equation ggggug t u 0 0 t ggugggugug t gpg gggu ug u uu t p p g ug u T 2 g gg ug ug g gg ugi 3 T 2 u u ui 3 pi u : 3 0 CFD imulation kin col CFB rier 10d 4 [1 go (1 e)] 96 (1 e ) g 5 o Stre Model 2 kin Loop - Seal d go e e g 1 e 3 e o 45 g 1 6gd o 1 e3e dg o(1 e) (1 ) / 5 go e kin d 5 2 P in P in 2 2 II 4in II u dd dd 0 2 g o max P 4in II u 2 dd 1 max max The CFD model developed incorporate the EMMS cheme and the new tre model for the recirculation ytem. 20

21 CFD imulation CFD modeling of plexi-gla cold model (Carbonator( Carbonator) ) of USTUTT - The EMMS cheme developed increae the accuracy of the model epecially in the dene bottom region which i hard to model, and in which the majority of CO 2 capture take place. 21

22 CFD imulation The model incorporating the EMMS cheme efficiently capture the hydrodynamic of the CFB carbonator with high accuracy. Regarding Preure profile the mean error i le than 10%. The error in the re-circulation flux i le than 2% depicting the ophitication of the developed model for the inter-particle iction force. 22

23 CFD imulation Contour of time averaged volume action of olid Rier exit - cyclone Bottom zone Loop Seal 23

24 CFD imulation Vector of time averaged olid velocity Bottom zone Loop Seal 24

25 Preentation overview Motivation CFD modeling EMMS Full loop imulation Reult Concluion

26 Concluion The developed EMMS cheme along with the implementation of a dene grid reulted in highly accurate reult with repect to the governing hydrodynamic of the CFB cold model carbonator. In full loop imulation of CFB the inter particle iction force hould be accurately imulated. The tre tenor formulation baed on the von- Mie yield criterion everely under predict the iction force. The developed tre tenor formulation baed on Pitman - Schaeffer - Gray Stile Yield criterion efficiently capture the hydrodynamic behavior of the Loop Seal.

27 CERTH/ISFTA Thank you for your attention! Quetion? Acknowledgement: The preent work wa funded by the Reearch Programme of the Reearch Fund for Coal and Steel Coal RTD (Reearch Project CaL Mod / RFCS-CT