A model for black liquor gasification in a fluidized bed

Transcription

1 A moel or lack liquor asiication in a luiize e Z. Chen a, A.F. Saroim a,, M.J. Bockelie a an K. Whitty a Reaction Enineerin International 77 W. S., Suite, Salt Lake City, U 84 Deartment o Chemical an Fuels Enineerin University o Utah, Salt Lake City, U 84

2 OULINE Backroun an Ojective Moel Develoment Devolatilization an Gasiication Kinetics Moel Results Conclusions Acknowleement

3 BACKGROUND AND OBJECIVE o evelo a moel to simulate lack liquor asiication in a ulin luiize e (Bi Islan steam reormer rocess) o examine the eects o oeratin conitions on synas quality, caron conversion, as temerature an axial variations o as comosition an temerature MCI rocess t BLS 4 tue unles

4 MODEL ASSUMPIONS he luiize e consists o A article-ree ule hase A wake-clou hase A ense hase Gas in ierent hases has the same temerature Particles in ierent hases also have the same temerature Dryin an evolatilization are instantaneous ense hase ule hase clou ule wake Fluiizin as

5 Bule Proerties Bule size an ule velocity are etermine usin correlations oun in the literature. Bule raction is calculate ase on the overall as mass alance. Bule reaku in the tue anks is reicte usin a roailistic moel.

6 Mass Balance Equations Bule Phase ( Convection Cross - low uac z A n j= α i, i,j ) (λ R i,,j C K w C A(C C Reaction Exchane i, λ i,w i, (u ) z i,w A) ) = Wake an Dense Phases Similar to the aove equation Freeoar C n i, uo α R z i,j i,,j = j=

7 Enery Balance Equations Gas Phase Q )R H ( )]ε ( [ )R H ( ε )R Η ( )] ( 6σ ) ( 6h )[ ε )]( ( [ ( 6σ ( 6h )[ ε ( z u ρ C t n i i,e, i,e, m w n i i,w, i,w, m w i, n l i i, 4 4 e m w 4 4 w m w = = = = )] ) Particle Phase ] H ) H ) n i = = = wat n i i,e,s i,e,s 4 4 e m w i,w,s i,w,s 4 4 w m w Q )R (- ) ( 6σ ) ( 6h )[ ε )]( ( [ ] R (- ( 6σ ) ( 6h )[ ε ( )R H ( z ρ C u i, i, n l i = = Freeoar

8 Devolatilization Emirical correlations are use to etermine C, H, O an S release (Freerick an Hua, 993; Freerick et al., 995) Volatiles are reresente y a mixture o CH 4, CO, H O an H S Ca H OcS = ech 4 CO H O hh S Amount o each as secies is etermine rom the element mole alance Char = BLS - volatiles

9 GASIFICAION KINEICS Steam asiication (Li an van Heininen, 99) 53 H O HO = CO H Rate =.56 9 ex 3 Cc kmol / m s H O.4 H C CO asiication (Li an van Heininen, 99) 37 C CO = CO Rate = ex C kmol / m s Other reactions consiere (MFIX) CO CO 3.4 CO c CH 4 HO = CO 3H C H = CH 4 CH4 O = CO HO H O = H O C O = CO CO H O H CO CO O = CO

10 PRELIMINARY RESULS Prouct as comosition Particle an as temerature Bule roerties Chane in as low rate in the e Variation o as comosition alon the heiht

11 Synas Comosition.5.4 mole raction.3. REI moel UU moel DESIGN. CO CO HO H as secies Moel results are in oo areement with availale ata Moel reicts 96% caron conversion

12 9 Particle an Gas emerature 8 temerature, K imensionless heiht Particle temerature is the same as as temerature ue to a lare contactin area emerature in the e is not uniorm

13 Bule Proerties averae ule size, m ule raction in the tue unles in oen sace tue-ree e imensionless heiht Bule size is airly uniorm in the tue unles

14 Gas Flow Rate an Suericial Velocity.9 3 suericial as velocity (u ), m/s as mass low rate, k/s imensionless heiht Gasiication takes lace aove a imensionless heiht o.

15 Gas Secies Mole Fraction mole raction CO CO HO H imensionless heiht Water-as shit reaction rocees in orwar irection in the reeoar

16 Gas Secies Mole Fraction CH4 mole raction HS mole raction CH4 HS imensionless heiht.

17 CONCLUSIONS A three-hase moel has een eveloe to simulate lack liquor asiication in a luiize e Preliminary results are in oo areement with availale ata Preicte caron conversion is consistent with iel ata

18 ACKNOWLEGDEMEN his roject has een une y the DOE uner a sucontract throuh the University o Utah (DE-FC6-N449). he DOE roject manaer is Parrish Galusky. he Georia-Paciic roject manaer or this eort is Roert DeCarrera.