Tutorial Chemical Reaction Engineering:

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1 Dpl.-Ing. ndeas Jöke Tutoal Chemal eaton Engneeng:. eal eatos, esdene tme dstbuton and seletvty / yeld fo eaton netwoks Insttute of Poess Engneeng, G5-7, andeas.joeke@ovgu.de 8-Jun-6

2 Tutoal CE: esdene tme dstbuton Ideal: no mxng (PFT) o pefet mxng (CST) Tehnal ealty s n between those ases! Fo tehnal / eal eatos: Measuements and modelng of the mxng state Calulaton of e.g. onveson fo the mxng state S S+P Flud elements take dffeent ways though paked bed ypass flow dead zones adal flow veloty pofle beause of bypass flows at low d T /d P (<) CST PFT CE: eal eatos and eaton netwoks 8-Jun-6

3 Tutoal CE: esdene tme dstbuton PFT eal CST Da T eatant eatant "tme gven" "tme needed" CE: eal eatos and eaton netwoks 8-Jun-6 3

4 Tutoal CE: esdene tme dstbuton Chaatezaton of esdene tme dstbuton wth measuement of pulse o step esponses C S C S t t t Dffeentaton t Despton of pulse esponse wth statstal moments Nomalzed pulse esponse: E t S t S t dt t. moment: t E t dt mean esdene tme t. moment: t E t dt vaane t CE: eal eatos and eaton netwoks 8-Jun-6 4

5 Nom. Pulse esponse E(t) Tutoal CE: esdene tme dstbuton Ideal eatos vs. asade model (N CST s) 3 4 N- N PFT: V V CST: V V Casade: Nom. esdene tme τ(t) VC VN N V V N CE: eal eatos and eaton netwoks 8-Jun-6 5

6 Tutoal CE: esdene tme dstbuton Dspeson model: Tubula eatos Intoduton of an axal dspeson tem n the mass balane M M V dv j, j j J, j j t j z j J Dax d dz V M Dax, j z z j j Chaatezaton possble wth odensten-numbe o: o V L vl D D ax ax "onvetve mass tanfe" "dffusve mass tansfe" PFT assumpton s easonable f o > and d T /d P > V V 8 o o THO CE: eal eatos and eaton netwoks 8-Jun-6 6

7 Tutoal CE: esdene tme dstbuton Segegaton model: Tubula eatos Splttng of a tubula eato nto paallel PFT s wth dffeent length (esdene tme, onveson) Calulaton of the mean onveson fom the esdene tme dstbuton possble: t X X t E t dt CE: eal eatos and eaton netwoks 8-Jun-6 7

8 Tutoal CE: eal tubula eato. eal tubula eato: Tae expement t mn t mn mol l E mn tae k k.45 mn T ool T ool d t t E t S t S t t S t S t t t E t dt t E t t mn t Etdt t Ett 3.4 mn t CE: eal eatos and eaton netwoks 8-Jun-6 8

9 Tutoal CE: eal tubula eato Pat b: Numbe of ST fo equvalent asade N Pat : Conveson fo asade model N X asade 4 % Mass balanes of all CST s n asade I d I I k dt k k.45 mn T ool T ool d k dt k N d N N N k dt N N k N N k N CE: eal eatos and eaton netwoks 8-Jun-6 9

10 Tutoal CE: eal tubula eato Pat d: Conveson fo segegaton model X X t E t dt X t E t t 4 % seg t Conveson as funton of tme? nalogy between PFT and bath eato! d k t kt d X t kt exp exp mn mn mol l mn t t E X tae k k.45 mn T ool Casade model and segegaton model gve the same esult! T ool CE: eal eatos and eaton netwoks 8-Jun-6

11 Tutoal CE: Seletvty / yeld fo netwoks.: Yeld and seletvty fo sees eatons Pat a: Maxmum yeld of fo CST k C k k k Maxmum yeld. devatve = (podut ule) k k k k dy k k d k k k k k k k Y,max k k C Y Y k k k CE: eal eatos and eaton netwoks 8-Jun-6

12 Tutoal CE: Seletvty / yeld fo netwoks.: Yeld and seletvty fo sees eatons Pat b: Maxmum yeld of fo /PFT d d d d dc d Y k k k k exp exp k exp k expk k k k k expk k k k C Y Maxmum yeld. devatve = dy d k exp k k exp k ln k k k Y,max k k k k CE: eal eatos and eaton netwoks 8-Jun-6

13 Tutoal CE: Seletvty / yeld fo netwoks Moe than one eaton: eaton netwok! Sees eaton: C Paallel eaton: C Hgh seletvty to desed podut! Dffeental seletvty: ds ds ds podued podut onsumed eatant k PFT, low onveson,sees k,paallel k k PFT o CST CE: eal eatos and eaton netwoks 8-Jun-6 3