Mathematical  modeling  of  a  two-­‐phase  bubble-­‐column  reactor  for   biodiesel  production  from  alternative  feedstocks
Minhazuddin  Mohammed
Advisor:  Dr.  Richard  Cairncross
Abstract:
This  thesis  project  explores  the  fundamental  mechanisms  that  control  biodiesel   production  performance  in  a  gas-­‐liquid  bubble  column  reactor.  A  mathematical   model  of  a  biodiesel  bubble-­‐column  reactor  was  developed  that  accounts  for  the   fundamental  mechanisms  of  mass  transport,  chemical  reaction  kinetics  and   chemical  reaction  equilibrium.  This  model  was  compared  to  experimental  data  from   a  semi-­‐batch  reactor  to  validate  the  model  and  determine  some  of  the  model   parameters.  The  model  contains  several  important  parameters  that  including  a   characteristic  absorption  time  scale  and  a  characteristic  reaction  time  scale,  the   ratio  of  which  is  a  Damköhler  number.  The  Damköhler  number  indicates  whether   the  reactor  is  operating  in  a  mass-­‐transfer  limited  or  reaction  kinetics  limited   regime.  It  was  found  from  model  predictions  that  the  reactor  is  operated  under   kinetics  limited  regime  (low  Da  ≈  0.03).  Because  the  model  predicts  the  equilibrium   limitations  of  the  reaction,  the  model  also  reproduced  trends  of  decreasing   conversion  and  increasing  conversion  times  when  water  is  present  in  the  methanol   vapor  feed.  A  steady  state  formulation  of  the  transient  model  was  derived  to   approximate  the  behavior  of  a  cross-­‐flow,  continuous  bubble-­‐column  reactor.
Multistage  modeling  results  showed  that  semi-­‐batch  reactor  performance  could  be   approximated  when  more  than  six  reactor  stages  are  connected  in  series.