Chapter 7 Part 1

<span class='text_page_counter'>(1)</span>Undergraduate  Lectures  on  .  . Material  Balances  for  Chemical  Engineers   April  8-­‐  23,  2013. Chapter  7:  Lecture  1:   Material Balances for Complex Systems!. Brian  G.  Higgins   Department  of  Chemical  Engineering  and    Materials  Science   University  of  California,  Davis  .

<span class='text_page_counter'>(2)</span> MulJple  ReacJons   Conversion,  SelecJvity  and  Yield  . reactions in series. Conversion:. Selectivity:. Yield:. reactions in parallel.

<span class='text_page_counter'>(3)</span> Conversion  . Example:  .

<span class='text_page_counter'>(4)</span> SelecJvity   cumene  . P-­‐dissopropyl  benzene  . benzene  . Example:  .

<span class='text_page_counter'>(5)</span> Yield   cumene  . P-­‐dissopropyl  benzene  . benzene  . Example:  .

<span class='text_page_counter'>(6)</span> Example  CalculaJon:   (CatalyJc  producJon  of  Ethylene)  . S = Selectivity of (C2 H4 /C3 H6 ) =. R C2 H 4 =5 R C3 H 6. R C2 H 4 Y = Yield of (C2 H4 /C2 H6 ) = = 0.75 R C2 H 6. Inlet  Feed:  . (ṀC2 H6 )1 = 100 mol/s.

<span class='text_page_counter'>(7)</span> Example  CalculaJon:   (CatalyJc  producJon  of  Ethylene)  . ConservaJon  of  Atoms:  . Axiom  II:  .

<span class='text_page_counter'>(8)</span> Example  CalculaJon:   Degree  of  Freedom  Analysis  .

<span class='text_page_counter'>(9)</span> Axiom  II:  . Example  CalculaJon:   Analysis  .

<span class='text_page_counter'>(10)</span> Axiom  II:  . Example  CalculaJon:   Analysis  .

<span class='text_page_counter'>(11)</span> Example  CalculaJon:   Analysis  . Given  Data:  . C = 0.2, S = 5, Y = 0.75 (ṀC2 H6 )1 = 100 mol/s.

<span class='text_page_counter'>(12)</span> CombusJon  ReacJon  . Typical  Fuel:  . C m Hn O p.

<span class='text_page_counter'>(13)</span> Total  CombusJon   Conversion  of  all  fuel  to:   ConservaJon  of  Atomic  Species:  . CO2 , H2 O.

<span class='text_page_counter'>(14)</span> Total  CombusJon   Row  Reduced  Echelon  Form  for  Atomic  Matrix  .

<span class='text_page_counter'>(15)</span> Total  CombusJon   Global  rates  of  producJon  in  terms  of  net  rate  of  producJon  of  water:    . Species  Balances  for  fuel  and  water:  .

<span class='text_page_counter'>(16)</span> Total  CombusJon   Species  balance  for  complete  combusJon:  . TheoreJcal  Air  for  Complete  CombusJon  . If  fuel  has  N  molecular  species  for  the  form   Cm Hn Op.

<span class='text_page_counter'>(17)</span> Example  CalculaJon:  .

<span class='text_page_counter'>(18)</span> Example  CalculaJon  Cont.  . Since  the  mole  fracJon  of  O2  in  air  is  0.21,  the  theoreJcal  air  is  .

<span class='text_page_counter'>(19)</span> Example  CalculaJon  2:  .

<span class='text_page_counter'>(20)</span> Example  CalculaJon  2  Cont.  . TheoreJcal  Oxygen  required:  . Species  molar  flow  rates  in  Stream  1  .

<span class='text_page_counter'>(21)</span> Example  CalculaJon  2  Cont.   TheoreJcal  Air  in  terms  of  molar  flow  rate  of  stream  1:  . Since  stream  1  contains  oxygen,  10%  excess  air  gives    . Solving  for  oxygen  in  stream  2  gives:  . Thus  molar  flow  rate  of  oxygen  in  stream  2  can  be  expressed  as  .

<span class='text_page_counter'>(22)</span>