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7.38: Untitled Page 183

  • Page ID
    18316
  • Chapter 7

    Figure 7‐2. The decomposition of CH Cl F produces C F and HCl in addition 2

    2 4

    to the undesirable homologous polymer, H CF

    Cl . The conversion of gaseous

    2 3

    monocholorodifluoromethane ( CH Cl F ) is given by

    2

     RCHClF

    C  Conversion of CHClF  

    2

     0 98

    .

    2

    ( M

    )

    CH Cl F2 feed

    and the yield for Teflon takes the form

    RC F

    Y  Yield of C F / CHClF

    0 4

    . 75

    2 

    2 4

    2 4

     RCHClF2

    For the first part of this problem, find a relation between the molar flow rate of the exit stream and the molar flow rate of the entrance stream in terms of the number of monomer units in the polymer pecie

    s

    s. For the second part, assume

    that  CH Cl F  H CF

     

    and assume that the input flow

    2

    Cl

    2 3

     where

    10

    rate is M

      100 mol / s in order to determine the mole fractions of the four 1

    omponents

    c

    in the product stream leaving the

    reactor.

    7‐11. In Example 7.1 numerical values for the conversion, selectivity and yield were given, in addition to the conditions for the inlet stream, i.e., M

      100 mol/s

    and x

     1 . 0 . Indicate what other

    quantities

    had to be

    ured

    meas

    in order to

    C2H6

    etermine

    d

    the conversion, selectivity and yield.

    7‐12. In Example .1

    7 the net rates of

    uc

    prod

    tion for methane and hydrogen were

    determined to be R

     1.0 mol/s a d

    n

     19 . 0

    .

    CH

    R

    mol/s

    Determine the rates

    H

    4

    2

    f

    o production represented by R

    , R

    , and R

    .

    C H

    C H

    C

    2

    6

    2

    4

    3 H6

    Section 7.2

    7‐13. Show how to obtain the row reduced

    echelon form of  N  given in

    JA

    q.

    E 7‐18 from the form given in Eq. 7‐16.

    7‐14. A stream of pure methane, ( CH ) , is partially burned with air in a furnace 4

    at a rate of 100 moles of methane per minute. The air is dry, the methane is in

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    Material Balances for Complex Systems

    343

    excess, and the nitrogen is inert in this particular process. The products of the reaction are illustrated in Figure 7.14. The exit gas contains a 1:1 ratio of Figure 7.14. Combustion of methane

    H O : H and a 10:1 ratio of CO : CO . Assuming that all of the oxygen and 2

    2

    2

    4%

    9

    of the methane are consumed by the reactions, determine the flow rate and composition of the exit gas stream.

    7‐15. Consider the special case in which two molecular species represented by C H O and C H O provide the fuel for complete combustion as illustrated in m

    n

    p

    q

    r

    s

    Figure 7.15. Assume that the molar flow rates of the two molecular species in the fuel are given in order to develop an expression for the theoretical air.

    Figure 7.15. Combustion of two molecular species

    7‐16. A flue gas (Stream #1) composed of carbon monoxide, carbon dioxide, and nitrogen can undergo reaction with “water gas” (Stream #2) and steam to produce the synthesis gas (Stream #3) for an ammonia converter. The carbon

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    index-353_2.png

    index-353_3.png

    344