Reactor Design

In a process it is desired to design a packed bed reactor to produce a certain amount

of ethylene from bioethanol per year. The following multiple reaction system

consisting of parallel and series reactions occurs during the process:

Main Reaction

$C_2{H}_{5}OH{C}_2{H}_4+H_{2}O$

$(1)r_1^{\text{'}}{?}_1{C}_2{H}_{5}OH=k_1{P}_{C_2{H}_{5}OH}$

Side Reactions

$2C_2{H}_{5}OH(C_2{H}_5{)}_{2}O+H_{2}O$

$(C_2{H}_5{)}_{2}O2C_2{H}_4+H_{2}O$

$2C_2{H}_4{C}_4{H}_8$

$r_{2C_2{H}_{5}OH}^{\text{'}}=k_2{P}_{C_2{H}_{5}OH}^2$

$r_{3(C_2{H}_5{)}_{2}O}^{\text{'}}=k_3{P}_{(C_2{H}_5{)}_{2}O}$

$r_{4C_2{H}_4}^{\text{'}}=k_4{P}_{C_2{H}_4}^2$

The reactor can be modeled by a single plug$-$flow packed bed and operated

nonadiabatically and nonisothermally. Also, there is substantial pressure drop

through the reactor, which cannot be disregarded.

a$)$ Write the equations necessary to model and analyze the packed bed reactor to

produce a certain amount of ethylene from bioethanol.

b$)$ Compare

i$.$ the total pressure

ii$.$ reaction rate of bioethanol

iii. conversion of bioethanol

iv$.$ concentration of ethylene

profiles through the reactor length for the cases of pressure drop and no pressure

drop by just sketching without making any calculation. What generalizations can

you make?

c$)$ Criticize the effect of one of the design parameters $($tube type, tube diameter,

number of tubes, catalyst, diameter etc.$)$ on process performance by considering

realistic constraints $($economic$,$ environmental, ethical issues etc.$).$