Question

Solve for CA, CB, and CC versus τ for the reactions A→B, r1 =k1 A→C, r2 =k2CA in a PFTR and in a CSTR for k1 =2 moles liter1 min1 and k2 =1 min1.

Find τ and SB at 90% conversion in a PFTR and in a CSTR for CAo =4 in the reactions of the previous problem. Which reactor type is better?

Answer 1

Given reactions

...........................................................................................(1)

.......................................................................................(2)

For reaction 1

i) PFR

...................................................................(1)

..................................................(2)

Equation 1 and 2 shows the concentration of A and B verses

ii) CSTR

......................................................(3)

..................................................................................(4)

Equation 3 and 4 shows the concentration of A and B verses

For reaction 2,

i) PFR

.................................................(5)

.................................................(6)

............................(7)

From eq 6,we have equation 7 as

.................................................................................(8)

Equation 6 and 8 shows variation of A and C with

ii) CSTR

..............................................................(9)

......................................................................(10)

.............................................................(11)

Using equation 10 and puting it in eq 11,we get

.................................................(12)

Equation 10 and 12 shows the variation of A and C with

B.)

For reaction 1

i) PFR

Using equation 1

From equation 2,we have

ii) CSTR

Using equation 3, we get

From equation 4,we have

Both the reactors are equal for first reaction

For reaction 2

i) PFR

Using equation 5,we get

ii) CSTR

Using equation 9, we get

PFR is better for second reaction as tau is small for PFR