cre lecture 13

8/16/2019 CRE Lecture 13

1/15

2016-04-27

1

Lecture 13: Isothermal Reactor Design

Membrane Reactors

2

Membrane reactors are mainly used to:

1. increase conversion when the reaction is thermodynamically

limited.

2. increase the selectivitywhen multiple reactions are occurring.


2/15

2016-04-27

2

3

Mole Balances

4

RB is the product of the molar flux of B, wB(mol/m2.s) and a, the surface area, per unit

volume of reactor.


3/15

2016-04-27

3

5

WB out of the reactor is a mass transfer coefficient times theconcentrati on driv ing force across the membrane.

6


4/15

2016-04-27

4

Solution

7

8


5/15

2016-04-27

5

9

10


6/15

2016-04-27

6

Unsteady State Operation of CSTRs

11

Start up of CSTRs, the time to reach steady state

operation

Semibatch reactor

Prediction of concentration and conversion as a

function of time.

Analytical solution can only be obtained for zero

and first order reactions.

12

Semi-batch Reactors


7/15

2016-04-27

7

Start up a CSTR

13

Start up a CSTR

14


8/15

2016-04-27

8

Semi-batch Reactors

15

We can increase the formation of D and decrease the

formation of U by keeping the concentration of A high and the

concentration of B low. This result can be achieved throughthe use of the semi-batch reactor, which is charged with Pure

A and to which B is fed slowly to A.

16


9/15

2016-04-27

9

Concentration

17

18


10/15

2016-04-27

10

Conversion

19

20


11/15

2016-04-27

11

21

Example: Gas-Phase Reaction in a

Microreactor

22


12/15

2016-04-27

12

23

Solution

24


13/15

2016-04-27

13

25

26


14/15

2016-04-27

14

Example

27

Solution

28


15/15

cre lecture 13

Documents