Continuous Stirred Tank Reactors
Continuous Stirred Tank Reactors (CSTRs)



Type of Reactor

Characteristics

Continuously Stirred Tank Reactor (CSTR)

Run at steady state with continuous flow of reactants and products; the feed assumes a uniform composition throughout the reactor, exit stream has the same composition as in the tank



Kinds of Phases Present

Usage

Advantages

Disadvantages

1. Liquid phase

2. Gas-liquid rxns

3. Solid-liquid rxns

1. When agitation is required

2. Series configurations for different concentration streams

1. Continuous operation

2. Good temperature control

3. Easily adapts to two phase runs

4. Good control

5. Simplicity of construction

6 Low operating (labor) cost

7. Easy to clean

1. Lowest conversion per unit volume

2. By-passing and channeling possible with poor agitation

General Mole Balance Equation

Assumptions

1) Steady state therefore

2) Well mixed therefore rA is the same throughout the reactor

Rearranging the generation

In terms of conversion

Reactor Sizing

Given rA as a function of conversion, rA = f(X), one can size any type of reactor. The volume of a CSTR can be represented as the shaded areas in the Levenspiel Plot shown below:

Reactors in Series

Given rA as a function of conversion, , rA = f(X), one can also design any sequence of reactors in series provided there are no side streams by defining the overall conversion at any point.

Mole Balance on Reactor 1

Mole Balance on Reactor 2

Given rA = f(X) the Levenspiel Plot can be used to find the reactor volume

For a PFR between two CSTRs



Here are some links to example problems. You could also use these problems as self tests.

CSTR Type 1 Home Problem

CSTR Type 2 Home Problem

CSTR Type 3 Home Problem




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