Also note the [[Baffle (in vessel)|baffle]] at the bottom of the image which also helps in mixing.]]
In a CSTR, one or more fluid reagents are introduced into a tank reactor (typically) equipped with an [[impeller]] while the reactor effluent is removed. The impeller stirs the reagents to ensure proper [[Mixing (process engineering)|mixing]]. Simply dividing the volume of the tank by the average [[volumetric flow rate]] through the tank gives the ''residence time'', or the average amount of time a discrete quantity of reagent spends inside the tank. Using [[chemical kinetics]], the reaction's expected [[percent]] completion can be calculated. Some important aspects of the CSTR:
* At steady-state, the mass flow
I edited this. its fake @dejeludire in must equal the mass flow rate out, otherwise the tank will overflow or go empty (transient state). While the reactor is in a transient state the model equation must be derived from the differential mass and energy balances.
* The reaction proceeds at the reaction rate associated with the final (output) concentration, since the concentration is assumed to be homogenous throughout the reactor.
* Often, it is economically beneficial to operate several CSTRs in series. This allows, for example, the first CSTR to operate at a higher reagent concentration and therefore a higher reaction rate. In these cases, the sizes of the reactors may be varied in order to minimize the total [[capital investment]] required to implement the process.