One of the first things that ChE's need to know about processes is the many different ways in which we may operate a process.
There are three major classification of processes:
In a batch process, material is placed in the vessel at the start and (only) removed at the end --no material is exchanged with the surroundings during the process.
Batch Examples: baking cookies, fermentations, small-scale chemicals (pharmaceuticals)
In a continuous process, material flows into and out of the process during the entire duration.
Continuous Examples: pool filter, distillation processes
A semi-batch process is one that does not neatly fit into either of the other categories (i.e., it is a catch-all classification).
Semi-Batch Examples: washing machine, fermentation with purge.
Each of the above classes of process may be further distinguished by their mode of operation with respect to time.
Continuous processes may be run:
At steady-state, none of the process variables change with time (if we ignore small, random fluctuations).
or it may be run
At unsteady-state, the process variables change with time. (One class of unsteady-state processes are oscillatory, where they process variables change with time in a regular way. All other unsteady processes may be called Transient meaning that the process variables continuously evolve over time).
Give original examples of (and identify) batch, semi-batch, continuous, steady, and transient processes
Under what modes of operation may batch or semi-batch process be run?