Page 115 - Analysis, Synthesis and Design of Chemical Processes, Third Edition

3.3 Nonoverlapping Operations, Overlapping Operations, and Cycle Times

In general, product is produced throughout an extended period of time by using a repeating sequence of
operations. For example, the batch process described in Example 3.1 produces a certain amount of
crystallized API, namely 634.5 kg. If it is desired to produce 5000 kg, then the sequence of steps must be
repeated 5000/634.5 ≅ 8 times. There are several ways to repeat the sequence of tasks needed to make

one batch, in order to make the desired total amount of product (5000 kg). An example of one such
nonoverlapping scheme is shown in Figure 3.1.

Figure 3.1 Example of a Nonoverlapping Sequence of Batch Operations

For the nonoverlapping (designated by the subscript NO) scheme, the total processing time is the number
of batches multiplied by the time to process a single batch.