Page 122 - Analysis, Synthesis and Design of Chemical Processes, Third Edition

Example 3.5

Consider the jobshop plant following the sequence shown in Figure 3.5(b) and described in Table E3.5.
Construct the Gantt charts for overlapping single-product campaigns for products A, B, and C and for the
multiproduct campaign with sequence ABCABCABC....

Table E3.5 Equipment Processing Times (in Hours) for Processes A, B, and C

Solution

The Gantt charts for the three processes are shown in Figure E3.5. The top chart shows the timing
sequences for each batch, and the next three charts show overlapping campaigns for products A, B, and C,
respectively. It can be seen that the rules and equations for overlapping campaigns given previously still
apply. The bottom chart shows the overlapping multiproduct campaign using the sequence
ABCABCABC.... Note that there are many time gaps separating the use of the different pieces of
equipment, and no one piece of equipment is used all the time. This situation is common in jobshop plants,
and strategies to increase equipment usage become increasingly important and complicated as the number
of products increases.

Figure E3.5 Gantt Charts for Single-Product and Multiproduct Campaigns