Rescheduling algorithms in case of unit failure for batch process management

Adjusting the operating schedule in real time is very important in constructing CIM and improving the safety and productivity of chemical processing systems. Computation for generating an optimal schedule at the scheduling level mostly requires a long time, so it is difficult to respond immediately to actual process disturbances such as unit failures, the absence of operators and reaction time variations. To modify the original schedule in real time, we developed rescheduling algorithms such as DSMM(Dynamic Shift Modification Method), PUOM(Parallel Unit Operation Method) and UVVM(Unit Validity Verification Method). Their main functions are to minimize the effects of unexpected events and to modify the schedule desirably corresponding to process time variations. As a result, the algorithms generate a new pertinent schedule in real-time which is close to the original schedule in order to provide an efficient way of responding to the variation of process environment, minimizing the inventory cost. Examples of shampoo production batch processes illustrate the efficiency of the algorithms.