The Study On Scheduling Of Batch Chemical Processes With Uncertainty Based On Inner-Outer Loop Optimization Strategies Simultaneously

The batch chemical processes scheduling is one of the most essential parts in the process industry, which is the joint of the production management and the industrial control. The study of scheduling received great attention from both the academia and the industry in past decade. The literatures in existence mostly assume that all data in system are certain, but there are lots of uncertainties in the actual production process such as the processing time, the demand of market and the availability of equipment. These uncertainties can often make the original scheduling diverse the predefined function or make it useless. Therefore, it is necessary to study the batch chemical processes scheduling with uncertainty.The scheduling of batch chemical processes with uncertainty is reviewed on the formulation and solution techniques, and the study on scheduling of batch chemical processes with uncertainty is presented in this paper. The primary contents in this thesis are as follows:1 An Inner-Outer Loop Optimization Strategies Simultaneously (IOLOSS) based on Stochastic Optimization Algorithms (SOA) was proposed for the solution of scheduling. The problem of scheduling of batch chemical process was divided into two parts, thesub-problem on processing sequence and sub-problem on processing timetable, according to its character, and the IOLOSS which integrated the advantages of SOA was proposed The outer loop of IOLOSS determines the optimal structure of the scheduling through integer programming by SOA and the inner loop obtains the optimal timetable through real programming respectively, and the optimization simultaneously was achieved by data transmission between them.. The classification of the variables shrinks the solution space and simplifies the problem, so the IOLOSS overcomes the combinatorial characteristic of the problem which exists through common optimization algorithm, and makes the solution of the scheduling more effective. Several examples about scheduling of batch chemical processes were solved by the proposed IOLOSS, and the results were satisfying.2 The formulation and solution of the scheduling of batch chemical processes under certain conditions was studied.The scheduling of batch processes with multiproduct, multipurpose, parallel units out of phase and multifunctional units was studied, and the proper formulation was proposed, and the corresponding method on chromosome encoding, crossover and mutation were developed based on IOLOSS. Several examples were used for the formulation and solution of the scheduling with certainty. Two examples on the scheduling of multiproduct plant with the objective function of the minimization of makespan and the maximization of profit were illustrated with and without the limit of batch size separately. Two examples were illustrated, the scheduling of multipurpose plants and that of parallel units out of phase, with the objective function of minimization of makespan. And one example was illustrated the scheduling of mulfunctional unit with the objective function of maximization of even profit.3 The on-line modification of batch chemical processes scheduling was studied.The on-line modification can deal with two kinds of uncertainties which include order changing and equipment failure (unit failure). Two kinds of uncertainties, order changing and equipment failure were formulated in this thesis. The influence of the time and the scenario of order changing on the objective function of scheduling were analyzed with order changing environment. And the influence of such factors as the disposal of materials, the span of maintenance time and the time the equipment fails on the scheduling was studied in the scheduling with equipment failure environment. Examples showed that the formulation of the on-line modification had a satisfying result for the scheduling of such kind of problem.4 The stochastic scheduling of batch chemical process was studied.The formulation and objective function of the expectation and probability for the stochastic scheduling of batch chemical processes was proposed which combined stochastic programming and certainty scheduling based on statistical probability theory. The problems of stochastic scheduling with random process time under uniform distribution and discrete distribution were studied. The relationship between the makespan limit and probability of the scheduling finished and the relationship between the makespan limit and the number of available scheduling were discussed and analyzed.5 The fuzzy scheduling of batch chemical process was studied.The formulation and objective function of the probability of fuzzy events, fuzzy probability of the clear events, and the fuzzy probability of fuzzy events for the fuzzy scheduling of batch chemical processes was proposed which combined fuzzy programming and certainty scheduling based on probability statistics and fuzzy statistical theory. The problem of fuzzy scheduling with process time under triangle fuzzy number distribution was studied. The relationships of the membership of fuzzy process time, the makespan limit and the fuzzy probability of the scheduling was discussed.6 Cases are studied by the thesis method.The scheduling got by the thesis formulation and solution is better than that based on heuristic method, and the objective function is flexible than the former. The application of the formulation and solution method for the scheduling with order changing showed that the method given has guidance to optimization of the scheduling with uncertainty.