Process systems with material integration

According to the developments in Section 2.3, the model of Equation (3.10) is in a nonstandard singularly perturbed form. We thus expect its dynamics (and, consequently, the dynamics of integrated process systems with large material recycle) to feature two distinct time scales. However, the analysis of the system dynamics is complicated by the presence of the term u1, which, as we will see below, precludes the direct application of the methods presented in Chapter 2 for deriving representations of the slow and fast components of the system dynamics. 

Dr. Richard Walentowicz provided the EPA CD-ROM disk entitled Exposure Models Library and Integrated Model Evaluation System" with other reference material. Lester Wittenberg of the Center for Chemical Process Safety, AIChE was particularly helpful in providing a chenncal industry perspective and reference material as was Dr. Steven Arendt of JBF Associates, Inc. Drs. David Hesse of Battelle Columbus Laboratories and Vinod Mubayi of Brookhaven National Laboratory were very helpful in providing material on the chemical consequence codes. 

To study different operating conditions in the pilot plant, a steady-state process simulator was used. Process simulators solve material- and energy-balance, but they do not generally integrate the equations of motion. The commercially-available program, Aspen Plus Tm, was used in this example. Other steady-state process simulators could be used as well. To describe the C02-solvent system, the predictive PSRK model [11,12], which was found suitable to treat this mixture, was applied. To obtain more reliable information, a model with parameters regressed from experimental data is required. 

Microreactor technology has developed to such an extent that a wide variety of microreactor components, e.g. micropumps, mixers, reaction chambers, heat exchangers, separators and complete integrated microreaction systems with process control units have been fabricated using the appropriate microfabrication process and materials that are suitable for specific applications. 

Design of products, processes, and systems must include integration and interconnectivity with available energy and materials flows. 

The previous chapters have concentrated on analyzing the material-balance dynamics of several classes of integrated process systems. We demonstrated that the dynamic behavior of the systems considered exhibits several time scales and described a method for the derivation of reduced-order models describing the dynamics in each time scale. Also, a hierarchical controller design framework was introduced, with distributed control of the fast dynamics and supervisory control of the dynamics at the systems level. 

As demonstrated in Chapters 3-5, the variables of the material balance of an integrated process system can themselves exhibit a dynamic behavior with up to three time scales. As such, it is intuitive that, when considering both the energy-balance and the material-balance equations, the dynamics of integrated process systems can span several (i.e., more than three) time scales. For clarity this aspect was not directly accounted for in the theoretical analysis presented above. We utilize the following examples to illustrate the concepts developed so far, as well as to confirm this observation. 

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