Product batch model approach

Evolving from efforts [22] to use the best features of trial-and-error, process model, expert system, and expert model approaches, QPA [23-25] combines KBES traits with online dielectric, pressure, and temperature data to implement autoclave curing control. QPA combines extensive sensor data with KBES rules to determine control actions. These rules determine curing progress based upon process feedback, and implement control action. QPA adjusts production parameters on-line as such—within the limits of its heuristics—QPA can accommodate batch-to-batch prepreg variations. 

Pure simulation approaches are proposed by Pitty et al. (2008) and Adhitya and Srini-vasan (2010). Pitty et al. (2008) propose a discrete-event simulation model for a refinery supply chain. Operational decisions such as unloading schedules and production planning are made based on simple priority rules. Various configurations of the modelled SC are studied and compared to reveal optimization potentials. This approach explicitly considers some details of ship and pipeline transports. Adhitya and Srinivasan (2010) describe a discrete-event simulation model for an SC producing and distributing lubricant additives. Here, batch production is modelled. Again, operational production decisions are made by priority rules and a scenario analysis is conducted to evaluate the effects of other priority... 

Example 5 (Modehng melt-phase PET production in a batch reactor using the functional-group modeling approach) Using the reaction rates in Equations 7.23-7.25, the following dynamic component material balance equations can be derived ... 

The discussion presented in the previous sections assumes that a process model is available. However, optimization of process operation is also possible when process models are not available. In this case, one must rely on available experimental process data and/or empirical modeling approaches. For instance, the process performance can be mapped within the experimental region of interest with the help of experimental design techniques. Experiments are performed in accordance with the proposed experimental design and empirical cubic models (or other types of empirical models) are fitted to the obtained experimental data. Then, the empirical models can be used to provide the searched optima. This type of experimental design-based optimization procedure was performed to optimize the operation of fermentors used for production of bacterial polyesters (177], as it is very difficult to develop a fundamental model for bacterial polymerizations. In this particular case, the medium composition was manipulated to allow for maximization of polymer production and rninirnization of the batch time. 

Functional design - It is the traditional approach and it has its foundation in traditional accounting mentality and the associated batch approach to production. In a functional setup, the work must progress sequentially through each unit. Because the batch model stresses worker and machine utilization while ignoring lead-time, the functional design is a natural response despite not so obvious penalties in terms of lead-time. 

In this chapter, SDA-free, SSC approach for the crystallization of sub-micrometer sized ZSM-5 zeolites including the influence of various synthesis p>arameters on the product properties and the crystallization mechanism will be discussed in detail. The relevant content is divided into five parts (1) Controllable synthesis, (2) Influence of batch alkalinity, (3) Influence of sodium ions and gel ageing, (4) Crystallization mechanism, and (5) Modeling approach. 

Mathews and Rawlings (1998) successfully applied model-based control using solids hold-up and liquid density measurements to control the filtrability of a photochemical product. Togkalidou etal. (2001) report results of a factorial design approach to investigate relative effects of operating conditions on the filtration resistance of slurry produced in a semi-continuous batch crystallizer using various empirical chemometric methods. This method is proposed as an alternative approach to the development of first principle mathematical models of crystallization for application to non-ideal crystals shapes such as needles found in many pharmaceutical crystals. 

One example of a miniaturized LC/MS strategy is the use of 96-well sample plates (Kaye et al., 1996) for extraction. This sample extraction procedure combines batch sample processing within a miniaturized format. Increased sensitivity and decreased volume advances have fostered a new wave of scale-down models. Experiments that were formerly performed at the bench are, instead, performed at the microliter scale in the batch mode. For example, synthetic process research was traditionally performed manually with apparatus at the milliliter level. This approach involves the testing of a range of synthetic conditions for optimum yield and minimum impurity production. Now, process research conditions are tested in microliter levels to produce information on purity and structure (Rourick et al., 1996). This strategy requires fewer reagents and accelerates the evaluation of a wider range of conditions in a shorter time. Another example includes the direct analysis of samples from cell culture experiments (Kerns et al., 1997). 

The principle of integral process development [26] covers much more than just the optimization of a process. This approach begins with computer-aided decision procedures in the conception phase. Tools are available in which the process structure is suggested, for example should the process be a batch or a continuous operation The software tool for process synthesis PROSYN uses databases which include knowledge of experts, material data and calculation models for unit operations. Interfaces to process simulation tools such as ASPENPLUS and material databases are also supplied. PROSYN also delivers an economic evaluation of the future production process. 

In the present study, two mass transfer models were adapted from other applications, and preliminary comparisons were made to conventional reaction-only models to assess their abilities to describe hemicellulose hydrolysis inbatch and flowthrough reactors. Particular attention was paid to including production and diffusion of oligomers in these models with the intent of exploring whether this approach holds promise for explaining the performance of batch and flowthrough systems in a more consistent manner. 

---