Batches and Recipes

Batches and Recipes Each batch of product is manufactured in accordance with a produc t recipe, which contains all information (formula and processing instructions) required to make a batch of the produc t (see Fig. 8-56). For each batch of product, there will be one and only one product recipe. However, a given product recipe is nor-... 

One of the main functions of this control activity is to select a master recipe from the recipe management control activity, edit that recipe and transform it into a control recipe suitable for downloading to the equipment-related control activity, downloading the recipe (i.e., initiating the batch), and then to supervise the execution of the recipe. 

The rate of polymerization with styrene-type monomers is directly proportional to the number of particles formed. In batch reactors most of the particles are nucleated early in the reaction and the number formed depends on the emulsifier available to stabilize these small particles. In a CSTR operating at steady-state the rate of nucleation of new particles depends on the concentration of free emulsifier, i.e. the emulsifier not adsorbed on other surfaces. Since the average particle size in a CSTR is larger than the average size at the end of the batch nucleation period, fewer particles are formed in a CSTR than if the same recipe were used in a batch reactor. Since rate is proportional to the number of particles for styrene-type monomers, the rate per unit volume in a CSTR will be less than the interval-two rate in a batch reactor. In fact, the maximum CSTR rate will be about 60 to 70 percent the batch rate for such monomers. Monomers for which the rate is not as strongly dependent on the number of particles will display less of a difference between batch and continuous reactors. Also, continuous reactors with a particle seed in the feed may be capable of higher rates. 

The scheduling module maintains a master list of all batches and control-recipes and sorts the basic operations of the chronologically next control-recipe by their position in the recipe. In the case of identical starting times a priority which can be specified on the batch level determines the sorting. During the sorting procedure parallel steps in the recipe with all associated basic operations are regarded as one unit. 

The batch charged recipes required more total surfactant, and a greater fraction of that surfactant as nonionic, than the monomer fed recipes employed to obtain the same particle size. 

Sequence control of process operations, and recipe/batch management and tracking. Alarm and device interlocking (often in addition to separate hard-wired systems). Event and alarm recording, and historical trend recording of process variables. 

Trends in the crystallization process development in the pharmaceutical industry is to carry out measurements at a small scale in addition to utilizing automation and high throughput systems as exemplified by the use of automated metastable zone measurement for 1 mL samples. It is expected that the future batch crystallization recipes will be designed based on the data collected from much smaller scale crystallizers than what is currently used in industry. 

The increased flexibility of a pipeless plant comes at the expense of a higher degree of complexity. Knowing the product demand, the number and size of the batches, the recipes and the plant layout, our objective is to find a schedule with minimum makespan that is feasible with respect to a set of constraints. 

Figure 4.15 Experimental and simulated boron dopant profiles, for two batch operating recipes [165].

During polymerization with a CSTR, the monomer and the other components of the polymerization recipe are fed continuously into the reactor while the polymerization product mixture is continually withdrawn from the reactor. The application of the CSTR in suitable polymerization processes reduces, to some extent, the heat removal problems encountered in batch and tubular reactors due to the cooling effect from the addition of cold feed and the removal of the heat of reaction with the effluent. Even though the supporting equipment requirements may be relatively substantial, continuous stirred tank reactors are economically attractive for industrial production and consistent product quality. 

Usually, for the production of small quantities of high-priced chemicals, such as in th manufacture of pharmaceuticals, foods, electronic materials, and specialty chemicals, batch fed-batch, and batch-product removal processes are preferred. This is often the case in bio processing, for example, when drugs are synthesized in a series of chemical reactions, eacl having small yields, and requiring difficult separations to recover small amounts of product This is also the case for banquet facilities in hotels, which prepare foods in batches, and fo many unit operations in the manufacture of semiconductors. As discussed in Chapters 3 am 4, these processes usually involve a recipe, that is, a sequence of tasks, to be carried out h various items of equipment. In the latter sections of this chapter, variations on batch proces schedules are discussed, as well as methods for optimizing the schedules. 

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