Batch process units

Figure 5.3-17. Flow-sheet of a batch process unit symbols E = heat exchanger, P = pump, R = reactor, T = storage tank, V = vessel controllers FC = flow controller, LC = level controller 0 stream number.

Economic analysis of costs based on pilot-scale demonstration results gave an estimated cost of 98 to 206 per ton of waste treated. 85 to 90% of these costs are for raw materials (cement and Chloranan) and labor. The lowest value ( 98 per ton) is based upon the vendor s expectation of reducing chemical consumption by 33%, attaining an on-stream factor of 90%, and using a new 2300-lb/min batch processing unit. These costs do not include profits of the... 

Flow sheets for preparing the components of various monomer and oligomer reactant mixtures do not differ significantly from each other, although they may have different sets of reactors. The choice depends mainly on the physical and chemical properties of the initial components. Fig. 4.2 shows a flow sheet for obtaining continuously molded polyurethane elastomers. Fig. 4.3 illustrates an elementary flow sheet for a batch process unit for manufacturing moldings of epoxy resin or epoxy-based composites filled with quartz sand. 

Let us consider a batch processing unit that can produce either 1000 kg of product Aina cycle time of 5 h or 900 kg of product B in a cycle time of 3 h. Thus, for this processing unit a standard hour is 200 kg of product A or 300 kg of product B. In a budget period of, say, 1000 h, it is possible to produce 200,000 kg of product A, or 300,000 kg of product B, or any appropriate combination of the two products. 

Tendency Model-based Improvement of the Slave Loop in Cascade Temperature Control of Batch Process Units... 

The dynamic behaviour of batch process units changes with time and this makes their precision control difficult. The aim of this paper is to highlight that the slave process of batch process units can have a more complex dynamics than the master loop has, and very often this could be the reason for the non-satisfying control performance. Since the slave process is determined by the mechanical construction of the unit, the above mentioned problem can be effectively handled by a model-based controller designed using an appropriate nonlinear tendency model. The paper presents the structure of the tendency model of typical slave processes and presents a case study where real-time control results show that the proposed methodology gives superior control performance over the widely applied cascade PID control scheme. 

In the pharmaceutical and food industry high-value-added products are manufactured mainly in batch process units. The heart of units is generally a jacketed stirred tank in which not only chemical transformation, but distillation, crystallisation, etc. can also be performed. As the aim of pharmaceutical industry is to produce high quality and purity products, the optimisation and control of operating conditions is the most efficient approach to produce efficiently, as well as to reach specific final conditions of the product in terms of quality and quantity (Cezerac, 1995). The S88.01 batch control standard defines three types of control needed for batch processing (ECES, 1997) ... 

The reason for the non-satisfying control performance of batch process units very often is the slave process that can have a more complex dynamics than the master loop has. As the slave process is determined by the mechanical construction, it is straightforward to design a model-based controller based on a nonlinear tendency model of the slave process. It has been shown that the parameters of the model-based slave controller (namely the parameters of the tendency model) can be easily determined by simple process experiments, and the complexity of the controller is comparable to that of a well furnished PID controller. Real-time control results showed that the proposed controller effectively handles the constraints (no windup) and gives superior control performance. 

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