Temperature Control Strategies

A polytropic reaction means the reactor is neither designed to work under isothermal conditions, nor under adiabatic conditions. The reactor control strategy comprises different periods of time, where different modes of temperature control are applied. These different temperature control strategies may include heating to... 

What other temperature control strategy could you propose ... 

In semi-batch operation, many elements determine the process safety. Among them we mention the temperature control strategy, the feed control strategy, and also the choice of reactant(s) to be initially charged and the reactant(s) to be fed. 

Concerning the temperature control strategy, semi-batch reactions are often at constant temperatures (isothermal). Another simple temperature control strategy is the isoperibolic mode, where only the jacket temperature is controlled. In rare cases, other temperature control strategies, such as adiabatic or non-isothermal, are used. 

This type of temperature control strategy may be very critical for highly exothermal reactions. In such cases, the choice of the operating conditions, that is, initial... 

Pareilleux and Chaubet (155,156) studied batch suspension cultures of apple cells and Medicago saliva cells, reporting comparable high yield and low maintenance coefficients. Bailey and Nicholson (157) employed in principle the same model structure. However, in order to describe also the changing fresh weight/dry weight ratio, product formation, and cell death and lysis, they extended the model. Two extra variables were added to allow the prediction of the extension phase and a more accurate prediction of the culture death phase caused by shear stress. Another two variables were introduced to describe product formation. In a later paper (158) the authors extended the model further to describe the influence of temperature. With this model an optimal temperature control strategy was predicted. 

The heterogeneous azeotropic column system using isobutyl acetate as the entrainer will be studied in detail in this section. The overall control strategy of this system will be developed in order to maintain bottom and top product specifications in spite of feed flowrate and feed composition changes. In the control strategy development, we will assume no online composition measurement is available. The composition control loops will be inferred by some tray temperature control strategy. This type of control strategy can easily be implemented in industry for wider applications. 

In most cases non-isothermal processes are used. A part of the energy of the reaction is used to heat the reactor to the desired process temperature in the so-called polytropic reaction mode. A typical temperature control strategy is to use an adiabatic phase, during which there is no cooling, so that the correct initiation of the reaction can be checked. Then, in a second stage, after reaching a specified temperature, the cooling system is switched. The correct choice of the initial temperature... 

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