Case Study Temperature Control

In this section, the proposed approach has been tested in a simulation case study, developed in the MATLAB/SIMULINK environment. In detail, the problem of temperature control of the phenol-formaldehyde reactive system, developed in Sect. 2.4, has been considered. 

In order to analyze the effects of different estimates of aq on the control scheme, the cascade controller (5.45)-(5.47) is used in conjunction with the three different observers presented in Sect. 5.6. Finally, the results are compared with those obtained by using the most widely used industrial controller, i.e., the PID controller. Therefore, five different control schemes have been compared  

In order to perform a fair comparison between the above-mentioned control strategies, all the schemes have been tuned so as to achieve the same control effort (i.e., so as to obtain the same time histories of u, as far as possible). 

A realistic temperature profile TT s(t) = yi,des(0, reported in Fig. 5.3, has been chosen as desired reactor temperature it is characterized by three phases  

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Case study example 4.6.2 (Temperature Control) %Use of feedback... 

The roles of nucleophilic assistance and stereoelectronic control in determining endo-versus exo-cyclic cleavage of pyranoside acetals have been investigated for a series of a- and j8-anomers.15 Exocyclic cleavage of a-anomers, via a cyclic oxocarbenium ion, is predicted by the theory of stereoelectronic control, and was found exclusively for the cases studied. The endocyclic route, with an acyclic ion, is predicted for the /1-structures, and a measurable amount was found in all cases, but its extent was dependent on temperature, solvent, and the nature of the aglycone group. 

The study and control of a chemical process may be accomplished by measuring the concentrations of the reactants and the properties of the end-products. Another way is to measure certain quantities that characterize the conversion process, such as the quantity of heat output in a reaction vessel, the mass of a reactant sample, etc. Taking into consideration the special features of the chemical molding process (transition from liquid to solid and sometimes to an insoluble state), the calorimetric method has obvious advantages both for controlling the process variables and for obtaining quantitative data. Calorimetric measurements give a direct correlation between the transformation rates and heat release. This allows to monitor the reaction rate by observation of the heat release rate. For these purposes, both isothermal and non-isothermal calorimetry may be used. In the first case, the heat output is effectively removed, and isothermal conditions are maintained for the reaction. This method is especially successful when applied to a sample in the form of a thin film of the reactant. The temperature increase under these conditions does not exceed IK, and treatment of the experimental results obtained is simple the experimental data are compared with solutions of the differential kinetic equation. 

These two designs use a condenser cooling water temperature Tcc of 317 K. If this is changed to 322 K, the condenser areas increase to 31.0 and 19.3 m2, respectively, in the two cases. The dynamic controllability of these alternative designs will be studied in Chapter 3. 

To quantify this effect, jacket thickness hj is changed from 0.1 down to 0.025 m. The 350 K reactor temperature with 85% conversion is the case studied. Figure 3.21 shows the effect on the Nyquist plot. The improvement in controllability is indicated by the curves dropping more into the third quadrant as hj is decreased. The ultimate gain increases from 8.51 to 17.1 to 24.8. The ultimate period decreases from 2711 to 1846 to 1429 s. These indicate improved closedloop performance. Figure 3.22 shows this to be true. The Tyreus-Luyben settings are used in the three cases. 

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