Fundamentals of Thermokinetics

The basis to thermokinetics is formed by a modified consideration about the relative conversion. Thermokinetic conversion is defined as the fitiction of the total energy output of the process which has been released between the start of reaction and the time currently considered. The total energy output results as integral value over all simultaneously progressing chemical reactions within the time interval of process start and the moment of reaching full conversion with respect to the desired reaction Xp. 

This procedure has many advantages, but it is also accompanied by boundary conditions, ch especially have to be observed in those cases where formal kinetic rate laws are used which have been determined with the help of this thermokinetic conversion. 

The main advantage lies in the easy access to all values necessary for the calculation. If the heat production rate due to the chemical process has been measured with the help of a reaction calorimeter, such as those described in the next section, then this power signal is exactly the gross value required for the calculation of the thermal conversion. Without any classical kinetic investigations, which rely on analytical measuring techniques, it is not possible to interpret the measured signal regarding the power fractions set fiee either by the desired reaction or by n side reactions at a certain point 

Another advantage lies in the application of this thermal conversion to determine the accumulation potential. The safety technical significance of the accumulation has already been outlined when discussing the normal operating conditions of a cooled SBR, and it will be of even greater importance in the discussion of maloperation. 

The limitations and boundary conditions of this concept, which were mentioned in the introduction, mainly refer to the question of extrapolation of the results obtained. The application of this concept remains comparatively simple as long as the process to be safety technically assessed belongs to the group of homogeneous liquid phase reactions. In heterogeneous processes, the thermal conversion obtained reflects the flow conditions of the measuring apparatus. Here, special care has to be taken in the experimental design in order to obtain results which, under full observation of all rules of the similarity theory, may be used for plant scale assessment. 

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