Safe Normal Operation of the Cooled Semibatch Reactor

4 Safe Normal Operation of the Cooled Semibatch Reactor 

In the case of isothermal operation one component with or without solvent is charged initially. The reactor contents are then heated up to the desired temperature. At this point the feed of the second reactant, separately premixed and preheated, is started with a constant rate. The jacket temperature is adjusted in proportion to the heat production rate with the help of controls. The maximum driving temperature difference occurs within the first half of the feed time. 

In the case of isoperibolic operation, again, one reactant is charged and if occasion arises premixed with solvent initially. The mixture is this time heated up to the set value of the cooling jacket Having reached this value the jacket temperature is subsequently kept constant and the addition of the second, separately premixed and preheated component is started. The feed rate, as in the other mode, is kqit constant. 

The internal temperature will rise in this case due to the self accelerating exothermic reaction. This rise will prevail until the heat removal power exceeds the thermal power of the reaction. In this case, too, the maximum driving temperature difference occurs within the first half of the feed time. The isoperibolic mode shall be treated first. 

The reason for this differing reactor behaviour becomes understandable if the relative concentration profiles of the added component, which are also shown in this figure, are discussed. Cases a and b are characterized by the fact that hardly any accumulation of this component occurs during the first half of the feed phase. In simple terms this means that each amount added to the reactor is converted spontaneously. Only towards the end of the feed time the added component accumulates slightly, reaching its maximum relative concentration at the stoichiometric point. 

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