The implementation of process intensification by multiscale equipment will have a profound impact on the way chemicals are produced. The shift to higher spacetime yields, higher temperatures, and a confined reaction volume comprises new risks, such as runaway reactions, decomposition, and incomplete conversion of reactants. Simplified spreadsheet calculations enable an estimation of the expected temperature profiles, conversion rates, and consequences of potential malfunction based on the reaction kinetics. The analysis illustrates that the range of optimal reaction conditions is almost congruent with the danger of an uncontrolled reaction. The risk of a spontaneous reaction with hot spots can be presumed if strong exothermic reactions are carried out in micro-designed reactors. At worst, decomposition follows the runaway reaction with the release of noncondensable gases. Calculations prove that a microreactor is not at risk in terms of overpressure as long as at least one end of the reactor is not blocked.

The implementation of process intensification by multiscale equipment will have a profound impact on the way chemicals are produced. The shift to higher space‐time yields for partial oxidation processes using micro‐designed reactors comprises the risk of having a permanent explosive atmosphere in the reaction section. In Part I, it was concluded that spontaneous reaction with hot spots can be presumed if highly exothermic reactions were performed and may cause ignition of an explosive atmosphere. The risk analysis of the situation, based on public information in the literature, leads to the conclusion that microreactors are inherently safe regarding the initiation and propagation of an explosion inside a microchannel by an uncontrolled reaction. The situation is the opposite when a propagating explosion enters the same micro‐designed reactor from one of the outside openings. The external explosion may enter the micro‐designed equipment and destroy it when the same starting conditions are present.

The new technology of process intensification by multiscale equipment can significantly contribute to achieve a safer design by going from batch/semi-batch to continuous operation combined with a reduction of inventory of hazardous substances in critical stages. On the other hand, the shift to higher space-time-yields comprises new risks such as runaway reactions with hot spot formation, described in Part I, and handling an explosive atmosphere in the presence of potential permanent ignition sources, described in Part II. A tool was developed for preliminary risk assessments, called HAZOP-LIKE study, to cover the characteristic features of micro-designed equipment that are relatively unimportant when handling conventional equipment. Two generic cases concerning liquid/liquid and gas/gas reactions were studied to demonstrate the method.

The new technology of process intensification by multiscale equipment can significantly contribute to the achievement of a safer design by switching from batch/semi-batch to continuous operation combined with a reduction of the inventory of hazardous substances in critical stages. On the other hand, the shift to higher space-time-yields and temperatures comprises new risks (see Parts I and II). A tool was developed for preliminary risk assessment to cover characteristic features of micro-designed equipment, called HAZOP-LIKE study (see Part III). The generic case studies were applied to two demonstration projects within the IMPULSE project: sulfur dioxide oxidation and the alkylation reaction for the production of ionic liquids. The generic templates proved to be applicable and support comprehensive risk analysis studies on processes with hidden deviations not obviously following traditional HAZOP studies.

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