Kinetic-Free Safe Operation of Fine Chemical Runaway Reactions: A General Criterion

Abstract

In this work, a simple and general method has been developed that, on the basis of an easy-to-measure quantity referred to as the ψ number, allows for ongoing detection of the displacement of the SBR operating regime from safe target conditions, without any information about the reaction kinetics. Such a feature is of particular importance because, when dealing with reaction processes in the fine-chemicals and pharmaceuticals industries, the estimation of the kinetic parameters of the reactions involved is often not practicable, because of the huge variety of productions encountered and the simultaneous occurrence of mass-transfer phenomena in heterogeneous systems. Moreover, the method in question has been confirmed to be useful for the early detection of low-reactivity or non-ignition regimes of the SBR, to prevent the dangerous accumulation phenomena resulting in a thermal loss of control of the main reaction and a further triggering of pressure-generating decomposition events. Finally, the criterion was validated by analyzing the available data from an industrial SBR in which the water emulsion polymerization of acrylic monomers was performed

Simple Monitoring of Fine Chemical Runaway Reactions in Multipurpose Plants: Nitration of 2,4-Dichloro Benzotrifluoride

“…However the procedure involved the kinetic parameters of the main reaction, since it is based on a direct comparison between the coreactant dosing time and the reaction characteristic time 12 .…”

“…The method is based on a targeted number of smaller scale isoperibolic experiments performed in a well stirred laboratory or pilot scale reactor, equipped for measuring the process variables used for the ongoing calculation of the Ψ, X and MTSRad parameters, which are defined as [12][13][14] :…”

“…However, such criteria require to characterize the chemical kinetics of the reactions involved, which is often not compatible with the time constraints to be faced when a rapid process turnover must be managed in an existing plant. For this reason, a family of criteria (referred to as energy criteria) which allow for a kinetic-free selection of the safe process conditions and for their monitoring on the basis of an early warning approach has been recently presented [12][13][14] .…”

Simple Monitoring of Semibatch Polymerization Processes: An Integrated Criterion

“…where the heat removal rate by the external coolant has been expressed in terms of directly measurable process variables, that is the coolant flowrate and temperature increase across the reactor jacket, coil or external heat exchanger 18,19 .…”

“…If the reactor undergoes a significant drop of the heat removal efficiency due to thickening phenomena of the reaction mass, the Ψ criterion cannot be univocally adopted for monitoring the ignition of the reaction system during the coreactant supply. Ψ is in fact a combined process variable, taking into account for both the reaction ignition and the heat transfer efficiency 18,19 . This means that Ψ numbers and to a heat transfer efficiency sudden decay to ¼ of its original value ( Figures 3A, 3B, 3C and 3D), both occurring at the 70% of the coreactant supply.…”