Simple Monitoring of Semibatch Polymerization Processes: An Integrated Criterion

Abstract

A number of potential runaway reaction systems of the fine chemical industry (e.g., polymerization processes) undergo significant changes of their physical properties with the reaction extent, resulting in thickening phenomena of the reaction mass and in a consequent decay of the reactor heat-transfer efficiency. In this work, a set of key process indicators have been developed, allowing for monitoring of safe operating conditions of industrial semibatch polymerization reactors without requiring any kinetic characterization of the reaction system. The only required information are the heat of reaction and some fully available process variables that are normally recorded for any industrial reactor. The proposed criterion has been successfully validated using some experimental data measured on an industrial polymerization reactor for the production of polyacrylic rheology modifiers

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

“…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] :…”

“…In this way, in fact, the reaction system can be characterized at the lower scale with respect to both its quick onset and expected heat removal efficiency 12 : this allows also for detecting too early thickening phenomena of the reaction mass (due e.g. to an excessive system concentration), which would occur when the energy release potential of the system could lead under low heat transfer conditions to excessive peak temperatures 13 .…”

“…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] .…”

“…This is due to the different sensitivity of the reaction rate to the charged reactant concentration that can induce a Ψ number decay in the last part of the dosing period. To solve this problem a more complete set of Key Process Indicators needs to be implemented in the SBR: such a set is the same previously proposed specifically for monitoring polymerization processes 13 , which experience thickening phenomena of the reaction mass and a consequent decay of the reactor heat-transfer efficiency.…”

“…DSC thermoanalytical curve (experimental data from13 ) for: (A) 2,4-diCl BTF; stainless steel crucible; heating rate: 10°C/minute. (B) 2,4-diCl 5-NO2 BTF; stainless steel crucible coated with gold; heating rate: 10°C/minute.…”