In this paper a review of recent developments on safety and runaway prevention in batch and semibatch reactors is given. To prevent thermal runaways in chemical reactors usually three lines of defense have to be considered: choice of the right operating conditions, early warning detection system and system to handle running away reactions. Because of its too specific nature, the last line of defense is not discussed in this review, while the former two are considered in detail. Firstly the capability and applicability of the reaction calorimeter for safety assessments are reviewed, then fundamental safety criteria for safe operation of batch and semibatch reactors are reported and discussed. A review of the most useful and efficient methods for a correct choice of safe operating conditions is split into two cases: one, when the reaction kinetics are known, and when kinetic information is not available. Also several promising recent developments of an early warning detection system for the on-line detection of unexpected situations leading to a thermal runaway are presented.

Safety and Runaway Prevention in Batch and Semibatch Reactors—A Review

Isothermal reaction calorimetry as a tool for kinetic analysis

The use of measurements to compensate for the effect of uncertainty has recently gained attention in the context of real-time optimization of dynamic systems. The commonly used approach consists of updating a process model and performing numerical optimization using the refined model. In contrast, this paper presents a two-level approach that does not require repeating the optimization:  At the upper level, the constraints that are active in the optimal solution are identified from optimization of a nominal process model; at the lower level, feedback control is used to enforce the necessary conditions of optimality, i.e., meet the identified active constraints and push selected gradients to zero. A key feature of this self-optimizing control scheme is the use of an input parametrization that is tailored to the identified active constraints. Another feature that is specific to batch processes is the possibility to meet the control objectives either online or on a run-to-run basis. The self-optimizing contr...

Real-Time Optimization of Batch Processes by Tracking the Necessary Conditions of Optimality

A Directional Modifier-Adaptation Algorithm for Real-Time Optimization

The use of calorimetry for on-line optimisation of isothermal semi-batch reactors

Maximising the yield of the second order reaction (2-butanol+propionic anhydride) by manipulating the inlet flow rate is considered for an isothermal semi-batch process. First a procedure for the determination of the kinetic parameters using coupled spectroscopic and calorimetric methods is presented. Then an optimisation of the reaction system is performed numerically and verified experimentally. Constraints on the amount of heat produced and on the temperature attainable in the case of cooling failure are imposed for safety consideration.

Pablo Lerena

Papers

Optimal Feed Profile for a Second-order Reaction in a Semi-batch Reactor under Safety Constraints - Experimental Study