Valentina Busini
Politecnico di Milano, Italy
Title: Temperature sensors position in chemical reactors: The use of CFD
Biography
Biography: Valentina Busini
Abstract
Statement of the Problem: Runaway reactions have always been a serious issue for the chemical industry. Failures that may lead to this type of accident may be different: block of the impeller, loss of the reactor temperature control, error in the loading of reagents. The rapid detection of this phenomena is crucial. One of the most widely used preventive systems is the so-called early warning system, which allows to give an early warning at the beginning of the fugitive reaction. Due to non-homogeneity of the temperature inside the reactor, the positioning of the sensors is of crucial importance. In fact, an incorrect localization of the temperature probe could lead to a false alarm, which would undermine the early warning system. The objective of this work is the computational fluid dynamic (CFD) simulation of different failure scenarios, in order to determine the best location of the temperature sensors. Methodology & Theoretical Orientation: For this work a semi-batch reactor was used to simulate an accident in a pilot scale reactor. An impeller fault and a reagent loading error has been investigated in CFD using a new kinetic model for liquid reactions, implemented in ANSYS Fluent. Findings: Differently from what is present in the literature, CFD results show that depending on the incident considered, the best position for the thermocouple varies within the reactor. For the impeller fault the best position is in the upper region of the reactor, while for the loading error accident the best position is always in the proximity of the reagent mass. Conclusion & Significance: The simulations performed show the usefulness of CFD in analyzing these kind of problems and that there is no unique positioning of thermocouples which would be optimal to early-detect every runaway scenario. Here rises the importance of redundant measurements in a reactor.
