Thermal Runaway in Tubular Reactor Systems with n-th Order Kinetics

This paper addresses the problem of predicting the critical parameters that characterize thermal runaway in a tubular reactor with wall cooling, introducing a new view of the n-th order kinetics reactions. The paper describes the trajectories of the system in the temperature-(concentration)n plane, and deduces the conditions for the thermal risk

Decomposition kinetics of materials combining biomass and electronic waste

The disposal of waste from electrical and electronic equipment is an actual problem of industrialized countries. In the present work, thermal decomposition of different materials has been studied in a thermobalance at different heating rates. Kinetic models are proposed for the pyrolysis, gasification and combustion of crushed wood pellets (CWP), halogen-free electrical wires (EWs) and printed circuit boards (PCBs). Three different heating rates were used at each atmosphere condition. One set of parameters can explain all the experiments at the different atmospheres and at the three different heating rates used. In the case of CWP, a model considering three independent first-order reactions gave very good correlations all the heating rates tested both in inert and oxidant atmosphere. The decomposition of synthetic materials (EW and PCB) is modeled by using nth order kinetics. On the other hand, mixtures of these three materials have been prepared and tested for decomposition behavior. A weighted sum of the curves simulated using kinetics of the materials separately gives a good concordance with the experimental curve in the case of PCBs, indicating that there is not chemical interaction between CWP and PCBs when heated and decomposed. This would indicate that the production of pollutants in the decomposition will not be affected by the presence of the other material. Nevertheless, a strong interaction is found with the mixtures between biomass and EW.Support for this work was provided Spanish Ministry of Culture and Sport and by the CTQ2013-41006-R project from the Ministry of Economy and Competitiveness (Spain) and the PROMETEOII/2014/007 project from the Valencian Community Government (Spain)

Fluid-Fluid Reactions: Study of the Surface Renewal Theory in Chemical Engineering Courses

The Surface Renewal Theory (SRT) is one of the most unfamiliar models in order to characterize fluid-fluid and fluid-fluid-solid reactions, which are of considerable industrial and academicals importance. In the present work, an approach to the resolution of the SRT model by numerical methods is presented, enabling the visualization of the influence of different variables which control the heterogeneous overall process. Its use in a classroom allowed the students to reach a great understanding of the process

Analysis of the Brominated Dioxin and Furan Emission Congener Pattern from Different Sources

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) have been studied for several decades and are well-known as unintentionally generated persistent organic pollutants (POPs), which pose serious health and environmental risks on a global scale1. Polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/F) have similar properties and effects to PCDD/F, as they are structural analogs with all the chlorine atoms substituted by bromine atoms. PBDD/F have been found in various matrices such as air, sediments, marine products, and human adipose samples.Support for this work was provided by the Generalitat Valenciana (Spain), research project Prometeo/2009/043/FEDER, and by the Spanish MCT, research project CTQ2008 05520

Thermogravimetric and kinetic analysis of the decomposition of solid recovered fuel from municipal solid waste

The thermal decomposition of a solid recovered fuel has been studied using thermogravimetry, in order to get information about the main steps in the decomposition of such material. The study comprises two different atmospheres: inert and oxidative. The kinetics of decomposition is determined at three different heating rates using the same kinetic constants and model for both atmospheres at all the heating rates simultaneously. A good correlation of the TG data is obtained using three nth-order parallel reactions.Authors acknowledge the financial support for this work provided by PROMETEOII/2014/007 of Generalitat Valenciana (Spain) and CTQ2013-41006-R (Spanish Ministry of Economy and Competitiveness)