Safety thermal

Velo, E., C. M. Bosch, and F. Recasens (1996). Thermal Safety of Batch Reactors and Storage Tanks. Development and Validation of Runaway Boundaries. Ind. Eng. Chem. Res. 35, 1288-99. 

Th is reached and decomposition can be triggered. Process safety depends on both rates, Qit.hi, and Qd mp-Decomposition will be triggered and 7), reached during a runaway of the decomposition reaction. The rate Qoer.hp determines the thermal safety of the process. 

Grewer, T., H. Klusacek, U. Loffler, R. L. Rogers, and J. Steinbach, "Determinations of the Characteristic Values for Evaluation of the Thermal Safety of Chemical Processes," J. of Loss Prev. Process Ind., 2 (1989). 

Steinbach, J., "Untersuchung zur Thermischen Sicherheit des Indirekt Gekue-hlten Semi-Batch Reaktors" ("Investigation into the Thermal Safety of Indirectly Cooled Semi-Batch Reactors"), Thesis, University of Berlin, Germany (1985). 

Fierz, H. (1994). "Assessment of Thermal Safety During Distillation of DMSO."... 

In contrast to that of solvents, the effect of the electrolyte solute, LiPFe, on the thermal decomposition of the cathode, LiCo02, was found to be suppression instead of catalyzation. The SHR of a partially delithiated cathode was measured in a series of electrolytes with various salt concentrations, and a strong suppression of the self-heating behavior was found as the concentration of LiPEe increased above 0.50 M. The mechanistic rationale behind this salt effect is still not well understood, but the authors speculated that the salt decomposition coated the cathode with a protective layer that acted as a combustion retardant. On the basis of these results, the authors recommended a higher salt concentration (>1.50 M) for LiCo02-based lithium ion cells is preferred in terms of thermal safety. 

Pointing out that the acidic nature of LiPFe assists the dissolution of Mn + into electrolyte solution, the authors speculated that HF in the electrolyte solution efficiently cleans up the spinel surface of MnO therefore, the bulk electrolyte solvents can be continuously exposed to the fresh surface of Mn204 and be oxidized. As a result, solvent oxidation would proceed more rapidly as compared with the case of an electrolyte that is less acidic. Therefore, for a spinel manganese-based lithium ion cell, a higher thermal safety would be obtained with lower salt concentration, and the authors suggested 0.5 M as the optimum concentration at which the ion... 

Several methods have been developed over the years for the thermochemical characterisation of compounds and reactions, and the assessment of thermal safety, e.g. differential scanning calorimetry (DSC) and differential thermal analysis (DTA), as well as reaction calorimetry. Of these, reaction calorimetry is the most directly applicable to reaction characterisation and, as the heat-flow rate during a chemical reaction is proportional to the rate of conversion, it represents a differential kinetic analysis technique. Consequently, calorimetry is uniquely able to provide kinetics as well as thermodynamics information to be exploited in mechanism studies as well as process development and optimisation [21]. 

For the determination of reaction parameters, as well as for the assessment of thermal safety, several thermokinetic methods have been developed such as differential scanning calorimetry (DSC), differential thermal analysis (DTA), accelerating rate calorimetry (ARC) and reaction calorimetry. Here, the discussion will be restricted to reaction calorimeters which resemble the later production-scale reactors of the corresponding industrial processes (batch or semi-batch reactors). We shall not discuss thermal analysis devices such as DSC or other micro-calorimetric devices which differ significantly from the production-scale reactor. 

Thermal Safety of Chemical Processes Risk Assessment and Process Design. Francis Stoessel Copyright 2008 WILEY-VCH Verlag GmbH Co. KGaA, Weinheim ISBN 978-3-527-31712-7... 

The six key questions presented above ensure that the essential knowledge about the thermal safety of a process is addressed. In this sense, they represent a systematic way of analysing the thermal safety of a process and building the cooling failure scenario. Once the scenario is defined, the next step is the actual assessment of the thermal risks, which requires assessment criteria. The criteria used for the assessment of severity and probability are presented below. 

Wiss, J. (1993) A systematic procedure for the assessment of the thermal safety and for the design of chemical processes at the boiling point. Chimia, 47 (11), 417-23. 

Using the thermogram represented in Figure 7.7, assess the thermal safety of the substitution reaction example A + B —> P (see Section 5.3.1) performed as an isothermal semi-batch reaction at 80 °C with a feed time of 4 hours. At industrial scale, the reaction is to be in a 4 m3 stainless steel reactor with an initial charge of 2000kg of reactant A (initial concentration 3molkg 1). The reactant B (1000kg) is fed with a stoichiometric excess of 25%. 

Assess the thermal safety of the intended storage. Propose technical solutions to improve the safety. 

Francis Stoessel Thermal Safety of Chemical Processes... 

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