2.1 Sicherheit von Energieträgern
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For a comprehensive safety assessment of stationary lithium-ion-battery applications, it is necessary to better understand the consequences of thermal runaway (TR). In this study, experimental tests comprising twelve TR experiments including four single-cell tests, two cell stack tests and six second-life module tests (2.65 kW h and 6.85 kW h) with an NMC-cathode under similar initial conditions were conducted. The temperature (direct at cells/modules and in near field), mass loss, cell/module voltage, and qualitative vent gas composition (Fourier transform infrared (FTIR) and diode laser spectroscopy (DLS) for HF) were measured. The results of the tests showed that the battery TR is accompanied by severe and in some cases violent chemical reactions. In most cases, TR was not accompanied by pregassing of the modules. Jet flames up to a length of 5 m and fragment throwing to distances to more than 30 m were detected. The TR of the tested modules was accompanied by significant mass loss of up to 82%. The maximum HF concentration measured was 76 ppm, whereby the measured HF concentrations in the module tests were not necessarily higher than that in the cell stack tests.
Subsequently, an explosion of the released vent gas occurred in one of the tests, resulting in the intensification of the negative consequences. According to the evaluation of the gas measurements with regard to toxicity base on the “Acute Exposure Guideline Levels” (AEGL), there is some concern with regards to CO, which may be equally as important to consider as the release of HF.
Die Präsentation zeigt in Bild und Video die Möglichkeiten auf dem BAM TTS zur Durchführung von Versuchen unterschiedlicher Gefährlichkeitsstufen auf. Sie wendet sich an potentielle künftige Kooperationspartner aus dem Bereich der zivilen Sicherheitsforschung (Polizeibehörden, Feuerwehr, THW, andere Forschungseinrichtungen), um deren Forschungsbedarf mit den an der BAM vorhandenen Testmöglichkeiten abzugleichen und so ebenfalls dem Aufbau von überflüssigen konkurrierenden Parallelstrukturen an anderen Forschungseinrichtungen vorzubeugen.
Tetrafluoroethylene (TFE) is an industrial scale starting material e.g. for polymer production (PTFE, FEP). When ignited the chemically unstable TFE is capable of decomposing in an explosive way. Explosion propagation through pipe systems of production plants have led to damage and fatalities within the last seven decades.
Incident analyses identified compression heat a relevant source of ignition. Chemical plants consist of pipes, vessels, separating valves, strainers and other components. Before restarting the process after maintenance work, different parts of the plant components could be filled with TFE, nitrogen or air at different initial pressures ranging from vacuum or atmospheric to TFE at operating pressure. Valve opening procedures may cause a temperature increase in the gas phase. Compression takes place at polytropic conditions. Heat losses cannot be neglected. The temperature development in the gas depends upon the surface to volume ratio of the enclosure, geometrical influences, the state of gas flow, how fast the valve opens, and the heat capacity of the gas being compressed.
Laboratory scale tests (Meyer, 2009) revealed ignition of TFE/air due to compression heat. Tests in pipes of 28 mm inner diameter, i.e. already industrial scale, were performed by (Kluge et. al., 2016). In the present contribution initial test results from a 63 mm pipe will be compared with existing 28 mm pipe data. A description of the experimental setup as well as an explanation of the hazard diagram will be given.
Furthermore, a method allowing for the identification of hazardous conditions will be discussed.
Tetrafluoroethylene (TFE) is an industrial scale starting material e.g. for polymer production (PTFE, FEP). When ignited the chemically unstable TFE is capable to decompose in an explosive way. Explosion propagation through pipe systems of production plants have led to damage and fatalities within the last 7 decades.
Incident analyses identified compression heat a relevant source of ignition. Chemical plants consist of pipes, vessels, separating valves, strainers and other components. Before restarting the process after maintenance work different parts of the plant components could be filled with TFE, Nitrogen or Air at different initial pressures ranging from vacuum or atmospheric to TFE at operating pressure. Valve opening procedures may cause a temperature increase in the gas phase. Compression takes place at polytropic conditions. Heat losses cannot be neglected. Therefore the temperature development in the gas depends upon the surface-to-volume-ratio of the enclosure, geometrical influences, the state of gas flow, how fast the valve opens and the heat capacity of the gas being compressed.
In the present work initial test results from a 2.5” pipe will be compared with existing 1.1” pipe data. Geometrical effects will be briefly discussed as well as some first results concerning the influence of orifices are reported. Furthermore a method allowing for the identification of hazardous initial conditions is discussed.