Abstract
Within the scope of safety related assessment of combustible dusts, burning tests are of huge importance in the field of fire and explosion protection as they evaluate the burning ability of sedimented dust resulting in the so-called combustibility index. Looking at certain technical processes and process plants, dust exists not only in a dispersed or sedimented form but can also be detected in fluid beds and thus is situated in a transitional form between the sedimented and the dispersed form, meaning in a quasi-stationary state. Up to now, there is a knowledge deficiency whether and in how far a combustibility index, which was identified appropriately for sedimented dust, is applicable and acceptable for a safety-related assessment of fluid beds.
A description about the combustion behaviour for dust in fluid beds with the result of a possible increase of the so-called combustible index was published in the VDI-Report 2225 (VDI: Association of German Engineers) in 2014. The authors reported about a modified burning test instrument for fluid beds and the experiments for the examination of the combustibility in the quasi-stationary state. Since the gained research results in the context to the safety characteristic of dusts are of fundamental importance for the operational practice of the fire and explosion hazard assessment, the topic quasi-stationary state in the updated VDI-Guideline 2263 deserves particularly mentioning. A detailed description of the modified burning test instrument and the test procedure is provided in the reworked VDI-Guideline 2263 Sheet 1. In other words a test method for the determination of a new safety characteristic of dust, the so-called Brandverhaltenszahla in quasi-stationary state (BVZqs) is developed, due the combustion behaviour in the modified burning test instrument for fluid beds cannot be described with the standardized combustion index definitions. The aim is to provide a basis of assessment for the user to recognize the quasi-stationary state in certain technical processes and plants which can be evaluate to take appropriate protective measures. In the following, the authors report about the future test- technical determinability of the combustion behaviour in the quasi-stationary state, as well as the determination of the test method and the modified burning test instrument.
The results of the research project are of huge importance for the fire and explosion hazard assessment in different sections, especially in industries of agriculture, food, chemical, pharmaceutical.
