The relation of cool flames and auto-ignition phenomena to process safety at elevated pressure and temperature.
The cool-flame phenomenon can occur in fuel-oxygen (air) mixtures within the flammable range and outside the flammable range, at fuel-rich compositions, at temperatures below the auto-ignition temperature (AIT). It is caused by chemical reactions occurring spontaneously at relatively low temperatures and is favoured by elevated pressure. The hazards that cool flames generate are described. These vary from spoiling a product specification through contamination and explosive decomposition of condensed peroxides to the appearance of unexpected normal (hot) flame (two-stage ignition).
A high pressure ignition delay time study of 2-methylfuran and tetrahydrofuran in shock tubes
Abstract Ignition delay time studies for tetrahydrofuran (THF) and 2-methylfuran (2MF) as well as optical investigations of combustion for 2MF have been carried out using two shock tubes. The experiments with undiluted THF/air mixtures were performed at 20 and 40 bar in a high pressure shock tube (HPST) at an equivalence ratio of Ф  = 1 covering an overall temperature range of 780–1100 K and 691–1006 K, respectively. Undiluted 2MF/air mixtures ( Ф  = 1) were also investigated in the HPST at 40 bar in the temperature range of 820–1215 K. The experimental data of 2MF obtained at 40 bar were supported with kinetic simulations of existing models from literature. Additionally, sensitivity analyses of 2MF at several temperatures were performed for finding out the most sensitive reactions. Schlieren imaging was employed in a rectangular shock tube (RST) utilizing a high speed video camera through which the ignition process was captured for a stoichiometric 2MF/O 2 /Ar mixture at pressures of about 10 bar and in the temperature range of 871–1098 K. The pressure signals of THF and 2MF at 40 bar indicate two types of pre-ignition at low temperatures: a short two-stage ignition for THF and a relatively long and smooth increase in pressure before main ignition for 2MF. Furthermore, in case of 2MF at 40 bar, far-wall ignitions at low temperatures could be observed. The deviation between simulation and experiment as well as the presence of pre-ignitions in the low temperature regime were the main reasons for undertaking optical investigations of 2MF. The Schlieren images show that the ignition process at low temperatures ( T  ⩽ 940 K) begins as a deflagrative phase in the form of flame kernels and ends in a strong ignition (explosion in explosion). The current study analyzes the auto-ignition of THF and 2MF at engine relevant pressures and temperatures. The optical investigations have been conducted to analyze the ignition behavior of 2MF.
Law in a law-governed union (Recht in einer Rechtsunion) : the Court of Justice of the European Union and the free law doctrine
The Court of Justice of the European Union characterizes the Union as a Rechtsunion: a law-governed union. The conception of “the law” in Article 19 paragraph 1 of the Treaty on European Union transcends the Treaties, according to the Vice-President of the Court of Justice, Koen Lenaerts. This thesis demonstrates with reference to the work of Georg Jellinek that the Union is a non-sovereign state and, with reference to the work of Eugen Ehrlich in particular, that the state-based perception of law is a misperception. Not all production of law is reserved to the state and not all law is state-recognized law. There is extra-state law. It has been alleged that the Court of Justice of the European Union has had “a free law attitude”. The author discusses the free law doctrine developed at the beginning of the twentieth century and has made literal translations of writings in German, French and Italian by the main representatives of the free law movement. The free law doctrine provides a descriptive framework for the case-law of courts. The author describes the creation by the Court of Justice of four constitutional principles of Union law through its case-law. He concludes that every court is, to quote Hermann Kantorowicz, praeter legem law-creatively active and has, in that sense, a free law attitude. The decisions of judges are often volitional decisions. How the law will be applied should be predictable but volitional decisions, because they are unpredictable, are inconsistent with the principle of legal certainty. In the Union and its member states the judiciary and not the statute or “the law” is pre-eminent. The author suggests how the concept of law should be defined in a material Rechtsunion. He argues that societal legal norms could be provided with an appropriate position consistent with the principle of legal certainty by making the validity of a societal legal norm contingent on its material lawfulness.