Hydrogen refuelling stations. Example of a safety study for a hydrogen-natural gas refuelling station

International audienceThe assessment of risks related to the operation of public and non-public hydrogen refuelling stations is a key step in the sitting approval process by legal authorities and eventually fire-department. Present work is underway at European level to facilitate approval procedures in order to ease technology deployment across Europe. In France, the ALTHYTUDE project co-ordinated by Gaz de France, deals with the use of a bus fleet fuelled with a mixture of hydrogen and natural gas in two different cities. Dunkerque in the North of France (two busses) and Toulouse in the South of France (three busses) have been selected. Refuelling stations will be built in each city. So as to get the sitting approval of the refuelling stations, risks analyses have been performed for each station. These risk assessments are in line with the new French regulation related to major accidents and somehow compatible with the health & safety at work regulation regarding explosion hazards. Methodology and first results of the risk analysis of the Dunkerque refuelling station are reviewed in this paper: hazardous scenarios have been proposed, safety barriers have been listed for each scenario, intensity quotation has been performed and scenario have been chosen for hazard quantification

Corrosion of Immersed Ceramic Heat Exchanger Tubes in Aluminium Foundry Baths

International audienceThe corrosion of three non-oxide ceramics by Al-9Si-3Cu baths and by fluxes (mixtures of chlorides and fluorides of sodium and potassium) at about 750 degrees C was studied in a foundry environment. Comparison of results of the metallurgical examination of A, a silicon-nitride-bonded silicon carbide and of B, a reaction-bonded silicon nitride, surface treated to fill all the external porosity provides some insight into the role of the bonding phase and the porosity. Grade C is a graphite bonded silicon carbide with an external protection by a ceramic glazing. The SiC phase in the tubes is inert to the corrosive liquids (attributed to the silicon content in the metal). A and C ceramics react only in the presence of a fur. Sodium and chlorine were identified in the corrosion products as well as AlN (A) and Al4C3 (C), resulting from reaction of the silicon nitride or of the graphite bonding phase with aluminium. This suggests that the fluxes are responsible for the corrosive process, by causing the formation of gaseous aluminium halides which penetrate the porous bonding phase and react with it to form AlN or Al4C3