Modelling and wind tunnel experiments of water barriers with chemical reaction; fluid dynamics characterization

Nowadays, water curtains are often employed in industry to contain flammable or toxic clouds due to accidental releases of process fluids (Deaves, 1983; St-Georges et al., 1992). The action of water curtains consists, essentially, in diluting vapour clouds down to safety level from both toxic effect threshold and lower flammability limit (Mc Quaid et al., 1983). The extent of dilution depends on the effectiveness of the mechanism involved: dispersion enhancement, owing to the air entrainment and the mixing of entrained air with the vapour released; physical absorption of the released gas, eventually joined to chemical reaction; heating of gas clouds (if gas behaving like heavy ones, due to low temperature, are concerned, e.g. cryogenically liquefied LNG or ammonia gas). Recently it has been observed that the effect of mitigation could be increased by the use of a chemical solution giving a non-reversible reaction with the released substance (Griolet et al., 1995). This research programme aims to design and realize the experimental equipment allowing experimenta1 simulation of water spray curtain interaction with gas plume; to carry out a complete fluidynamic analysis; to evaluate the effect of physical absorption; to evaluate the effect of combined chemical and physical absorption and, finally, to develop a theoretical model, validated by experimental results and useful in scale-up operation.