1 Zaretskiy N.P., Chaivanov B.B., Chernenko E.V., Mayorov A.S., Ponomariov N.N., Efimenko A.A., Schepetov N.G., Alekseev V.I., Aleksandrov A.O., Matsukov I.D., Gavrikov A.I., Privezentsev S.S. FULL SUPPRESSION OF HYDROGEN EXPLOSION USING PHLEGMATIZATION ADDITIVES. EXPERIMENTAL RESULTS National Research Center Kurchatov Institute San Francisco, USA September 12-14, 2011 2 Objective Full suppression of hydrogen explosion using phlegmatizing additives under conditions typical for industrial accidents including NPP. Process of mixture ignition is significantly scale dependent. Correct test of mixture inflammability should be performed with large enough ignition source. Of course, experimental volume size should be much greater then ignition source size. All results were obtained for stoichiometric mixtures (30% H 2 ). Our research strategy: Step 1. Preliminary search for effective phlegmatizing additives was made using small scale laboratory facility at temperature range and 1 atm initial pressure. Step 2. Obtaining of more accurate value of minimal phlegmatizing concentration (MPhC) of additive in hydrogen-air mixture was made using medium scale facility at temperature range and 1 atm initial pressure. Step 3. Testing of inflammability of stoichiometric hydrogen-air mixture with phlegmatizing additives was made using large scale facility at temperature 20 and 1 atm initial pressure. 3 Small scale laboratory facility L = 1 m, ID = 66 mm, V = 3.5 l Initial temperature 20120 (1 ) Ignition: platinum wire l = 15 mm, d = 0.8 mm, T ~ 1500 , temperature rise time ~ 1 ms, duration of ignition temperature peak ~ 0.5 s Set of pressure and light transducers 4 Preliminary search criteria for individual phlegmatizing additives 1. Main components for phlegmatization full combustion suppression at less then 20% vol. concentration. 2. Additional phlegmatizing components ability of significant decrees of flame speed, full combustion suppression is not necessary. X-t - diagram 11% C 2 F 4 Br 2. Quenching Visible flame speed v v.s. C 2 F 4 Br 2 concentration Example C 2 F 4 Br 2 Example CF 3 I X-t - diagram 20% CF 3 I. Flame propagation Visible flame speed v v.s. CF 3 I concentration MPhC 11% No MPhC (Minimal phlegmatizing concentration) 5 Small scale experimental results (10 substances). Individual phlegmatizing additives. = 20 Main components for phlegmatization C 2 F 4 Br 2, CF 3 Br, C 2 F 3 Cl 3 Additional components for phlegmatization CF 3 I, C 2 F 3 ClBr 2, CF 2 Br 2 Best component is C 2 F 4 Br 2. It has minimal MPhC at temperature range . 6 Small scale experimental results (160 ss experiments): best individual phlegmatizing additive and binary mixtures #Phlegmatizator Concentration at =20 , % vol. Concentration at =120 , % vol. 1C 2 F 4 Br 2 + C 2 F 3 Cl 3 12 (8+4) 13 (9+4) 2C 2 F 4 Br C 2 F 4 Br 2 + CF 3 I 11 (9+2) 13 (10+3) Binary mixtures could have lesser MPhC then C 2 F 4 Br 2 or they could be more technologically attractive B inary mixtures tested : C 2 F 4 Br 2 + C 2 F 3 ClBr 2 C 2 F 4 Br 2 + CF 3 I C 2 F 4 Br 2 + CF 3 Br C 2 F 4 Br 2 + C 2 F 3 Cl 3 C 2 F 4 Br 2 + CF 2 Br 2 MPhC v.s. temperature 7 Medium scale facility L = 8 m, ID = 121 mm, V = 92 l Initial temperature 20120 (1 ) Ignition: NiCr ribbon S = 30 cm 2, T ~ 1200 , Temperature rise time ~ 10 ms, Duration of ignition temperature peak ~ 1 s Set of pressure and light transducers T= o C Ignition source 8 Medium scale experimental results (40 ms experiments): corrected MPhC values for the best individual phlegmatizing additive and binary mixtures #PhlegmatizatorConcentration at =20 , % vol. Concentration at =120 , % vol. 1C 2 F 4 Br 2 12 (ss 11) 14 (ss 14) 2C 2 F 4 Br 2 + C 2 F 3 Cl 3 12 (8+4) (ss 12) 13 (9+4) (ss 14) 3C 2 F 4 Br 2 + CF 3 I 12 (10+2) (ss 11) 15 (12+3) (ss 13) MPhC v.s. temperature 9 L = 3 m, V = 10.6 m 3 Initial temperature 20 (1 ) Ignition: NiCr ribbon S = 200 cm 2, T ~ 1200 , Temperature rise time ~ 10 ms, Duration of ignition temperature peak ~ 1 s High speed camera Large scale facility Temperature control system Ignition 10 Phlegmatizator: 8,5% C 2 F 4 Br 2. Combustion (slowdown 10x) ms0 ms400 ms 700 ms1000 ms 2000 ms 3000 ms4000 ms 6000 ms Phlegmatizator: 8,5% C 2 F 4 Br 2. Combustion 12 Phlegmatizator: 13,6% C 2 F 4 Br 2. Quenching (slowdown 10x) 13 20 ms 200 ms 300 ms800 ms Phlegmatizator: 13,6% C 2 F 4 Br 2. Quenching 14 Large scale experimental results. T = 20 o C (11 ls experiments) # PhlegmatizatorConcentration at =20 , % vol. Results 1 C 2 F 4 Br 2 8.5combustion 13.6quenching 2 C 2 F 4 Br 2 + C 2 F 3 Cl ( )combustion 14.6 ( )quenching 3 C 2 F 4 Br 2 + CF 3 I 8.6 ( )combustion 12.1 ( )quenching Our estimation: To suppress hydrogen explosion at Fukushima only 50 tons of C 2 F 4 Br 2 was necessary (half of railway tank). 15 Conclusions Possibility of full suppression of hydrogen explosion is shown in full scale experiments (160 ss + 40 ms + 11 ls) Best phlegmatizing additives at 20120 : C 2 F 4 Br 2 (14% vol.) C 2 F 4 Br 2 + C 2 F 3 Cl 3 (13% (9+4) vol.) Further investigations are necessary in following directions: 1. Large scale experiments at elevated initial temperature and pressure. 2. Development of technologies for use in the chemical industry facilities and power engineering. 16 Thank you for attention! 17