Self-ignition water steam effect

Until recently a water steam effect on H2 + air mixture self-ignitions, especially at practicable pressures, has been poorly investigated. Figure 6.31 shows the zones of parameters where there have been attempts to calculate and obtain experimental data [36]. Experiments with water steam additives of 1% volume described in [36] are applicable for practical use. It is definitely not sufficient when it is necessary to analyze inflammable mixture combustion and explosion for cases of severe accidents in NPPs caused by energetic material leakage. In such mixtures the water steam volume content can reach 20-40%. 

The water steam effect on H2 + air mixture self-ignition has been analyzed using calculations with up-dated kinetic schemes and is illustrated by the diagrams in Fig. 6.32 (1,000-1,200 K temperature) [7]. The increase in self-ignition delay time Tr2o, for mixtures with water steam, compared to t, for a dry mixture, at several temperature levels, is presented in Fig. 6.33 as a function of the initial pressure. 

The temperature dependence of t, in Fig. 6.35 proves the weak pressure effect on the self-ignition delay at temperatures exceeding 1100 K. For practical assessment of the water steam effect on H2 + air self-ignition within the temperature range 950-1100 K, it is advisable to use the kinetic scheme from [93]. 

Diethylmagnesium, Mg(C2H5)2, is described as a pyrophoric compound that is violently reactive to water and steam and that self-ignites in air, burning even in a carbon dioxide atmosphere. Describe the significance of this description in terms of reactivity, susceptibility to hydrolysis or oxidation, and potential toxic effects. 

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