Reaction time in the fizz zone

The rate of temperature increase in the fizz zone, (dT/dt)f, indicates the heating rate due to the exothermic reaction in the fizz zone. As shown in Fig. 6.12, the heating rate increases linearly in a plot of In dT/dt)f versus KNO2) at 2.0 MPa. The reaction time in the fizz zone, Xf, can be obtained by means of a similar relationship to Eq. (6.5), adapted to the fizz zone reaction. Fig. 6.13 shows Xy versus KNOj) at 2.0 MPa. The reaction time decreases linearly with increasing KNOj) in a plot of In Xj versus (N02) and is represented by... 

Fig. 6.13 Reaction time in the fizz zone decreases with increasing...

In the dark zone, the temperature increases relatively slowly and so for the most part the temperature gradient is much less steep than that in the fizz zone. However, the temperature increases rapidly at about 50 pm from where the flame reaction starts to produce the luminous flame zone. The gas flow velocity increases with increasing distance due to the increase in temperature. The mole fractions of NO, CO, and Hj decrease and those of N2, CO2, and H2O increase with increasing distance in the dark zone. The results imply that the overall reaction in the dark zone is highly exothermic and that the order of reaction is higher than second order because of the reduction reaction involving NO. The derivative of temperature with respect to time t in the dark zone is expressed empirically by the formulal =l... 

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