Home – Home – Jornals – Combustion, Explosion and Shock Waves 2018 number 2

Obtaining of hydrogen during pyrolysis and partial oxidation of hydrogen sulphide is analyzed on the basis of a detailed kinetic model of H2S oxidation. It is shown that the H2 output in the case of H2S pyrolysis in adiabatic flow reactor with a residence time of ≈1 s. Even for the initial temperature of the mixture T₀ = 1400 K, the molar fraction of H₂ is only 12%, though the equilibrium value is reached within the reactor. At T₀ <1200 K, there is no enough time for the chemical equilibrium inside the reactor to be established, and the H₂ concentration is lower than the equilibrium value. At T₀ <1000 K, there is practically no pyrolysis reaction in the reactor. Addition of a small amount of air to H2S leads to energy release, to an increase in temperature, and, as a consequence, to acceleration of H2S conversion. The normalized output of H₂ can be increased by several times. For each value of T₀, there exists an optimal value of the fuel-to-air equivalence ratio φ that ensures the maximum H₂ output in the H₂S-air mixture. The process of partial oxidation at high values of φ > φ_b and low values of T₀ is essentially nonequilibrium; as a result, the H₂ concentration at the exit from a finite-length reactor can be higher than its equilibrium value, e.g., by 30-40% at T₀ = 800 K and φ = 6-10. The reasons responsible for reaching a “superequilibrium” concentration of H₂ at the flow reactor exit are determined.