Numerical study of syngas production via CH4–H2S mixture partial oxidation

• Published in: International journal of hydrogen energy Vol. 44; no. 33; pp. 17551 - 17564
• Main Authors: Savelieva, V.A., Titova, N.S., Favorskii, O.N.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 05.07.2019
• Subjects: CH4–H2S mixture; Numerical study; Partial oxidation; Syngas production; Partial oxidation; Syngas production; CH4–H2S mixture; Numerical study
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2019.05.033

The detailed kinetic mechanism of pyrolysis and oxidation of the H2S–CH4 mixture was developed. The mechanism was validated on experimental data on the ignition delay, laminar flame velocity, conversion degree of H2S and CH4, as well as on the yield of main conversion products – H2 and CO. The developed mechanism was used for a numerical study of the conversion degree of H2S and CH4, the syngas yield and syngas composition during partial oxidation of the H2S–CH4 mixture with H2S/CH4 = 1/9, 1/4 and 3/1 in a plug flow reactor of 1 m in length in the wide range of initial temperature (T0 = 600–1400 K) and fuel-to-air equivalence ratio (ϕ = 1–30). It is shown that the maximum relative yield of syngas can be obtained at ϕ = 3–5 depending on T0 and the H2S/CH4 ratio in the fuel. The mole fraction of H2 in syngas is higher than that of CO. For the mixture with H2S/CH4 = 3/1, the mole fraction of H2 can be greater than the equilibrium value in a certain range of ϕ∼6–10. The reasons for this effect are analyzed. The mole fraction of CO in conversion products rapidly decreases with increasing ϕ. As a result, the ratio γH2/γCO increases fast with the growth of ϕ. Besides H2 and CO, the conversion products can contain S2 and NO (at ϕ∼2), CS (at ϕ∼3), CS2 (at 3 < ϕ < 10), unburned hydrocarbons (at ϕ > 3) and other species. The least amount of conversion byproducts is observed at ϕ = 3–3.5 when there is the maximum syngas yield. Syngas selectivity turned out maximal at ϕ = 2.5–3. Therefore, ϕ∼3 seems to be the most optimal value for carrying out the conversion of H2S–CH4 mixtures. •The detailed kinetic mechanism of H2S–CH4 mixture pyrolysis and oxidation was developed.•Syngas production during partial oxidation of H2S–CH4 is studied numerically.•Maximum relative yield of syngas is at fuel-to-oxygen equivalence ratio ϕ = 3–5.•The molar fraction of H2 in syngas increases with the growth of ϕ.•The least amount of conversion byproducts is at ϕ = 3–3.5.