Pressure history in the explosion of moist syngas/air mixtures

• Effect of syngas composition on pressure development in syngas explosion is studied.
• Explosion parameters are obtained from the experiment and analyzed.
• H2O addition has different effects on the explosion parameters for syngas with various CO/H2 ratios.
• The effect of heat loss on the explosion propagation of syngas/air mixtures is estimated.

The pressure history in the explosion syngas/air mixtures with H2O addition over a wide range of equivalence ratios at elevated temperatures was recorded to study the explosion characteristics in a constant volume confined vessel. CO mole fractions in syngas are from 0.5 to 0.95, initial temperatures are from 373 K to 473 K, and H2O addition ratios are from 0 to 30%. The explosion parameters such as explosion pressure, explosion time, maximum rate of pressure rise, and deflagration index are obtained from the experiment. Effects of the equivalence ratio, initial temperature, CO/H2 ratio and dilution ratio on the explosion parameters are examined. These parameters are important input properties for evaluation of hazards of the explosion and the design the combustion vessel. In addition, the adiabatic explosion pressure is also calculated assuming the flame propagation is a constant-volume and adiabatic process. Results show the experimentally determined normalized explosion pressure and the normalized adiabatic explosion pressure show different trends with the increase of CO/H2 ratio. The experimental determined normalized explosion pressure decreases but normalized adiabatic explosion pressure increases with the increase of CO/H2 ratio in the syngas mixture. This is mainly because the heat loss is larger for the mixture with a higher CO/H2 ratio. At last, the heat loss during the combustion process was calculated by the difference between experimental and adiabatic explosion pressure. With the addition of CO dilution ratio in the mixture, the amount of heat loss transferred to the wall heat loss to the unit area increases greatly.