Numerical study on characteristics and hazard consequences of the hydrogen cloud explosion in a hydrogenation unit

During the operation of a hydrogenation unit, there is the danger of leakage and explosion of high-pressure hydrogen. In order to study the evolution of the flame and shock wave in hydrogen explosion accidents, the explosion process and the impact range of hydrogen leakage in the hydrogenation unit are simulated based on the FLACS simulation software. First, we have established a high-precision three-dimensional physical model for the hydrogenation unit and investigated the influence of different equivalence ratio (ER) on the overpressure of the hydrogen cloud explosion. The result shows that, at ER = 0.8–1.4, the peak temperature, flame propagation velocity, and overpressure peak value generated by the hydrogen cloud explosion increase first and then decrease with an increase in the equivalence ratio. At ER = 1.05, the peak temperature and overpressure after the explosion have the largest values, and the flame propagation velocity at this time is 38.2 and 31.7% higher than that at ER = 0.8 and 1.4, respectively. At the same time, flame acceleration during its propagation can effectively promote an increase in the explosion overpressure inside the flame. In addition, the simulation results of this paper also provide theoretical guidance for the antiknock engineering transformation of chemical plant buildings.