H2 and corn stalk dust hybrid explosion overpressure and molecular dynamics of reaction analysis

Abstract

During biomass hydrogen production, H₂ and corn stalk dust hybrid explosion threatens process safety. To reveal the overpressure characteristics and molecular dynamics of reaction during H₂-corn stalk hybrid explosion, 20 L explosion experiments and ReaxFF-MD simulations are conducted. Results indicate that as the H₂ volume fraction increases from 0 to 20%, the reaction activation energy decreases, the P_max and (dP/dt)_max increase, and the optimal explosion concentration of corn stalk dust is reduced significantly. When H₂ volume fraction exceeds 10%, the dominated explosion mode is shifted from corn stalk combustion induced to H₂ combustion induced, which can exacerbate the explosion hazard (with the K_st exceeding 30 MPa·m/s, St3 level). H₂ exhibits a dual promotion mechanism during hybrid explosion. Firstly, the oxidative heat release of H₂ provides extra energy for the pyrolysis of corn stalk. Secondly, the reaction between H₂ and O₂ generates free radicals such as ·H and ·OH, which alter the reaction pathway of corn stalk and accelerate its pyrolysis into small-molecule gases. This increases the concentration of combustible gases and enhances the intensity of the explosion reaction. The revealed H₂-corn stalk hybrid explosion mechanism can provide theoretical support for the explosion accidents prevention and mitigation.