Abstract:

To rapidly and accurately assess the consequences of flammable and explosive chemical fire accidents. The Pyrolyzer-Gas Chromatography-Mass Spectrometry (Py-GCMS) combined device was utilized, and the combustion reaction process of flammable and explosive chemicals was reproduced through rapid heating pyrolysis experiments. The small molecule intermediate products and their proportion coefficients were obtained, and a simplified model was constructed. Further coupling was achieved with Fluent, and the calculation of the combustion and explosion process of petroleum-based liquid hydrocarbon fuels such as n-heptane was realized. The research results show that the pyrdysis products of n-heptane are significantly affected by the pyrdysis duration and the heating rate, but less by the pyrdysis temperature. Among them, the critical point for the stable combustion of n-heptane is 600 ℃. When the temperature is above this point, the content of the pyrdysis product components will remain constant. At a heating rate of 1 000 K/s and a pyrdysis duration of 8 s, the pyrdysis is the most complete. The main products are C₃, C₄, and C₅ alkanes and alkenes, which are the core components for constructing its alternative model. Compared with the Primary Reference Fuel (PRF) combustion reaction mechanism, it was found that the similarity of flame shape and characteristic gas distributions such as CO/CO₂ in the alkene substitution model was the highest. The flame geometric parameters such as flame height and flame width of the mixed substitution model had the best matching degree. However, the alkane substitution model showed significant deviations in flame distribution and the transport and diffusion of characteristic gases.

Key words: multicomponent small-molecule hydrocarbon, combustion reaction, simplified model, pyrolysis, ion peak, petroleum-based liquid hydrocarbon fuels