Experimental study on the inhibition of hydrogen deflagration by flame retardant compounded ultrafine dry powder fire extinguishing media containing magnesium-aluminum hydrotalcite

With the gradual improvement of the hydrogen energy industry chain and the continuous expansion of application scenarios, the hazardous consequences brought about by hydrogen combustion and explosion need to be emphasized. In this paper, compounded superfine dry powder fire extinguishing media (CSFDP) and flame retardant compounded ultrafine dry powder fire extinguishing media (CSFDP-MgAl-LDHs) were prepared, respectively. On this basis, a hydrogen deflagration experimental platform was constructed to investigate the inhibition efficiency of different extinguishing media. The results showed that the inhibition rates of CSFDP-MgAl-LDHs on the peak overpressure of hydrogen explosion were 68.57%, 68.43% and 81.72%, which were significantly higher than the corresponding inhibition rates of CSFDP (28.28%, 53.23% and 54.85%) when the hydrogen release pressure was 2.0, 4.0 and 6.0 MPa, respectively. Furthermore, under a release pressure condition of 2.0 MPa, the suppression rates of jet flame front propagation speeds under the action of CSFDP and CSFDP-MgAl-LDHs reached 15.99% and 23.65%, respectively. In addition, the pyrolysis properties of CSFDP-MgAl-LDHs were explored and the chemical reaction mechanism between them and the reactive radicals within the hydrogen jet flame was predicted by thermogravimetric analysis, differential scanning calorimeter and fourier transform infrared spectroscopy, respectively. Ultimately, the physicochemical synergistic inhibition mechanism exerted by CSFDP-MgAl-LDHs during pure hydrogen deflagration was revealed. This study demonstrates broad prospects and value in the areas of hydrogen energy safety and sustainable development, as well as providing a basis for the establishment of safety standards and regulations in the hydrogen energy industry.