RESUMEN
The corrosive environment in sulfur-containing equipment is often complicated and changeable. This study adopted the Taguchi method to optimize the immersion test, and the L27(313) orthogonal table was used to design an immersion corrosion experiment. The influence of four factors, namely, the total acid number (TAN), sulfur, chlorine, and water, on the corrosion of AISI 1020 in the oil phase was studied. It showed that the effect of chlorine is the most pronounced and that of sulfur is second followed by that of the TAN and H2O. It was also found that the effect of H2O exceeds that of the TAN after 336 h; meanwhile, the interaction between the four factors varies over time and stabilizes after 336 h. Moreover, corrosion rate curves reveal that the stable corrosion product film formed on the metal surface gradually slows down the corrosion process. Analysis of corrosion morphology and product composition was done by scanning electron microscopy and energy-dispersive X-ray spectroscopy. Overall, the synergistic effect of the corrosion rate changing with time provides a certain reference for the corrosion protection of sulfur-containing storage equipment.
RESUMEN
The suppression effects of pure ultrafine water mist and 5% mass fraction alkali metal (NaCl, Na2CO3, KHCO3, KCl and K2CO3) solutions ultrafine water mist on methane explosion were conducted under five mist concentrations in a sealed visual vessel. Mist diameters of different additive solutions were measured by a phase doppler particle analyzer. Pressure data and dynamic flame pictures were recorded respectively by a high-frequency pressure sensor and a high-speed camera. Results indicate that alkali metal compound can enhance the suppression effect of ultrafine water mist and it was related to the additive type. The suppression order of alkali metal compound for methane explosion was K2CO3>KCl > KHCO3>Na2CO3>NaCl. Meanwhile, additive radicals can obviously affect explosion intensity and it mainly reflected in the reduction of explosion pressure under different mist conditions (K+>Na+, Cl- >HCO3-). The pressure generated from combustion wave accelerating propagation underwent two accelerating rises and was affected by additive type and mist amount. The effect of additive type on explosion intensity (maximum explosion overpressure (ΔPmax), two peak values of pressure rising rate) was similar with flame propagation velocity and were decreased evidently with increasing mist concentration. The enhancement in explosion suppression was due to the combination of improved physical and chemical effects.
RESUMEN
The inhibition effects of ultrafine water mists on 6.5%, 8%, 9.5%, 11%, and 13.5% methane explosions were experimentally studied in a sealed visual vessel. The mist (10µm) produced by a mist generation system in the vessel was measured by a phase doppler particle analyzer. A high-speed camera was used to record the explosion flame affected by spraying concentration and a high frequency pressure sensor was used to acquire the explosion pressure. Meanwhile, the relationship between flame propagation and pressure rising with time was analyzed. The appearance height of "tulip" flame was increased and appearance moment was delayed obviously with the mist amount increased. The variation trend was illustrated from the viewpoint of the interactions among the flame front, the flame-induced reverse flow and the vortices. Moreover, cellular structure appeared in the burned zone and experienced four developing stages, and its formation indicates that water vapor can cause the intrinsic flame instability and absorb heat on the burned zone further. The pressure underwent two accelerating rises, which was affected by mist amount. The accelerating rise processes were related to the accelerating propagation of combustion wave. Furthermore, methane explosion can be absolutely suppressed by the mist.
RESUMEN
The suppression effect of ultrafine mists on methane/air explosions with methane concentrations of 6.5%, 8%, 9.5%, 11%, and 13.5% were experimentally studied in a closed visual vessel. Ultrafine water/NaCl solution mist as well as pure water mist was adopted and the droplet sizes of mists were measured by phase doppler particle analyzer (PDPA). A high speed camera was used to record the flame evolution processes. In contrast to pure water mist, the flame propagation speed, the maximum explosion overpressure (ΔP(max)), and the maximum pressure rising rate ((dP/dt)max) decreased significantly, with the "tulip" flame disappearing and the flame getting brighter. The results show that the suppressing effect on methane explosion by ultrafine water/NaCl solution mist is influenced by the mist amount and methane concentration. With the increase of the mist amount, the pressure, and the flame speed both descended significantly. And when the mist amount reached 74.08 g/m(3) and 37.04 g/m(3), the flames of 6.5% and 13.5% methane explosions can be absolutely suppressed, respectively. All of results indicate that addition of NaCl can improve the suppression effect of ultrafine pure water mist on the methane explosions, and the suppression effect is considered due to the combination effect of physical and chemical inhibitions.