Current Issue : October - December Volume : 2019 Issue Number : 4 Articles : 5 Articles
LPG olefins (propene and butenes) are key building blocks in the petrochemical industry whose demand has been expanding\nsteadily in recent years. The use of FCC (fluid catalytic cracking) units for conversion of triglycerides is a promising option for the\nfuture to boost production of LPG olefins. However, a need for innovative cracking catalysts is rising due to the different nature\nbetween petroleum and biomass-derived feedstocks. In this study, series of hierarchical ZSM-5 materials, namely, mesoporous\nZSM-5, nanosized ZSM-5, and composite ZSM-5 were prepared, aiming to enhance the production of LPG olefins along with\ntransportation fuels. Mesoporous ZSM-5 materials were synthesized by the postsynthetic modifications involving base treatment\nand subsequent acid washing, whereas nanosized ZSM-5 and composite ZSM-5 were synthesized by the direct-synthetic routes for\na comparative purpose. The obtained materials were characterized by XRD, FTIR, N2 sorption, TEM, AAS, ICP-AES, and NH3-\nTPD, and their catalytic performance was assessed in the cracking of triolein as a representative of triglycerides under FCC\nconditions. It was found that the subsequent strong acid washing step of alkaline treated ZSM-5 for removal of aluminum debris\nand external acid sites is needed to improve the catalytic performance. The resulting mesoporous ZSM-5 material shows higher\nyields of the desired products, i.e., gasoline and LPG olefins than its parent, commercial ZSM-5 at the almost complete conversion\n(ca. 90 wt.%). The selectivity toward LPG olefins is also enhanced over all the hierarchical ZSM-5 materials, particularly high for\ncomposite ZSM-5 (ca. 94 wt.%). The improved diffusion and lowered acidity of the hierarchical ZSM-5 materials might be\nresponsible for their superior catalytic performance....
Ammonium phosphate fire-extinguishing agents are one of the best substitutes for halon in many powder media. Here, 11 micro m\nmedian diameter ammonium phosphate ultrafine dry powder was used as a fire-extinguishing medium. The fire-extinguishing\nperformance of ultrafine powder under different pressures was studied by analyzing fire-extinguishing time, amount of\nextinguishing agent, and temperature during the fire-extinguishing process. The results show that the fire-extinguishing performance\nof the ultrafine powder is improved with increasing injection pressure. Finally, we used FDS software for fire simulation\nto study the influence of injection pressure on the extinguishing agent. The results show that the extinguishing time is shortened\nwith increasing injection pressure. From 0.2 MPa to 1.0 MPa, the extinguishing time decreases from 34 seconds to 4 seconds....
A simplified single channel wave rotor combustor (WRC) experimental rig was established, in which the spoilers with different\nblockage ratios (BR) could be conveniently installed and disassembled. The spoilers were firstly used for WRC to improve the\npressure rise. The effects of different blockage ratios on the pressure rise and flame acceleration characteristics in a single\nchannel of the WRC were investigated. The addition of spoilers could remarkably improve the pressure rise and flame\npropagation speed in a single channel of the WRC. While the blockage ratio of the spoiler increases, both pressure rise and\nmean flame propagation speed are improved. When the spoilers with a blockage ratio of 38.91% are used, the peak pressure\nincreases by 200% compared to that of WRC without the spoilers. When the spoilers of different blockage ratios (23.35%,\n31.13%, and 38.91%) are used, it is found that the flame propagation speed is significantly improved with the increasing of the\nblockage ratio. Specifically, the maximum flame propagation speed reaches 55 m/s, and the maximum mean flame propagation\nspeed is 36.95 m/s. Furthermore, combustion becomes more intense, and the flame is brighter around the spoiler....
Computational Fluid Dynamics (CFD) simulations of airflow through a retention\nhead residential oil burner were carried out to study the velocity field\nnear and around the fuel spray. The simulations revealed (as expected, based\non some previous experimental measurements) the velocity flow field to be\nfar from axisymmetric. Moreover, the center of the swirling airflow was found\nto be at some radial distance away from the physical center line of the flame\ntube. Since it was suspected that the two electrodes just upstream of the retention\nring of the burner might be responsible for this flow distortion, additional\nCFD simulations were then carried out for the cases of no electrodes\nand 4-electrodes. The results clearly show that all flow distortions (velocity\ndeviations from axisymmetric value) vanish when no electrodes are present\nand that the flow distortions are reduced by a factor of 2 when two additional\ndummy electrodes (for a total of 4 electrodes) are included in the burner design.\nFurthermore, for the 4-electrode case, the eccentricity of the swirling\nairflow is reduced by almost a factor of 3 as compared to the base design case\nof 2-electrodes....
Strain measurement is an important component in model tests of combustible internal explosions. Strain gauges are used to\nmeasure strain in traditional electrical measurement methods and have some limitations, such as susceptibility to electromagnetic\ninterference, short life, and inability to distribute. Fiber Bragg gratings (FBGs) are developing into useful sensing tools that can\nrespond to changes in stress, strain, and temperature by changing wavelengths. FBGs have excellent sensing performance, such as\nlong life, antielectromagnetic interference, easy networking, and good reusability. In this paper, FBG sensors are applied to strain\nmonitoring in ethylene flammable implosion experiments. In the ethylene flammable implosion tests, an FBG was placed on the\ninner surface of the bottom plate of the rectangular steel test device near the detonation vent by the sticking method. -e reliability\nand repeatability of the strain change of the FBG affected by detonation overpressure and combustion were tested at this point.\nFour explosion tests were carried out. -e test results showed that FBG sensors could obtain stable and reliable strain data in all\nfour tests. -e strain variation reflects the development of overpressure and combustion in the whole process from ignition. For\nthe strain amplitude formed by overpressure, the minimum was...........................
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