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71.
油页岩矿物质催化半焦燃烧特性及机理 总被引:1,自引:0,他引:1
利用微型流化床反应分析仪(MFBRA)研究了油页岩矿物质催化半焦燃烧特性,重点考察了半焦内部矿物质和外部页岩灰床料对半焦燃烧的催化作用,揭示了流化床反应器中半焦燃烧过程和机理。结果表明:内部矿物质和外部床料对半焦燃烧均具有明显催化作用,而两者共同催化效果最为显著。矿物质中CaO和Fe2O3对半焦燃烧具有催化活性,CaO催化作用强于Fe2O3。油页岩半焦燃烧反应活化能在60.41~78.97 kJ/mol之间,矿物质的催化作用会明显降低反应活化能。流化床反应器中,矿物质对半焦燃烧的催化作用主要表现在四个反应,即:挥发分裂解和燃烧、半焦表面炭燃烧、半焦内部炭燃烧以及一氧化碳燃烧。 相似文献
72.
Environmental problems caused by polymers and polymers have historically dominated both academic and industrial attention. Sustainable biodegradable wood-plastic composites (WPCs) as an optimum can solve the environmentally critical problems caused by petroleum-based polymers. However, they are flammable, prone to fire accidents, and often have a contradiction between mechanical performance and flame-retardant properties, which limits their range of applications. Here, we reported a flame-retarded poly(butylene succinate) (PBS) WPC prepared with modified natural fiber-magnesium hydroxide sulfate whisker (MHSH) hybrids and intumescent flame retardant s (IFRs). The mechanical performance, flame-retardant properties , thermal stability, and actual fire simulation parameters of composites were investigated. Owing to the unique composition characteristics of modified cassava dregs-MHSH hybrids, the mechanical properties (70P/23I/5C/2M, flexural strength was 39.2 ± 1.960/MPa, impact strength was 7.95 ± 0.3975/ [KJ/m2]), flame retardant properties (70P/23I/5C/2M, the limiting oxygen index value was 39.6%, UL-94 was V0) and thermal stability of WPC have been improved. Thereby, the balance between mechanical performance and flame retardant properties of biocomposites has been achieved in the practical engineering requirements. Furthermore, cone calorimeter data indicated that modified cassava dregs–MHSH hybrids played a role in improving the fire safety of composites. The total heat release, total smoke produce, toxic gas release, and total oxygen consumed of 70P/23I/5C/2M were lowered compared with those of 70P/25I/5C. Dynamics analysis indicated that the addition of modified cassava dregs–MHSH hybrids increased the activation energy of composites. Based on the experimental and analyses data, especially the morphological characterization of char residue analysis, it illustrated that modified cassava dregs–MHSH hybrids have a reinforcement and flame-retardant effect. The combusted residue of the incorporated modified cassava dregs–MHSH hybrids could support the three-dimensional charred layer formed by the combustion products of the IFR and the PBS. Thus, the more stable three-dimensional charred layer could not only effectively reduce thermal conductivity of composites but also hinder the propagation of heat into the interior substrate, thereby improving the flame-retardant properties of the WPC. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48490. 相似文献
73.
《International Journal of Hydrogen Energy》2020,45(16):9353-9367
Hydrogen addition effectively reduces the fuel consumption of spark ignition engines. We propose a new on-board reformer that produces hydrogen at high concentrations and enables multi-mode operations. For the proposed reformer, we employ a catalytic fuel decomposition reaction via a commercial NiO–CaAl2O4 catalyst. We explore the physical and chemical aspects of the reforming process using a fixed bed micro-reactor operating at temperatures of 550–700 °C. During reduction, methane is decomposed to form hydrogen and carbon. Carbon formation is critical to hydrogen production, and free space for carbon growth is essential at low temperatures (≤600 °C). We define a new accumulated conversion ratio that quantitatively measures highly transient catalytic decomposition. The free space of the coated monolith clearly aided low-temperature decomposition with negligible pressure drop. The coated substrate is therefore suitable for on-board applications considering that our reformer concept also utilizes the catalytic fuel decomposition reaction. 相似文献
74.
Erfan Khodabandeh Hesam Moghadasi Mohsen Saffari Pour Mikael Ersson P r G. J nsson Marc A. Rosen Alireza Rahbari 《中国化学工程学报》2020,28(4):1029-1038
This research investigates a numerical simulation of swirling turbulent non-premixed combustion. The effects on the combustion characteristics are examined with three turbulence models: namely as the Reynolds stress model, spectral turbulence analysis and Re-Normalization Group. In addition, the P-1 and discrete ordinate (DO) models are used to simulate the radiative heat transfer in this model. The governing equations associated with the required boundary conditions are solved using the numerical model. The accuracy of this model is validated with the published experimental data and the comparison elucidates that there is a reasonable agreement between the obtained values from this model and the corresponding experimental quantities. Among different models proposed in this research, the Reynolds stress model with the Probability Density Function (PDF) approach is more accurate (nearly up to 50%) than other turbulent models for a swirling flow field. Regarding the effect of radiative heat transfer model, it is observed that the discrete ordinate model is more precise than the P-1 model in anticipating the experimental behavior. This model is able to simulate the subcritical nature of the isothermal flow as well as the size and shape of the internal recirculation induced by the swirl due to combustion. 相似文献
75.
针对红阳二矿12号煤层遗煤氧化的规律与特点,有效地进行防灭火工作,掌握采空区中遗煤氧化的速度,对红阳二矿12号煤层进行了煤样升温氧化实验,在温度不断升高的过程中检测出CO与多种烯烃气体,并且在不同温度下煤体析出气体的速度不同,最终选择CO、C2H4、C2H2作为标志性气体,产生的临界温度分别为59、176、403 ℃。在采空区检测出CO气体,说明采空区遗煤进入快速氧化阶段;检测出C2H4气体时,遗煤进入剧烈氧化状态;检测出C2H2气体时,说明采空区中已经产生明火,井下人员需要迅速撤离。通过煤体标志性气体的确定,建立12号煤层自燃预警系统,保证井下工作人员的生命安全与能源的充分利用。 相似文献
76.
以五虎山煤矿010908工作面为背景,采用理论分析、数值模拟和现场实测等手段对浅埋深高瓦斯工作面瓦斯抽放对采空区自燃"三带"影响进行研究。研究结果表明:当瓦斯绝对涌出量与采空区漏风量处于均衡状态时,此时瓦斯对煤自燃将出现明显的耦合影响;当采空区漏风量小于瓦斯绝对涌出量时,采空区遗煤自燃将受到阻碍;与之相反,当漏风量大于瓦斯涌出量时,采空区遗煤自燃受瓦斯涌出量的影响较小;高位钻孔与工作面距离越远,采空区内部的漏风路径也越长,采空区氧化带、窒息带所处的区域越向采空区深部扩大,但靠近工作面一侧的氧化带范围并没有出现明显变化。 相似文献
77.
Karen S. Torosyan Alexey S. Sedegov Kirill V. Kuskov Mohammad Abedi Dmitry I. Arkhipov Philipp V. Kiryukhantsev-Korneev Stepan Vorotilo Dmitry O. Moskovskikh Alexander S. Mukasyan 《Journal of the American Ceramic Society》2020,103(1):520-530
The influence of different SPS-based methods, that is, conventional spark plasma sintering (SPS), flash SPS (FSPS), and reactive SPS (RSPS) on the properties of Al2O3/SiC composite was investigated. It was shown that the application of preliminary high energy ball milling of the powders significantly enhances the sinterability of the ceramics. It was also demonstrated that FSPS provides unique conditions for rapid, that is, less than a minute, consolidation of refractory ceramics. The Al2O3-20 wt% SiC composite produced by FSPS possesses the highest relative density (~99%), fracture toughness (7.5 MPa m1/2), hardness (20.3 GPa) and wear resistance among all ceramics produced by other SPS-based approaches with dwelling time 10 minutes. The RSPS ceramics hold the highest Young's modulus (390 GPa). Substitution of micron-sized Al2O3 particles by nano alumina does not lead to measurable enhancement of the mechanical properties. 相似文献
78.
《International Journal of Hydrogen Energy》2019,44(47):25277-25286
The different methods for the generation of hydrogen are well known, as well as their applications, advantages and complications for their use. Every day it is essential to replace fossil fuels, so it is necessary to improve and take advantage of the different devices that we already have. The alkaline electrolyser is one of the best options, due to the simplicity of its components and its simple assembling; it is a relatively inexpensive device for the production of hydrogen. In this article, three different alkaline electrolyser stacks are presented, ECH-001 model. The difference between them lies in the fact that the configuration of the electrode changes with the number of drill holes. This has the purpose of optimizing the maximum productivity of the oxyhydrogen gas (OH2G) with respect to input power and the performance with different operation parameters, like the number of serial plates, geometry and the distance between them. The performance curves of parallel and serial arrangements are shown. The performance of a DEKTM diesel engine (monocylinder of 406 cc) with and without OH2G was evaluated, with flows of one, two and three sL min-1. Tests for CO, CO2, HC and NOx emissions were measured using the exhaust gas analyzer and varying the engine speed. The results show that the electrolyser assembly with four holes electrodes achieved the best performance with an OH2G productivity of 2 sL min-1 when using; 7 serial plates at the anode (which is called arrangement 1, 5–10), 3 mm gap and a 5% solution of NaOH. The results also shows a 14% reduction in fuel consumption, 22% reduction in HC, 23% reduction in CO, 7% reduction in CO2 and 15.5% NOx reduction with 2 sL min-1 of OH2G all this for 2500 rpm. The obtained results show a great advantage for the use of dual combustion with the diesel-hydrogen combination. 相似文献
79.
《International Journal of Hydrogen Energy》2019,44(47):26063-26075
The need of fast regulation of electricity production leads to a number of inconveniences occurred to the electric generation system and the electric market, especially to the nuclear power. A new concept to control nuclear power production is posed in order to allow the regulation of the electricity sent to the grid. This concept proposes the joint operation of a nuclear power plant, a coal power plant with postcombustion capture and a methanation plant. The cost effectiveness of this technology and its capability to reduce the CO2 emissions -consumed in the methanation process- are assessed through the design and economic and environmental analysis of a hybrid facility. Mainly due to the increase of the operating hours of the coal-fired power plant, the environmental feasibility of the initial proposal seems to be limited. However, given that benefits are expected in the medium and long-term (2020–2030) for the Power to Gas facility, a future alternative use is proposed. The target of this new alternative configuration will be the storage of CO2 together with the storage of renewable energy. 相似文献
80.
《Advanced Powder Technology》2022,33(1):103377
Hierarchical structure and surface properties of selective support afford some special effects on the catalytic activity, which could be tuned to achieve improved performance. Herein, using a combination of hydrothermal coprecipitation and thermal processing, we integrated highly-distributed Co3O4 spinel nanospecies on laminated hierarchically structured Al2O3 which could be used as a highly efficient VOCs treatment catalyst. Impressively, compared to Co-free Al2O3 counterpart (SBET = 188.2 m2·g?1), these obtained Co3O4 spinel functionalized catalysts are endowed with adjustable Co loading, optimized Co activity state, and obviously improved hierarchically structural properties (SBET = 274.7 m2·g?1). The microporous and mesoporous structures both existed in the obtained Al2O3, which is beneficial to the heterogeneous catalytic reaction process. The results reveal that the proper Co loading in the hierarchically structured Al2O3 could enable the rational modulation of catalytic activity in the combustion of toluene and exceeds the commercial 5 wt% Pd/C catalyst in the light of total catalytic oxidation ability. This developed heterogeneous Co3O4 compositing hierarchically structured Al2O3 provides a significant potential value for practical VOCs treatment. 相似文献