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关于影响煤燃烧固硫反应的主要因素及其机理的研究进展 总被引:1,自引:0,他引:1
燃烧过程中的脱硫是锅炉脱硫工艺的重要组成部分之一 ,已被广泛应用于各种流化床锅炉和煤粉炉中。为开发低成本、高效率的燃煤固硫技术 ,世界各国学者进行了大量的实验和机理性的研究。本文对这方面的研究进展做了总体回顾 ,并在前人研究的基础上提出了关于燃烧过程中固硫化学反应机理研究的发展趋势。 相似文献
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Jin Jing Zhang Zhongxiao Li Ruiyang 《Frontiers of Energy and Power Engineering in China》2007,1(1):91-95
Numerical simulation and experimental study on NO
x
release along the boiler during pulverized coal combustion have been conducted. With the increase of temperature the NO
x
emission increased and the peak value of NO
x
release moved forward. But when the temperature increased to a certain degree, NO
x
emission began to reduce. NO
x
emission increased with the increase of nitrogen content of coal. The peak value of NO
x
release moved backwards with the increase of coal rank. NO
x
emission increased obviously with the increase of stoichiometric ratio. There existed a critical average diameter of the
pulverized coal (d
c
). If d ⩽ d
c
, NO
x
emission reduced with the decrease of pulverized coal size. If d > d
c
, NO
x
emission reduced with the increase of the pulverized coal size. The results showed that the simulation results are in agreement
with the experimental results for concentration distribution of NO
x
along the axis of the furnace.
Translated from Proceeding of the CSEE, 2006, 26(1): 35–39 [译自: 中国电机工程学报] 相似文献
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《能源学会志》2020,93(4):1460-1472
Chemical Looping Combustion (CLC) is one of the emerging technologies for carbon capture, with less energy penalty. The present way of using pulverized coals in a fluidized bed (FB)-CLC have limitations like loss of unconverted char and gaseous combustibles, which could be mitigated by use of coarser fuel particles. Devolatilization time is a critical input for the effective design of FB-CLC systems, primarily when large fuel particles are used. The present study investigates the devolatilization time and the char yield of three coals of two shapes, namely, two high ash Indian coals and a low ash Indonesian coal and a wood (Casuarina equisetifolia) in the size range of +8–25 mm, at different fuel reactor temperatures (800–950 °C) of a hematite based CLC unit. The devolatilization times of single fuel particles during CLC are determined using a visual method called ‘Color Indistinction Method’. Indonesian coal has the longest devolatilization time among the fuels, and biomass has the least. Increasing the bed temperature enhances the rate of volatile release, whereas this effect is less pronounced in larger particles. Devolatilization of Indonesian coal is found to be strongly influenced by the changes in operating conditions. With the decrease in sphericity, a maximum of 56% reduction in devolatilization time is observed for the +20–25 mm slender particles of Indonesian coals when compared to the near-round particles. The maximum average char yields at the end of the devolatilization phase for coal and biomass are about 55–76% and 16% respectively. Char yield in coal particles increases with an increase in particle size, whereas biomass particles show relatively consistent yield across all experimental conditions. Increase in bed temperature reduces the char yields of coal up to 12% and in biomass up to 30%. High volatile Indian coal is the most influenced fuel by the changes in fuels shape. A correlation for determining devolatilization time under CLC environment is presented, and it successfully fits most of the experimental values within ±20% deviation for coals (R2 = 0.95) and within ±15% deviation for biomass (R2 = 0.97). 相似文献
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文章通过稀薄氨气在固定床反应器中的燃烧,研究了反应温度、停留时间、氨气浓度和氧气浓度对低浓度氨气燃烧特性的影响,并描述了氨气在氧气过量条件下在陶瓷蜂窝蓄热体中燃烧的动力学过程。研究结果表明:提高反应温度、延长停留时间以及增大氧气浓度和氨气浓度均可以提高NH3转化率,氧气浓度过高会促进NO生成;当反应温度为740~770℃、氨气浓度为1%、氧气浓度为15%时,氨气在陶瓷蓄热体中燃烧的活化能为253.56 kJ/mol;与氨气在自由空间内的燃烧相比,氨气在陶瓷蜂窝蓄热体中主要发生表面燃烧反应。 相似文献
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《可再生能源》2014,(10)
采用热重分析仪研究了棉秆、玉米芯和大同煤以及它们之间混合燃料的富氧燃烧特性。分析了富氧条件混合燃料的燃烧特征参数,如着火温度、峰值燃烧速率及其对应温度、燃尽温度及综合燃烧特性指数。采用Coat-Redfern法计算混合燃烧动力学参数。结果表明:在O2/CO2气氛下,提高氧气浓度可以改善生物质与煤混合燃料的燃烧反应,降低燃尽温度,使混合燃料的燃烧反应向低温区域移动;燃烧反应活化能在挥发分析出和固定碳燃烧的两个阶段均增大;但生物质与煤的掺混比例在30%情况下,氧气浓度的变化对混合燃料的着火温度的影响规律并不明显。在50%O2/50%CO2气氛下,随着生物质比例的增加,所有特征参数向低温区域前移,混合燃料燃烧反应活化能在挥发分析出阶段逐渐减小,在固定碳燃烧阶段逐渐增大。Coat-Redfern模型可以较好的描述棉秆或玉米芯与大同煤混合物在空气或富氧条件下的主要燃烧过程。 相似文献
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《能源学会志》2020,93(5):2074-2083
Gaseous sulfur is released during fluidized bed coal gasification, and control the yield of gaseous sulfur or the conversion between gaseous organic sulfur and inorganic sulfur at source is necessary, because it can economically satisfy the requirements of industrial production and protect the environments. In this study, sulfur release behaviors of a middle-sulfur coal called Guizhou coal were quantitatively determined through controlled experiments in a lab-scale fluidized bed during oxygen rich-steam gasification. The measured gaseous sulfur species were H2S, SO2, COS and CS2. The effects of temperature (850OC-950OC) and limestone (Ca/S = 2) on the sulfur release behaviors were investigated. Among the above four gaseous sulfur, the yield of H2S is the highest, followed by COS, while only less than 1.5% of sulfur in coal is released as SO2 and CS2. With the increase in temperature, the yield of H2S increases while that of SO2 decreases, and the change of COS yield and CS2 yield is not obvious. The molar ratio of H2S/COS increases with increasing temperature, which is qualitatively matched by thermodynamic analysis. The addition of limestone reduces the released sulfur but not change the distribution of gaseous sulfur forms. Meanwhile, the molar ratio of H2S/COS increases after adding limestone, while the trend with temperature of H2S/COS does not change. The removal rate of H2S is between 23% and 28%, which increases with temperature. The distributions of sulfur in bottom char and fly ash are similar. The main sulfur species in the bottom char is organic sulfur, and thiophene dominates the organic sulfur. The increase of temperature and the addition of limestone will both promote the increase of inorganic sulfur content, and the decrease of organic sulfur content. 相似文献
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《International Journal of Hydrogen Energy》2020,45(30):15142-15156
Uniform mesoporous alumina (MA) nanospheres with excellent thermal stability and controllable pore size distribution were facilely obtained through ultrasonic assisted sol-gel method then taken as carriers for synthesizing a series of supported palladium catalysts. Results evidenced that the pore size distribution of MA significantly affected the catalytic performance of as-prepared catalysts. More importantly, the methane pretreatment tuned valence state of palladium species and distribution of surface oxygen species, along with promoting the adsorption of CH4 on catalysts and the generation of CH31 group to form methane-derived adsorbates. Moreover, the synergistic effect of PdO and surface adsorbed oxygen effectively activated CH4 and invoked the oxidation of methane-derived adsorbates, hence boosting the catalytic activity with the 90% CH4 conversion temperature (T90) decreased by 40 °C relative to the unpretreated catalyst. Noticeably, the T90 of Pd/MA(CH4) catalyst could be attained at 380 °C after subsequent long term and cyclic stability test. 相似文献
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Meijun Wang Chunhui Fu Kechang Xie 《Energy Sources, Part A: Recovery, Utilization, and Environmental Effects》2016,38(3):347-353
Two Chinese coals were selected to investigate the effects of flotation on the release behavior of sulfur and nitrogen during pyrolysis. The results show that the removal rate of minerals and sulfur-containing compounds from raw coal by flotation are closely related to coal properties. The significant alterations of sulfur and nitrogen forms on coal surface are mainly presented in the decrease of sulfidic-S, thiophenic-S, and pyridinic-N, the increase of sulfones-S and quaternary-N after flotation. The release of sulfur- and nitrogen-containing gases during pyrolysis of raw and clean coals has evident differences, which are mainly caused by the change of the relative proportions of different sulfur and nitrogen forms in the process of flotation. 相似文献
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《能源学会志》2020,93(6):2388-2398
This paper studied the effect of high temperature (up to 1873K) and separated combustion mode (volatile combustion and char combustion are separated) on SO2 release characteristics during pulverized coal combustion under O2/CO2 atmosphere. Coal combustion experiments were conducted at different combustion environment temperatures utilizing a high temperature fixed-bed setup. The results show that as temperature rises, the SO2 release curve is transformed from a single-peak process to a double-peak process. In separated combustion, temperature has little effect on the volatile-SO2 (SO2 released during volatile combustion) but brings about a significant effect on char-SO2 (SO2 released during char combustion). Char-SO2 release amount and the ratio of it to fuel-SO2 release amount (total SO2 released during coal combustion) increase with temperature rising. The increase of temperature leads to a dramatic decreasing of sulphur mass fixed in the ash and causes SO2 release amount to rise when temperature is lower than 1573 K. Separated combustion causes a higher SO2 release amount than coupled combustion (the same as conventional combustion, volatile combustion and char combustion are simultaneous). Thermochemistry equilibrium composition calculation results show that alkali metals and alkaline-earth metals are significant in sulphur retention. CaSO4 and Na2SO4 are the main sulphates at high temperatures. 相似文献
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《International Journal of Hydrogen Energy》2022,47(12):8060-8070
Based on the self-designed and developed gas mixture combustion and flame ion current measurement and control system, this paper studies correlation research between the ion current integral signal and combustion pressure under different initial pressures, equivalent ratios and hydrogen and carbon dioxide volume fractions. The experiments obtained the change rules under the different initial parameters of the ion current waveform and combustion pressure waveform along with the combustion time, the change rules of the characteristic parameters of ion current integral signal (, ) and combustion pressure (, ) are analysed, revealing a high correlation between the and the ; a method for timely and effective determining the pressure peak moment using ion current integral signals is presented. The conclusions of this study provide new technological approaches for effectively and accurately acquiring the combustion pressure information of gas mixture in cylinders using ion current integral signals, thereby realising accurate combustion control. 相似文献
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Jerald A. Caton 《国际能源研究杂志》2012,36(3):368-384
The second law of thermodynamics provides different perspectives compared with the first law, and provides the property exergy. Exergy is a measure of the work potential of energy from a given thermodynamic state. Unlike energy, exergy may be destroyed, and for reciprocating engines, the major source of this destruction is during the combustion process. This paper provides an overview of the quantitative levels of exergy destruction during the combustion process as function of engine operating and design parameters, and for eight fuels. The results of this study are based on a spark‐ignition, automotive engine. The amount of exergy destroyed during the combustion process has been determined as functions of speed, load, equivalence ratio, start of combustion, combustion duration, combustion rate parameters, exhaust gas recirculation (EGR), inlet oxygen concentration, and compression ratio. In addition, design parameters that were examined included expansion ratio and the use of turbocharging. The fuels examined included isooctane (base), methane, propane, hexane, methanol, ethanol, hydrogen and carbon monoxide. For the part load base case (1400 rpm and a bmep of 325 kPa) using isooctane, the destruction of exergy was 20.8% of the fuel exergy. For many of the engine operating and design parameter changes, this destruction was relatively constant (between about 20 and 23%). The parameters that resulted in the greatest change of the exergy destruction were (1) equivalence ratio, (2) EGR, and (3) inlet oxygen concentration. For the base case conditions, the exergy destruction during the combustion process was different for the different fuels. The lowest destruction (8.1%) was for carbon monoxide and the highest destruction (20.8%) was for isooctane. The differences between the various fuels appear to relate to the complexity of the fuel molecule and the presence (or absence) of an oxygen atom. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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针对锅炉燃烧优化存在的问题,通过对电站锅炉应用燃烧优化技术现状的分析,指出了燃烧优化闭环控制系统的一种发展方向,提出了燃烧可视化监测和闭环控制系统研究课题,并详细介绍了课题研究内容与组成模块. 相似文献
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乳化燃油理化特性及在内燃机中的燃烧和排放 总被引:3,自引:0,他引:3
研究开发新型代用燃料已成为解决能源短缺、环境污染问题的主要途径之一,而乳化燃油燃烧技术被视为是一种降低油耗、改善放的有效手段。文章根据 多年来国内外学者所作的研究,就乳化油的稳定性、着火延迟以及节油和降低排放的机理等问题的研究现状进行了综合评述。 相似文献
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