共查询到20条相似文献,搜索用时 62 毫秒
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研究了热态流化床实验台中燃烧褐煤、烟煤和无烟煤时SO_2、NO和N_2O同步排放浓度随过量空气系数、燃烧温度和钙硫比的变化规律。试验中过量空气系数变化范围为0.8~1.8,燃烧温度变化范围为750~950℃,钙硫比变化范围为0~3。结果表明:过量空气系数增加时NO和N_2O的排放浓度增加,SO_2排放浓度先增加后降低;燃烧温度增加时NO排放浓度增加,N_2O排放浓度降低,SO_2的排放浓度增加;加入碳酸钙后NO排放量增加,N_2O和SO_2的排放量减少。加入碳酸钙后可以有效降低SO_2排放,同时会使NO排放增加、N_2O排放降低;烟煤、无烟煤和褐煤燃烧时NO、SO_2和N_2O随过量空气系数的变化规律存在差别。 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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循环流化床能实现高氧气浓度下的O2/CO2燃烧,进而减少燃烧室尺寸并降低再循环烟气量.本研究使用两种烟煤、一种褐煤,分别在15 kW循环流化床试验系统和0.15MW循环流化床试验系统上进行试验,研究了氧气浓度对NOx和N2O的影响.结果表明,3个煤种均在一次风氧气浓度44.3% ~55.3%、二次风氧气浓度43.2%~ 60.2%下实现稳定燃烧.氧气浓度约50%燃烧时,煤中氮向NOx的转化率降低到空气气氛燃烧的19% ~ 60%,煤中氮向N2O的转化率降低到空气气氛燃烧的20% ~81%. 相似文献
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《能源学会志》2020,93(1):1-14
The difference in combustion performance between brown coal and black coal blended with Eucalyptus woodchip and woodchar in varying blending ratios were examined in the air and oxy firing conditions. On top of the experimental investigation using a drop tube furnace (DTF), a computational fluid dynamics (CFD) model was further developed to interpret these results, validated using the experimental data. The CFD model incorporates a comprehensive reaction for devolatilisation reaction to predict the gas release utilising predictions based on chemical percolation devolatilisation (CPD) model. The heterogeneous reactions are defined based on the intrinsic reaction model that accounts for the influence of char properties in chemical and pore diffusion reactions using a user-defined function (UDF). Moreover, the C–CO2 gasification reaction rate which is critical in an oxy-firing mode was further studied using the CFD tool to determine how the role of gasification varied for various fuel blends. Based on carbon burnout and average particle temperature profiles, the blending of woodchips is highly beneficial to the overall combustion performance in particular for low reactive black coal while its effect on brown coal is marginal. Woodchar and black coal are comparable with similar temperature plots and relatively constant burnout but it behaves relatively inert with a highly reactive brown coal. During oxy firing, increasing the woodchip content enhanced the effect of C–CO2 gasification due to its extremely large pre-exponential factor for the CO2 gasification reactivity which explains the improved burnout. The blending of woodchar caused a gradual reduction in the gasification extent for both coals explained by the low heating rates under which woodchar was pyrolysed and also due to the decrease in the peak particle temperature. However, the observed gasification was found to be less than the expected value based on the linear addition of the two single fuels for both biomass blends. 相似文献
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Ge Pu Wending Wang Ruixiang Peng Weilin Zhu Fangyuan Zhao Fanxuan Fu 《Energy Sources, Part A: Recovery, Utilization, and Environmental Effects》2016,38(23):3497-3503
A fixed-bed combustion system was used to study the NO emission characteristics of co-combustion of biomass and coal in an O2/CO2 atmosphere. With the concentration of oxygen varied in 21%, 30%, and 40% while the biomass blended proportion mounts raised from zero to 10% then to 30%, the generated NO was classified to Vdaf-NO and FCad-NO, respectively, and the emission rate and conversion ratio of NO were analyzed. The results showed that the NO emission rate and concentration increased with increase in oxygen concentration, but the conversion ratio decreased. Meanwhile, the blended biomass reduced the NO emission concentration and conversion ratio. 相似文献
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《能源学会志》2020,93(3):1125-1137
Non-isothermal thermogravimetric analysis was employed to study the combustion reaction behavior of three different hydrochars and one anthracite in the paper. The particle size distribution analysis, scanning electron microscopy, specific surface area and Raman spectroscopy were also used to observe and characterize physiochemical properties. The Coats-Redfern kinetic model method was used to calculate the activation energy of different combustion reactions. The results showed that the combustion of fiber reject had a more effective combustion property than the other two hydrochars. The main reason was that fiber reject had higher specific surface area and lower carbon microcrystalline structure. Meanwhile, the co-combustion of different hydrochars with coal had similar combustion trends, and with the increase of hydrochar proportion, the combustion rate was higher. The results of the kinetic calculation correspond to this conclusion. It can be found that as the proportion of the three hydrochar increased, the activation energy of two stages gradually decreased. 相似文献
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利用热重分析仪,在空气氛围下对工业污泥、煤及两者的掺混物进行了热重实验,得到掺混物的TG和DTG曲线以及表征燃烧特性的着火温度、燃尽温度、最大燃烧速率、可燃性指数和综合燃烧特性指数等。通过稳态模拟软件Aspen plus建立了污泥和煤的掺混燃烧模型,研究过量空气系数对掺混燃烧性能的影响。结果表明:①掺混比为5∶5,6∶4,7∶3时,混合物的燃烧范围最大,而掺混比为5∶5时混合物的可燃性最好,燃烧速度快,燃尽时间也较短;②过量的空气能增加湍流度,提高燃烧效率,但会降低炉内温度,增加SO3的生成。对于质量比为5∶5的混合物,过量空气系数应控制在1.6左右。 相似文献
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为了探究市政污泥燃烧过程中的气态污染物排放特性,在30 kW鼓泡流化床实验台上进行了市政污泥的燃烧实验,研究燃烧温度、二次风率、秸秆掺混比等参数对气态污染物排放特性的影响。结果表明:燃烧温度的升高会显著提高NO与SO2的排放;提高二次风率使NO排放浓度减少,SO2排放浓度增加;由于生物质中较低的N、S含量以及生物质与污泥燃烧的协同作用,污泥掺烧生物质能够有效地减少NO与SO2的排放;秸秆占比由0提升至40%,NO由289 mg/m3下降至140 mg/m3,而SO2排放浓度也从3 949 mg/m3下降至1 725 mg/m3;污泥掺烧秸秆时,NO与SO2的整体排放特性与污泥单独焚烧相似,掺烧秸秆能够加快整体的燃烧速率,并加强燃烧气氛的氧化性,进而影响气态污染物的排放。 相似文献
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文章利用沉降炉系统开展了河南烟煤与海草和桃木两种生物质的混燃成渣特性实验,对混燃灰的理化性能、矿物质转化过程及其聚集成渣的趋势进行了研究。研究结果表明:藻类生物质海草能够加剧混燃灰渣颗粒的聚集成块趋势,而木本生物质桃木仅造成混燃灰颗粒粒径的略微增长;掺混海草导致混燃灰中的碱金属,Cl和S元素含量增加,灰渣中出现大量低熔点的长石和类长石矿物质,从而增强了灰渣的黏附能力,表现为由包覆引起的成渣机制;掺混桃木的混燃灰因含有较高的Ca和Fe等元素,从而生成了较多的能够抑制低温共熔物形成的钙质硅(铝)酸盐,其提高了混燃灰的熔融温度,并减缓了成渣趋势;藻类生物质中的碱金属,Cl和S等元素除对成渣过程有较大影响外,还会引起冷凝腐蚀等问题,从而对其资源化应用产生负面影响。 相似文献
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Dong Yu 《Energy Sources, Part A: Recovery, Utilization, and Environmental Effects》2016,38(7):994-1001
The oxy-fuel co-combustion behavior of two herbaceous biomass species (Bermuda grass and cornstalk) with bituminous coal was investigated by thermal gravimetric analysis (40°C/min). The incorporation of Bermuda grass or cornstalk could improve combustion indices of the bituminous coal. Once blending the biomass with bituminous coal, ignition temperatures of blends could be advanced by about 100–170°C. With increasing the oxygen concentration or blending ratio, the comprehensive performance index of the most blends and their parent samples increased. For the 80%grass/20%coal blend, there was a strong synergistic effect in its parent samples at 60% oxygen concentration. 相似文献
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Dongdong Feng Dawei Guo Yijun Zhao Heping Tan Guozhang Chang Tianpeng Zhang Shaozeng Sun 《能源学会志》2019,92(6):1670-1682
Oxygen-fuel combustion is a promising technology for CO2 emission reduction. The high-temperature entrained flow reactor and high-temperature drop tube furnace were used to analyses the formation and O2/CO2 combustion characteristics of real-environment coal char in high-temperature oxy-fuel conditions. It proposed “inflection point standard” of high-temperature flame method for the preparation of real-environmental oxy-fuel coal char according to the flame method. The results show that the ratios of C=O/C-O and C=O/Car increase in the coal char compared with the raw coals. The trend of C=O/Car in oxy-fuel condition is opposite to that in the inert atmosphere, due to the effect of high-concentration CO2. To achieve the burnout rate similar to air combustion for coal char, with the increase of coal rank, the O2 concentration should be enhanced. The optimal O2 concentration for the oxy-fuel combustion of JC anthracite is 30%, while that of other low-rank coals could be lower than 30%. The combustion characteristic of JC anthracite is with the highest sensitivity to temperature and O2 concentration. 相似文献
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In this study, two types of coals were used as the reburning fuel to investigate the influence of the reburning zone stoichiometry SR2, the primary NO level and the particle size on NO reduction. For both coals, the NO reduction can reach as high as 60–70% in the tested SR2 range of 0.7–1.1. No optimum reburning zone stoichiometry was observed in this study. The NO reduction decreases monotonically with the decrease of reburning zone stoichiometry. The effect of particle size is only obvious for larger particle sizes. 相似文献