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An atmospheric test system of dual fluidized beds for coal multi-generation was built.One bubbling fluidized bedis for gasification and a circulating fluidized bed for combustion.The two beds are combined with two valves:one valve to send high temperature ash from combustion bed to the gasification bed and another valve to sendchar and ash from gasification bed to combustion bed.Experiments on Shenhua coal multi-generation were madeat temperatures from 1112 K to 1191 K in the dual fluidized beds.The temperatures of the combustor are stableand the char combustion efficiency is about 98%.Increasing air/coal ratio to the fluidized bed leads to theincrease of temperature and gasification efficiency.The maximum gasification efficiency is 36.7% and thecalorific value of fuel gas is 10.7 MJ/Nm3.The tar yield in this work is 1.5%,much lower than that of pyrolysis.Carbon conversion efficiency to fuel gas and flue gas is about 90%. 相似文献
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Fluidized bed combustion offers great potential for the utilization of high-sulphur coal and low-grade coal in an environmentally acceptable manner. Utilization of fluidized bed technology, especially for the combustion of low quality lignites, enables pollutant emission control as well as efficient combustion. The most important stage during the combustion of coal particles is devolatilization, in which various factors such as heat transfer from the surroundings to the particle surface, heat conduction within the particle, the chemicals involved, the kinetics and the transport of volatile compounds within the particle play significant roles. The heat transfer coefficient, thermal diffusivity, thermal conductivity, heating coefficient and lag factor are the most significant thermal parameters in this process. In this study, a 1-D transient heat transfer analysis is carried out for a granular coal particle during devolatilization in a fluidized bed. The particle is idealized as a spherical solid body. Models are developed to determine the thermal parameters of such particles, and are verified using experimental centre temperatures of a 10 mm granular coal particle subjected to devolatilization at a medium temperature of 960 K. The data are taken from the literature. The results show that the thermal parameters determined here are in good agreement with experimental findings. 相似文献
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The aim of this paper is to increase the understanding of the role of the binary circulating fluidized bed in the process of clean and ecological coal combustion. The operating range of a stable fluidized bed, as a function of gas velocity changes and the flow rate of fine particles, is determined for all possible conditions. Experiments concerning the combustion and desulfurization processes in multi-solid fluidized bed (MSFB) and circulating fluidized bed (CFB) systems give evidence that the residence time of burnt particles in the combustion chamber of MSFB is much extended. This is directly reflected in better combustion conditions, especially those for fine particles, as well as in the process of desulfurization. The advantages of the binary circulating fluidized bed over typical circulating systems make it one of the most efficient methods of clean and ecological coal combustion. 相似文献
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循环流化床(CFB)锅炉炉内的燃烧及传热与炉内床料的状态密切相关,而炉内床料主要是由燃煤含有的矿物组分经过燃烧、爆裂和磨耗过程形成的。文中对6种煤样在固定床燃烧后,使用可视化显微仪,获取了灰颗粒的微观形貌特征,根据灰颗粒的机械强度和耐磨性能的不同,将灰颗粒定义为3类不同性质的灰。以此为基点,采用固定床燃烧后冷态振动筛分和流化床实验台热态流化后筛分的方法,研究了不同燃烧温度下升温速率对灰颗粒粒径变化的影响,以及不同燃烧温度下燃烧时间对灰颗粒粒径变化的影响,推演了不同煤样在燃烧过程中的演化特征。结果表明:3类灰颗粒在不同的燃烧温度和时间的演化过程存在明显的不同,从而为预测循环流化床中的床料粒径分布提供了理论依据。 相似文献
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《Combustion and Flame》2001,124(1-2):156-164
This paper reports an experimental study of the combustion of volatiles from coal, simulated by propane, and its interaction with char gasification reactions in a fluidized-bed coal gasifier (FBG). Experiments were performed under conditions of propane pyrolysis (in a bed fluidized by nitrogen and steam), propane reacting with oxygen and steam (in a bed fluidized by air and steam), char gasification only (in a bed fluidized by air and steam without propane) and in char gasification (in a bed fluidized by air and steam with propane). Axial concentration profiles of various species were obtained at 750, 850 and 950 °C. It was observed that the combustion of propane in an FBG, but without char, behaves as reported in the literature for fluidized-bed combustion (FBC). However, upon introducing char into the bed to simulate the reducing atmosphere in an FBG, oxygen was rapidly consumed within a short distance of the distributor, by significant partial oxidation of both propane and its decomposition products to carbon monoxide. The char was found to aid the pyrolysis of propane, limiting the amount of hydrocarbons surviving into the freeboard. The experimental results reported here are believed to be the first observations on the combustion of volatiles under conditions in an FBG. 相似文献
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Nurdil Eskin Arif Hepbasli 《Energy Sources, Part A: Recovery, Utilization, and Environmental Effects》2013,35(12):1085-1097
Power generation in Europe and elsewhere relies heavily on coal and coal-based fuels as the source of energy. The reliance will increase in the future due to the decreasing stability of price and security of oil supply. In other words, the studies on fluidized bed combustion systems, which is one of the clean coal technologies, will maintain its importance. The main objective of the present study is to introduce the development and the applications of the fluidized bed technology (FBT) and to review the fluidized bed combustion studies conducted in Turkey. The industrial applications of the fluidized bed technology in the country date back to the 1980s. Since then, the number of the fluidized bed boilers has increased. The majority of the installations are in the textile sector. In Turkey, there is also a circulating fluidized bed thermal power plant with a capacity of 2 × 160 MW under construction at Can in Canakkale. It is expected that the FBT has had, or will have, a significant and increasing role in dictating the energy strategies for Turkey. 相似文献
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归纳用于衡量破碎程度的参数,分析产生破碎的机理,研究影响热破碎的因素,讨论破碎现象对燃烧的作用。总结认为。流化床燃烧中。无烟煤的破碎具有较大随机性,受煤质影响极大,粒径、炉床温度、停留时间、流化介质及流化速度等对破碎也有重要影响。煤的破碎有利于提高煤焦颗粒的燃烧速率,但同时也会增加炉床内可扬析颗粒数量,导致飞灰未燃碳含量增加的后果。实现破碎物料的准确快速取样和建立破碎前后颗粒平均粒径之间的关系是今后破碎研究工作尚待解决的问题。 相似文献
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循环流化床中含钒石煤料球的焙烧特性试验研究 总被引:2,自引:0,他引:2
为避免传统提钒工艺所存在的问题,采用循环流化床钙法焙烧工艺,以添加钙基原料的石煤料球为焙烧原料,在热输入功率为1 MW的循环流化床燃烧试验台上进行了含钒石煤焙烧特性试验,研究了燃烧稳定性、燃烧效率、污染物排放特性、燃烧后灰渣特性和灰渣钒浸出特性.结果表明:在以烟煤为助燃燃料的条件下,石煤料球可以在1 MW循环流化床试验台上稳定焙烧运行,且燃烧效率较高;料球中的钙基添加剂有较好的脱硫作用,但对于高硫石煤,要达到国家污染物排放标准,必须采取尾部烟气脱硫措施;焙烧产物以飞灰为主,飞灰中V2O5浸出率接近70%,表明循环流化床对石煤中的钒矿物具有良好的焙烧氧化作用. 相似文献
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循环流化床中颗粒内循环与循环流化床锅炉的设计 总被引:2,自引:0,他引:2
本文从循环床锅炉密相区的热平衡计算出发,探讨了密相区内受热面面积及密相区高度与飞灰循环倍率、密相区燃烧份额的关系,并以4种典型煤种为例,分析了煤种变化对密相区高度的影响。设计计算和运行经验相结合,在密相区热平衡分析中,引入了床内粒子循环的概念,从而对密相区内热平衡和受热面面积的确定有更深入的理解。 相似文献
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流化床中高水分煤的燃烧与排放试验研究 总被引:1,自引:0,他引:1
通过在一小型流化床中进行高水分煤的燃烧与排放的试验研究,表明水分含量和空气-燃料比对于高水分煤的燃烧与排放有较大影响。随着水分增加,流化床床温下降,NOx、SOx排放量也下降。空气-燃料比存在一最佳值,这时床温最高,而偏离此值,床温下降,随着空气量的增加,NOx、SOx排放量也增加。当空气-燃料比变化时,燃烧干煤与燃烧高水分煤有着类似的试验结果。 相似文献
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流化床-煤粉复合燃烧锅炉的炉膛传热计算方法 总被引:2,自引:2,他引:0
针对流化床-煤粉复合燃烧锅炉的特点,在综合考虑流化床、火焰和受热面之间换热的基础上,推导了流化床-煤粉复合燃烧锅炉炉膛传热计算的基本方程,得到了复合燃烧锅炉炉膛传热计算的零维模型半径验法。以某75t/h树皮流化床-煤粉复合燃烧锅炉为例,进行了炉膛传热计算。图1表6参5 相似文献
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利用循环流化床内气-固两相流动等基础方面的研究成果,根据本文床内气固浓-淡流动模型,建立适用不同结构参数的循环流化床燃烧模型,考虑了床内气体、固体颗粒的返混、循环过程,以及煤燃烧、NO的生成和分解、颗粒磨损等因素。在循环流化床燃烧试验台上进行实验研究,模型仿真结果和实验数据吻合良好,表明气固两相浓-淡流动模型所建立的循环流化床燃烧系统模型可以正确地模拟循环流化床的燃烧过程。 相似文献
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This is a study of the devolatilization of coal in a laboratory-scale bed of silica sand, fluidized with either air or N2 and electrically heated to 750 or 900°C. Coal particles (diameter 1.4–1.7 or 2.0–2.36 mm) were fed in batches to the surface of the bed and allowed to devolatilize in either an oxidizing atmosphere of air or inert N2. In the first case, combustion of the volatiles occurred, but there was only thermal decomposition (pyrolysis) in the second situation. The resulting chars were recovered and analyzed for composition and structure, so that comparisons could be made between the effects of devolatilization with combustion and of pyrolysis in an inert atmosphere. It was found that the fractions of C and H in the char were only slightly sensitive to the type of fluidizing gas used. The amount of nitrogen in the recovered char and also the devolatilization time showed no dependence on the type of fluidizing gas, whereas BET areas were slightly larger after combustion in air. It is concluded that these effects are small relative to other errors, inherent in experiments on coal combustion, so that chars prepared in a bed fluidized by hot N2 are very similar to those formed during coal combustion at nominally the same temperature. Equally, the overall composition of the volatile matter released during combustion in a fluidized bed is the same as in pyrolysis in nitrogen. The effects of other parameters, such as the temperature of the bed, the flow rate of the fluidizing gas and the size of the coal particles are also discussed in detail. It is concluded that most of the volatiles burn in a fluidized bed (at or less than 900°C) far away from the original coal particle. Also, NOx is in effect a primary product of devolatilization, being produced in appreciable amounts when coal is heated in inert N2. The ratio of C/N in the volatiles is found to be a constant during the latter stages of devolatilization, but beforehand at lower temperatures, carbon species are preferentially released. Overall, devolatilization of small particles (< 2.4 mm) in a fluidized bed at 900°C is kinetically controlled. The activation energy is small, being 15 ± 6 kJ/mol. 相似文献