共查询到18条相似文献,搜索用时 171 毫秒
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高温气固流化床的流化特性 总被引:1,自引:1,他引:1
气固流化床中的压力脉动信号是研究流化床内流体动力特性的一个重要途径,本文在20℃~640℃的温度范围内,测试了3种颗粒在不同流化速度下气固流化床中的瞬态压力脉动信号,通过分析压力脉动进一步研究了温度对床内流化特性的影响。研究结果表明:高温下气固流化床内的流化特性与常温下有显著的差异,随温度的升高,床内的流化质量有所改善;对于同一种颗粒,不能将常温下所得到的流化特性推广到高温的条件下。 相似文献
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对循环流化床锅炉的结构、部件、传热特性作了简要介绍,并根据该类锅炉的特点着重叙述了如何进行燃烧控制、调节以及操作过程中应密切注意的运行参数。 相似文献
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根据粒径分布将燃料灰分为飞灰、循环灰及底灰,它们有不同的燃烧和传热特点;灰的含量及特性对循环流化床锅炉的性能和运行产生影响,锅炉结构设计应予以充分考虑。 相似文献
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石油焦在燃烧过程中有不同于煤的燃烧特性.与煤差异很大。本文通过对某台燃烧石油焦循环流化床锅炉设计与运行的分析,探讨燃烧石油焦循环流化床锅炉设计中石油焦及石灰石的粒径分布对流化速度、过量空气系数、风艟比、床温、循环倍率、分离量效率、对流受热面烟气流速等主要热力参数的影响.为烧石油焦循环流化床锅炉的设计与运行提供实践依据。 相似文献
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循环流化床传热综述(试验部分) 总被引:4,自引:0,他引:4
对国、内外在循环流化床传热研究领域发表的130篇文章进行了综述,总结在循环流化床传热试验理论研究发展的现状和结果,讨论各有关运行参数的影响与传统机理。 相似文献
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对脉动热管的运行进行了可视化实验 ,在不同的充灌率、倾角、截面形状、加热量条件下对脉动热管的运行进行了测试 ,实验结果表明 :脉动热管是一种十分有效的散热技术 ;脉动热管存在传热极限 ;在最佳充灌率 (5 0 % )和最佳倾角 (5 0°)下运行的脉动热管传热极限最高 ,高热流密度下的传热热阻最低 ;当热流密度较小时 ,三角形通道的脉动热管要优于正方形通道的脉动热管 ,但当热流密度较大时 ,通道形状对热阻和单位截面传热极限影响不大 ;通道大小对热管的热性能影响很小 相似文献
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Akira Nishimura Seiichi Deguchi Hitoki Matsuda Masanobu Hasatani Arun S. Mujumdar 《亚洲传热研究》2002,31(4):307-319
A pulsating fluidized bed is operated with two sequential durations designated as an on‐period with injecting fluidization gas and an off‐period without it. The heat transfer coefficient between a vertically immersed heater and bed in a pulsating fluidized bed is measured under various pulse cycles and fluidized particles. The obtained results are compared with those in a normal fluidized bed with continuous fluidization air injection. The relationship between heat transfer coefficients and bubble characteristics, evaluated using a digital video camera, has also been investigated. For certain fluidized particles and operating pulse cycles, the fluidization of particles and the increment of heat transfer coefficients can be obtained under a mean air velocity based on a pulse cycle duration smaller than the minimum fluidization air velocity in a normal fluidized bed. Under the pulse cycles where a static bed through the whole bed is formed in the off‐period duration, the improved heat transfer rate over that in a normal fluidized bed can be measured. This may be attributed to large bubble formation. As heat transfer in the pulsating fluidized bed is obstructed with increasing time to keep a static bed due to the excessive off‐period duration, it is indicated that there is an optimum off‐period duration based on the heat transfer rate. © 2002 Wiley Periodicals, Inc. Heat Trans Asian Res, 31(4): 307–319, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.10038 相似文献
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Xiehe YANG Yang ZHANG Daoyin LIU Jiansheng ZHANG Hai ZHANG Junfu LYU Guangxi YUE 《Frontiers in Energy》2021,15(1):99
A one-dimensional transient single coal particle combustion model was proposed to investigate the characteristics of single coal particle combustion in both O2/N2 and O2/CO2 atmospheres under the fluidized bed combustion condition. The model accounted for the fuel devolatilization, moisture evaporation, heterogeneous reaction as well as homogeneous reactions integrated with the heat and mass transfer from the fluidized bed environment to the coal particle. This model was validated by comparing the model prediction with the experimental results in the literature, and a satisfactory agreement between modeling and experiments proved the reliability of the model. The modeling results demonstrated that the carbon conversion rate of a single coal particle (diameter 6 to 8 mm) under fluidized bed conditions (bed temperature 1088 K) in an O2/CO2 (30:70) atmosphere was promoted by the gasification reaction, which was considerably greater than that in the O2/N2 (30:70) atmosphere. In addition, the surface and center temperatures of the particle evolved similarly, no matter it is under the O2/N2 condition or the O2/CO2 condition. A further analysis indicated that similar trends of the temperature evolution under different atmospheres were caused by the fact that the strong heat transfer under the fluidized bed condition overwhelmingly dominated the temperature evolution rather than the heat release of the chemical reaction. 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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The characteristics of heat transfer from bubbling gas-fired fluidized bed to a horizontal staggered water-tube bundle located in the freeboard region is experimentally investigated. The purpose is to demonstrate the effect of bed temperature on the coefficients of heat transfer by the different modes to each of the four rows of the bundle, which experiences heat transfer by convection from flue gases, luminous radiation from bed material and non-luminous radiation from gases. The bed temperature itself is varied and controlled through the fuel–air mass ratio. Sixteen runs have been conducted with bed temperature ranging from 1114 to 1429 K, resulting in an overall heat transfer coefficient in the range 74·0–105·0 W m−2 K−1 for the first row and 58·0–65·0 W m−2 K−1 for the last. An overall convective heat transfer coefficient from gases, and possible carried over sand particles, to the bundle is formulated. © 1997 by John Wiley & Sons, Ltd. 相似文献
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大型循环流化床锅炉的传热研究 总被引:9,自引:2,他引:7
作者对1台大型循环流化床锅炉中受热面的传热情况进行了研究,分析了受热面的传热系数变化规律,提出了计算大型循环流化床锅炉内受热面的传热计算经验公式,可供设计、调试和运行时参考。图11参9 相似文献