惰性粒子流化床烟气脱硫的试验研究

对惰性粒子流化床的烟气脱硫过程进行了试验,分析和研究了Ca/S、入口SO2浓度、静止床高、惰性粒子粒径、近绝热饱和温度和床层温度对脱硫效率的影响.结果表明:近绝热饱和温度和Ca/S对脱硫效率影响较大,惰性粒子粒径和静止床高对脱硫效率也有一定影响;近绝热饱和温度越低、Ca/S越大、流化床床层温度越低、烟气表观速度越小、惰性粒子粒径越小以及静止床层越高,则烟气脱硫效率越高;当烟气入口SO2浓度小于7×10-4时,随着入口SO2浓度的增大,脱硫效率相应提高;当烟气入口SO2浓度增加到7×10-4以上时,随着入口SO2浓度的增大,脱硫效率反而降低;在基本试验工况下,惰性粒子流化床的烟气脱硫效率达到85%以上.     

内循环流化床及其粒子带出率的试验研究

在分析目前流化床存在问题的基础上,提出了“内循环流化床”的概念。指出下旋流场是实现粒子内循环的重要条件。用三种物料进行了粒子带出率试验,验证了内循环流化床对控制粒子带出率的有效性。在内循环流化床中,气固扰动强烈,混合充分,粒子停留时间长,有利于提高燃烧和脱硫效率。内循环流化床还具有结构简单、紧凑、投资省、运行维护方便等特点。     

循环流化床内局部颗粒昆合特性的研究

为了研究流化床内固体粒子的混合特性,从固体粒子运动速度的脉动特性和浓度分布出发,提出了局部颗粒混合因子的概念及数学模型.并利用高速摄影CCD和相关分析等图像处理方法对该模型进行了试验验证和分析.从试验结果来看:混合因子的分布与粒子混合的剧烈程度有较好的对应关系,描述了流化床投影面上粒子的混和特性.在实现上,计算混合因子所需要的信息全部来自粒子运动图像,属于非接触测量,易于在线分析.因此,该因子可以作为一个定性参数来描述流化床内局部区域粒子的混合特性.图6参11     

循环流化床内局部颗粒混合特性的研究

为了研究流化床内固体粒子的混合特性，从固体粒子运动速度的脉动特性和浓度分布出发，提出了局部颗粒混合因子的概念及数学模型。并利用高速摄影CCD和相关分析等图像处理方法对该模型进行了试验验证和分析。从试验结果来看：混合因子的分布与粒子混合的剧烈程度有较好的对应关系，描述了流化床投影面上粒子的混和特性。在实现上，计算混合因子所需要的信息全部来自粒子运动图像，属于非接触测量，易于在线分析。因此，该因子可以作为一个定性参数来描述流化床内局部区域粒子的混合特性。图6参11     

基于新型混合粒子群算法的含分布式电源的配电网规划

针对粒子群算法易出现"惰性"粒子的问题,提出新型混合粒子群算法,即首先利用混沌理论初始化粒子群,使生成的初始解遍历整个搜索空间,再融入交叉、变异、混沌扰动操作帮助"惰性"粒子跳出局部最优,进而以有功网络损耗最小为目标函数,应用新型混合粒子群算法对IEEE33节点配电系统中分布式电源的位置和容量进行规划。结果表明,新型混合粒子群算法应用于含分布式电源的配电网规划中具有可行性。     

流化床煤燃烧与气化过程中的辐射换热

流化床反应器中颗粒与颗粒之间的传热在一定程度上决定了化学反应的速率及反应的中间历程。本文通过对气固流化床乳化相中颗粒群结构的进一步认识，建立了颗粒间的辐射换热模型，比较了不同颗粒直径、不同床层温度水平及不同流化工况下颗粒间辐射换热与通过气膜导热份额的大小，并预测了流化床反应器中反应颗粒与惰性床料之间的温差，对于流化床反应器选择合理的运行工况和进行操作参数优化具有参考价值     

流化床内多组分颗粒传质过程模拟

为了揭示活性颗粒的传质特性,采用Euler-Euler双流体模型,并结合气泡介尺度曳力模型和多组分传质模型,利用计算流体动力学(CFD)软件对存在惰性颗粒情况下多组分颗粒流化床内水蒸气吸附过程进行了数值模拟,得到流化床内固体颗粒体积分数和水蒸气质量分数分布,验证了气泡介尺度曳力模型的合理性,分析了入口表观气体速度、水蒸...     

一种新型的节能燃烧方式—媒体流化床燃烧

近几年在国外兴起了一种媒体流化床锅炉,又称为“线”流化床锅炉,现在发展很快。这种流化床锅炉的特点是在流化床中加入一种隋性的粒子,这些粒子的比重大、粒很小,作为流化媒体,使粒径很大的燃料粒子在床中可以在较低的风速下良好流化,与空气充分混合,造成优越的燃烧条件。它除了具有一般流化床锅炉的共有优点之外,还有床位薄、阻力小,对燃料粒度要求低,煤种适应性广等一系列优点。而且这种燃烧方式所占的空间小,在锅壳式锅炉中采用也很     

造纸污泥流化特性试验研究

在一床截面积为０４×０．４ｍ２的冷态流化床试验台上对一全水份为１２７５％的造纸污泥进行了流化特性试验研究。试验表明，只用该种物料作床料，床层无法正常流化。它必须与异比重的惰性物料配制成双组份床料后才能获得理想的流化效果。通过对比试验确定了合适的惰性物料粒径；研究了床料配比对临界流化速度的影响并给出一回归公式。还通过试验测定了造纸污泥的终端速度。上述研究结果对该类物料的流化干燥装置及燃用该类物料的流化床锅炉（或焚烧炉）的设计和运行均有重要的参考价值。     

循环流化床锅炉炉内压降分布及物料粒径分布的计算

根据物料总体平衡建立了循环流化床锅炉炉内压降分布和物料粒径分布的数学模型 ,模型中考虑了颗粒破碎、磨损以及缩核对物料粒径分布变化的影响。作为循环流化床锅炉整体数学模型的基础 ,该模型不仅计算了所有物料的总体粒径分布 ,也计算了焦炭、石灰石和惰性床料单独的粒径分布。最后给出了炉内压降和不同位置处物料粒径分布的仿真结果 ,并对结果进行了分析     

循环流化床锅炉传热数学模型研究

在国内外研究的基础上,结合环－核结构的流动模型建立了循环流化床锅炉的传热数学模型。利用该模型对循环流化床锅炉的对流、辐射传热特性进行了仿真研究,并对结果进行分析。仿真结果表明,循环流化床锅炉的对流传热系数与截面平均颗粒体积份额有密切关系,而辐射传热系数与环形区内温度密切相关;循环流化床锅炉辐射传热占总传热的份额随炉膛高度的增加而增大．     

The devolatilization of coal and a comparison of chars produced in oxidizing and inert atmospheres in fluidized beds

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, NO_x 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.     

非均匀布风流化床的DEM模拟

对二维非均匀布风流化床内的颗粒运动进行了数值模拟,用欧拉方法处理气相场的同时用拉格朗日方法处理离散颗粒场,直接跟踪颗粒场中的每个颗粒。模拟结果表明,非均匀布风流化床内存在颗粒的内循环运动,因此颗粒的混合特性优于均匀布风流化床。     

气固流化床内颗粒的内循环特性的研究

分析了气固流化床内颗粒内循环产生的原因,进而,分析了流化床气体速度,静态床层高度,颗粒粒径以及压力对颗凿内循环的影响。当流化床循环增强;而压力增大将使颗粒的内循环减弱。当颗粒的内循环增强时,流化床的脉冲信号（温度,浓度和灰度等）响应曲线的振荡加剧,流化床内颗粒的横向混合将得到改善。     

CFBB蒸发管和高温过热器爆管的判定及处理

云天化股份公司的1^#、2^#循环流化床锅炉运行近4年，蒸发管和高温过热器由于严重的均匀磨损，开始频繁的发生爆管事故。文章通过对云天化股份公司中温分离CFB锅炉蒸发管、高温过热器因磨损造成的爆管事故的分析，找出了及时准确判定的方法及相应的处理措施，并提出了相关的一些技改措施。     

Analysis of mass loss of a coal particle during the course of burning in a flow of inert material

This paper is an attempt to explain the role of erosion during the process of coal combustion in a circulating fluidized bed. Different kinds of carbon deposits found in Poland, both bituminous as well as lignite with the particle of 10 mm in diameter were the subject of the research. According to many publications it is well known that erosion plays a significant role in coal combustion, by changing its mechanism as well as generating an additional mass loss of the mother particle. The purpose of this research was to determine the influence of an inert material on an erosive mass loss of a single coal particle burning in a two-phase flow. The determination of the influence of a coal type, the rate of flow of inert material and the temperature inside the furnace on the erosive mass loss of burning coal particle was also taken into consideration. The results obtained indicate that the velocity of the erosive mass loss depends on the chemical composition and petrographic structure of burning coal. The mechanical interaction of inert and burning coal particles leads to the shortening of the period of overall mass loss of the coal particle by even two times. The increase in the rate of flow of the inert material intensifies the generation of mass loss by up to 100%. The drop in temperature which slows down the combustion process, decreases the mass loss of the coal particle as the result of mechanical interaction of the inert material. As was observed, the process of percolation plays a significant role by weakening the surface of the burning coal.     

Simulation study of the effect of the restitution coefficient on interphase heat transfer processes and flow characteristics in a fluidized bed

This article discusses a simulation study performed to investigate the effect of particle collision on inter-particle and gas–solid heat transfer processes, and other related bed flow characteristics. The effect of particle elasticity is presented using different values of the particle–particle coefficient of restitution. The simulation study was carried out using a two-dimensional model of a fluidized bed reactor incorporated to ANSYS Fluent 16.2 software. Two different materials, steel beads and sand particles, were used as the bed material fluidized by air. The simulation results are compared to those from previous studies on fluidized bed reactors containing a single bed material. The coefficient of restitution affected the bed hydrodynamics. Specifically, an increasing coefficient of restitution resulted in an increasing bed pressure drop and decreasing void fraction, granular temperature, particle velocity, and collision frequency. Conversely, increasing the particle coefficient of restitution resulted in decreasing the particle–particle heat exchange coefficient and the gas–particle heat transfer coefficient. The gas–particle heat transfer coefficient for sand particles was higher than that for steel beads. The effect of the coefficient of restitution on the flow characteristics from a binary mixture bed was quite similar to those of single material beds found in previous studies. This study demonstrated that the restitution coefficient clearly affected both the particle–particle and gas–particle heat transfer processes.     

循环流化床流体动力学研究进展

论述了国内外在循环流化床流体动力学研究领域的进展,对循环流态化颗粒流动问题、颗粒聚集及传热以及循环流态经数学模型等热点问题进行了重点回顾,并指出了当前循环流化床流体动力学研究的一些新动向。     

生物质颗粒热载体流化床热解模型

应用热解的分布活化能模型,考虑生物质热解的吸热效应,对生物质颗粒在热载体流化床中的热解过程进行了数值计算,计算结果表明:由于导热热阻的存在,生物质颗粒内部存在一定的温度分布,开始时表面和中心温差较大,随着时间的推移,颗粒内部逐渐趋于等温;生物质颗粒的热解时间随粒径的增大而增加;在0.5～2.0m/s的气速计算范围内,生物质颗粒的热解时间随操作气速的升高而缩短,随床温的升高而减小;热解吸热效应对生物质颗粒挥发份释放过程影响很大,在计算的时候不能予以忽略.