充气喷动床内微细粒子的析出率

在一内径92mm,高1000mm的不锈钢充气喷动床反应器内,以三种不同直径折玻璃珠为惰性粒子,采用五种不同的粉末物料为微细粒子,以空气为充气和喷动气体对微细粒子进行淘洗,综合考察了设备结构,物性,以及操作方式等对充气喷动床内微细粒子的析出率的影响,结果表明：五种粉末物料的析出率均随喷动气速的增加先增加而后变化不大,且粉末粒径越小,粒径分布越均匀其析出率越大;对同一惰性粒子床层的高度有一适宜床高;随着惰性粒子粒径增加,粉末物料的析出率先降低而后增加;当充气速度达到最大允许充气速度时粉末物料的析出率最高;随着床层温度的增加,粉末粒子的析出率有所增加。     

开孔导流管喷动床脱硫率的实验研究

脱硫率是喷动床设计及应用中的重要参数之一.在120×240的双喷嘴矩形不锈钢床内,对新型的双喷嘴矩形开孔导流管喷动床在不同Ca/S摩尔比、进气温度、入口SO2浓度、静床层高度及绝热饱和温差条件下的脱硫率进行研究,并与不开孔导流管喷动床进行比较.结果表明:开孔导流管喷动床的脱硫率比不开孔导流管喷动床有明显的提高,并得出了脱硫率的关联式.     

控轧控冷低碳Mn─Nb─RE钢中微细粒子沉淀强化

测定了控轧控冷低碳Ｍｎ─Ｎｂ─ＲＥ钢中析出相微细粒子化学成分、直径及形状因子；研究了控冷冷却速度对微细粒子直径、形状因子及屈服强度增量的影响和控轧控冷铌钢屈服强度增量与微细粒子平均直径的关系；探讨了析出相微细粒子的强化作用机理。     

红土矿流态化特性的实验研究

以红土矿为原料,氮气为流化介质,在实验室研究流化床分布板开孔率、床层高度、物料粒径、流化床床径和物料含水率对物料的最小流化速度和流化质量的影响。从而得到了物料在不同粒径范围的最小流化速度和流化质量较好的物料的粒径范围等红土矿流态化特性,为以后做红土矿热态还原做好准备。     

二维导流管喷动床的流动特征

带导流管的二维喷动床（２－ＤＳＢＤＰ）是传统喷动床的改进型式,矩形床内设置的与床同厚的垂直导流管可以控制固体颗粒的循环速率,同时使下行区中的气固移动床维持平推流。本文实验测定了不同表观气速、床层高度、固体颗粒与气体入口尺寸时,二维导流管喷动床的床降及相应的空隙率,藉以阐述２－ＤＳＢＤＰ的流动特征。     

高炉煤粉燃烧率通用模型

建立了煤粉燃烧率通用模型,模型可以根据煤粉的工业分析值计算燃烧动力学参数并预测煤粉燃烧率.通过对比前人的实验数据,验证了模型的准确性,同时研究了影响高炉煤粉燃烧率的若干因素.研究结果表明:在高炉喷煤过程中,煤粉颗粒在2 ms左右就可以达到热风速度,由于煤粉颗粒在直吹管内停留时间短并且温度较低,因此在直吹管内煤粉不会发生燃烧.煤粉进入风口回旋区后,挥发分瞬间全部析出,并且颗粒粒径越小,挥发分开始析出时间越早.降低煤粉粒径和增加氧气体积分数均有利于提高煤粉燃烧率.氧气体积分数每增加1%,燃烧率提高2%.随着喷煤量的增加,煤粉燃烧率逐渐降低.当提高煤粉喷吹量时,为了保证较高的燃烧率,实际操作过程中应提高富氧率并适当降低煤粉粒径.      

连续运转的加压喷动流化床内颗粒停留特性

在一喷动流化床（直径５０ｍｍ）试验台上，采用０．６３￣１．６０ｍｍ的原煤颗粒，进行了加料速率、流化气、喷动气以及压力等不同因素对颗粒在床内停留时间影响的实验研究，发现改变喷动床中气体流量，物料停留时间基本不变；改变流化气或喷动气，尤其后者，对仪时间影响明显；而一旦增加压力，会使停留时间延长。实验数据可为此类床型作为干燥器、气化裂解炉等的研究和应用提供有益参考。     

吸附及解吸压力对快速变压吸附床内速度及循环性能的影响

快速(真空)变压吸附循环周期较短,床层压力周期性变化快,使吸附床内流动及传热传质特性变化较大,本文研究吸附及解吸压力对快速变压吸附制氧床内速度及循环性能的影响.快速变压吸附(rapid pressure swing adsorption,RPSA)循环中原料气充压阶段气流速度远大于顺流的气体流速极限值,快速真空变压吸附(rapid vacuum pressure swing adsorption,RVPSA)循环中原料气充压阶段气流速度略大于顺流的气体流速极限值,而RPSA循环和RVPSA循环中放空降压阶段气流速度均较大.在所研究的吸附和解吸压力范围内,RPSA循环和RVPSA循环中气体温度在循环周期内变化均约为10℃,而RVPSA循环中气体温度在循环周期内温度梯度更大.RPSA循环中吸附压力越高,氧气回收率越高,床层因子越小;而RVPSA循环中解吸压力越低,氧气回收率越高,床层因子越小.      

高密度颗粒相HfO_2的流态化特性研究

研究了高密度物料HfO2在流态化方面的特点。在物料类型的研究中,使用床层塌落法对粒度为74~100μm的HfO2颗粒进行研究,结果表明:粒度为74~100μm的Hf O2属于B类物料,适用于鼓泡床或者湍流床。使用公式计算和实际实验进行对比,结果表明:低密度物料的临界流化速度经验公式同样适用于高密度物料HfO2的临界流态化速度计算;74~100μm的HfO2颗粒物料在流化过程未形成散式流态化状态,直接从沟流状态进入聚式流化状态;在粒度为74~100μm的HfO2颗粒的冷态流态化实验中,气流速度小于5 m3·h-1时,床层局部出现气孔,气流速度为5~8 m3·h-1时,床层处于沟流和完全流态化的过渡态;气流速度大于8 m3·h-1后基本完成了流态化;气流速度大于12 m3·h-1时,底部死角区域开始流动;气流速度从12降到6 m3·h-1的过程中,床层保持了一个较为稳定的床高和压力波动,可以获得更多的稳态流态化操作范围。     

气淬高炉熔渣粒化性能研究

通过试验研究了不同气流速度及熔渣黏度对气淬高炉熔渣粒化性能的影响,包括平均粒径、粒径分布及成珠率。结果表明:气淬高炉渣粒径主要分布在1～3 mm;随气流速度增加,渣粒平均粒径减小,成珠率先增加后降低,3 mm粒径比例逐渐增加;随黏度增加,渣粒平均粒径增加,成珠率降低,3 mm粒径比例有所减少;最佳气流速度为550 m/s,低黏度有利于提高粒化性能。气流速度增加不稳定波增强且液丝变细容易破碎,液滴平均粒径降低,但换热效果增强,导致容易形成纤维,所以成珠率先增加后降低;黏度增加不稳定波降低且液丝变粗不容易破碎,液滴平均粒径增加,成珠率下降。     

导向管喷动床电极处理低浓度含铜废水的研究

以铜颗粒为阴极颗粒,低浓度硫酸铜溶液为电解液,在横截面积为105.5mm×17mm的矩形导向管喷动床电极中,研究了硫酸浓度、颗粒粒径、电流密度以及电解液中铜离子的浓度对电流效率和铜的沉积速率的影响,找出了适宜的电解条件.     

流态化法氧化钕氟化实验的研究

在直径80 mm振动流化床中,研究Nd2O3超细颗粒常温条件下的流化状态,考察了粉体物性,粉体填料量和流化速度等因素对原料Nd2O3流化质量的影响.由此确定了后期高温氟化反应的最佳流化速度和初始床层高度.并探索了不同条件下NdF3产品的氟化率,实验结果表明,在600℃下反应时间30min为相对最优氟化条件.     

Spouted bed electrowinning of zinc: Part II. Investigations of the dynamics of particles in large thin spouted beds

The behavior of particles in thin spouted beds, mostly equipped with draft tubes, has been investigated. Three apparatuses have been used: a laboratory-scale cylindrical bed, a 2-m-tall “flat” (rectangular cross section) bed and a 2-m-wide flat bed, the last equipped with multiple draft tubes. Most of the results were obtained on the tall bed. Minimum spouting flow rate, pressure distribution, particle velocities, and solid circulation rates were determined as a function of bed geometry (including draft tube dimensions and position). Observations were made of the direction of liquid flow in the bed outside the draft tube and of the occurrence of zones in the bed where the particles appeared stationary. The wide bed was used to determine that there is a maximum separation between draft tubes beyond which particles cannot be kept in motion across the whole width of the bed.     

Reduction kinetics of Fe<Subscript>2</Subscript>MoO<Subscript>4</Subscript> fine powder by hydrogen in a fluidized bed

Iron molybdate (Fe₂MoO₄) powders with an average particle size of 100 μm were reduced by hydrogen using a fluidized-bed batch reactor in the temperature range of 923 to 1173 K. The extent of the reaction was followed as a function of time by gas chromatography. The fluidizing-gas velocity was set at about 1.5 times the minimum fluidization velocity. The ratio of the height of the static bed to its diameter is about 1. Under the prevailing experimental conditions, it was found that the chemical reaction was the rate-controlling factor. The activation energy for this process was 158±17 kJ/mol. The crystal size of the Fe₂Mo powder produced at lower temperatures was in the nanometer range, indicating the possibility of mass production of alloys and intermetallics in the nanorange, using a fluidized bed.     

喷动流化床内砂状氢氧化铝结晶实验研究

在直径为100 mm的喷动流化床中,苛性比小于1.9,流化速度分别为1.42×10-3m/s,1.98×10-3m/s,2.55×10-3m/s的条件下进行了砂状氢氧化铝结晶实验,考察了苛性比和流化速度对晶粒生长和次生晶核形成的影响,建立了适宜的喷动流化结晶条件。     

废轮胎流化特性的冷态实验研究

在流化床冷态实验台上,对废轮胎的流化特性进行了实验研究.研究了粒径、床层高度对废轮胎流化性能及临界流化风速的影响,同时将几种不同粒径废轮胎颗粒与石英砂进行混合,对混合物的流化、混合性能进行了研究.研究结果表明,单一废轮胎颗粒不易流化,一定量的石英砂加入能够改善其流化特性.     

Experimental study on resistance characteristics in vertical tank for recovering sinter waste heat

The resistance characteristics of gas flowing through sinter bed layer were tested in different cases on the homemade experimental platform. The pressure drop of gas flowing through sinter bed layer was measured, and the influence of relevant parameters was fully studied. Also, the experimental correlation formula of dimensionless number to reflect sinter layer resistance characteristic, was derived from applying dimensional analysis. The regression analysis was used to determine the coefficient and index of the empirical correlation. The results show that for a given particle size distribution, pressure drop of unit bed layer height in sinter bed layer increases as a form of power function whose power exponent is 1. 681 with the increase of gas superficial velocity. For a given gas superficial velocity, pressure drop of unit bed layer height increases as an exponential relationship with the decrease of particle size distribution. The pressure drop formula is adapted for the whole experimental data. The pressure drop can be accurately predicted while using dimensional formula whose mean error is 12% comparing with former modifier Ergun formula.     

Rapid Increase in Suspended Load at High Bed Shear

When the dimensionless shear stress θ exceeds 0.8 a plane shear layer develops on the top of a granular bed. This layer is stabilized by the mixture density gradient within it. Its thickness typically increases linearly with θ, and so does the ratio of the effective roughness size to particle diameter, ks/d. If the ratio of shear velocity U* to particle fall velocity Vf is sufficiently large, the shear layer may be destabilized, giving a rapid increase in turbulent suspension. New closed-conduit experiments with 0.11?mm sand show that for U*/Vf>6.5 the ratio ks/d has a pronounced increase above the typical shear-layer trend, and so does the suspended-load concentration (measured at the mid-height between the stationary bed and the top of the flow). These observations differ significantly from the sediment pick-up function in common use, indicating that the latter must be reconsidered. The present experiments also show a tie-in with hyperconcentrated flow as observed in the rivers of Northern China.     

不同惰性物对抑制流化还原过程中黏结失流行为的研究

本文采用可视化流化床进行了石灰石粉、煤粉、干馏煤粉和焦粉作为惰性物对抑制流化还原黏结失流行为的研究.结果表明:配入少量的石灰石粉会降低黏结失流温度,加剧黏结失流现象,因此石灰石粉不宜作为流化还原过程中抑制黏结失流的惰性物;直接使用煤粉作为惰性物会带来难以解决的煤焦油问题,在生产实践中是不可行的;干馏煤对黏结失流具有很好的抑制作用,添加15%粒度为0.11~0.12 mm的干馏煤可将黏结失流温度提高75℃;焦粉对黏结失流具有很好的抑制作用,考虑工业生产的可行性与经济性,适宜的焦粉粒度可以取0.08~0.12 mm.