氯化氢制氯气反应器的冷模实验

在流化床冷模实验装置上,以空气和氯化氢制氯气催化剂为介质,研究了不同操作条件对轴向、径向密相颗粒浓度和稀相段内颗粒浓度的影响以及分离系统的分离效率。实验结果表明,随着表观气速的增加,床层径向密度逐渐降低,表明床层的流化质量有所改善;同时,轴向密度分布在高度H=500 mm处最大,截面平均密度随着表观气速的增加而降低;当表观气速为0.3 m/s时,H=5345 mm处的稀相密度为8.44 kg/m~3,已经不满足原旋风分离器入口浓度的要求;卧式快速分离器分离效率在实验条件下均大于99.6%,改造后过滤器反吹间隔时间也满足生产要求。     

新疆油砂直接流化床焦化中试装置的工艺方案

以新疆油砂为原料,采用油砂直接流化床焦化新技术,对10kt／a油砂直接流化床焦化的中试装置进行了工艺计算。结果表明,焦化反应器适宜的操作条件为：温度490℃,压力200kPa,表观气速0．4m／s。烧焦器适宜的操作条件为：温度690℃,压力180kPa,密相床层表观气速0．8m／s,稀相床层表观气速0．4m／s。由焦化反应器和烧焦器的物料平衡和热量平衡计算可知,循环热砂量为3533．10kg／h,进料油砂含油量为118．25kg／h,产品产量为100．52kg／h,系统补热消耗的标准油量为21．83kg／h,表明采用该装置和方法具有显著的经济效益。     

催化裂化再生器树枝状气体分布器射流作用区的床层压力脉动特性

在催化裂化装置中再生器底部通常设置有树枝状气体分布器,通过分布器上的喷嘴分布气体。分布器射流区的压力信号可以很好地反应分布器的流场特性,为减小磨损进行结构改进提供理论依据。为此,在二维床实验装置上针对分布器射流区压力分布及压力脉动进行了实验研究,结果表明：分支管间床层压力沿床层轴向高度逐渐减小,随喷射角度增大而减小,随喷嘴出口气速和静床高度增大而增大,由测点以上的物料量决定,可用来判断不同操作工况;当喷射角度为0°和22.5°时,分支管间处于密相区,压力脉动先增后减,对应着气泡的产生、聚并和破碎的规律;当喷射角度为45.0°和67.5°时,分支管间由射流形成稀相区,压力脉动由气流湍流度决定,高于密相区,随喷嘴出口气速和静床高度增大而增大,可为减小分支管外部磨损提供依据;影响喷嘴射流压力脉动的因素为相邻喷嘴射流冲击和颗粒的作用,喷射角度为22.5°时的射流压力脉动存在临界气速,取决于是否受到相邻射流的冲击,可以为喷嘴射流稳定性及工业上减小分布器的内部和外部冲蚀磨损提供理论依据。     

聚酯切片流态化特性的研究

聚酯切片的含水量和结晶度明显影响后续的固相缩聚过程,采用特殊流化床进行干燥和结晶处理是发展方向。在内径为85 mm的流化床中对聚酯切片的流态化特性进行了冷态模拟实验研究,测定了聚酯切片的起始流化速度和床层膨胀比,并通过对床层的压力脉动进行功率谱分析,考察了聚酯切片的流态化动力学特性和流型转变。实验结果表明,所研究的聚酯切片属于Geldart D类颗粒,起始流化速度为0.66 m/s。对床层压力脉动进行快速傅里叶变换分析的结果表明,聚酯切片的流化状态不稳定,首先形成节涌流态化;当流化气速大于3 m/s时,形成湍动流态化。当流化床处于湍动流态化状态时,气体与聚酯切片间传热传质效率高,可实现快速干燥和结晶。     

流化床反应器压力监控方案探讨

有机硅单体合成工艺是气-固两相的反应过程,由于硅粉的硬度大而且反应的附加物有黏性,经常出现磨损和堵塞造成生产装置检修频率高,操作状况难,现场检测仪表经常处于瘫痪状态。简单介绍有机硅单体合成流化床反应工艺过程及其对测量控制的要求,剖析流化床理想流化状态的床层压降是一个固定值,得出床层是否处于理想流化状态,可以通过测量床层压力来间接判断。详细叙述了吹气法测量流化床压力方法和具体实施方案。     

耦合流化床反应器提升管段颗粒速度及滑落的研究

在不同操作条件下，采用PV-4A型颗粒速度、密度测定仪测量了提升管与流化床耦合反应器大型冷态实验装置提升管内速度沿轴向、径向的分布。结果表明，在耦合流化床反应器提升管段，当表观气速一定时，颗粒的时均速度随循环强度的增加而减小；当循环强度相近时，在床层任何轴向、径向位置的颗粒时均速度都随着表观气速的增大而增大。由于提升管出口流化床层及分布器的存在，提升管内轴向速度呈现先增加后减小的分布特征。利用实验数据回归的提升管内颗粒滑落系数的经验模型计算值与实验值吻合较好     

湍动流化床中气泡行为和压力脉动特性的研究

 详细研究了在500mm×30mm×6000mm大型二维湍动流化床中FCC催化剂颗粒的床层轴向空隙率分布和床层的压力脉动。根据床层空隙率变化,建立了1个可以同时适用于鼓泡流化床和湍动流化床的气泡平均直径模型。该模型的计算结果与实验观察和实验测得的床膨胀规律均一致,并且与床层压力脉动的变化趋势也一致。在压力脉动沿床层轴向高度的分布图中,曲线呈水平“S”型。根据压力脉动的变化,床层可以分为分布板影响区、气泡生长区、料面影响区和稀相区4个区。根据床层稀、密相压力脉动的剧烈变化,提出了一种确定稀－密相界面高度的新方法,该方法简单实用。     

大差异颗粒双组分流化床颗粒传热实验

 本文将冷的降烯烃催化剂加入至热的处于流化状态下的FCC催化剂和降烯烃催化剂混合颗粒中,考察流化状态下的颗粒间混合换热研究.结果表明,当换热前后大差异颗粒流化床均处于完全混合状态时,混合颗粒平均粒径越小,床层气速越高和床温越高则传热系数就越大;在进行颗粒Nu准数和Re准数关联回归时必须考虑床层温度的影响,并在关联式中引入流化床加热后的床层气速与入床气速的比速度,计算结果表明修改后的关联式总体误差不超过30%,能够满足实验设计的需要,可为新型双组分流态床换热分级系统的设计提供基础.     

稠密气-固流中介尺度结构的识别

在冷模气-固流化床实验装置中,研究了鼓泡床与湍流床内的介观两相流动结构。测量了床层内不同轴、径向位置处的瞬时固含率脉动信号,编写了Matlab软件对光纤信号进行解耦。采用三阶统计矩法(偏斜度法)确定了气泡相阈值,发现在床层中心区域,气泡相阈值在0.26~0.35内变化。气泡相与乳化相的平均固含率随气速的增大而减小,颗粒聚团的平均固含率在0.550~0.555之间变化,基本不受操作气速以及径向位置变化的影响,颗粒聚团的出现频率在0.5~3.2 Hz之间变化。     

流化催化裂化再生器湍流流化床密相区两相流动规律的研究

分别在φ710mm×4000mm/φ870mm×11000mm有机玻璃流化床和800kt/a重油流化催化裂化装置的再生器中对湍流流化床密相区的两相流动规律进行了研究.通过对实验结果的分析,建立了适合于湍流流化床的两相模型.由因次分析出发给出的床层密相区的截面平均密度沿轴向高度分布的准数关联式可用于工程设计.     

Modeling of gas-solid flow in a CFB riser based on computational particle fluid dynamics

A three-dimensional model for gas-solid flow in a circulating fluidized bed(CFB) riser was developed based on computational particle fluid dynamics(CPFD).The model was used to simulate the gas-solid flow behavior inside a circulating fluidized bed riser operating at various superficial gas velocities and solids mass fluxes in two fluidization regimes,a dilute phase transport(DPT) regime and a fast fluidization(FF) regime.The simulation results were evaluated based on comparison with experimental data of solids velocity and holdup,obtained from non-invasive automated radioactive particle tracking and gamma-ray tomography techniques,respectively.The agreement of the predicted solids velocity and holdup with experimental data validated the CPFD model for the CFB riser.The model predicted the main features of the gas-solid flows in the two regimes;the uniform dilute phase in the DPT regime,and the coexistence of the dilute phase in the upper region and the dense phase in the lower region in the FF regime.The clustering and solids back mixing in the FF regime were stronger than those in the DPT regime.     

Fluidization characteristics of different sizes of quartz particles in the fluidized bed

Fluidization characteristics of quartz particles with different sizes are experimentally investigated in a fluidized bed with an inner diameter of 300 mm and height of 8250 mm. Results show that the average solid holdup increases with the increase in superficial gas velocity and the decrease in initial solid holdup in the dense zone of the fluidized bed. The average cross-sectional solid holdup decreases with increasing bed height and superficial gas velocity. The bed expansion coefficient increases with the increase in superficial gas velocity and the decrease in solid holdup. Correlations of average solid holdup, average cross-sectional solid holdup and bed expansion coefficient are also established and discussed. These correlations can provide guidelines for better understanding of the fluidization characteristics.     

鼓泡床、湍动床固含率的相似分布规律

在内径为４７４ｍｍ的流化床中，采用双光路光纤密度探头分别研究了流化床密相区、稀相区空隙率径向分布，发现无论是在密相区还是在稀相区，鼓泡床、湍动床中的固含率径向分布均比提升管均匀得多。鼓泡床、湍动床中的固含率径向分布符合相似分布规律，即局部固含率与截面平均固含率成正比，仅是径向位置的函数，与操作气速无直接关系。     

CFD simulation of pressure fluctuation characteristics in the gas-solid fluidized bed: Comparisons with experiments

A simple hydrodynamic model based on two-fluid theory,taking into account the effect of discrete particles on both the gas-and solid-phase momentum equations,was used to numerically investigate the pressure fluctuation characteristics in a gas-solid fluidized bed with the aid of CFX 4.4,a commercial CFD software package,by adding user-defined Fortran subroutines.Numerical simulations together with typical experimental measurements show that pressure fluctuations originate above the distributor when a gas pulse is injected into the fluidized bed.The pressure above the bubble gradually increases due to the presence of a rising bubble.When the bubble passes through the bed surface,the pressure near the bed surface gradually decreases to a lower value.Moreover,the pressure signals in the bubbling fluidized beds show obviously periodic characteristics.The major frequency of pressure fluctuations at the same vertical position is affected slightly by the operating gas velocity,and the amplitude of pressure fluctuations is related to both the operating gas velocity and the vertical height.In this study,the influence of the operating gas velocity on the pressure wave propagation velocity can be ignored,and only two peak frequencies in the power spectrum of the pressure fluctuations are observed which are associated with the bubble formation above the distributor and its eruption at the bed surface.     

不同形状垂直筛板流化床性能

用FCC催化剂和空气对垂直筛板流化床的性能进行实验研究。考察了圆型、方型及倒锥型垂直筛板内构件的板孔气速、帽罩孔面积/板孔面积比等筛板结构和流化条件对流化床床层压力降的影响。结果表明,垂直筛板流化床属快速流化床,床内无气泡,颗粒返混小,气-固流化好。板孔气速、筛板结构等对3种垂直筛板床层压力降的影响规律相同。方型垂直筛板的床层压力降最大,圆型与倒锥型垂直筛板的床层压力降相差不大,床层压力降随板孔气速、帽罩底隙高度增加而增大,随固体循环量增加有一最大值,随帽罩孔面积/板孔面积比、板孔径的增大而减小。适宜的帽罩结构尺寸为,板孔面积与帽罩截面积比为0.42,帽罩底隙高与板孔径比0.36~0.64,帽罩孔面积与板孔面积之比大于1.2。最大板孔气速可达6.4 m/s。     

催化裂化装置提升管T型出口结构压力降的实验分析

在大型循环流化床装置上对提升管的T型出口结构压力降进行了实验研究。首先,在不同实验条件下对循环流化床提升管T型出口结构的压力降进行了实验测量。重点分析了提升管浓度和气体速度与提升管T型出口结构压力降的关系。实验结果表明,由于大型循环流化床提升管T型出口结构处特殊的气流输送机制,循环流化床提升管T型出口结构的压力降主要受提升管T型出口结构处变截面尺寸、提升管出口处流体转向和提升管内气固两相之间摩擦的影响,在循环流化床提升管T型出口结构处形成较大的压力降。循环流化床提升管T型出口结构的压力降与提升管内催化剂浓度的一次方成正比关系,与提升管内气体速度的二次方成正比关系。最后,在实验数据的基础上,给出循环流化床提升管T型出口结构的压力降计算公式。     

进料方式对固定流化床流态化行为影响的研究

An experimental installation of cold model simulation was set up to study the bed pressure drop in different regionsof fixed fluidized bed reactor during top feeding and bottom feeding, respectively, at various gas velocities with thefluidization image of solid particles monitored at the same time. By comparing the changes in bed density and operating gasvelocity in different regions of fixed fluidized bed reactor, the influence of top feeding and bottom feeding patterns on fluidizationbehavior could be investigated. The results showed that the bed density in top feeding reactor responded more stablyto the change in gas velocity along with the advantage of working in a wider range of operating gas velocities. Based on thisstudy, it is concluded that existing bottom feeding reactor configurations cannot meet the fluidization requirements; and optimizationof bottom feeding reactor will be needed.