旋风分离器料腿漏风对压降影响的实验分析

以直径300 mm的旋风分离器为实验对象,考察了在不同入口速度下料腿漏风量对旋风分离器压降的影响,并以此为基础,分析了某现场催化裂化装置旋风分离器压降出现的不稳定波动现象。实验结果表明,旋风分离器下部料腿是一个负压差立管,外部的压力大于料腿内的压力,易产生漏风,从而导致旋风分离器的压降降低。旋风分离器的压降随漏风量增大而降低,入口速度越低漏风量影响的作用就越明显。该旋风分离器的压降波动是由于不稳定的翼阀排料产生的漏风变化造成的。     

循环流化床立管物料反窜现象的分析

介绍了循环流化床流态化及工作原理,分析了立管物料反窜时前后气化炉压差及温差变化情况,确定了中试装置的循环流化床在运行过程中产生立管物料反窜的原因,并提出了稳定返料系统阀门的操作、控制物料循环流动速率、控制好密封腿的气量和料腿的料位高度、保持气化炉流化状态稳定、调整流化气速为4～6 m/s、控制粉煤粒径为0.3～0.4 mm等解决方法。经优化改进后,确保了立管物料不反窜,使床层料位稳定,气化炉流化状态稳定,实现了循环流化床的长周期稳定运行,为循环流化床的工业化推进提供技术支撑。     

旋风分离器进气口尺寸对甲基氯硅烷单体合成的影响

通过对60 kt/a甲基氯硅烷单体生产装置中4种不同进气口尺寸旋风分离器的运行数据分析,结合理论计算,对不同工况下各种生产现象产生的原因及对工业生产的影响进行了讨论。结果表明,旋风分离器进气口尺寸影响合成的含尘气体的进气速度,使流化床反应器系统压力、旋风分离器本身压力降、除尘效率等发生变化影响实际生产。当旋风分离器进气口面积一定的情况下,适当增加进气口宽度,可以获得较高的粒级效率。由于原料颗粒粒径较小,旋风分离器的进气速度应该控制在12~25 m/s。旋风分离器较佳的尺寸是高度450 mm、宽度200 mm,进气速度16.6 m/s。     

循环流化床两级返料器冷态试验研究

在高度为3 m、直径为0.1 m的循环流化床冷态试验台上,通过测量不同工况下的系统压力及物料循环流率,研究了采用两级返料器时,不同压力平衡口位置对系统运行特性的影响,并对比研究了采用单级返料器和两级返料器结构形式循环流化床系统的运行特性。试验结果表明:当采用两级返料器时,在合理的压力平衡口位置范围内,相同工况下不同压力平衡口位置对系统运行特性影响不大;在相同的操作条件下,采用不同结构形式的返料器,系统物料循环流率的变化趋势基本一致,采用两级返料器结构形式时各级立管压降之和与采用单级返料器立管压降基本相同;利用压力的标准方差来表示压力脉动的大小,结果显示:采用单级返料器时,在提升管不同高度处和立管底部压力脉动均比较大,而采用两级返料器结构形式运行更加稳定。     

天然气净化用多管旋风分离器的分离性能

为了系统评价天然气净化用多管旋风分离器的分离性能,在线测量了入口气速6~24 m/s、入口颗粒浓度30~2000 mg/m3范围内多管旋风分离器的分离效率和分级效率. 结果表明,多管旋风分离器的分离效率和分级效率都随入口气速和入口颗粒浓度增大而提高. 与单管旋风分离器相比,在相同实验条件下,多管旋风分离器的分离效率下降2%~15%;单管旋风分离器基本能除净粒径大于10 mm的颗粒,而多管旋风分离器只能去除15 mm以上的颗粒. 多管旋风分离器的压降主要是内部单管旋风分离器的压降,占整个压降的80%~90%.     

催化裂化装置旋风分离器料腿断裂的原因分析

基于气固两相流诱导振动的观点对催化裂化装置旋风分离器料腿断裂的原因进行了分析,认为料腿内不稳定的催化剂颗粒下料产生了压力脉动,进而形成了诱发料腿振动的激振力,料腿振动产生的交变应力导致了料腿金属材料疲劳断裂。最后提出了避免料腿发生断裂的技术措施。     

内置并联式旋风分离器在多晶硅氯氢化反应器中的应用

在氯氢化流化床装置中,旋风分离器系统的分离性能不仅与旋风分离器个性有关,还与旋风分离器串并联组合、内外置选择、料腿底阀排料区域等因素相关。在项目设计和生产过程优化时,要从危险化学品生产装置的特性出发,追求整体运行的平稳可靠。对内外置、串并联旋风分离器组合的优缺点及其在多晶硅氯氢化系统中的应用作了评析。     

旋风分离器锥体局部磨损对内流场及性能的影响

为了探究局部磨损对旋风分离器性能的影响,采用Oka磨损方程以及计算流体动力学(CFD)对旋风分离器壁面磨损以及内流场特性进行数值模拟,考察旋风分离器内流场等参数随磨损厚度增大的变化规律。结果表明,旋风分离器壁在锥体底部排尘口附近壁面局部磨损严重,形成螺旋形冲蚀磨损带。磨损引起设备几何结构的改变会导致切向速度降低,颗粒所受离心力降低,锥体内局部涡强度及影响范围增大,涡核旋进(PVC)的影响加大,不利于主流的稳定与固体颗粒的分离。与未磨损时相比,当局部磨损厚度为20 mm时,粒径为4μm的颗粒分离效率由100%降低至93%,分割粒径由1.3增大至1.9μm,设备压降降低了约40%。研究工作对保障旋风分离器的长期安全稳定运行具有重要理论指导意义。     

多喷嘴对置式水煤浆加压气化工艺的优化改进

多喷嘴对置式水煤浆加压气化工艺自工业化应用以来,其技术研发团队与业主单位不断进行优化改造,如双煤储斗设计、高压氮气系统优化、气化炉液位计改造、渣池泵和沉降槽底流泵改为变频调控、旋风分离器分离室和黑水室压力平衡管改平衡孔、新鲜水补入位置优化、增设高温热水储罐事故补水管线、低压闪蒸气优化利用等。这些举措,促进了系统的节能降耗,保障了装置的长周期、稳定运行。     

催化裂化沉降器内两端敞开型旋风分离器内气相流动规律

研究考察了催化裂化沉降器内两端敞开型旋风分离器内油气流动规律.用CFX软件采用DSM模型进行了数值模拟,并与用五孔探针测试的流场进行了比较,表明DSM模型有良好的预测精度.在此基础上,采用标量输运方程研究了气体在旋风分离器内的停留时间分布规律.实验和模拟结果均表明,该类旋风分离器内流场与常规旋风分离器的有很大的不同,升气管和料腿均存在回流区,升气管回流区最大可波及分离空间,对分离空间流场有很大干扰.气体示踪模拟结果表明,由入口进入旋风分离器,由升气管、料腿排出的气体的停留时间近似呈对数正态分布;升气管、料腿回流区内气体停留时间呈双峰分布;升气管回流区的存在可使总气体平均停留时间增大约5%～10%;料腿直径的减小以及灰斗的存在均可增大由升气管排出的气量并使升气管、料腿回流区大幅减小,进而减小粗旋风分离器内气体总平均停留时间.     

CFB煤燃烧／热解双反应器立管内气固流动模型分析

在循环流化床（CFB）煤燃烧／热解双反应器冷态实验装置上,以硅胶和电厂锅炉灰为实验物料,考察了立管内的气固流动特性,其中立管的内径44mm、高3m。研究结果表明,立管内的气固流动形态为移动床流动,Leung的立管流动模型适合对该系统中立管内移动床流动的描述,经拟合分别得到了立管内气、同速率以及气同相对速率与固体速率之间的经验方程,对热态实验过程中判断立管内的气固流动型态以及料封的稳定性均具有一定的参考价值。     

Study on the stress distribution and modeling of the stand pipe in a circulating moving bed

The liquid-solid circulating moving bed reactor is a novel one, which consists of two reaction chambers and a particle transport system. Particles move down to the lower reaction chamber from the upper reaction chamber through a coupling standpipe and to the particle transport system through a bottom standpipe, and are then conveyed into the upper reaction chamber through a riser. A stress distribution model based on the equations of continuity and momentum balance in the reactor is established and used for simulations which shows that the stress concentration regions are at the coupling standpipe and the bottom of the regeneration chamber. To reduce the largest stress in the stress concentration regions and to minimize catalyst consumption, the regeneration chamber should be designed to give a low ratio of height to diameter. Zoning diagrams of the flow patterns in the bottom standpipe are proposed and the flow patterns can be readily deduced from the pressure gradient.     

STRUCTURE OPTIMIZATION OF A CIRCULATING MOVING BED REACTOR

A stress distribution model for a liquid-solid circulating moving bed reactor that consists of a bottom reaction chamber, a top regeneration chamber, a coupling standpipe, a particle transportation system, and a bottom standpipe is established based on the equations of continuity and momentum balance. Simulations show that the stress concentration regions are at the bottom of the regeneration chamber and the coupling standpipe. To reduce the maximal stress and increase the operation flexibility in a reactor for the 2000-ton-per-year production of linear alkylbenzene, the regeneration chamber should have a low height-to-radius ratio (about 9), a suitable half-conical angle between 28° and 35°, and standpipe radius of about 0.05 m.     

STRUCTURE OPTIMIZATION OF A CIRCULATING MOVING BED REACTOR

A stress distribution model for a liquid-solid circulating moving bed reactor that consists of a bottom reaction chamber, a top regeneration chamber, a coupling standpipe, a particle transportation system, and a bottom standpipe is established based on the equations of continuity and momentum balance. Simulations show that the stress concentration regions are at the bottom of the regeneration chamber and the coupling standpipe. To reduce the maximal stress and increase the operation flexibility in a reactor for the 2000-ton-per-year production of linear alkylbenzene, the regeneration chamber should have a low height-to-radius ratio (about 9), a suitable half-conical angle between 28° and 35°, and standpipe radius of about 0.05 m.     

流化床粉煤气体热载体快速热解反应器的计算

在冷态模拟实验和煤热解动力学计算的基础上,对粉煤气体热载体快速热解提升管反应器的高度进行了计算。利用高速摄像粒子测速法结合互相关算法研究了不同气体流量和不同颗粒粒径时固体颗粒在热解提升管中的运动速度,通过求解神府煤热解动力学方程,得到了不同粒径神府煤颗粒热解挥发分析出的时间,从而确定了快速热解提升管反应器的高度。研究结果表明:当气体流量在850 m3/h,粉煤的粒径主要集中在0.7—3.0 mm时,提升管的高度应选择在10.0 m。     

A novel interconnected fluidised bed for the combined flash pyrolysis of biomass and combustion of char

A novel system of two adjacent fluidised beds operating in different gas atmospheres and exchanging solids was developed for the combined flash pyrolysis of biomass and combustion of the produced char. Fluidised sand particles (200 μm < d_p < 400 μm) are transported from the pyrolysis reactor to the combustor through an orifice and recycled by a standpipe, riser and cyclone. Advantages of the new design are its compactness and the high level of heat integration. The solids circulation rate and holdup distribution between the two compartments could be controlled adequately in experiments at room temperature and atmospheric pressure. A model, developed to predict the solids and gas exchange between the two reactor compartments, was validated with experiments in which the three relevant gas flows, the orifice diameter and the particle diameter were varied.     

Cross‐Scale Modeling and Simulation of Coal Pyrolysis to Acetylene in Hydrogen Plasma Reactors

Coal pyrolysis to acetylene in hydrogen plasma is carried out under ultrahigh temperature and milliseconds residence time. To better understand the complex gas‐particle reaction behavior, a comprehensive computational fluid dynamics with discrete phase model has been established, with special consideration of the particle‐scale physics such as the heat conduction inside particle. The improved chemical percolation devolatilization model that incorporates the tar cracking reactions is adopted. The model predictions are in good agreement with the performances of two pilot‐plant reactors. The simulations reveal the detailed unmeasurable information of gas phase and particle‐scale behaviors, then point out the facts that coal devolatilization almost finishes in the first 100 mm of the reaction chamber and the optimal particle diameter is suggested to be 20–50 μm. The different reactor performances during the scale‐up from 2‐ to 5‐MW unit are analyzed based on the detailed simulation results in combination with the operational experience. © 2012 American Institute of Chemical Engineers AIChE J, 59: 2119–2133, 2013     

垂直立管中催化剂流动特性的实验研究

对垂直立管中催化剂的流动性能进行了实验研究,测定了各种操作条件下立管中的轴向压力分布、催化剂循环速率以及附加吹气的影响. 实验结果表明,立管中的气固流动存在分别处于负压差下移下流区的"脱气段"和处于正压差下移下流区的"持气段"两种流动状态;下料阀开度对固体循环流率有明显的约束作用,且使"持气段"总压降增加较"脱气段"更为明显;对立管引入附加吹气有明显的增压作用,并使立管的压力分布有较大的改变. 根据实验结果及分析,对垂直立管的管形设计和催化剂在垂直立管中的密相输送提出了分析与建议.     

High density and high solids flux CFB risers for steam gasification of solids fuels

The application of high density and high solids flux CFB risers for steam gasification of solids fuels like coal and biomass has been examined in this paper. A simple mass and energy balance analysis revealed that a steam gasification riser needed to be operated at high solids fluxes in order to supply sufficient heat from the standpipe by circulating hot solids to the endothermic gasification reactor. The important design considerations to achieve high solids circulation rate in the CFB unit were discussed in this paper with emphasis given to the riser height, solids inventory, standpipe to riser diameter ratio, and solids feeding control device.     

热管式气液固三相固定床鼓泡反应器试验研究

为了研究热管式气液固三相固定床鼓泡反应器的性能,在一内径为50 mm、高800 mm床内装填多孔填料,内插一根16 mm×2 mm的水-不锈钢热管的反应器中,对2乙-基己烯醛选择性加氢反应进行试验研究,并进行模拟计算。结果表明:在取消外循环的条件下,反应器具有良好的床层温度分布,反应能够得到较高的转化率和良好的选择性。对提高经济效益和设备安全性能具有一定意义。