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.     

REACTOR MODELING OF AN INNOVATIVE LIQUID-SOLID CIRCULATING MOVING BED FOR THE SYNTHESIS OF LINEAR ALKYL BENZENES

The circulating moving bed is an innovative coupled reactor for producing linear alkyl benzenes. It can be used with shorter life span catalysts compared to traditional fixed bed reactors. A model is developed in which the effect of catalyst deactivation on the reaction is simulated using infinitesimal balance equations. The results of step changes between steady states and unsteady states have been calculated with the model.     

REACTOR MODELING OF AN INNOVATIVE LIQUID-SOLID CIRCULATING MOVING BED FOR THE SYNTHESIS OF LINEAR ALKYL BENZENES

The circulating moving bed is an innovative coupled reactor for producing linear alkyl benzenes. It can be used with shorter life span catalysts compared to traditional fixed bed reactors. A model is developed in which the effect of catalyst deactivation on the reaction is simulated using infinitesimal balance equations. The results of step changes between steady states and unsteady states have been calculated with the model.     

并流下行循环流化床反应器中的气固传质特性

采用稳态吸附方法，测定了示踪剂在下行式流化床反应器中的轴向浓度分布，并与理论分布进行拟合，利用Ｍａｒｑｕａｒｄｔ法，求取了不同操作条件下的轴向扩散系数与气固传质系数，藉以揭示并流下行循环流化床反应器中的气固传质特性．基于实验结果，通过因次分析与线性回归，得到了轴向扩散系数Ｅａ及传质系数ＫＦａ与操作条件的经验关联式：Ｐｅ１≡（Ｌｕｆ）／Ｅａ＝０．２２６Ｒｅ０．４９９ＰΘ－０．３０２Ｐｅ２≡ｕｆ／（ＫＦａ．Ｌ）＝０．０００１８５Ｒｅ０．６１８ｐΘ－０．９８３Θ≡Ｇｓ／（ｕｆρｐ）＝ｕｓ（１－ε）／（ｕｇε）关联式与实验数据拟合较好．     

COMPREHENSIVE STUDY OF PRESSURE-DROP BALANCE AND PERFORMANCE OF AN L-VALVE IN A CIRCULATING FLUIDIZED BED

Pressure-drop balance and L-valve performance in a circulating fluidized bed (CFB) were investigated for variation in gas superficial velocity (U_g), secondary air fraction (SA), total solids inventory (I_s), and external aeration flow rate (Q_A), at ambient temperature. The study shows that the solids discharge rate of an L-valve (G_s) changes with the system control variables. Apparently, a wider range of G_s is achieved at increasing U_g, decreasing SA, increasing I_s, and increasing Q_A. The pressure-drop analysis indicates that these characteristics are directly governed by the loop pressure balance. Standpipe bottom pressure is found to be an important indicator of the operating status of the riser, standpipe, and L-valve. The experimental results confirm that an L-valve can be operated effectively by regulating the standpipe bottom pressure. The knowledge obtained from this study is essential for maintaining the performance of a CFB system for combustion operation, as well as for operating circulating fluidized beds on a practical scale.     

循环床非流化回料管内竖管传热的强化

非流化移动床内颗粒的流动为柱塞流，颗粒间无相对运动，竖管传热主要靠颗粒间导热。由于导热热阻大，在管壁周围的颗粒吸热后不易传出，而在其周围形成一个热边界层，阻止了传热。利用在竖管上加上的扰流圈，使近壁处颗粒发生扰动，而使热颗粒传出，冷颗粒得以进入管壁周围，从而起到强化传热的作用。强化后的平均传热系数可增加２０％左右。平均传热系数值可达２２０Ｗ／（ｍ￣２·Ｋ）。     

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.     

低密度循环流化床反应器床层截面平均颗粒速度的变化规律

本文在高8m,内径186mm 的循环流化床中采用 FCC 颗粒,利用 TSI 光纤激光多普勒测速仪测定了局部颗粒速度的径向分布,并获得了床层截面平均颗粒速度。实验结果表明:截面平均颗粒速度随操作气速的增大而增大,随固体循环速率的增大而略有减小。由实验数据回归得到了计算本实验条件下低密度速度的经验关联式。论文还从基本流体力学理论出发,在考虑颗粒加速运动的条件下,建立了一维气、固两相流模型,可以用于预测床层截面平均颗粒速度和空隙率的变化规律,模型计算结果和实验数据吻合较好。     

液固循环移动床反应-再生系统的颗粒循环量调节和输送

液固循环移动床反应－再生系统由上下两个或两个以上的反应室、再生室、连通管和颗粒提升管组成。颗粒经再生室、反应室向下移动,进入输送管后被向上输送返回至再生室。颗粒循环能力决定了反应室和再生室内的颗粒更新速率。是循环移动床操作的关键之一,对反应器的颗粒循环进行了实验研究,提出了一种射流输送和调节结构并对射流输送行为进行了模拟计算。     

OPERATION CHARACTERISTICS OF A NEW LIQUID-SOLID CIRCULATING MOVING BED REACTOR

The liquid-solid circulating moving bed reactor is a novel one, which consists of two or more reaction chambers and a particle transport system. Particles move down to the lower reaction chamber from the upper reaction chamber through an upper conduit and to the particle transport system through a lower conduit, and then are conveyed into the upper reaction chamber through a riser. The circulating rate of particles and the flow of liquid in the two conduits are key factors to the continuous steady operation of the reactor; they can be controlled by varying operating conditions: the outlet liquid flow rate in the regeneration chamber, the outlet liquid flow rate in the reaction chamber, the inlet liquid flow rate of the reactants, and the flow rate of driving flow. A flow model has been proposed to quantify the operation characteristics of the reactor. The results predicted by the model show satisfactory agreement with the experimental data.     

液固循环移动床反应器操作规律和模拟

液固循环移动床反应 -再生系统由上下两个或两个以上的反应室、再生室、连通管和颗粒提升管组成 .颗粒经再生室、反应室向下移动 ,进入输送管后被向上输送返回至再生室 .颗粒循环能力和各流股间的窜液行为是循环移动床连续操作的关键 .通过实验对该液固循环移动床的颗粒循环、斜管窜液和连接段窜液的规律进行了研究 ,同时建立了循环移动床的液固流动模型 ,并进行了模拟计算     

移动床径向反应器中气体离心流动对颗粒移动状况的影响

对于催化剂不断失活但可再生的工业过程,广泛采用移动床径向反应器在较低的系统压降下进行连续操作.此时存在由贴壁和空腔现象所决定的径向气体流量的上限值.本文分析了有径向离心气体流动时颗粒层中的应力分布,应用散料力学理论建立了计算床中初始形成空腔时无因次床层总压降的理论模型,模型预测值与实验值符合很好.同时测定了不同条件下空腔界面的形状.     

循环流化床底部加速段特性的研究

在直径为φ260mm 的循环流化床中,采用工业 FCC(Y—7)催化剂,于气速1.45～4.71m/s 范围内测量了颗粒循环速率及循环床沿轴向的压力分布。根据轴向压力分布的分段特性,确定了循环床底部加速段的长度。引入了粒子团聚度系数 C 的概念,用所提出的模型对加速段内颗粒的加速规律进行了模拟计算。计算结果与实验数据吻合较好,并得出最合适的 C_(z)关系式为:C_(z)=C_(n)exp(-bZ)     

合成直链烷基苯用循环移动床反应器的模拟

循环移动床是一种新型的耦合式反应器,用于合成直链烷基苯.通过试验研究了操作条件对反应的影响,并通过微元物料平衡建立了反应器热态模型.该模型考虑了催化剂失活对反应的影响,同时对反应过程的稳态操作情况和非稳态阶跃操作情况进行了模拟计算.     

移动床生物膜反应器处理奶牛场废水的性能研究

利用移动床生物膜反应器(MBBR)工艺处理干清粪工艺的奶牛场废水。试验结果表明,进水NH4+-N含量、气水比、水力停留时间(HRT)以及是否回流对MBBR的处理效果影响明显,回流比对MBBR的脱氮效果有一定的影响。当进水NH4+-N、TN的质量浓度和COD分别为134.4、156.7 mg/L和460.7 mg/L时,在HRT和气水体积比、回流体积比分别为18 h和30:1、2:1的条件下,NH4+-N、TN和COD的去除率分别为98.04%、62.38%和75.18%。MBBR工艺可以有效地处理干清粪条件下的奶牛场废水,适应性强且效果稳定可靠。     

EFFECT OF OPERATING VARIABLES ON BED TO WALL HEAT TRANSFER IN A CIRCULATING FLUIDIZED BED

Heat transfer coefficients were measured for 227 and 87 micron size particles of silica sand in a 102 mm dia. and 5.5 m tall circulating fluidized bed made of plexiglass. Effects of solid circulation rate, fluidization velocity, bed density and particle sizes were studied. The heat transfer coefficients were calculated from the temperatures measured along the axis of a 25 mm dia 100 mm long cylindrical heat flux meter.     

液固反应-再生循环流化系统连续合成十二烷基苯

在新型液固循环反应-再生流化系统中研究了十二烷基苯的合成。探讨了反应转化率、表观反应速率常数、催化剂活性因子等随接触及操作时间的变化规律。分析了新工艺中的产物分布。预测了具有工业意义转化率的反应器结构尺寸和操作条件。     

模拟移动床吸附分离间二甲苯

采用多柱串联连续吸附流程,利用模拟移动床从混合二甲苯中分离间二甲苯。讨论了进料组成、吸附比、置换比、脱附比、温度、压力等因素对产品纯度的影响,产品质量分数达９９．５％以上     

膜法SBR三相外循环流化床反应器

本文分析了以多孔高分子载体为固相的三相外循环流化床反应器的优点,通过与膜法SBR工艺相结合,在处理COD浓度范围为600～1400mg/L,容积负荷范围为1.78～4.15kgCOD/m3.d的有机废水,其COD去除率能高达90.0%以上,NH4 -N的去除率能高达70.0%以上。结果还表明,该工艺具有处理较高浓度废水的潜力。     

气固错流移动颗粒床过滤器除尘效率

研究了气固错流移动颗粒床过滤器除尘效率与表观过滤气速、颗粒层移动速度、过滤气体粉尘含量的关系,并进一步探讨了粉尘在颗粒层内的沉积对除尘效果的影响.结果表明,颗粒层内粉尘沉积量较低时,沉积的粉尘有效地促进了颗粒层除尘效率的提高,但随粉尘沉积量增大,沉积粉尘的二次飞扬变得严重,其促进效应逐渐减小.在考虑了沉积粉尘对除尘效率影响和颗粒层内粉尘沉积不均匀性的基础上,基于捕集单元的收缩管模型,建立了计算移动颗粒层除尘效率和床层内粉尘沉积分布的数学模型.模型计算结果和实验数据比较表明,在操作气速0.1～0.3m•s^-1范围内,计算值与实验结果吻合较好.据此对除尘效率和床层内粉尘沉积的变化趋势进行了模拟分析.