Prediction of Flooding in Packed Liquid-Liquid and High-Pressure Extraction Columns Using a Gaussian Process

Reliable prediction of flooding conditions is needed for sizing and operating packed extraction columns. Due to the complex interplay of physicochemical properties, operational parameters and the packing-specific properties, it is challenging to develop accurate semi-empirical or rigorous models with a high validity range. State of the art models may therefore fail to predict flooding accurately. To overcome this problem, a data-driven model based on Gaussian processes is developed to predict flooding for packed liquid-liquid and high-pressure extraction columns. The optimized Gaussian process for the liquid-liquid extraction column results in an average absolute relative error (AARE) of 15.23 %, whereas the algorithm for the high-pressure extraction column results in an AARE of 13.68 %. Both algorithms can predict flooding curves for different packing geometries and chemical systems precisely.     

Life cycle of hydroprocessing catalysts and total catalyst management

Hydroprocessing catalysts based on Ni, Co, Mo and W are used in various refinery processing applications where several deactivation mechanisms become of importance (coke formation, active phase sintering, metals deposition, poisoning) in the catalyst's life cycle. The life cycle of commercial hydroprocessing catalysts is very complex and includes the catalyst production, sulfidation, use, oxidative regeneration followed by re-sulfidation and reuse or, if reuse is not possible, recycling or disposal. To understand the changes in catalyst properties taking place during a life cycle, the catalyst quality in the different stages can be best monitored by using advanced analytical techniques. The catalyst's life cycle is further complicated by numerous technical, environmental and organizational issues involved. In principle, different companies can be involved in each of the life cycle steps. Leading catalyst manufacturers, together with specialized firms, offer refineries a total catalyst management concept, starting with the purchase of the fresh catalyst and ending with its final recycling or disposal. Total catalyst management includes a broad range of services, ensuring optimal timing during the change-out process, reliable, smooth and safe operations, minimal downtime and maximum catalyst and unit performance.     

Aromatic nitrations by mixed acid. Slow liquid-liquid reaction regime

Aromatic nitrations by mixed acid have been selected as a specific case of a heterogeneous liquid-liquid reaction. An extensive experimental programme has been followed using adiabatic and heat-flow calorimetry and pilot reactor experiments, supported by chemical analysis. A series of nitration experiments has been carried out to study the influences of different initial and operating conditions such as temperature, stirring speed and sulphuric acid concentration. In parallel, a mathematical model to predict the overall conversion rate has been developed. In this paper the mathematical modelling and the implementation and experimental validation for benzene, toluene and chlorobenzene mononitration in the kinetic control regime (slow liquid-liquid reaction) are presented and discussed.     

三氯乙烯与糠醛水溶液的液液平衡及萃取模拟计算

本文采用液液平衡釜了糠醛水溶液与三氯乙烯的液液平衡数据，用ＵＮＩＱＵＡＣ方程关联糠醛－水－三氯乙烯体系的液液平衡数据，以ＵＮＩＱＵＡＣ方程的模型，采用液液萃取法模拟计算糖醛和水的分离结果。     

CDMA时变色散信道的两级盲辨识算法

本文通过对时变信道的扩展函数在时频域进行正则采样，得到了CDMA时变系统的离散正则模型。针对该模型提出了一种具有较低运算量的两级盲辨识算法。为避免两级算法产生的误差传播效应，文章将理想SIMO模型等效为加性噪声模型来处理。与基展开模型方法相比，该算法具有不需利用观测数据的高阶统计量估计展开基频率的优点。文章通过仿真验证了该算法是可行的。     

工业化陶瓷超滤膜的表征

以液-液排除法测定工业化陶瓷超滤膜的孔径及孔径分布，比较了两种渗透体系对测定结果的影响；用已知分子量标准物质考察了不同膜的截留行为，获得了各膜的切割分子量值，并分析了截留率与孔径的对应关系，为工业化陶瓷膜的开发提供依据。     

Investigation on the flocculation of asphaltenes and the colloidal stability of the crude oil fraction (> 210°C)

Several problems are encountered with asphaltenes during the exploitation, transportation, storage and treatment of crude oil. The purpose of the present work was to study the behaviour of the crude oil fraction (<210°C) by varying the temperature and doping with some hydrocarbons including solid paraffin and aromatic concentrate. The effect of flooding water was investigated. A preliminary characterization study on asphaltenes removed from the crude oil using two different solvents was performed. The state of the oil was determined by the stability factor which indicates the susceptibility of asphaltenes to agglomerate or to disperse in the continuous phase.     

电场作用下液液系统中液滴变形的计算模型

基于单元变形的思路,由单元守恒方程出发,建立电场中液滴变形的数值计算模型. 在此基础上,将该模型与偶极模型相耦合,提出液滴聚结的计算方法. 由所建模型及计算方法,编制数值计算程序对几种参数下液滴的变形及聚结进行模拟计算. 结果表明,所建模型对液滴变形的预测与实验结果相符较好,对液滴聚结过程的模拟与实验结果大致相符,预测的聚结时间稍低于实验值. 如果进一步提高单元阻力的模化精度及单元离散精度,所建模型会有较好的适用性. 所建模型可实现对液滴的扁平形变形的预测. 研究结果对液滴电变形的理论分析及数值模拟具有一定的借鉴意义.     

偏晶合金液-液相变过程模拟

建立了能描述在弥散相液滴形核、扩散长大、碰撞凝并及两液相空间分离等因素共同作用下，偏晶合金液-液相变过程中组织演变过程的数学模型。将计算的温度场和浓度场与控制凝固组织演变的动力学方程相耦合，模拟研究了单向冷却条件下Al-Pb合金液-液相变过程中的组织演变过程。结果表明，随着冷却的进行，液-液相变区不断由试样底部向试样顶部推进，直至贯穿整个试样。由于在凝固过程中弥散相液滴进行Marangoni迁移和Stokes运动，试样中的某些部位会出现液滴贫化、过饱和度增加和多次形核现象。     

搅拌槽内的液-液临界分散

在φ391mm搅拌槽中,分别采用双层Brumagin桨、双层三叶后掠式桨和双层A310桨与7种内构件相组合,在无乳化剂下对油水比(质量比)分别为1∶1.5,1∶2.0的煤油-水体系的液-液临界分散进行了研究。从工业实用的角度出发,对前两种桨找到了一种可替代“轻液挡板”的小挡板及其安装方法:内冷管上均布4块小挡板,B/D=0.08,插入液面深度为0.2D。在φ188mm搅拌槽中,于全挡板条件下,以歧化松香皂为乳化剂,分别采用3种不同几何参数的双层Brumagin桨对油水质量比为1∶1.5的煤油-水体系的临界分散进行了研究。结果表明,与无乳化剂情况相比,液-液临界分散转速(N_c)下降30％～40％,临界分散功耗(P_(cv))下降53％～66％;桨径减小会使N_c和P_(cv)增加。