A novel dynamic bayesian network‐based networked process monitoring approach for fault detection,propagation identification,and root cause diagnosis

A novel networked process monitoring, fault propagation identification, and root cause diagnosis approach is developed in this study. First, process network structure is determined from prior process knowledge and analysis. The network model parameters including the conditional probability density functions of different nodes are then estimated from process operating data to characterize the causal relationships among the monitored variables. Subsequently, the Bayesian inference‐based abnormality likelihood index is proposed to detect abnormal events in chemical processes. After the process fault is detected, the novel dynamic Bayesian probability and contribution indices are further developed from the transitional probabilities of monitored variables to identify the major faulty effect variables with significant upsets. With the dynamic Bayesian contribution index, the statistical inference rules are, thus, designed to search for the fault propagation pathways from the downstream backwards to the upstream process. In this way, the ending nodes in the identified propagation pathways can be captured as the root cause variables of process faults. Meanwhile, the identified fault propagation sequence provides an in‐depth understanding as to the interactive effects of faults throughout the processes. The proposed approach is demonstrated using the illustrative continuous stirred tank reactor system and the Tennessee Eastman chemical process with the fault propagation identification results compared against those of the transfer entropy‐based monitoring method. The results show that the novel networked process monitoring and diagnosis approach can accurately detect abnormal events, identify the fault propagation pathways, and diagnose the root cause variables. © 2013 American Institute of Chemical Engineers AIChE J, 59: 2348–2365, 2013     

基于ICA混合模型的多工况过程故障诊断方法

针对工业过程数据的多模态和非高斯特性,提出一种基于独立元混合模型（independent component analysis mixture model,ICAMM）的多工况过程故障诊断方法。该方法将独立元分析与贝叶斯估计结合,同时完成各个工况的数据聚类和模型参数求取,并建立基于贝叶斯框架下的集成监控统计量实时监控过程变化。在检测到故障后,针对传统的变量贡献图方法无法表征变量之间信息传递关系的缺点,提出基于信息传递贡献图的故障识别方法。该方法首先计算各变量对独立元混合模型统计量的贡献度,进一步通过最近邻传递熵描述故障变量之间的传递性,挖掘故障变量之间的因果关系,从而确定故障源变量和故障传播过程。最后对一个数值系统和连续搅拌反应釜（CSTR）过程进行仿真研究,结果验证了本文所提出方法的有效性。     

Evaluation of an Entropy‐Based Combustion Model using Stochastic Reactors

The entropy transport concept (ETC) presented in this paper is a novel approach to describe reaction systems such that the dynamic behavior of a chemical system can be reproduced with a minimum in independent parameters. It is shown that, for adiabatic conditions, the mixture fraction and the reaction entropy are sufficient to describe combustion processes without significant loss of information. Entropy is used as a measure of the reaction progress in this context. In order to evaluate the applicability of the ETC for combustion modeling in turbulent systems, the entropy transport concept was implemented into a stochastic reactor model. For several test cases, the results of this ETC‐based reactor were compared with a reactor that directly integrates the species transport equations.     

Thermodynamic analysis in the design of process networks

Thermodynamic analyses based on the concepts of irreversible entropy increases or exergy losses have frequently been suggested as pointers to sources on inefficiency in chemical processes. For instance, by evaluating the entropy gain in distillation systems, an incentive might be identified for research into thermodynamically more effient separation technology.

However, a process engineer seeking to design a practical flowsheet with present day technology is much less certain about the value of thermodynamic analysis. In his environment of technical constraints, the interpretation of thermodynamic criteria is by no means straightforward and may even lead to incorrect conclusions unless some care is taken.

The present paper describes an approach overcoming this problem. Examples are quoted from the studies of two industrial processes (Sulphuric acid and nitric acid). Further, a generalised discussion is given and results are quoted from the successful application of the approach in fourteen ICI design projects.     

电磁流体中火用的传递和转换特性

审视了多组分黏性电磁流体（包含热传输、对流、电磁能传输、质量传输和化学反应过程）的动量传递方程、质量传递方程、能量传递方程，重新构建了电磁流体的熵传递方程。通过定义热火用、压火用、化学火用、动能火用、势能火用、电磁火用，重新构建了不同形式火用传递的分量方程及其总火用传递方程。通过分解这些传递方程，揭示了不同形式火用之间可逆与不可逆的传递和转换关系，为理解不可逆传递过程的机制、正确计算不可逆性的火用损及其改善电磁流体传递过程的性能和用能效率提供了有效的途径。     

Entropy Analyses of Droplet Combustion in Convective Environment with Small Reynolds Number

This paper analyzes the entropy generation rate of simple pure droplet combustion in a temperature-elevated air convective environment based on the solutions of flow, and heat and mass transfer between the two phases. The flow-field calculations are carried out by solving the respective conservation equations for each phase, accounting for the droplet deformation with the axisymmetric model. The effects of the temperature, velocity and oxygen fraction of the free stream air on the total entropy generation rate in the process of the droplet combustion are investigated. Special attention is given to analyze the quantitative effects of droplet deformation. The results reveal that the entropy generation rate due to chemical reaction occupies a large fraction of the total entropy generated, as a result of the large areas covered by the flame. Although, the magnitude of the entropy generation rate per volume due to heat transfer and combined mass and heat transfer has a magnitude of one order greater than that due to chemical reaction, they cover a very limited area, leading to a small fraction of the total entropy generated. The entropy generation rate due to mass transfer is negligible. High temperature and high velocity of the free stream are advantageous to increase the exergy efficiency in the range of small Reynolds number (<1) from the viewpoint of the second-law analysis over the droplet lifetime. The effect of droplet deformation on the total entropy generation is the modest.     

Elimination of Third-series Effect and Defining Partial Measures of Causality

Using the one-way effect extraction method, this paper presents a set of partial causal measures which represents quantitatively the interdependence between a pair of vector-valued processes in the presence of a third process. Those measures are defined for stationary as well as for a class of non-stationary time series. In contrast to conventional conditioning methods, the partial concept defined in the paper would be mostly devoid of feedback distortion by the third process. The paper also discusses statistical inference on the proposed measures.     

决策网络图方法用于天然气化工企业发展的规划决策

针对生态工业决策的实践需要设计了“生态工业决策网络图”作为结构化表征生态工业决策问题的工具,探讨了基于这一工具的决策流程;然后以某天然气化工企业产业发展规划的制定过程为例,进行“生态工业决策网络图”应用的案例分析,说明了决策方案的提出,对应的生态工业决策网络图生成和修剪过程,通过直接定性、层次分析法综合以及逻辑推理3类过程完成了系统的决策。     

Methods for root cause diagnosis of plant‐wide oscillations

Plant‐wide oscillations are common in many industrial processes. They may impact the overall process performance and reduce profitability. It is important to detect and diagnose such oscillations. This paper reviews advances in diagnosis of plant‐wide oscillations. The main focus of this study is on identifying possible root causes of oscillations using two techniques, one based on data analysis in the temporal and spectral domains and the other based on process connectivity analysis. The process data‐based analysis provides an effective way to capture the difference between the root cause variable and the secondary propagated oscillating variables. It is shown that process topology‐based methods are capable of finding oscillation propagation pathways and, thus, help in determining the root cause. This paper discusses and compares five such methods—spectral envelope, adjacency matrix, Granger causality, transfer entropy, and Bayesian network inference methods— by application to an industrial benchmark dataset. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2019–2034, 2014     

Comparison of Concentration Profiles for Boundary Layers in Absorption with Chemical Reaction Processes

An analysis of five different systems of absorption‐with‐chemical‐reaction in gas‐liquid reactors, commonly encountered in various industrial processes, is presented. To analyze the interphase mass transfer from gas to liquid, the rate limiting parameters and the concentrations at the gas‐liquid interface were determined on the basis of pertinent theories. The calculations presented, are based on the Whitman theory for gas and liquid phase mass transfer coefficients and Henry equilibrium constants. The necessary diffusion coefficients were calculated from existing correlations, and the corresponding chemical reaction rate constants were obtained from the literature, assuming pseudo first order chemical reaction. The process parameters required (pressure, temperature, and the gas‐liquid contact time) were within the values that occur in industrial processes. The results presented, are the concentration profiles in the boundary layers for the systems studied, calculated and graphically presented, together with the gas and liquid film thicknesses and Hatta numbers, obtained from calculations for the liquid phase mass transfer. The results may contribute to a better understanding of the absorption‐with‐chemical‐reaction processes in industrial plants, thus lowering the operational costs of these processes and alleviating the ecological problems of existing technologies.     

Control of Dynamical Processes in Solution: An Overview and Personal Perspective

A brief overview of studies of optical control of dynamical processes in solution is presented, with a focus on control of selection of product in a chemical reaction. It is argued that there are circumstances under which adiabatic population transfer in the liquid phase is possible, and that variations of such transfer processes can be used to control dynamical processes in solution.     

Perspektiven für die Forschung im Chemieingenieurwesen: Die französische Politik

The future of chemical engineering research – the French policy . Future prospects of chemical engineering research are set forth, as they result from discussions organized by the French government. In the first part, the situation in French Research Institutes is briefly described: programmes, structure, financial support and co-operation with industry. In the second part, the role of Chemical Engineering in solving problems in industrial societies is discussed. Prominence is given to cases of successful industrial scaling-up of laboratory processes, with emphasis given to the following: systems approach, modelling methods for fast and safe design, rapid adaptation of process industries to changes in economic conditions, application of chemical engineering concepts to new areas of biology, nutritional and soil sciences, electrochemical, solar and nuclear engineering etc. Problems which remain unsolved and future research topics are presented: heat and mass transfer in multiphase media, exergetic process analysis and causes of exergy losses in unit processes, new separation processes and reactor types, processes based on materials which can be regenerated, and automation of chemical processes.     

基于开源组件的SDG推理平台

符号有向图(SDG)是定性研究化工过程中变量间关系的有力工具,利用SDG的正向反向推理机制可以快速发掘出系统中变量之间影响的因果关系,不仅可以用于在线的故障诊断,还可以用于离线的危险和可操作性(HAZOP)分析。近年来,随着计算机和信息技术的发展,人们利用GensymG2或者C++开发了一些针对特定研究体系的SDG模型的计算机辅助推理系统,但是,目前还没有一个通用的SDG推理平台。为促进SDG在科研和教学中的广泛应用,本文介绍了通过公共组件来搭建的一套开放体系的SDG推理平台系统,这是服务器/浏览器结构的推理平台,使用方便,维护便捷。使用这套系统,可以方便地绘制特定研究体系的SDG模型的图形;可以快速建立针对特定研究体系的SDG系统并且进行相应的推理分析。本文通过一个例子演示了如何在SDG推理平台上建立特定SDG推理系统的方法,之后通过对两个研究体系建立SDG推理系统来展现该平台的有效性。     

Efficient hydrogen generation from organic chemical hydrides by using catalytic reactor on the basis of superheated liquid-film concept

Under boiling and refluxing conditions for catalytic dehydrogenation of organic chemical hydrides (decalin, methylcyclohexane and others) in a batch-wise reactor, either suspended states with excess amounts of substrate or sand-bath states with its scarce amounts were found to be inferior generally to the so-called “liquid-film states” with adequate amount ratios of substrate to catalyst, where the catalyst-layer temperatures were superheated or raised higher than the boiling point, and, consequently, reactivities became more favorable at higher heating temperatures in contrast to the boiling suspended states.Equilibrium shifts due to reactive distillation were well demonstrated under boiling and refluxing conditions in naphthene dehydrogenation. Moreover, desorption of hydrogen from the active sites to the bubble space was enhanced in the superheated liquid-film states, with large translational entropy endowed.Provided the extents of equilibrium deviation were large enough (Prigogine's approach), thermodynamic couplings among irreversible processes would be realized between heat transfer and mass transfer as an example of the extended De Donder's equation. Restriction of chemical equilibrium could be removed under temperature gradient conditions, as the consequence that its Gibbs energy change became more negative than that under iso-temperature conditions.Within the framework of irreversible thermodynamics, the decreased retardation constant K in the superheated liquid-film states was interpreted in terms of a vector-level coupling between temperature gradient and desorption. Moreover, vigorous bubble formation would give additional favor to the reaction rates owing to enlarged repeating frequencies of sequential non-microreversible processes in dehydrogenation catalysis.Organic chemical hydrides are attractive from the viewpoints of safe, economical, exergy-saving and large hydrogen contents for hydrogen storage and distribution. Their main defects have been pointed out hitherto that the endothermic reaction temperatures are too high. In this paper, a new concept on superheated liquid-film catalysis is explored for dehydrogenation temperatures to decrease, which would result in not only saving exergy for external heating but also avoiding catalyst deactivation due to carbon deposit.     

“边界层”在多种化工单元操作中的体现

诸多的化工单元操作过程中,普遍存在着"边界层"现象。"边界层"的存在对化工单元的操作过程会产生明显的影响。本文描述和类比了多种"边界层"的特征,并在物理化学的知识层面上对其产生机理进行了阐述,最后指出通过削弱边界层可以提高动量传递、质量传递和热量传递的速率和效率。     

Bayesian Inference for Time Series with Stable Innovations

This paper describes Bayesian inference for a linear time series model with stable innovations. An advantage of the Bayesian approach is that it enables the simultaneous estimation of the parameters characterizing the stable law and the parameters of the linear autoregressive moving-average model. Our approach uses a Metropolis–Hastings algorithm to generate samples from the joint posterior distribution of all the parameters and subsequent inference is based on these samples. We illustrate our approach using data simulated from three linear processes with stable innovations and a real data set     

Modeling Intermittent Drying Using an Adaptive Neuro-Fuzzy Inference System

Artificial intelligence systems such as artificial neural networks (ANN) and fuzzy inference systems (FIS) are widely accepted as a technology offering an alternative way to tackle complex and ill-defined problems. The advantages of a combination of ANN and FIS are obvious. This article presents the application of a hybrid neuro-fuzzy system called adaptive-network-based fuzzy inference system (ANFIS) to time dependent drying processes and is illustrated by an application to model intermittent drying of grains in a spouted bed. An introduction to the ANFIS modeling approach is also presented. The model showed good performance in terms of various statistical indices.     

Nonlinear Heat and Mass Transfer with Consideration of Deformation in a Chemical Reaction Wave

A new approach is developed to perform mathematical modeling of heat transfer with consideration of deformation of a physical system in a chemical reaction zone. This approach describes boundary conditions using fractional differential-integral calculus. A numerical analysis using the model proposed is undertaken to examine processes during nonlinear heat transfer accompanied by deformation of a physical system due to intense gas release in chemical reactions, particularly in processes of the production of materials by self-propagating high-temperature synthesis.     

Multi-dimensional design process management by extended product modeling for concurrent process engineering

Conventional product and process models have focused on static features. That means product models are mainly based on structural decomposition of products, and process models are also often described by activity decomposition such as work breakdown structure. From the view of design process management, it is difficult to describe dynamic features of design processes appropriately through conventional methodologies. In this paper, a multidimensional approach for design process management was explored to manifest characteristics of design processes for chemical plant design. Parallelized design process for concurrent process engineering should be managed by twodimensional design activity flows. The process management makes it possible to guide progress of design processes in a helix structure by horizontal and vertical activity control simultaneously. They stand for teleological and causal relation between design activities, respectively. That can be achieved based on an extended product model, which represents various design perspectives explicitly from a conventional design activity model. The extended product model is composed of product data, design activities, and activity drivers. Dynamic features of the extended product model are expressed by an activity chain model. These concepts will support the realization of concurrent process engineering for chemical plant design in the sense that they provide design process management strategies.     

Drehrohrreaktoren in der Chemietechnik

Rotary kiln in chemical engineering. This review stresses the importance of rotary kilns in industry. After a brief account of design considerations, the following processes are treated: particle and product motion, longitudinal and transverse transfer of solids, mass- and heat transfer, as well as chemical reactions. Common models used for rotary kilns are discussed. Typical industrial processes employing rotary kilns are presented. The present status of control and automation of these plants are discussed.