Zur Nutzung neuer Informationstechnologien im Chemieingenieurwesen (Stand und Entwicklungstrends)

Use of information technologies in chemical engineering (state of the art and trends) . Information saves energy, time and money. Data processing has developed very rapidly within recent years. The number of data bases and their volumes have multiplied. An end-user is initially confused when choosing a new system suitable for his purpose. At the chemical engineer's disposal are computing performance, data bases about special literature and physical properties, CAD for designing, process computers improve the running of production plants, simulations by computer and programmes, respectively, help to solve development problems without incurring any risk, thus lowering costs, and the new personal computers are programmable directly at the job. Engineers are still not as familiar with word processing and office communication as commercial people are. Steadily increasing speed of data transmission and higher data density reduce costs, e. g. by public data nets like EURONET or DATEX or private so-called ?inhouse nets”?. The commercial use of ?Bildschirmtext”? and ?Videotext”? has been started. Information about the new facilities enables the chemical engineer to choose the most effective systems for his work.     

Expedition ins Datenreich: Wie kann man Informationen in Produkt- und Prozeßdaten umfassend erschließen?

Exploring the Data World: How Can We Extract the Maximum Information from Product and Process Data? In various areas of the chemical industry a wealth of product and process data of various kinds is generated and recorded. In the majority of cases these data have only been evaluated fragmentarily and not systematically in terms of their information contained. Following the acquisition and possible short term visualization they end up in regular “data graveyards”. Furthermore, these data often stem from different sources such as distributed control systems (DCS), laboratory information and management systems (LIMS), or shift logs. There is a great potential for an improvement of product quality, process control, and plant safety, as well as for a reduction of inspection costs in the compilation and systematic analysis of these data. In addition to classical statistical methods, new data analysis techniques are increasingly used. After a brief explanation of the procedure used in data analysis projects and a presentation of several methods, an example illustrates which results can be obtained from an approach to data analysis that is not yet widespread in the process industry.     

Aufgabengerechte Informationssammlung für die Verfahrensentwicklung

Information system for process development. An essential requirement for successful process development is the availability of relevant specialist information. Structuring the necessary activities by the techniques of systems engineering during the course of process development can provide detailed knowledge of the information required. However, comparison of available supply and demand shows that an essential part of the information, i.e. the solutions of unit operations and the accompanying equipment, have not hitherto been collected in systematic information systems. There fore principles are developed for the creation of information systems for process development and are demonstrated by the example of a ?solution catalogue”? for filter equipments for the solid/fluid separation.     

Use of microelectronics to upgrade process control into production control

Process control in oil extraction and processing is traditionally done by independent control loops and logic (sequence) controls. In the best case, all controls are located in one central control room. The operator’s task is to draw the right conclusions from the process conditions signalled to him, to coordinate, to plan and to keep logsheets. On the basis of this information, he can coordinate between control loops and optimize unit operations. With the application of modern microelectronic-based control systems (integrated control systems), it is possible to present the operator’s information on a higher level (e.g., yield figures and energy consumptions computed from basic data), to do computerized planning operations and updatings, and to retrieve data which are used as an input for accounting systems and management information systems. Underlying principles, means for implementation, as well as benefits (both proven and potential) are described. The available hardware and software packages hardly form any limitations; on the contrary, we must often limit ourselves to optimal use of the available tools and not fall into the trap of “maximal automation.” Our aim is not to automate and control as much as possible, but to use automation as one of the means to process oilseeds and edible oils with the highest possible efficiency.     

Integrated cyberattack detection and resilient control strategies using Lyapunov-based economic model predictive control

The use of an integrated system framework, characterized by numerous cyber/physical components (sensor measurements, signals to actuators) connected through wired/wireless networks, has not only increased the ability to control industrial systems but also the vulnerabilities to cyberattacks. State measurement cyberattacks could pose threats to process control systems since feedback control may be lost if the attack policy is not thwarted. Motivated by this, we propose three detection concepts based on Lyapunov-based economic model predictive control (LEMPC) for nonlinear systems. The first approach utilizes randomized modifications to an LEMPC formulation online to potentially detect cyberattacks. The second method detects attacks when a threshold on the difference between state measurements and state predictions is exceeded. Finally, the third strategy utilizes redundant state estimators to flag deviations from “normal” process behavior as cyberattacks.     

A graphical approach to cause and effect analysis of chemical processing systems

A method for cause and effect analysis of chemical processing systems has been developed on the concept of a signed directed graph. The signed directed graph, called a “model graph,” is used for representing cause and effect relationships among process variables in a system, and a “Pattern” on the graph is introduced to represent a state of the system, which is specified by “0” for normal state, “ + ” and “ ? ” for larger and smaller deviation from the normal state, respectively. For a given model graph and pattern on it, the cause of state changes and the manner of their propagation are easily found out by the present approach, which is mainly based on the depth-first search algorithm developed by Tarjan. As an illustrative example, a propane vaporizer has been taken to show the usefulness of the present approach.     

Safety securing approach against cyber-attacks for process control system

After the appearance of Stuxnet, the safety assurance against cyber-attacks has been a serious problem for process control. For safety assurance, not only information system securing approaches but also process control original measures are necessary. In this paper, a new protection approach is proposed. Application of an information system securing technique called “zones and conduits” to process control is discussed. By dividing the control system network into plural zones, higher possibility of detecting cyber-attacks and preventing operational accidents can be achieved. By defining detectability and reachability matrices, zone division for cyber-attack detection can be designed.     

Prozeßsystemtechnik — Gedanken zu Notwendigkeit und Inhalt einer akademischen Lehre

Process System Engineering. Thoughts on the need for and curriculum of an academic course of instruction . The raw material, energy, and environmental situation, international competition, and the decline in product innovation are increasingly casting doubts on conventional processes and their realization. Hence, in the future-training of chemical engineers a reasonable amount of time should be devoted to the study of system facets, i. e. to thinking and acting in complex systems of interrelationships. Under the general leading ?Process System Engineering”? those activities are discussed which are relevant to the design and planning of chemical engineering systems (process synthesis) and the mathematical analysis of a given system (process analysis). Process synthesis is the creative facet of project planning involving several methodologies. Process analysis embraces steady-state and non-steady state mass- and energy-balancing and the mathematical evaluation of various process alternatives on the basis of operating costs and investment as well as the simulation of operational behaviour and optimization of process configurations using mathematical models. The following article discusses a selection of points which should play an important part in the teaching of process synthesis and process analysis and considers some examples by way of illustration.     

Erforderliche Informationsstrukturen für die Qualitätssicherung

Information Structures Required for Quality Assurance. An information model ?quality”? is developed on the basis of an object-oriented structuring of the production process into the two object classes of ?product”? and ?process element”?. The pertinent product and process properties are represented as set and actual values in property profiles. Particular attention is paid to the scaling necessary or possible for each value representing a property. The histogram has proved to be an appropriate method of representation. Changes in the product-describing properties occurring during the production process are shown. The information structure selected permits definition of a quality assurance concept and the information and equipment necessary for its implementation.     

Review of information management in computer-aided engineering

The database sector of information technology is a rapidly developing area of academic and commercial interest, but until recently it has had little impact on the chemical engineering industry. Database-management systems (DBMSs) have been used as the foundation for some proprietary computer-aided process engineering (CAPE) packages, but the potential also exists for individual users of CAPE applications software to create their own tailor-made design environments by integrating packages around a DBMS. Unfortunately, traditional DBMSs are not designed to handle the complex static and dynamic nature of process engineering design data. This paper briefly examines this “data problem”, reviews a variety of proposals to deal with it and, finally, points to a need for database tools to be specifically designed for process engineering applications.     

Composite fast‐slow MPC design for nonlinear singularly perturbed systems

The design of a composite control system for nonlinear singularly perturbed systems using model predictive control (MPC) is described. Specifically, a composite control system comprised of a “fast” MPC acting to regulate the fast dynamics and a “slow” MPC acting to regulate the slow dynamics is designed. The composite MPC system uses multirate sampling of the plant state measurements, i.e., fast sampling of the fast state variables is used in the fast MPC and slow‐sampling of the slow state variables is used in the slow MPC. Using singular perturbation theory, the stability and optimality of the closed‐loop nonlinear singularly perturbed system are analyzed. A chemical process example which exhibits two‐time‐scale behavior is used to demonstrate the structure and implementation of the proposed fast–slow MPC architecture in a practical setting. © 2012 American Institute of Chemical Engineers AIChE J, 58: 1802–1811, 2012     

Globally stable control systems for processes with input multiplicities

A nonlinear process with input multiplicity has two or more input values for a given output at the steady state, and the process steady state gain changes its sign as the operating point changes. A control system with integral action will be unstable when both signs of the process gain and the controller integral gain are different, and its stability region will be limited to the boundary where the process steady state gain is zero. Unlike processes with output multiplicities, feedback controllers cannot be used to correct the sign changes of process gain. To remove such stability limitation, a simple control system with parallel compensator is proposed. The parallel compensator can be easily designed based on the process steady state gain information and tuned in the field. Using the two time scale method, the stability of proposed control systems for processes with input multiplicities can be checked.     

Membranen in der medizinischen Verfahrenstechnik

Membranes in medical process engineering . Synthetic membranes not only represent the essential components of an artificial kidney or an artificial lung but are also used as wound dressing and in systems for controlled release of drugs in certain long-term therapeutic measures or as part of an artificial pancreas. By far the greatest present economic significance of membranes is their use in the so-called artificial kidney. Considerable cost saving would result if patients could undertake ?home dialysis”?. This requires the development of new, simpler artificial kidneys and thus higher-performance membranes. The latest trend in ?artificial kidneys”?, the so-called method of ?hemodiafiltration”? warants special mention. The separation process is no longer effected only by diffusion but also by convection, i.e. the driving force is the pressure difference between the two sides of the membrane. This paper addresses problems encountered in the development and use of membranes in medicine, recent applications such as the controlled release of active components, or plasma separation, and demonstrates the potential of membranes in medicine.     

Wechselbeziehungen zwischen Physikalischer und Technischer Chemie

Interactions between physical and industrial chemistry. The most important interactions for the two areas of chemistry are found in the following three fields: (1)states of materials (states of aggregation) and thermodynamics; (2) kinetics of molecular processes as a basis for macroscopic models; (3) methods of testing and measurement and development of equipment. The ?classical state”? of each of these areas is first sketched out and then the principal developments which are still in course of flux; directions of future development are then deduced. Such directions are exposed to be: extension of the scope of application of supercritical states as solvents and reaction media, as part of a general expansion of industrial application of elevated pressures; increase in knowledge of nonlinear dynamics of chemical systems with regard to transient behaviour and control mechanisms; increase in basic research on molecular structure and dynamics at the interfaces of dispersed systems – especially micelles and catalyst surface – using ?in situ”? methods, and more extensive utilization of the results in industrial chemistry.     

并联通道汽液两相流不稳定性的非线性数学模型

提出了并联通道密度波型不稳定性的非线性数学模型,经计算发现,在所研究的范围内,系统的稳定性与初始扰动的幅度无关,仅取决于运行条件。计算结果与实验结果相吻合。     

Periodic steady-state flow crystallization of a pharmaceutical drug using MSMPR operation

In this paper, a novel concept of periodic mixed suspension mixed product removal (PMSMPR) crystallization process is demonstrated. An integrated array of process analytical technologies (PATs), based on attenuated total reflectance ultra violet/visible spectroscopy, focused beam reflectance measurement, particle vision microscopy and Raman spectroscopy, and in-house developed crystallization process informatics system software (CryPRINS) were used to monitor the periodic steady-state flow crystallization of paracetamol. Periodic steady-state is a new concept defined as a state of a system that maintains itself despite transitory effects caused by periodic, but controlled disruptions (state of controlled operation). This work also illustrates the concept of “state of controlled operation” instead of “steady-state operation” as a state that can characterize continuous (periodic) operation. The PMSMPR was configured as either a single- or two-stage unit and operated for up to 11 residence times without blockage or encrustation problems. The number of PMSMPR stages, seed characteristics (size, shape and distribution), and use of recycle stream were the main variables that influenced the periodic operation, significantly affecting the extent of secondary nucleation and growth. The results further illustrate the use of PAT and information system tools together to determine when the periodic operation reaches a state of controlled operation (periodic steady-state). These tools provided a better understanding of the variables and operating procedures influencing the periodic operation.     

A pattern based strategy for using multidimensional sensors in process control

Multidimensional sensors can deliver vast and rich information about the industrial processes operation. At industrial level, they are becoming widely available for supervising tasks. However, their use at control level is not very widespread, since there are no standard methodologies for including the information provided by this type of sensors into existing control systems. This paper describes the traditional approach to include multidimensional information into conventional control systems, and proposes a new structure based on pattern recognition. The latter makes use of artificial neural networks and finite state machines as a framework for designing the control system. The main characteristics and limitations of both approaches are illustrated by the image based control of an experimental fluidization bed.     

Resource aware quasi-decentralized control of networked process systems over wireless sensor networks

This paper develops an integrated model-based networked control and scheduling framework for plants with interconnected units and distributed control systems that exchange information using a resource-constrained wireless sensor network (WSN). The framework aims to enforce closed-loop stability while simultaneously minimizing the rate at which each node in the WSN must collect and transmit measurements. Initially, the exchange of information between the local control systems is reduced by embedding, within each control system, dynamic models that provide forecasts of the evolution of the plant units when measurements are not transmitted through the WSN, and updating the state of each model when communication is re-established at discrete time instances. To further reduce WSN utilization, only a subset of the deployed sensor suites are allowed to transmit their data at any given time to provide updates to their target models according to a certain scheduling strategy. By formulating the networked closed-loop plant as a combined discrete-continuous system, explicit characterizations of both the stability and performance properties of the networked closed-loop system under state and output feedback control are obtained in terms of the communication rate, the sensor transmission schedule, the accuracy of the models, as well as the controller and observer design parameters. The results are illustrated using a chemical plant example where it is shown that by judicious management of the interplays between the control, communication and scheduling design parameters, it is possible to enhance the savings in WSN resource utilization beyond what is possible with concurrent transmission configurations.     

Process systems engineering tools in the pharmaceutical industry

The purpose of this paper is to provide a summary of the current state of the application of process systems engineering tools in the pharmaceutical industry. In this paper, we present the compiled results of an industrial questionnaire submitted to pharmaceutical industry professionals. The topics covered in the questionnaire include process analytics, process monitoring, plant-wide information systems, unit operation modeling, quality control, and process optimization. A futuristic view of what process systems engineering tools will enable the pharmaceutical industry will be also be presented. While the industry is regularly using the traditional Design of Experiments approach to identify key parameters and to define control spaces, these approaches result in passive control strategies that do not attempt to compensate for disturbances. Special new approaches are needed for batch processes due to their essential dependence on time-varying conditions. Lastly, we briefly describe a novel data driven modeling approach, called Design of Dynamic Experiments that enables the optimization of batch processes with respect to time-varying conditions through an example of a simulated chemical reaction process. Many more approaches of this type are needed for the calculation of the design and control spaces of the process, and the effective design of feedback systems.