Vladimir Jovan

Use of Key Performance Indicators in Production Management

Improving production performance requires the definition of global production objectives with a proper implementation strategy and suitable closed-loop control for their achievement. Closed-loop control structures for simple systems like temperature or velocity control are well defined, but a synthesis of plant-wide control structures is still recognised as the most crucial production management design problem in process industries. One vital issue to be resolved is how to translate implicit operating objectives, such as the minimisation of production costs into a set of measurable variables that can be then used in a feedback-control. A promising solution is the use of the key performance indicator (KPI) approach. To verify the idea of production feedback control using production KPIs as referenced controlled variables, a procedural model of a production process for a polymerisation plant has been developed. The model has been used during a number of simulation runs performed with the aim of developing and verifying the idea of KPI-based production control

Integration of Business and Production Levels in Process Industries

Abstract Process control systems are operated more or less in isolation from business systems relating to the same plant. As the potential benefits of integration have become clearer. there have been several attempts to link process control and business control systems. One aspect of linking is described in this paper. A primary function of a process control system, which was in 1996 successfully installed in a Slovenian brick/work, is efficient control of the drying process in the factory. and so far this system is conceived as classic computer-based process control systenl. With regard to the possible need to incorporate this control system into a future CIM information system, a concept of flexible recipes was applied as a possible integration link between planning. which is a typical business-level activity, and process control which is a production-level activity. Flexible recipes thus may provide a modest contribution to the integration of shop floor control and logistical functions.

An approach to process production reactive scheduling

Process manufacturing has some characteristics that make it different from other types of industry. In practice, there are many examples of process industrial settings where production resources are shared and there is no intermediate storage between two processing units. Perhaps the most important issue usually to be excluded from the academic discussion of process production scheduling/control problems is the uncertainty of the duration of real chemical processes. These properties of process manufacturing result in blocking, no-wait, and other constraints that must be taken into account during designing the production scheduling system. The first part of the paper addresses some features of process manufacturing and their influence on production scheduling. The main part of the paper analyzes the scheduling problems under the presence of typical process constraints and unpredictable process duration times and introduces a simple and reliable approach to avoid these problems. The proposed concept is presented on a case study of an industrial two-stage washing batch subprocess. It is considered that the presented approach would be relatively easy to implement in a process production scheduling system and that it can contribute to more effective process production scheduling.

An assessment of water conditions in a PEM fuel cell stack using Electrochemical Impedance Spectroscopy

The success of the fuel-cells technology penetration into commercial applications depends on the fuel-cells-based systems (FCS) durability, reliability and cost competitiveness. One way to improve the FCS durability is usage of advanced diagnostic methods in the context of holistic control. Electrochemical Impedance Spectroscopy (EIS) is for this purpose one of the more promising diagnostic methods because of its non-invasivity and ability to distinguish between the flooding and drying out of the Proton Exchange Membrane (PEM), a key part of each fuel-cell in a stack. Namely, a proper wetness of the stack membranes has an essential impact on the overall fuel cells system performance. This paper deals with the employment of EIS to commercially available PEM FCS. It presents the measuring system, describes EIS methodology, measurements, data processing, calculation procedures and final results.

Process control as an element in a CIM concept-a case study

The paper describes the design and implementation of a control system which in 1996 was successfully installed in a Slovenian brickworks. Its primary function is efficient control of the drying process in the factory, and so far this system is conceived as a classic computer-based process control system. With regard to the possible need to incorporate this control system into a future CIM information system, a concept of flexible recipes was applied as a possible integration link between planning, which is a typical business-level activity and process control, which is a production level activity. Flexible recipes thus may provide a modest contribution to the integration of shop floor control and logistical functions.

Improvement of the Drying Process Control in a Clay Product Plant

Abstract Clay products are formed by pressing raw clay bodies. The resulting green ware products contain a certain amount of water that varies around 20% by mass. Before entering the next production phase the water has to be removed from the green ware. This is attained by convection drying. Since the energy consumed in a drying process represents a significant part of the total energy consumed for production of clay products the optimisation of the drying process is especially sensible. We are focusing on the possibilities for reducing the energy consumption that are reached by introduction of a proper control of the process. Both theoretical and experimental analyses of the process serve for proper design of a control system, whose functions and the fmal goal are all finally proved in practice.

A Process Laboratory for Analysis, Education and Research of Control Engineering Approaches and Methods - A Concept

Abstract Design of a process control laboratory requires a detailed definition of the purpose and form of laboratory process equipment, the structure of the control system and the system of flexible signal connections. This paper describes the main purposes of process control laboratory, the essential criteria which have influenced the choice of laboratory process equipment, the design of laboratory process control system and the guidelines for designing the signal connections between the laboratory process equipment and its control system.

Theory Versus Practice

The aim of the chapter is to present a view of the relationship between control theory and practice resulting from more than three decades of the authors’ work in applied research and industrial applications.

Production Control of a Polymerization Plant using a Reduced Set of Control Variables

The specifics of process manufacturing have a great influence on production management, and the focus of process-production control is to maintain stable and cost-effective production within given constraints. The synthesis of production-control structures is thus recognized as one of the most important design problems in process-production management. This paper proposes a closed-loop control structure with the utilization of production-performance indicators (pPIs) as a possible solution to this problem. pPIs represent the translation of operating objectives, such as the minimization of production costs, to a reduced set of control variables that can then be used in a feedback control. The idea of production-feedback control using production PIs as referenced, controlled variables was implemented on a procedural model of a production process for a polymerization plant. Some preliminary results demonstrate the usefulness of the proposed methodology.

A transportable dwelling container with in-built fuel cells cogeneration system

The paper deals with an estimation of the real energetic flows in a commercial proton-exchange-membrane fuel-cell system (PEMFCS). The PEMFCS considered here is the source of both electrical and thermal energy of a fuel fells based cogeneration system in a transportable dwelling container, and for the design of a cogeneration unit the actual amount of disposable energy from the PEMFC unit should be estimated. The assessment of the actual energetic flows, the disposable energy and the consequent electrical efficiency of the PEMFCS considered is carried out using commercial technical data for the PEMFCS.