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The pulp and paper industry produces and consumes a remarkable amount of energy in its processes. Thus energy management is very important in a paper mill. There are many control problems in different types of power plants. The coordination of the power generation and consumption also has to be considered carefully. We here present five cases in which estimation, control and coordination problems in peat, coal, bark, recovery and multi-fuel boilers are examined. The main idea is to formulate the control structure so that the active functions in and between different subprocesses along the production line are directed at the same goal. Thus the controlled variables in a power plant are e.g. fuel power, heat power in the furnace, steam power and electric power. In the fuel power and heat power control this leads to a cascade type control strategy. As an example of a solution of the coordination we present a specialized hierarchical control structure of a multi-fuel boiler house.

A system for the development of the work process, work activity, and the mental models for work in the paper industry was created in this study. A developmental program for the personnel of a paper mill was planned and carried out to eliminate the problems and to develop the work process. During the program the five crews as well as the technicians and engineers working on one paper machine analyzed their own work process in detail. Several problems and developmental needs were recognized. These dealt with the equipment, flow of information, work activities, work division and professional qualifications of the personnel. More than 60 specified problems or developmental needs that came up were solved. The solutions, prerequisites for their realization, persons responsible for carrying out the improvements, and the schedule for the execution were created and documented. This developmental program rested on the activity and knowledge of the personnel of the paper mill. The researchers structured the program, created the tasks for the participants, and led the discussions. After the intervention the mental models for the work process have become more complete, the assessments of work characteristics are more positive, and the productivity of the machine has increased by about 30%.

A new system for the non-contact velocity-and length-measurement of paper is discussed. The system consists of a μC-controlled open-loop correlator and an optical sensing unit with light barriers. The light-beams permeate the paper. The intensity of the received light is influenced by the paper (texture, fibres). The correlator calculates the cross-correlation-function from the two sensor-signals. The correlator calculates the velocity of the time delay at the correlation maximum and the distance between the light barriers. The length is measured by integration of the velocity signal. The design of the system and the signal conversion are shown. Hard-and software of the correlator are described. The “master-slave;”-system with two correlators is discussed. Requirement on the sensors for cross-correlation measurement are shown. The influence of a high-pass-filtering of the sensed signals is mentioned

This paper proposes a new algorithm for the decoupling design with additional design aims involved. A reference model which represents the desired closed-loop dynamic response is first used, then a quadratic performance index is introduced to measure both the amount of coupling and the tracking error in the closed-loop system. The control law can be obtained from optimal control technique. This algorithm has been applied on a paper machine headbox using a process control computer. The results under different conditions are obtained.

The principle and advantages of using attenuation of a microwave signal in a waveguide to measure paper moisture are introduced on a practical level. A table instrument is used for dynamic comparison of loss with gravimetric moisture, leading to collected experimental results of the loss effects caused by paper moisture, various pulp types, inert fillers (clay, TiO 2 ) and paper temperature. A chart is given for microwave loss of various paper types at a standard condition of 7% m.c. 100 g/m 2 , to which is now added a further dimension-the appropriate moisture response slope. The on-line application of this technique is described, giving the constraints within which satisfactory operation can be obtained. If a modest microwave moisture equipment is used to standardise an elementary infra-red profile measurement then the combined advantages of both principles might be produced with least complexity, most genius. Towards this, the simple on-line installation of a table microwave instrument is described.

It is difficult to estimate the economic benefits of integrated management information systems, but the needs of increasingly complicated mills, modern personnel management and environmental protection may make MIS-systems necessary in pulp and paper mills. The paper examines the most important reasons why the systems often have been expensive and unreliable. The main problems do not lie in mathematical algorithms or computer technology. The most important goal is to design a co-operative system, in which man and computer can discuss fluently in a common language.

Several authors have pointed to the importance of optimal paper headbox control as a crucial part of the global paper making process. External disturbances influence the output, also many startups of the process may be required. Since the paper quality can be improved by better control, the evaluation of advanced control algorithms is well justified. The introduction of process computers and microprocessors in the control environment has opened new perspectives for the control of paper making too. To design a good controller, a number of numerical coefficients must be known accurately. The determination of these parameters can be cumbersome. However, this can be considerably alleviated by adding an on-line parameter estimator to the controller. Then the regulator can adapt itself to slowly changing process characteristics. These parameter-adaptive controllers were extensively tested on the Laboratory of Automatic Control in Ghent. Several combinations of controllers and parameter estimators are possible. It will be demonstrated in the paper that several of these controllers improve the control quality of the paper headbox. They are not very sensitive to the noise structure and cause no offset of the output variable. Since the implementation of such adaptive controllers requires very few a priori knowledge, it may be expected that in the future many industrial applications of these will be seen.

This paper is intended to give some background survey of the “industrial management systems” research in the recent years, and also to give some comments on the six papers in Session 26. Since the industrial management systems is one of the typical large-scale systems with hierarchical structure, the three basic types of hierarchies in industrial management systems, which is systematically proposed by Mesarovic, et al., are presented. Each paper is looked at again from the basic types of hierarchies point of view. Finally, the promising area of future research in industrial management systems is anticipated.

Summary As converting operations increase in speed, the need for greater uniformity in reel performance increases, leading to stricter and more objective specifications of reel properties. This paper reviews efforts to define and control them. Reel properties depend on paper properties, winding tension, reel size, and core properties. The cross directional variations of paper properties and tension cause the main problems in producing satisfactory reels. It has been shown by experiment and by theory that the sheet tension within a reel is lower than its wound-on value; it is usually necessary to increase the wound-on tension steadily to maintain a tight reel. Complications to the calculation of the stress distribution arise from several features: the non-Hookean compressive characteristics of paper, its viscoelastic nature, the spiral form of a reel, friction between layers, and the increase in wound-on tension caused by a drum winder. Assessment of reel quality is based on various tests: visible defects, moisture content, average density, hardness (level and variability), diameter variability, and roundness. The uniformity within one reel is particularly troublesome and many studies have been made attempting to relate reel hardness and diameter variations with, on the one hand variations in web characteristics and, on the other, reel performance. Several useful correlations have been found but their interpretation, it is considered, is confused by the local interactions of web properties (thickness, compressibility, tension) and by the difficulty in understanding how hardness depends on them. It is concluded that the theoretical and experimental study of these interactions is required, with cross directional variations in mind, before the type of instrumental control could be suggested with confidence. Subjective control of reeling might then be replaced by instrumental control, since the need for instrumentation, once establ ished, can only lead to a rapid development of their technology.

This paper outlines new development in the design of Decision Support Systems and Mill Wide control. These developments have been implemented .in a system for a board mill at Thames Purfleet whose management worked closely with the university based Systems Group at Imperial College. The system design to control a multiproduct plant producing a range of reels, sheet and board in various dimensions, consistency, colour and surface finish. It uses advanced procedures for scheduling, deckling, sales forecasting and stock control and employs an advanced “what-if” evolutionary simulation for prediction, management decision support and production control via a terminal network. The system has rapid “conversational” response.

The principles of infrared gauging are considered with particular reference to the measurement of moisture in paper and the thickness of both clear and pigmented polymer films. It is shown how the Beer-Lambert and the Kubelka-Munk equations can be used to describe the optical properties of the materials to be measured. Techniques for minimising the effort in deriving and maintaining calibration are examined. Consideration is given to the most appropriate optical configuration for the various measurements and the importance of the main components in the hardware. Observations are offered concerning the role of the microprocessor as a component of the infrared gauge.

The paper discusses the r|ole of mathematical modelling in a context of development planning. Different planning functions are identified: opening-up questions, presenting alternatives, and providing plans of action. Each of these planning functions require different types of information and therefore different approaches to modelling

The objective of process control at the Rauma paper mill is to maintain a certain output and quality level at minimum cost. Computerized process control systems include an automated laboratory measurement and data transmission system and on-line test equipment combined with local automatic control systems. There is clear trend towards more automated laboratory routines and on-line measurements. Some of the laboratory measurements are difficult to automate, and the poor reliability of on-line test equipment still causes problems. However, the increased demands set on process control today cannot be fulfilled without advanced computer applications.

When industrial processes operate under variable production conditions, linear models and linear controllers are generally not efficient. When a paper machine operates at variable speed, the control of the headbox must be efficient for large operating point transitions. We present a dual model reference adaptive controller (DMRAC) that allows the control of linear time varying systems and the explicit on line identification of the process with delayed inputs. The application of the DMRAC to a pressurized headbox when large operating point transitions are applied is presented. Finally a functional decomposition of the DMRAC algorithm for its implementation in a multi-microprocessor system is presented.

In this paper we develop an algorithm for estimating, in the presence of noise, cross and machine direction (CD and MD) moisture profiles based on a model described in the literature. The algorithm consists of a least squares parameter identifier for estimating CD profile deviations and a Kalman filter for estimating MD profiles. Simulation results of the algorithm are given. The preliminary results of the application of the algorithm to industrial data are also given. The algorithm developed can be extended to other measurement models

The general capabilities and some operational results obtained by two new important control developments with immediate applications in paper making are described. SADACOLOR - the first system to be described is based on Reed’s original stand-alone sampled data controller SADAC, but includes colour display of cross machine variables and multirate sample and control techniques. The successful application of these techniques has led to the development of a new stand-alone sampled data controller, SADAC-M, which is the second system to be described. It is essentially a low cost, partially programmable multivariable controller based on a microprocessor.

When, in a paper dryinr machine, drive groups equi pped wi th conventi ona1 fabri cs are refitted with single felting, changes in the specific evaporation rate as well as in the functionin0 of the steam and condensate systems are evident. To observe the resultina chanoes and to make an analysis of the-changed conditions, an on-line study was made on two production machines. The measurements taken indicate that the sheet cools some 2.5 to 8.0 QC while passing the bottom cylinders, on the outward side of the fabric. Specific evaporation rates measured for single feltin9 were approx. 70 percent of the corresponding evaporation figures for a conventional double fabric configuration. Despite this, the annual output of the machine may increase, due to smoother machine operation. However, if the instantaneous drying intensity is to remain unchanged, an increase of a few tenths of a bar in the machine supply steam pressure will be required. This results in a power loss at the power plant, and a corresponding additional cost, in case the machine operating efficiency is not improved. This presentation further examines the combining of the pressure duration curves of two machines, and the feasibility of target adaptive back pressure control, whereas a general rise of the pressure level also increases fluctuation and thereby makes control more desirable.

Increasing demands for efficient utilization of available resources and ever more complex production systems create a strongly growing interest in improving the efficiency of computer control by linking different systems together and applying a more integrated approach to the design and use of the overall system. This paper will review a large number of typical integrated systems in different types of mills, concentrated to Scandinavia, with respect to e.g. system structure and supervisory functions. Special emphasis is given to aspects of the integrability of available system components on different levels (instrumentation, process and plant) and different strategies of system design. Inadequate compatibility as regards functional distribution and data communication is a strongly limiting factor to the growth rate of integrated systems, and some desirable developments and standardization efforts to remedy this sitatution are presented. The need and possibilities for active user participation are also discussed, in particular the demands for much higher flexibility of packaged control systems.

A control system for the energy supply to a paper factory needed re-designing to overcome stability problems and uneconomic plant operation. A modelling and simulation study was undertaken with a view to the proposal of a new control structure. The system was simulated using a microprocessor-based colour display system and the BASIC interpretative language with some enhancements. This led to a control proposal which on the simulation overcame the original problems and enabled the desired plant goals to be achieved. Little direct use was made of modern control theory, as this appeared to be inapplicable to the detailed requirements of the problem. Rather, the general principles of modern control and dynamic systems theory led to a heuristic design based on plant understanding and simplified physical cause and effect relationships.

The development of algorithms for producing cutting schedules for the paper and board industry is reviewed. Three new algorithms are then presented for particular classes of problems. The first two purely heuristic algorithms permit explicit constraints on the number of cutting patterns and on the run-length. The third algorithm, which can be viewed as a heuristic algorithm set in a linear programming context allows implicit control of cutting patterns and run-length. These two difficulties have been the major limiting factor on the acceptance of routine computerised production of cutting schedules. It is argued that these algorithms and modifications based on the same basic approach will resolve all of the technical difficulties remaining.

Summary A brief study has been carried out into the possible applications of real-time infra-red thermal imaging devices in the paper and board industry. Because of lack of experience the interpretation of the displays produced by the devices can be difficult. It appears that under some circumstances the instruments can be used to study non-uniformity problems and though the presence of these can be demonstrated, the data available as yet does not allow detailed diagnosis by employing IR thermal images.

Summary Paper stock flowing at constant velocity through a pipe has a consistency which is proportional to the mass of solids flowing through the system. If the flow is turbulent the local concentration of suspended solids varies in a random manner; these concentration variations are proportional to the mass of suspended solids which can be measured by an electrical transducer. Only the dynamic a.c. component of conductivity is measured and the d.c. component is ignored; in th is way the variation of concentration due to the solids can be accurately measured and any drift in conductivity, due for example to polarisation or to changes in the mean conductivity of the liquid phase, is of no consequence.

This paper constitutes a review of the research work completed at the Computing Center of the USSR Academy of Sciences dealing with the theory of optimal orbit transfers for space vehicles powered by low-thrust rocket engines.

The Danish Natural Gas system is scheduled to operate from October 1932. The natural gas system will, when fully established, supply energy from wells in the North Sea for room heating in around 25 per cent of the Danish houses, and further substitute a substantial part of industry's energy supply. It involves within a five year period the construction of 800 kilometres of transmission pipeline, 1,500 kilometres of secondary transmission pipeline, and 15,000 kilometres of reticulation pipeline. The project is evolving under strict time restrictions. The decision of introduction of natural gas was taken in 1979, the first gas to be delivered in 1982, and the full flow (2.5 billion cubic metres, representing 100 PJ of energy, annually) to be reached in 1986. The planning of the project directly involves one transmission company (state owned), 5 distribution companies (municipally owned), 100 primary municipalities (200 in later phases), secondary municipalities and central authorities. The article describes aspects of the planning process in this hierarchical multiobjective decision-making system. The emphasis is on the development and use of the operational indicators of the quality of a given area with respect to natural gas consumption (the socalled priority indexes) and the introduction and use of optimization techniques. The objective of introducing these was to coordinate the local planning efforts with the overall requirements and goals of the total natural gas system. The priority indexes are intuitively interpretable, easily calculatable. The article discusses the relation of the indexes to the overall objectives and evaluates the trade-off between precision, operationality and optimality, and the tendencies towards economization and centralization.

A case study of model-based predictive control of an evaporation process in a kraft pulp mill is presented. Two cases are considered. In the first, the process is represented by a linear model with two manipulated and two output variables. The control objectives are formulated as a quadratic programming (QP) problem, i.e., minimization of a quadratic objective with linear inequality constraints on the manipulated variables. This approach is tested on the full-scale process and its performance is compared with that of PI control. The QP method meets the objectives of the plant operators and in general performs better than the PI controller. It was also found to be easier to tune once a model of the process had been determined. In the second case the scope of the model is expanded to include additional up- and down-stream process elements. The control objective is reformulated to include constraints on both manipulated and output variables. Simulation is used to demonstrate the potential of this broader approach to the problem.

Control and management in a large water resource system is discussed. A model of the system is presented. The control problem is stated so as to accomplish prescribed goals assuring desired performance of the system. The resulting control system is split into three interdependent subsystems: water retention control, water distribution control and water quality control subsystems. A mathematical formulation of each control unit is derived. The final decision making and control structure is found to be multiobjective and hierarchical. Chosen simulation results are presented, reflecting some features important for control structure design.

Summary 1 Aim function formulation is given and criterion of optimum stock inlet process control is chosen. 2 Mathematical stock inlet process model is represented with nonlinear differential equation system with variable coefficients. It concerns the whole stock inlet system and also the stock feeding system, pipelines, stock flowmeter, inlet chamber and so on. 3 After model linearization and grounding connected with it idealization computerized calculation methods of stock inlet system design are worked out. It allows to increase dynamical stock flow stability during inlet without control systems. 4 The further increase of dynamical stock flow stability is ensured with feedback control. During computerized investigation transition processes in control system variants the peculiarities of different control systems are found.

Summary The paper describes a control system particularly suitable for processes with long transit time lags, but which is equally suitable for other applications. The system uses a time proportional pulse to actuate the controlled element, the time proportionality being arrived at by plant modelling. The amount of correction given does not rely on feedback, but a sampling technique is used to check that the amount of correction given is correct. Provision can be made to cater for non-linear control functions, backlash correction and differing degrees of control in the positive and negative directions. “Bump-less” transfer from automatic to manual and vice versa is an inherent feature of the system.

Nearly 4 years ago in the field of Artificial Intelligence a learning machine called STeLLA was conceived. After three years of computer simulation of the machine in a variety of problem environments, the design is greatly improved, although the main features have survived. Since the machine is being simulated with a vehicle-steering control problem which is second order, non-linear and stochastic it would appear that STeLLA now qualifies for the title of “adaptive controller”.

More advanced instrumentation, control and automation are necessary to meet the tightening standards for effluent quality from wastewater treatment plants (WWTPs) treating pulp and paper mill wastewater. Although the methods and equipment necessary for implementing process control at WWTPs have been developed, there is not much prior experience of their application in industrial WWTPs making the plant operators hesitant to make the necessary investments. Modeling and simulation is an inexpensive method to evaluate the benefits of improved process control. This paper presents the development of a simulator for evaluating the potential for process control in an activated sludge process (ASP) treating pulp mill wastewater. A simple control strategy developed to improve the operation of the pulp mill ASP and to decrease operating costs is evaluated with the simulator. The benefits of process control are evaluated based on effluent quality and costs of operation.

It was of some surprise, after listening to all the contributions, to conclude that nothing had been said about the theory and application of extremum-seeking devices based on Evolutionary Operation EVOP and its associated modifications such as SIMPLEX and COMPLEX. In many real control systems the values of the measured variables are obtained at discrete intervals of time, which may be of the order of minutes, and consequently there may be considerable delay in the evaluation of the Performance Index. Many of the continuous-perturbation methods proposed at the Symposium do not lend themselves to systems of the former type, and it is thus desirable to be aware of alternative methods of control.

The traffic analysis and traffic forecasting is a fundamental stage of a cost-benefit analysis (CBA) for planned transport investment projects including ITS systems. The paper presents an analytical complexity of a 4-step travel demand/land use model. A model for 13 cities of the Upper-Silesian Agglomeration (Poland), which has a road network and a public transportation network (tram, bus and railway) of a great density, is presented as an example. It is worth emphasising that this is one of the biggest models of transport networks in Poland – regarding the size of modelled area and the number of cities, which transport systems were represented. According to the new mobility culture ( Green Paper (2007) five challenges have been identified and presented in this paper. Also user services of ITS architecture and a micro-simulation model for evaluation of ITS solutions have been presented.

Papermaking is considered as an energy-intensive industry partly due to the fact that the machinery and procedures have been designed at the time when energy was both cheap and plentiful. A typical paper machine manufactures a variety of different products (grades) which impose variable per-unit raw material and energy costs to the mill. It is known that during a grade change operation the products are not market-worthy. Therefore, two different production regimes, i.e. steady state and grade transition can be recognised in papermaking practice. Among the costs associated with paper manufacture, the energy cost is ‘more variable’ due to (usually) day-to-day variations of the energy prices. Moreover, the production of a grade is often constrained by customer delivery time requirements. Given the above constraints and production modes, the product scheduling technique proposed in this paper aims at optimising the sequence of orders in a single machine so that the cost of production (mainly determined by the energy) is minimised. Simulation results obtained from a commercial board machine in the UK confirm the effectiveness of the proposed method.

Ultrasonic treatment of waste activated sludge is one of the possibilities to reduce excess sludge production through the mechanism of sludge disintegration and cell lysis. In the past, several attempts have been made to model the process of solubilisation of the particulate volatile suspended solid part of the activated sludge (VSS) into soluble COD (sCOD). However, the focus of these models was predominantly on predicting an efficiency factor for the release of sCOD (Disintegration Degree, DD COD ) and provided no information on the release of nutrients and the instantaneous reduction of VSS. Moreover, often insufficient influential variables were included in the model equations, making the models only applicable on the training dataset of their own experimental research. This paper, therefore, seeks to build a simple model, which contains all influential input variables, that can predict not only the sCOD release but also the nutrients release (ortho-PO 4 -P and soluble Kjeldahl nitrogen) and VSS reduction simultaneously. Therefore, in first instance, a Principal Component Analysis (PCA) is carried out on the input and output data matrix of obtained experimental observations that will be used as training data. In this way, certain correlated input variables and independent output variables can be removed from the model, in order to increase its simplicity and predictive nature. Then, the model is built on the basis of Partial Least Squares Regression (PLS-R) and a part of the observations is used to validate the predictive strength of the model.

In this paper the authors have undertaken an attempt to implement the Multi-agent technology on controlling a recovery boiler, aiming to manage and integrate production, quality and security to the process. The operation of the recovery boiler has two well defined objectives, each one with its operational constraints: (1) steam production, an important asset in the pulp and paper process, and, (2) reduction of inorganic reagents to recover sulfate and sodium carbonates, the necessary chemicals in the Kraft pulp production. Each one of these functions, is an independent system inside the recovery boiler, however they have their performances connected to each other by common variables present in the process. This is exactly the definition of an agent system, in other words, a definition of a Multi-Agent System (MAS), for which there is not an optimization, but the search for the best possible outcome. Agents’ engineering aspects are addressed by adopting the domain independent software standard, formulated by FIPA. Jade core Java classes are used as a FIPA specification implementation. A dynamic model of a Kraft Recovery Boiler was built on a Matlab-Simulink platform.

This paper studies the possible application of Iterative Feedback Tuning (IFT) to the paper machine cross-directional (CD) control. Although the CD control is naturally a multi-input-multi-output (MIMO) problem, by enforcing the circulant assumption, IFT for CD control is as simple as the single-input-single-output (SISO) case, i.e. only one gradient experiment is needed for estimating the gradient. Simulation of a simple disturbance rejection problem is included to demonstrate the main ideas.

Real-time optimization (RTO) is applied for the broke recirculation in the stock approach system of an integrated newsprint mill simulation. New optimal broke ratio profiles are set for the paper machine recipes each time the process is confronted with an important disturbance. The variability in the four paper machine headboxes is minimized while the inventory management is handled. The proposed approach is compared to the actual mill operation, making use of a detailed plant simulation. While maintaining broke tank level within an acceptable range, RTO brings the pulp variability down about an order of magnitude. It is expected that it could significantly reduce the sheet break occurrence in a real plant and therefore enhance its economical efficiency.