Data-driven Soft Sensors in the Process Industry

In the last two decades Soft Sensors established themselves as a valuable alternative to the traditional means for the acquisition of critical process variables, process monitoring and other tasks which are related to process control. This paper discusses characteristics of the process industry data which are critical for the development of data-driven Soft Sensors. These characteristics are common to a large number of process industry fields, like the chemical industry, bioprocess industry, steel industry, etc. The focus of this work is put on the data-driven Soft Sensors because of their growing popularity, already demonstrated usefulness and huge, though yet not completely realised, potential. A comprehensive selection of case studies covering the three most important Soft Sensor application fields, a general introduction to the most popular Soft Sensor modelling techniques as well as a discussion of some open issues in the Soft Sensor development and maintenance and their possible solutions are the main contributions of this work

Techniques and Emerging Trends for State of the Art Equipment Maintenance Systems - A Bibliometric Analysis

The increasing interconnection of machines in industrial production on one hand, and the improved capabilities to store, retrieve, and analyze large amounts of data on the other, offer promising perspectives for maintaining production machines. Recently, predictive maintenance has gained increasing attention in the context of equipment maintenance systems. As opposed to other approaches, predictive maintenance relies on machine behavior models, which offer several advantages. In this highly interdisciplinary field, there is a lack of a literature review of relevant research fields and realization techniques. To obtain a comprehensive overview on the state of the art, large data sets of relevant literature need to be considered and, best case, be automatically partitioned into relevant research fields. A proper methodology to obtain such an overview is the bibliometric analysis method. In the presented work, we apply a bibliometric analysis to the field of equipment maintenance systems. To be more precise, we analyzed clusters of identified literature with the goal to obtain deeper insight into the related research fields. Moreover, cluster metrics reveal the importance of a single paper and an investigation of the temporal cluster development indicates the evolution of research topics. In this context, we introduce a new measure to compare results from different time periods in an appropriate way. In turn, among others, this simplifies the analysis of topics, with a vast amount of subtopics. Altogether, the obtained results particularly provide a comprehensive overview of established techniques and emerging trends for equipment maintenance systems

Horno cementero rotatorio: una revisión al control mediante sistemas expertos

This article presents a review of research carried out using different control strategies applied in rotary cement kilns, a system where clinker is manufactured, an essential material for cement production. This exploration mentions studies that have been developed from the eighties to the present, highlighting in each one the control methodology used, the benefits obtained in the process and its future applications, in order to provide the reader with a global vision of the use of control techniques for rotary cement kilns and how scientific advances, over the years, have contributed to this industry in the efficiency and improvement of its production processes; therefore, contributions and control methods such as expert systems (ES), model predictive control (MPC), artificial neural networks and fuzzy logic are mentioned. At the end of the aforementioned review, it is inferred that artificial intelligence and industry 4.0 technologies that are currently available such as cloud computing, the processing of large volumes of data, the use of digital twins, the execution of machine learning algorithms and it’s prediction tools, together with the application of ES and other control techniques mentioned, would allow advanced control, which can respond satisfactorily to current production needs and offer multiple benefits such as response time control, stability, and improvements in production and material quality in a rotary kiln.Este artículo presenta una revisión de investigaciones realizadas mediante diferentes estrategias de control aplicadas en hornos cementeros rotatorios, sistema donde se da la fabricación de clínker, material indispensable para la elaboración del cemento. Esta exploración menciona estudios que se han desarrollado desde los años ochenta hasta el presente, destacando en cada una la metodología de control utilizada, los beneficios obtenidos en el proceso y sus futuras aplicaciones, esto con el fin de brindar al lector una visión global del uso de técnicas de control para hornos cementeros rotatorios y de cómo los avances científicos, con el paso de los años, han contribuido a esta industria en la eficiencia y mejora de sus procesos productivos; por tanto, se mencionan aportes y métodos de control como sistemas expertos (SE), control predictivo basado en modelo (MPC), redes neuronales artificiales y lógica difusa. Al finalizar la mencionada revisión se infiere que tecnologías de inteligencia artificial y de la industria 4.0 que se tienen actualmente como la computación en la nube, el procesamiento de grandes volúmenes de datos, el uso de los gemelos digitales, la ejecución de algoritmos de aprendizaje automático (machine learning) y sus herramientas de predicción, junto con la aplicación de SE y demás técnicas de control mencionadas, permitirían realizar un control avanzado, que pueda responder de forma satisfactoria a las necesidades de producción actuales y ofrecer múltiples beneficios como el tiempo de respuesta del control, la estabilidad, y mejoras en producción y calidad del material en un horno rotatorio

Soft sensor development using artificial intelligence and statistical multivariate methods

The lack of real-time measurement of certain critical product and process characteristics is a major problem in the manufacturing industry, and it can lead to an out of specification production. A soft sensor is a predictive model that uses readily available process measurements to infer variables that are impossible or difficult to obtain in real-time. In this work, historical process data related to the black liquor recovery circuit from a Canadian kraft pulp and paper mill is used to develop soft sensor models for the black liquor solid content at the concentrator feed. Prior to modeling, irrelevant variables and observations not representative of a normal operating regime are eliminated from the dataset. For practical reasons related to modeling restrictions and soft sensor industrial implementation, is proposed that a limited number of variables be used as model inputs. Two Partial Least Squares-based selection criteria are used to select the most relevant predictors. Two different sets of ten variables are obtained and used to develop Sugeno-type fuzzy logic, neural network and Partial Least Regression models. Their predictive performance is compared in order to determine the best model configuration and input selection method. iii Currently, the black liquor solid content at the concentrator feed is measured once every eight hours, by performing a laboratory analysis. The proposed soft sensor model can be used to provide a real-time value of the solid content, allowing operators to monitor the process and act timely if corrective actions are required

Data-driven modelling and monitoring of industrial processes with applications in nuclear waste vitrification

PhD ThesisProcess models are critical for process monitoring, control, and optimisation. With the increasing amount of process data and advancements in computational hardware, data-driven models are a good alternative to mechanistic models, which often have inaccuracies or are too costly to develop. One problem with data-driven models is the difficulty in ensuring that the models perform well on new data and produce accurate predictions in complex situations, which are frequently encountered in the process industry. Within this context, part of this thesis explores developing better data-driven models through using a latent variable technique, known as slow feature analysis, as a pre-processing step to regression. Slow feature analysis extracts slow varying features that contain underlying trends in the data, which can improve model performance through providing more meaningful information to regression, reducing noise, and reducing dimensionality. Firstly, the effectiveness of combining linear slow feature analysis with a neural network is demonstrated on two industrial case studies of soft sensor development and is compared with conventional techniques, such as neural networks and integration of principal component analysis with a neural network. It is shown that integration of slow feature analysis with neural networks can significantly improve model performance. However, linear slow feature analysis can fail to extract the driving forces behind data in nonlinear situations such as batch processes. Therefore, using kernel slow feature analysis with a neural network is proposed to further enhance process model performance. A numerical example was used to demonstrate the effective extraction of driving forces in a nonlinear case where linear slow feature analysis cannot. Model generalisation performance was improved using the proposed method on both this numerical example, and an industrial penicillin process case study. Dealing with radioactive nuclear waste is an important obstacle in nuclear energy. Sellafield Ltd have a nuclear waste vitrification plant which converts high-level nuclear waste into a more stable, lower volume glass form, which is more appropriate for long term storage in sealed containers. This thesis presents three applications of data-driven modelling to this nuclear waste vitrification process. A predictive model of the pour rate of processed nuclear waste into containers, an early detection system for blockages in the dust scrubber, and a model of the long-term chemical durability of the stored glass waste. These applications use the previously developed slow feature analysis methods, as well as other data-driven techniques such as extreme learning machine and bootstrap aggregation, for enhancing the model performance.Engineering and Physical Sciences Research Council (EPSRC) and Sellafield Lt

Data-based modelling of a multiple hearth furnace

Monitoring and control of process operations is highly essential in process industries for the successful operation of a chemical process. Control over process variables and other process variations ensure a reliable end product quality and provide stability and efficiency for the process. The process considered in this thesis is the calcination of Kaolin in a Multiple Hearth furnace which consists of 8 hearths with four burners each on hearths 4 and 6 that supply the energy required for calcination. The aim of this thesis is to develop data based models for the gas temperature profile in the multiple hearth furnace which is a key process variable determining the gas-solid heat exchange, and thus, affecting the final product quality. The models can be utilized to forecast furnace dynamics, to develop a model-based control which reduces variations in the gas flow rates into the hearths as well as for model based optimization which determines the optimal gas flow rates to hearths 4 and 6. These benefits of the gas temperature profile prediction may help to minimize the energy consumed by the burners and also to improve the control of the final product quality while maintaining the quality constraints. In this thesis, the relevant literature on statistical data processing methods are reviewed and case studies are presented to demonstrate the application of data based modeling in mineral processing. Thereafter, required data-based static and dynamic models are constructed using statistical techniques such as the Principal Component Analysis (PCA), and the Partial Least Squares (PLS). The model accuracy is improved by combining the process data with the chemical engineering knowledge of the process. The models are constructed for the most common feed rates and finally validated using process data not used for training. Results are presented and the models were able to predict the gas temperature profiles in the furnace in each of the hearths; the dynamic models improved the model quality when compared to the static models. In addition, a future prediction of the temperature profile was carried out to confirm the ability of the dynamic models to predict the furnace behavior. Also, the possibility of utilizing the dynamic models for process control and optimization is discussed

Reinforcement Learning

Brains rule the world, and brain-like computation is increasingly used in computers and electronic devices. Brain-like computation is about processing and interpreting data or directly putting forward and performing actions. Learning is a very important aspect. This book is on reinforcement learning which involves performing actions to achieve a goal. The first 11 chapters of this book describe and extend the scope of reinforcement learning. The remaining 11 chapters show that there is already wide usage in numerous fields. Reinforcement learning can tackle control tasks that are too complex for traditional, hand-designed, non-learning controllers. As learning computers can deal with technical complexities, the tasks of human operators remain to specify goals on increasingly higher levels. This book shows that reinforcement learning is a very dynamic area in terms of theory and applications and it shall stimulate and encourage new research in this field

Classification by Neural Network and Statistical Models in Tandem: Does Integration Enhance Performance?

The major purposes of the current research are twofold. The first purpose is to present a composite approach to the general classification problem by using outputs from various parametric statistical procedures and neural networks. The second purpose is to compare several parametric and neural network models on a transportation planning related classification problem and five simulated classification problems