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Please follow the links to view the publication.Wireless sensor networks Zigbee applied on sewage treatment station
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0598
The good efficiency in a sewage treatment plant (WWTP) is a great importance to the environment. The management of electromechanical equipment installed in these stations is a major challenge due to the fact that they are installed on areas of difficult access and maintenance unhealthy and making the time for the correction of any faults is extended. This paper proposes the development of a Wireless Sensor Network (WSN), in order to monitor electromechanical equipment, allowing the Concessionaire a predictive control in real time. The design of a wireless sensors network for monitoring equipment requires not only the development and assembly of the sensor modules, but must also include the development of software for managing the data collected. Thus, this work includes a Zigbee WSN, small, adapted for monitoring of electromechanical equipment and environmental conditions of a WWTP, type stabilization pond, installed in an area of approximately 0.15 km<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sup> and the average flow of 320 liters of treatment per second. The experimental results show that this monitoring system can perform with the collection of parameters of performance and quality assessment at the station. (5 pages)Analysis of electrochemical degradation of coking wastewater using multiwall carbon nanotubes modified electrode
http://dl-live.theiet.org/content/conferences/10.1049/cp.2010.1342
A modified electrode coating with admixture of multi-walled carbon nanotubes and PTFE was used to treat the coking wastewater after biological purification. UV-VIS, GC/MS and COD measurement were used to observe the change of organic compositions in wastewater. The degrading efficiency of the prepared electrode was compared with that of the IrSnSb/Ti electrode. The results showed that after electrochemical degradation by MWNT-ME for 2 hours, the number of organic pollutants in coking wastewater reduced from 107 to 49, and COD was reduced by 51%. Compared with IrSnSb/Ti electrode, MWCNT-ME showed better electrochemical reactivity, electrochemical oxidation is the major fact of the degradation of organic pollutants during the electrolyzing of coking wastewater.ALARP and CBA implications for SIL determination
http://dl-live.theiet.org/content/conferences/10.1049/ic.2009.0214
The article consists of a set of powerpoint slides covering the following topics: risk assessment process; cost benefit analysis; ALARP; SIL determination; tolerability; chemical sector incidents; societal risk; and human harm. (21 pages)An industry scale corona-plasma for flue gas DESO2/DENO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">x</sub> technique by high frequency AC+DC power supply with a semi-wet flow
http://dl-live.theiet.org/content/conferences/10.1049/cp.2009.1657
An Industry Scale corona-plasma system for coal-fired flue gas DeSO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub>/DeNO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">x</sub> technique by AC+DC (AC superimposed DC) power supply with a semi-wet flow is introduced in this paper. The design of an AC + DC power supply is presented in detail. A wet reactor system can be used to overcome the disadvantage of the great power-consumption and viscid resultant on the wall of the pulse mode. The semi-wet technological process with the resultant of (NH<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">4</sub>)<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub>SO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">4</sub> and NH<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">4</sub>NO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">4</sub> is the first time to be used for flue gas DeSO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub>/DeNO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">x</sub> in an industry scale using corona-plasma with a perfect industry flow. The experiments were carried out on the corona-plasma flue gas DeSO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub>/DeNO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">x</sub> system with a capacity of 12,000 Nm<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">3</sup>/h under the following conditions: gas temperature at the reactor entrance of 135°C, gas temperature at the reactor exit of 90°C, the power supply's parameters is 40 kVpp/48kHz AC voltage and 40kV DC voltage. The experiments of DeSO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> and DeNO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">x</sub> were implemented simultaneously, 98% of SO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> and 44% of NO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">x</sub> are removed with an energy consumption of 1.8Wh/Nm<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">3</sup> and the final products are qualified fertilizer. It has an expectable industrial application in the future. (4 pages)ANFIS gain scheduled CSTR with genetic algorithm based PID minimizing integral square error
http://dl-live.theiet.org/content/conferences/10.1049/ic_20070587
In this paper, a new control scheme, the artificial neuro fuzzy inference system (ANFIS) gain scheduled genetic algorithm (GA) based PID is proposed for continuous stirred tank reactor (CSTR). CSTR is a highly nonlinear process that exhibits stability in certain region and instability in some regions. The proposed control scheme implements the characteristics of the genetic algorithm's (GA) global optimization to optimize the PID's three control parameters: k<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">p</sub>, k<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">i</sub>, k<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">d</sub>, to obtain the best control effect by minimizing integral square error online. The GA tuned PID controller parameters are gain scheduled using ANFIS. ANFIS gain- scheduling is a special form of neuro-fuzzy control that uses linguistic rules and fuzzy reasoning to determine the controller parameter transition policy for the dynamic plant subject to large changes in its operating state. Simulation result shows the feasibility of using the proposed controller for the control of the dynamical nonlinear CSTR.Fuzzy gain scheduled pole placement based state feedback control of CSTR
http://dl-live.theiet.org/content/conferences/10.1049/ic_20070588
CSTR plays a vital role in almost all the chemical industries. Continuous stirred tank reactor (CSTR) is a highly nonlinear process exhibiting stable and unstable steady state at different regions. Control of CSTR in the complete range is a mind boggling problem. In this paper, a fuzzy scheduled pole placement based state feedback control of CSTR is investigated. The entire region is divided into three regions; low, middle and the high region. The low and the high region have stable steady state and the middle region have unstable steady state. Initially, the gain matrix of the state feedback controller is computed for each region using pole placement technique. Then using fuzzy gain scheduler, the complete controller is formed. The result shows the feasibility of using the proposed controller for the control of CSTR. In this chapter optimal control of CSTR is investigated for the tracking and regulatory problems.Practicality of implementing risk based protection system design to vendor packages in the petrochemical industry
http://dl-live.theiet.org/content/conferences/10.1049/cp_20070463
This paper looks at the implementation of the standards relating to IEC 61508 electrical / electronic / programmable electronic safety related systems (referred to as E/E/PES), parts 1-7, for the design of the vendor safety instrumented systems. Vendor packages are essential and integral to petrochemical plants; however there has been a slow transition within the industry in terms of implementing these standards. This paper will attempt to address the following points, concerning the application of the safety standards; 1) Definition of a vendor package 2) Traditional instrumented design for vendor safety systems 3) Introduction of safety governance standards 4) Application of the risk based approach 5) An example of the application of IEC 61508 on major vendor packages 6) Assessment of safety functions 7) Implementation of safety integrity levels 8) Example of SIL implementation within a vendor package 9) Dealing with purely economic integrity levels 10) Cost benefit analysis.Research and implementation of an on-line fault diagnosis expert system for the chemical process
http://dl-live.theiet.org/content/conferences/10.1049/cp_20061131
An expert system for online fault diagnosis of the lubricating oil refining process is presented. Design of the expert system structure, the knowledge base, and the inference machine are discussed in detail. A new strategy for conflict resolution of knowledge - the sorting strategy of antecedents and a selection strategy of knowledge rules in the memory knowledge base are proposed. Knowledge acquisition mechanism is discussed in the work, while knowledge verification is carried out based on the directed graph approach. The diagnose system has been developed for an industrial lubricating oil refining process. The system responds with the process faults promptly and satisfies requirement of the production.Cause and effect analysis of chemical processes - analysis of a plant-wide disturbance
http://dl-live.theiet.org/content/conferences/10.1049/ic_20050171
In continuous chemical processes, disturbances in the process conditions can propagate widely and cause secondary upsets in remote locations. The aim of this paper is to apply some recent data-driven methods for detection and diagnosis of process disturbances using historical process data that have been proving successful in a range of applications. An industrial case study is presented in which a plant-wide control system disturbance caused by the presence of a recycle was successfully located and then verified by further plant testing.Application of wavelet transform to control system diagnosis
http://dl-live.theiet.org/content/conferences/10.1049/ic_20050176
Process systems are usually implemented feedback control systems such as PID controller for stabilizing the systems. The principle of PID control system is simple and the function is robust if it were well tuned, however, it tends to fall in sustaining oscillation state because of bad tuning in actual plants. By applying wavelet transform to chemical process data, sustaining oscillation was identified and root cause of it was isolated for better tuning.Electrical safety management on a large industrial site
http://dl-live.theiet.org/content/conferences/10.1049/ic_20040007
Sembcorp Utilities Teesside Limited (SUTL) operates and owns a services and utilities business, employing just fewer than 600 people on the Wilton international site, which is near Middlesbrough on Teesside. The site is predominantly a petrochemicals manufacturing site formerly owned by ICI but now occupied by a number of international chemical companies producing bulk and speciality products. SUTL owns land, infrastructure and utility production assets including an 186MW CHP power station, and supplies: steam, power, gases and waters to the site. It also provides asset management for plant and equipment, operates stores, transport, office and workshop facilities, security, fire services, environmental management and control, laboratory analytical services and a contact centre. Part of the asset management group is a high voltage team specialising in HV asset care and project work. This paper describes the management philosophy, the responsibilities for electrical safety, and some of the measures employed to manage electrical risks and promote electrical safety. (8 pages)Benefits of a risk based approach - a user's view
http://dl-live.theiet.org/content/conferences/10.1049/ic_20030267
The author is an Instrument Engineer working for a multi-national company in the Petro-Chemicals industry. Areas of specific interest are Operation and Maintenance of Safety Instrumented Systems and Maintenance Systems. Recent project experience includes the upgrade of SIS's with transfer of operation from satellite to central control rooms. (12 pages)The assessment of performance of multivariable controllers
http://dl-live.theiet.org/content/conferences/10.1049/ic_20020228
The aim of this paper is to draw attention to the new area of performance monitoring in multivariable controllers. It provides an end-user's view of industrial multivariable control, especially model predictive control, and addresses the question of its benchmarking and assessment. It mentions areas where satisfactory solutions have already been found and highlights areas that need further research. (3 pages)Monitoring the performance of controllers on batch plants
http://dl-live.theiet.org/content/conferences/10.1049/ic_20020224
This paper investigates the benefits that the partial least squares (PLS) modelling approach offers engineers involved in the operation of fed-batch fermentation systems. It is shown that PLS can be used to provide accurate inference of quality variables that are difficult to measure online, such as biomass concentration. It is further shown that the same PLS model can be used to provide fault detection and isolation capabilities and that it can be integrated within a model predictive control framework to regulate the growth of biomass within the fermenter. This model predictive controller is shown to provide its own monitoring capabilities that can be used to identify faults within the process and also within the controller itself. (4 pages)A filter concept for an electrolysis in a chemical plant [industrial power system harmonics]
http://dl-live.theiet.org/content/conferences/10.1049/cp_20010768
An electrical plant was rated for improving of the voltage quality in a chemical industry power supply system where high-power electrolysis is operated. Compared with conventional approaches, the found solution is very simple and, therefore, not very expensive. As presented in the paper and documented by simulations, it is distinguished by an optimal effect with respect to an increase in voltage quality. (5 pages)Practical distillation control
http://dl-live.theiet.org/content/conferences/10.1049/ic_20000114
The presentation highlights the practical experiences gained in adapting predictive control technology to solve a difficult distillation control problem. Control of product impurity and product losses using off-line 8-hourly laboratory measurements combined with predictive inferential techniques avoids the need for online analysers and enables more consistent column performance. Introduction of complex control technology offers benefits in terms of solution flexibility, but may pose potential operating and system management problems. Developing a hierarchical control strategy plus a simple operator interface helps to minimise operator complexity. Implementing a structured control engineering tool with a reliable communication interface minimises support costs. The experience highlights that process inconsistencies are a major cause of performance problems and continuous control engineering support is needed. It is therefore essential that the support control engineer be fully familiar with the process application, interactions and data inconsistencies. (2 pages)On-line implementation of a neural network model predictive controller
http://dl-live.theiet.org/content/conferences/10.1049/ic_20000119
Applications of neural networks in chemical process modelling and model predictive control (MPC) have been investigated for SISO systems. A multivariable, neural network modelling and MPC technique is investigated in this paper for application to a laboratory-scale chemical reactor. The reactor exhibits characteristics typical of many industrial processes, due to its nonlinearity, coupling effects among the controlled variables (temperature, pH and dissolved oxygen) and a long time-delay in the heat exchanger. Three neural models are developed for the three MISO subsystems of the process used in simulation to initially determine the control parameters and subsequently used online for the MPC of the process. Online control results are presented to illustrate the closed-loop performance of the MPC scheme. (4 pages)Predictive control using multiple model networks
http://dl-live.theiet.org/content/conferences/10.1049/ic_19990533
The aim of this paper is to describe a nonlinear modelling architecture, called the local model network (LMN), which introduces transparency while offering distinct advantages for nonlinear model-based control. Simulation results for a pH neutralisation process are used to illustrate the performance benefits of LMNs for two novel nonlinear dynamic matrix control schemes. (7 pages)On-line implementation of a model predictive controller on a multivariable chemical process
http://dl-live.theiet.org/content/conferences/10.1049/ic_19990539
An investigation into neural network model predictive control is described in this paper. The control strategy developed is applied to a laboratory process to control temperature, pH and dissolved oxygen. The main difficulties in control of this process are nonlinearity, coupling effects among variables and long time-delay in the heat exchanger. Parallel neural models are developed from real process data for the use with online model predictive control and off-line simulations. The online control results are demonstrated. (5 pages)DMCplus<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">TM</sup> model predictive control applications
http://dl-live.theiet.org/content/conferences/10.1049/ic_19990543
This paper gives two brief illustrations of the successful DMCplus<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">TM</sup> constrained, multivariable, model predictive control (MPC) scheme, using case studies of applications in the refining and chemicals industries. The case studies give a brief overview of the processes, describing process and optimisation strategies, the scope of the DMCplus controllers, how process nonlinearities are accommodated and a discussion of the critical success factors in these projects. The software uses graphic tools and interfaces. (6 pages)The control of major accidents and hazards directive - implications for electrical and control engineers
http://dl-live.theiet.org/content/conferences/10.1049/ic_19990811
The Control of Major Accidents and Hazards Directive is the replacement of an existing regulation which came out of the EEC (Seveso Directive) and is known as CIMAH in the UK, the scope of the newer directive is wider and will require to be adopted within industries which have no track record of managing such legislation. The author describes a case study which is a safety report within the existing CZMAH regulations which will be updated to meet the new requirements. The case study is that for an agrochemical active ingredient plant, the utility in question is the power system. In the event of a power system failure the operation of some critical drives will cease which will prevent the circulation of cooling water to the chemical reactors which at certain stages of the process can be exothermic, the failure could lead to over pressurisation of the reactor leading to the release of toxic chemicals into the environment. Options to counter the probability of failure are many and varied from fully installed spare pumps through to emergency shut down systems to take the process through to a safe state. The chosen system was a closed loop cooling water system with a cooling tower and three pumps; of the three pumps one would be operational, one standby and one available for maintenance. (3 pages)Fieldbus for process automation in hazardous locations - actual developments
http://dl-live.theiet.org/content/conferences/10.1049/cp_19991069
The introduction of the fieldbus in the chemical and petrochemical industry will, due to reliable estimations, replace the currently used conventional signal transmission between the sensors and the actors in the field area and the automation system in the near future. The changes in process techniques related with this development will be more important than all other improvements and developments in the last decades. The chemical and petrochemical industry demands a set of characteristics, which are the condition for the future overall use of these new systems. Important terms are such as transmission reliability, availability, development and use of open standards and easy maintenance. But also, in many applications, these installations must be explosion-protected in the field area, whereby traditionally the type of protection “intrinsic safety” is preferred. The principles, areas of application and the functional and economical advantages related with the application of field bus systems are reported as well as the different safety concepts with regard to explosion protection.Feedback-linearization using neural process models
http://dl-live.theiet.org/content/conferences/10.1049/cp_19991081
This work shows that feedback linearization using neural process models can successfully be applied to nonlinear systems, even to systems with a relative degree higher than one. A highly nonlinear and complex batch polymerization process of relative degree two was used as an example for a simulation case study. The unknown system dynamics was approximated by neural networks, using only measured state variables of one batch for training. Based on the learned model, a feedback-linearization was designed which significantly improved the control performance compared to conventional control.Control structure selection for plantwide chemical processes
http://dl-live.theiet.org/content/conferences/10.1049/ic_19980402
The selection of inputs and outputs for control design in plantwide chemical processes is the topic of this paper. The issues concerning the systematic selection of manipulable inputs and measurable outputs are discussed. Tools developed to help the design engineer select the “best”, in some sense, process configuration are presented. Case studies are used to demonstrate the usefulness of the tools and their limitations. (2 pages)A hybrid method for the optimal control of chemical processes
http://dl-live.theiet.org/content/conferences/10.1049/cp_19980352
A new hybrid method for the (open loop) optimal control of chemical processes is presented. This method combines stochastic and deterministic techniques in order to compensate for their weaknesses while enhancing their strengths. The significant advantages of this approach are demonstrated considering three difficult case studies.Control of non-linear time-varying systems using fuzzy relational models
http://dl-live.theiet.org/content/conferences/10.1049/cp_19980202
The majority of chemical processes are non-linear in nature. Increasingly, nonlinear models are being used as key parts of chemical plant control schemes. A problem with any model is that it can become inaccurate over time and consequently for good control of time-varying processes some sort of model adaptation is required. In this paper a fuzzy relational model (FRM) is incorporated into a multivariable fuzzy internal model controller (FIMC). A mechanism for online adaptation of the model is described and implemented. Results are presented for a simulated MIMO system.Advanced process control using DMCplus<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">TM</sup>
http://dl-live.theiet.org/content/conferences/10.1049/cp_19980269
The purpose of advanced process control (APC) is to improve profitability by applying strategies which coordinate the regulatory control systems on the plant. This paper gives two illustrations of the successful DMCplus<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">TM</sup> approach to APC, using case studies of applications in the refining and chemicals industries. The case studies give a brief overview of the processes, describing process and optimisation strategies, the scope of the DMCplus controllers, how process nonlinearities are accommodated and a discussion of the critical success factors in these projects. APC has been particularly successful and well accepted in the refining industry. The case study 1 discusses a typical refinery unit - the fluid catalytic cracking unit. The case study 2 discusses an air separation unit which is a much less well covered APC application. In discussing the applications, various features of DMCplus are introduced.A fault isolation procedure for self-validating control loops
http://dl-live.theiet.org/content/conferences/10.1049/cp_19980260
With the long-term aim of providing each control system with its own diagnostic capability so that it is not only self-validating, but also able to isolate in-process faults that affect the control system, this paper describes a steady state procedure for isolating faults in plants with control loops that inherently eliminate steady state error. The procedure is tested on a simple continuous stirred tank reactor simulation.Evolutionary design of process controllers
http://dl-live.theiet.org/content/conferences/10.1049/cp_19980444
The genetic programming (GP) architecture offers a potentially powerful framework for `intelligent' controller design due to its inherent matching of structure to utility. The article describes the use of GP to design discrete time single loop controllers for two different processes: a linear auto-regressive exogeneous (ARX) type system and a non-linear simulated continuous stirred tank reactor (CSTR), both with constraints on the actuator outputs. It is demonstrated that the GP methodology is capable of designing recursive controllers that, for a specific class of control objectives, offer similar performance to PID controllers on the nominal systems. The advantages and disadvantages of controllers designed in this way are also discussed.Controllability analysis by Plant Oriented Techniques: application to the Tennessee Eastman benchmark
http://dl-live.theiet.org/content/conferences/10.1049/cp_19980351
A controllability analysis based on plant oriented techniques (POT) is applied to the TE benchmark. These techniques have large potential in performing a preliminary screen among manipulated variables in large scale plants, thus reducing the number of control schemes to be analysed by scheme oriented techniques. Advantages and limitations of POT, as well as the role of heuristics, are pointed out in the paper.Verification of control logic based on Process Control Event Diagram
http://dl-live.theiet.org/content/conferences/10.1049/cp_19980381
Computer based logic control has been widely used in chemical processes, which is responsible for safe and reliable start-up, shut-down and sequence control. Some incidents in the computer controlled processes occur not because of computer hardware failures but because of errors in the control logic. Achieving a safe control logic is the first step of designing a safe logic control system. In this paper an improved modelling representation, process control event diagram (PCED), is described and used to express the control logic and its effect on a process. The control logic is verified by qualitative simulation based on the PCED. The technique is illustrated by reference to a case study.Model predictive control of a chemical process using neural networks
http://dl-live.theiet.org/content/conferences/10.1049/cp_19980331
A simulation study on the control of a multivariable chemical process by using a neural network model predictive control strategy is described in this paper. The laboratory process, in which temperature, pH and dissolved oxygen are involved, has characteristics typical of industrial processes. The main difficulties in control of this process are non-linearity, coupling effects among variables and long time-delay in heat exchange. Neural sub-system models are developed from real process data for the model predictive control strategy and also for use as a bank of parallel models to represent the process in the control simulation. The control simulations are performed before the online control to gain more insight of the process and to determine suitable controller parameters. The simulation results are demonstrated in the paper.Fault detection and isolation for a three tank system based on a bilinear model of the supervised process
http://dl-live.theiet.org/content/conferences/10.1049/cp_19980449
Time varying innovation generators combined with generalized likelihood ratio (GLR) tests are designed for detection and isolation of faults in a three tank system. This diagnosis system is based on a bilinear model of the supervised process. It is shown to work properly in a larger working range than a fault detection and isolation (FDI) system based on a linear model. As the faults enter in a bilinear way in the model, achieving exact decoupling of the residuals with respect to some of the faults is not possible. One has to resort to approximation methods such as the approach developed in Patton and Chen (1993). The whole FDI system is designed and tuned on the basis of a simulation of the three tank system. Next it is applied to actual pilot plant data and it is shown to perform well. To be able to detect temporary faults (namely fault appearance and disappearance) with the GLR test, a strategy based on the use of two Kalman filters running in parallel is used.Multivariate SPC using radial basis functions
http://dl-live.theiet.org/content/conferences/10.1049/cp_19980276
Advances in computing and instrumentation have led to a major increase in the data logging capabilities of many modern chemical plants, which has in turn led to enhanced interest in dimensionally-reducing statistical techniques such as principal component analysis (PCA). The paper analyses linear PCA, and proposes a nonlinear extension of this methodology using a series of radial basis function (RBF) neural networks. Sample applications showing the benefits of using such a scheme are given, including a fault detection scenario on a validated model of an industrial overheads condenser and reflux drum plant.Optimal design and control of double-effect distillation systems
http://dl-live.theiet.org/content/conferences/10.1049/cp_19980382
A general, rigorous dynamic model is described for studying the interactions of design and control in double-effect distillation systems. A sequential strategy for optimal design and control is implemented for a binary system; potential operability bottlenecks are identified and the economic advantage of double-effect systems over conventional single column systems is demonstrated. A simultaneous optimization strategy is also adopted and used to obtain a more economically beneficial double-effect design and control system than that obtained using the sequential approach.Hazard analysis for DCS based advanced control algorithm
http://dl-live.theiet.org/content/conferences/10.1049/cp_19980402
Distributed control systems (DCS) have been widely used in chemical and petrochemical processes. DCS are one of the most powerful platform to implement advanced control algorithms that can improve productivity significantly. However, the use of advanced control algorithms in DCS introduces hazards as well as benefits. In this work, a case study of hazard analysis is described especially for this kind of continuous control systems. The usefulness of applying hazard analysis to design and implementation of safe advanced control algorithm in DCS is shown.Neuro-fuzzy networks for process modelling and model-based control
http://dl-live.theiet.org/content/conferences/10.1049/ic_19970735
The article describes the concept and performance of neuro fuzzy modelling and neuro fuzzy model based control. The technique has been applied to a highly nonlinear neutralisation process. It is shown that the neuro fuzzy model is easy to interpret and provides accurate predictions. The proposed neuro fuzzy model based control strategy utilises local incremental models which can naturally eliminate steady state offsets. It is shown that the neuro fuzzy model based controller gives much improved performance compared to that of a linear model based controller. (4 pages)Alarm management in the chemical and power industries - a survey for the HSE
http://dl-live.theiet.org/content/conferences/10.1049/ic_19970739
This paper is concerned with a research project that is being carried out to survey best practice in the engineering and management of alarm systems in the chemical and power industries. This work is being carried out by Bransby Automation Ltd. under contract to the UK Health and Safety Executive. The key conclusions from this paper are: alarm system performance is very important to plant safety and to the avoidance of incidents that can result in significant financial loss; the survey found significant shortcomings in the alarm systems at a number of the plants that were visited; practical methods exist for improving the performance of alarm systems and these have been proven to work on a number of operating plants; a commitment to invest the necessary engineering and operations resources is key to improving alarm systems at operating sites; and measurable performance targets are a valuable tool in the management of alarm system improvements. (8 pages)Experiences and responsibilities of a supplier of process control systems
http://dl-live.theiet.org/content/conferences/10.1049/ic_19970932
Process control systems tend to fall somewhere between the hardware of the plant and the software needed to achieve the process that chemists requirements. Design, implementation and testing of such systems therefore also tends to fall, sometimes uncomfortably, between the hardware and software aspects. Before outlining the areas of responsibility and some experiences in the supply of such systems, the author considers their main components and their associated engineering activities. (3 pages)Neural networks and multivariate SPC
http://dl-live.theiet.org/content/conferences/10.1049/ic_19970941
Recent developments in the instrumentation of plants has led to multivariate statistical process control (MSPC) techniques becoming increasingly popular for process monitoring in the chemical industry over the last few years. This paper examines one such algorithm, the partial least squares (PLS), and shows how the basic principles of this linear technique can be extended into the nonlinear domain via the application of radial basis function (RBF) neural networks. Results showing the successful application of these methods to fault detection in a validated model of an industrial overheads condenser and reflux drum plant are also given. (5 pages)Local model networks for nonlinear system identification
http://dl-live.theiet.org/content/conferences/10.1049/ic_19970785
Local model networks represent a nonlinear dynamical system by a set of locally valid submodels across the operating range. Training such feedforward structures involves the combined estimation of the submodel parameters and those of the interpolation functions. The paper describes a new hybrid learning approach for local model networks that uses a combination of singular value decomposition and second order gradient optimization. A new nonlinear internal model control scheme is proposed which has the important property that the controller can be derived analytically. Simulation studies of a pH neutralization process confirm the excellent modelling and control performance using the local model approach. (3 pages)Chemical moisture barrier power and control cable for petrochemical plants and refineries
http://dl-live.theiet.org/content/conferences/10.1049/cp_19970542
A new cable sheath technology has been developed to address the chemical, and contamination in cables rated through 138 kV. The sheath design is based on the use of copolymer coated metal tapes bonded to a plastic oversheath. The “bonded” or “laminate” construction is commonly called a “chemical moisture barrier” (CMB) sheath. The tapes frequently serve a dual function by providing electrical shielding as well as chemical and moisture protection. The components of the CMB sheath, starting from the outside of the cable, are the plastic oversheath, copolymer coated metallic tape as shield and chemical-moisture barrier, sealed overlap, inner jacket (optional), and the cable core. The performance benefits associated with the specification, selection, installation, and operation of CMB sheathed cable for use in industrial and utility electrical systems are described. (5 pages)Condition monitoring methods, failure identification and analysis for high voltage motors in petrochemical industry
http://dl-live.theiet.org/content/conferences/10.1049/cp_19971048
The study gives a synopsis over condition monitoring methods both as a diagnostic tool and as a technique for failure identification in high voltage induction motors in the petrochemical industry. New running experience data for 356 units are registered and processed statistically to reveal the connection between motor data, protection and condition monitoring methods, maintenance philosophy and different types of faults. The different types of faults are further analyzed to failure-initiators, contributors and underlying causes. The results have been compared with those of a previous survey by these authors, and one by an IEEE Report. Methods of fault detection are reviewed and analyzed: mechanical (vibrations, shock pulses, acoustic, speed fluctuations), electro mechanical (currents, surges, partial discharges, leakage fluxes) and temperature-, oil particle-, gas, analysis, and performance- and visual methods. Different types of fault generate different frequency components in vibration spectra, in motor supply current, in torque and in magnetic field, and relationships between fault types and spectra have been studied.The testing of thin films
http://dl-live.theiet.org/content/conferences/10.1049/cp_19970123
This paper describes an instrument being developed by Rhopoint Instrumentation Ltd. in conjunction with Kingston University. The instrument is based on a proof of concept model developed by Reading (1992). The instrument automatically monitors the build up of mechanical and rheological properties in coatings drying on a test panel, across a range of temperatures. This paper describes the design and development of the instrument and discuss a number of its applications. In practical terms the instrument undertakes the role of a 2D robot which is capable of positioning various measuring probes over a drying film. A general purpose thermomechanical testing device of this type is potentially of great value for the of thin films in the coatings industry. This paper is based on a TCS program at Rhopoint Ltd. The purpose of the program was to build a thin film analyser for the paint and coatings industry.Fault detection in an overheads condenser using multivariate SPC
http://dl-live.theiet.org/content/conferences/10.1049/ic_19961377
Fault detection has, for obvious reasons, long been a part of every industrial engineer's brief; this is particularly the case for engineers in chemical plants, where the failure to detect a fault can have potentially catastrophic consequences. Traditional detection methods in this field have depended on limit checking of measurable output variables using standard statistical process control (SPC) techniques, e.g. Shewhart and CuSum charts; however, this approach is fraught with problems notably. The approach described in this paper uses a combination of two procedures. A statistical model is generated via partial least squares, a multivariate statistical modelling technique. Results from simulation studies on an EPSRC-funded benchmark plant, consisting of an overheads condenser and a reflux drum, are presented to illustrate the success of the approach. Standard SPC techniques are then used to detect simulated faults by analysis of the mismatch between the PLS model prediction and the original plant. The results show that the fault would remain undetected throughout the test if these standard SPC techniques were used alone. The paper concludes with suggestions for future work in this field. (6 pages)Constrained receding horizon predictive control of a binary distillation column
http://dl-live.theiet.org/content/conferences/10.1049/cp_19960653
A state space predictive control algorithm, with state constraints at the end-point, is evaluated on a real plant showing nonlinear behaviour. Predictive control techniques based on linear state space model description can find difficulties when applied to a real system with nonlinear behaviour, for example the controlled system may present a steady state offset or bias in the step response. We illustrate, in a real application, a multivariable extension of the constrained receding horizon predictive control (CRHPC) with an error correction on the set point in such a way to avoid the above problem. Specifically, we estimate with a Kalman filter the error between the model prediction and the real response of the plant. The benchmark in this paper is a laboratory distillation column.Analysis and nonlinear model predictive control of the Chylla-Haase benchmark problem
http://dl-live.theiet.org/content/conferences/10.1049/cp_19960719
A model based control solution is given for an industrial benchmark problem concerning temperature control of a semibatch polymerization reactor. The original model given by Chylla and Haase (1993) is critically analyzed. The simulation study carried out with a modified benchmark model treats a realistic industrial scenario where process knowledge is incomplete. Reaction kinetics and heat transfer coefficient are assumed to be unknown and measurement information is limited. The proposed control strategy is based on nonlinear model predictive control in combination with an extended Kalman filter. The process model used in both the controller and filter comprises a calorimetric reactor model and a nonlinear model of the cooling system. The control strategy is shown to be robust against parametric uncertainties and batch to batch variations. It is compared to PID control with and without compensation of the estimated heat of reaction.Modular procedural control of chemical processes
http://dl-live.theiet.org/content/conferences/10.1049/cp_19960640
Procedural control theory (PCT) encompasses chemical process modelling, specification, controller synthesis and analysis. In particular, techniques have been presented for designing sequential controllers for chemical systems which are guaranteed to generate a behaviour which conforms to a functional specification and terminates in a desired process state (non blocking). Until now, the techniques within PCT have been limited to simple chemical systems modelled by no more than a few thousand states and for which the specifications are relatively straightforward. The aim of this work is to apply the same techniques to a broader category of control problems in chemical batch processing, for which the size of the state models may be many orders of magnitude greater, and the specifications quite complex. In this work, size complexity is addressed using reduced models of the process which are easily calculable within the modular approach for process modelling in PCT. A complementary method for handling specification complexity is addressed by borrowing from AI the concept of subgoals. Both decomposition techniques serve to modularise the controller synthesis problem.Fault detection in an overheads condenser using multivariate SPC
http://dl-live.theiet.org/content/conferences/10.1049/cp_19960568
Fault detection is a part of every industrial engineer's brief, particularly in chemical plants. Traditional detection methods in this field have depended on limit checking of measurable output variables using standard SPC techniques; however, this approach is fraught with problems, notably: alarms are not raised until the fault is actually manifesting itself at the outputs; noise on the outputs may mask incipient faults; and many plants have too many variables to monitor them all. More recent fault detection schemes have tended to be model-based, using various types of model. The major problem is model identification, particularly in large plants with input and output variables. The approach described in this paper uses a combination of these two procedures. A statistical model is generated via partial least squares (PLS), a multivariate statistical modelling technique. Results from simulation studies on an EPSRC-funded benchmark plant, consisting of an overheads condenser and a reflux drum, are presented to illustrate the success of the approach. Standard SPC techniques are then used to detect simulated faults by analysis of the mismatch between the PLS model prediction and the original plant.New developments in batch process input profile optimisation
http://dl-live.theiet.org/content/conferences/10.1049/cp_19960651
A novel algorithm for solving nonlinear discrete time optimal control problems with model-reality differences is presented. The technique uses dynamic integrated system optimisation and parameter estimation (DISOPE) which achieves the correct optimal solution in spite of deficiencies in the mathematical model employed in the optimisation procedure. A new method for approximating some Jacobian trajectories required by the algorithm is introduced. It is shown that the iterative procedure associated with the algorithm naturally suits applications to batch chemical processes.