SMART CONTROL FOR TOMORROWS PROCESSES The process modelling journey 70 Author – Professor R S Benson FREng Director of Technology ABB UK 60 Dynamic Dynamic solution Sequential 40 30 models Steady state sequential 20 Graphical A quotation that the author finds particularly significant is as follows: - 10 Process Modelling Process Control Digital Communication Supply Chain Performance All four are approaching a common point that demands smart control for tomorrows processes. PROCESS MODELLING The process industries involve some form of chemical or physical transformation. These transformation processes are often non-linear, poorly understood and preparing a dynamic model is difficult. A typical example would be an agrochemical batch reactor where the kinetics is complex with main and side reactions. The process-modelling journey is illustrated below. modelling techniques 0 60's 70's 80's 90's 00's © ABB - 47 50's This paper builds on the author’s experience of over thirty years in the process industries and process control learning from other people. During that period a number of significant trends became apparent which indicate the direction for the future. The particular trends selected are: - g-proms solution Dynamic INTRODUCTION “Smart people learn from experience, wise people learn from others”. reconciliation sequential 50 It was in the early sixties that Professor Roger Sergeant at Imperial College (Reference 1), ICI and others started to explore the potential for using computers to solve the basic unit operations of chemical engineering. Prior to that graphical techniques were used to design these unit operations such as distillation columns. Given that the model of a distillation column is a series of counter current equations, this was ideally suited to the early digital computers. The incentive was to significantly reduce the time and effort involved while improving the design accuracy. Models were totally steady state but nonetheless proved of great benefit. The techniques used involved flow sheeting languages that have since evolved into the solutions now offered by companies like Aspen and Hyprotech. A feature of these early models is that they solve them in a sequential manner that follows the process. E.g. solve the reactor equations and use the outputs as the inputs to the distillation column. While this approach felt intuitively correct, the drawback was the relatively slow speed of solution. In the late seventies increasing computer power plus research into the basic mathematics and chemical engineering, encouraged researchers to consider the solution of dynamic processes models. Again Imperial College was the leader and the result was the “Speed Up” product (Reference 2). This was eventually licensed by Aspen and is now a standard product that is available on the market. One of the drivers was At around the same time, the concept of simultaneous equation-based solution was developed. In this approach all the model equations are solved simultaneously. This brings real benefits in accuracy and speed. A key component of any process model is accurate physical properties data. Initially government laboratories developed these models. These have now transferred to private ownership, which develop and manage the core physical properties used by many of the process mathematical models. Over 20 years steady state modelling moved from research to the norm in the industry and the vast majority of engineers now use some form of steady state modelling. This includes the Process Engineering Library (PEL) (Reference 3), which was originally developed by ICI and is available from ABB and larger packages available from companies like Aspen. In the nineties the concept of combing equationbased solutions with dynamic models was developed, again by Imperial College (Reference 4). The result is g-proms, which is the latest development in dynamic modelling and flow sheeting. ABB have had an exclusive licence for this technology in the automation area and have worked in partnership with PSE to develop their own version of g-proms applicable to the process industries. The key feature for this has been the development of a dynamic data reconciliation module. Complete Life Cycle Models for Multiple Uses Control, equipment design optimization P l an t data Offlin e On lin e I nitial m odel Estim ation Raw plant data U p-todate m odel MPC Lin ear m odels [ A,B ,C,D] Advanced MPC Fitted m odel Data Reconciliation P aram eter Estim ation Plant © ABB - 23 to improve the process control of the chemical processes. As a generalisation, chemical processes have considerable capacity within them in the form of tanks, reboilers etc. This often means that the dynamics are relatively slow; hence it was possible to tackle dynamic control problems using models of this type. Lin earization Linearized models Decision support Operating procedure optimization Many others R econciled plan t i nform ati on Yield accounting Soft sensing Diagnosis and troubleshooting Optimization (ss + dynamic) Dynamic reconciliation allows the user to ensure that all the heat and material balances of the process are reconciled at any time without having to wait for the process to attain steady state. This has numerous advantages to the user in the form of accuracy, removal of arguments on yields etc, ability to monitor leak detection, instrument failures, heat exchanger efficiency as well as the option to provide a “fit and forget” model based predictive control. Hence, the evolution of process modelling over forty years has led to a solution where it is potentially possible now to model dynamically almost any chemical process and to apply the latest advanced control techniques on a “fit and forget” basis. This means there is no longer requirement for the time consuming step tests and recalibration of the previous multi-variable control models. It is an example where process modelling and process control is now coming together to the benefit of process industries. PROCESS CONTROL Process control has also gone through a similar cycle over the last forty years. This is illustrated in the diagram below. The process control journey 70 60 Multi-variable Statistical 50 Model based 40 predictive DCS Electronic Pneumatic controller 10 control process control control Systems Multivariable 30 20 Parametric control controllers Single loop Single loop 0 60's 70's 80's 90's 00's © ABB - 48 50's In this area the industrial applications have followed the research applications at universities. In the fifties the research focused on single loop controllers with the work of Bode and Nichols developed single loop control theory. The process industries followed, though initially they were inhibited by the limitations of pneumatic controllers. Advanced control was restricted to ratio or possibly feed forward control. In the sixties universities such as UMIST and others began to develop the concept of multi variable control with the work of Professor Alistair MacFarlane. In addition, the development of computer control demanded the development of the theory of sample data control. It seems interesting to reflect that it is only thirty years ago that control engineers such as the author had to argue the case for using computers to control process plants. They are now the norm. The key however, to multi variable control in the process industries was the development of model based predictive control by Professor Manfred Morari and others in the late seventies. In this control a form of process model is inverted to provide feedback to the control variables. This was initially exploited industrially by Shell and it was in the refining area that model based predictive control really became established. This is increasingly the norm for the advanced control in that area and it is also increasingly finding acceptance in other industries where it is required. The problem however with model based predictive control is that it required a dynamic model of the process. Normally this is determined by engineers carrying out numerous disturbance tests on the process to develop this dynamic model. While this proves quite effective until the process changes significantly, it is both time consuming, and it is difficult to know exactly how good the model based predictive control is compared with best possible. In the nineties the learning from the nonprocess industries began to spread into the process industries. One only has to go round an electronics company or a car company to realise that their method of control is statistical process control. Terms like Six Sigma are growing in importance. This is a single variant form of control. The process industries are usually multi-variant. University research at Newcastle upon Tyne University and others has developed Multi Variable Statistic Process Control (MVSPC). This applies the concept of statistical process control to the process industries. This is growing in importance, particularly in the batch processes, and will be very significant in the first ten years of the twentieth century. In every case, the suppliers of process control equipment such as ABB have followed the lead provided by the universities, possibly with a five-year or more gaps between the research and the first commercial applications. It is interesting to reflect that in the past forty years, many of the large process companies had large leading edge process control groups that were able to develop and prototype university research in industry before the equipment suppliers developed and offered them as standard products. Very few companies now retain this skill and it is increasingly the obligation of supply companies such as ABB, to be the direct translators of university research into industrial products. Increasingly such companies are becoming the first tier suppliers to the process industries. DATA COMMUNICATION AND INDUSTRIALIT Again, this is a history of very rapid evolution of the last forty years. The journey is illustrated in the figure below. The data communication and IndustrialIT control journey 70 60 IndustrialIT OCP 50 World-wide standards web 40 Fieldbus DCS 30 Systems This led to an industry demand for a concept, which eventually became known as Fieldbus. The concept of Fieldbus was that anybody’s instruments could communicate with anybody’s computers over a single standard interface. It is interesting to note that the author first heard of Fieldbus in the late seventies, and it is only now that it is becoming the standard demanded by the industry. A gap of almost 30 years! The evolution of this has been long and torturous, and it may well be suspected that it was not in everybody’s interests to make it succeed. DDC 20 computers 0 60's 70's 80's 90's 00's © ABB - 49 50's On reflection, and not surprisingly, the key driver of this whole evolution has been the digital computer. It is only forty years ago that the majority of process plants used pneumatic instrumentation. While in its own way very clever, and very simple, it was clearly very difficult to transfer data from these instruments to any form of central location. In fact the best that could be done was the operators manual recording information that may be manually analysed by others. Rotating pneumatic scanning valves that converted pneumatic signals into digital signals were developed but these were restricted to a very few applications. It was in the late sixties that the first direct use of computers to control process plants was developed by ICI in the UK and Monsanto in the US. Unfortunately all the instruments and all the valves were pneumatic, hence numerous analogue to digital and digital to analogue converters had to be installed to make this possible. Nonetheless the principle was established. This rapidly took off through the seventies and computer controls were installed in many large plants, primarily to allow concepts such as advanced control and optimisation. For anybody who was working in that era a real challenge was the need to communicate with numerous different standards of interfaces with pneumatics, electronics and other people’s instruments. In the early nineties the concept of the Internet and the worldwide web arose. This came from a totally different direction, and was developed for the totally different need of transferring huge amounts of data across the world using existing spare computer capacity. It had nothing like the standards effort of Fieldbus nor the numerous committees that made it possible. Nonetheless it rapidly gained acceptance as a worldwide standard because of its ease of use, availability and effective low cost. As a consequence of this, suppliers are now exploring the use of the web for communication between instruments and computers etc, and it may eventually replace some components of Fieldbus. In the nineties, ABB took a fundamental review of the whole question of information flow both between plants and business systems and between components across plants. The result was the concept of IndustrialIT (Reference 3). IndustrialIT - What does it mean? Industrial IndustrialIT IT--The Thesuccessful successfulcombination combinationof of: : Industrial Industrial- -Tradition, Tradition,long-term long-termcommitments, commitments,stability, stability,experience, experience,knowledge, knowledge,...... Creativity, speed, innovation, agility, new technology, IT IT - Creativity, speed, innovation, agility, new technology,...... Industrial IndustrialIT IT--The TheNext NextWay Wayof ofThinking Thinking: : © ABB Ltd. - 2 Pneumatic 10 One Onescalable, scalable,consistent consistentconcept conceptfor forall allaspects aspectsof ofautomation: automation: Field Fielddevices, devices,drives, drives,PLC, PLC,DCS, DCS,OCS, OCS,SCADA, SCADA,safety, safety,substation substationautomation, automation, MES, MES,maintenance maintenancesystems, systems,ERP ERPintegration, integration,BMS BMS...... IndustrialIT - Information availability Aspect integrator Production order Production schedule Product specification Operator interaction Stock report Production report © ABB Ltd. - 16 Quality report Trend data Aspect integrator - Information availability Aspects Aspect systems Stock report Real Object Model Object Product specification Microsoft Excel Microsoft Word Operating procedures Production schedule SAP, IFS . . . Mechanical drawing AutoCAD © ABB Ltd. - 17 To put the significance of IndustrialIT into context is probably appropriate to remind people that there was a time before Windows Office when letters were typed on typewriters and duplicates used carbon paper. That is probably no more than thirty years ago. Within that time typewriters have disappeared, carbon paper is a thing for a museum, and Microsoft Office has been the standard for all offices in the world. ABB believes that IndustrialIT will become the standard for communication in the industrial world. The key and unique feature of IndustrialIT is to recognise that every object in the plant has information associated with it that ABB call aspects. Consider a typical control valve, which is an object, illustrated below. The result from the user is a system that is cheaper to install, whose documentation is always up to date, and which allows transparency of information at all levels. It is this transparency and instant access to information, plus the potential that it is dynamically reconciled, that makes this system potentially so powerful for tomorrow’s processes. IMPACT OF SUPPLY CHAIN This is a much shorter but equally significant journey as illustrated below. The supply chain journey 70 Each object has associated with it many aspects of information. This is all the information that is associated with that control valve. Quite deliberately, this is all made available to the users in standard Microsoft or other world leading packages. This is illustrated below. 60 Supply chain pressures 50 on the process industries 40 Benchmarking 30 manufacturing process ERP 20 systems World class 10 manufacturing in cars 0 60's 70's 80's 90's 00's © ABB - 50 50's The process industries operate in a supply chain between raw materials supply such as oil and final customers such as supermarkets. Strange as it may seem this has not always been the case. In the sixties it was a market where demand exceeded supply in most products, hence the only requirement was to ensure that you could produce the product. If available the product then it was sold and how it was sold and the economics of sale was not really important. Supply chain pressures did not really impact the process industries until the late eighties. The impact was felt earlier in industries such as cars and electronics. This led in the seventies to the concepts of world class manufacturing of cars which was first exploited in Japan and had significant impact on the western world in the late seventies. This led to a whole new manufacturing paradigm with phrases such as lean manufacture, total productive management and others being developed into the new industrial language. It was only in the early nineties that it began to be recognised that the concepts of world-class manufacturing applied to the process industries. The author would claim to be one of the people that brought this thinking into the industry, and has prepared a book on benchmarking in process manufacturing (Reference 5), which lays out some of the thinking behind world class manufacturing. A key requirement of world class manufacturing is the recognition that you must benchmark against world class, and that the performance metrics refer to manufacturing performance, not process engineering performance, the table below gives a brief table of some of these world class manufacturing metrics for Refining and Petrochemicals. Similar figures apply to batch processes. Performance Benchmarks – Refining and Petrochemical Processes © ABB - 6 Supply chain costs as %of sales Manufacturing Added Value / Empl or : Manu Added Value / Avg. Salary Cost Customer OTIF % Customer Complaints (%orders) Adherence to Production Schedule Process Capability Product Rate Quality Rate Availability Turnaround Frequency (months) * Overall Equipment Effectiveness Maintenance Cost as %Replacement Value Stock Turn (process) Supplier OTIF Absenteeism Training Days / Employee Average 12% >£200k >3 90% 2% 70% 2 90% 90% 88% 36 75% 2.00% 20 90% 4% 5 World Class 6% >£400k >6 >99% <0.01% >98% >3 >98% >99% >99% 72 >97% <1.5% >50 >99% <1% >12 To those familiar with the process industries, measures in safety will be very familiar, but measures such as OEE will be less familiar and one measure in particular, supply chain costs as a percentage of sales would probably be totally new. Supply chain costs as a percent of sales is defined as all the costs associated with the supply chain, excluding manufacturing, divided by the sales revenue. All the costs include things like sales, marketing, the information management systems, the head office costs, the cost of warehouse, the cost of distribution etc. You will see from the above table that a typical figure in the process industries is probably in the order of 14% but we have experienced it as high as 25%. World class it is in the order of 5 – 6%. Companies like Dell, Amazon and others in the leading edge markets set world class. Note that the difference between 5% and 14% is 9% of sales, which is an enormous figure, which immediately impacts a company’s bottom line. This is fundamentally the reason why improving supply chain performance is a high priority task in many companies and that it has accelerated rapidly up the agenda from a start in the nineties to become the hot topic in the first decade of the twentieth century. In improving supply chain costs it should first be remembered:“World class manufacturing is a necessary but not sufficient condition for world class supply chain performance” To deliver world-class manufacturing that delivers world leading supply chain performance will, in many cases, require radically different processes. Smart control for tomorrow's processes Tomorrow’s opportunities The process modelling journey • • • • • • • • Fire fighting Poor performance, SHE, OEE, etc. Manufacturing is a cost to the business Internal conflict 60 reconciliation Multi-variable sequ ential 50 Radical improvement Excellent manufacturing velocity etc Supply chain is value adding Outstanding customer service with zero stock solution Sequential 40 30 20 Model based 40 10 models Electro nic modelling 20 techniques Step changes in process technology Agile controller 60's 70's 80's 90's 00's control controllers Single loop Single loop 50's 70's 80's 90's 00's © ABB - 48 60's Smart control for tomorrow's processes - Customize Agile - Supply Chain The supply chain journey 70 Customize Manufacture 70 60 pressures SMART CONTROL FOR TOMORROWS PROCESSES All four of the trends identified are now approaching a common point where the market will demand smart control for the processes of tomorrow. manufacturing proces s ERP computers 20 systems World cla ss 10 0 50's 60's 70's 80's 90's manufacturing in cars 0 00's 50's 60's 70's 80's 90's 00's © ABB - 50 © ABB - 49 © ABB - 51 Be nchmarking 30 DDC 20 Pneumatic For example world-class supply chain performance demands that you make to order with minimum raw material and finish goods stock. Unfortunately many process plants were built twenty or thirty years ago when the philosophy was to run them steadily at a fixed rate, or to manufacture a batch with a large minimum batch size. The consequence of this is that you absorb swings in the market by using inventory. This is totally opposite to requirements of world-class supply chain. Incidentally, one of the reasons they were built this way, was a lack of full understanding and process modelling to cover the wide range of operations. To move to world class supply chain would demand processes that are capable of manufacturing “to a unit of one” as described by Manufacturing Foresight (Reference 6). This basically says that if the customer orders one drum of chemicals, you make one drum of chemicals. If there are no orders you do not manufacture. This will require agile process manufacturing, plants that can be run at any rate in an automatic manner are providing perfect product. This is a natural introduction to the title of this paper. 40 DCS Systems 10 World Class……….’The Journey’……….Tomorrow on the process industries web Field bus 30 Measure and Act Supply chain 50 World-widestandards 40 Improve the Core Practices 60 IndustrialIT OCP 50 Strategy and People Capability © ABB Eutech 2001 control 0 The data communication and IndustrialIT control journey Gaining Gaining Control Control Pneumatic 10 50's process control Systems Multivariable 30 sequ ential Grap hical 0 Continuous improvement Excellent OEE etc. Manufacturing is value adding Focus upon customers predictive DCS Steady state Parametric control Stat istical 50 g-pr oms solution Dynamic Distributed World Class Traditional Dynamic Dynamic © ABB - 47 • • • • 70 60 Virtuous Reactive The process control journey 70 Proactive The prime driver is the market as represented by the supply chain. The final customers will require just in time delivery in full of products at all time with zero defects. This has been recognised in the UK Foresight exercise that recently produced a report called Manufacturing 2020:We can make it! (Reference 6). The report highlighted five significant themes for the future, which are summarised in the figure below. Manufacturing 2020 Foresight Making the future work for you T Manufacturing to a unit of one T Distributed manufacture, design for Agility, link customer <-> manufacturer T Value chain co-management T Full Service propositions, shared technology development T An environmentally and socially sustainable future T Zero safety and environmental arising. Plants with limited volumes T Technology and innovation T b2b comes of age, information and knowledge key T An educated constantly re-skilled flexible workforce T Partnerships with Universities, learning for life, electronic learning 36 ©Copyright 2000 ABB Ltd Manufacture to a unit of one is the key flexibility driver. One interpretation is that the chemical plant has to be designed to be able to produce a batch size equal to the smallest order size, even to the case where the order size may be one drum of chemicals. This demands manufacturing processes with the following characteristics. Design for minimum inherent volume and capacity. Build quality into the whole process from beginning to end such that Six Sigma performance is achievable. To meet these requirements will demand a wider spectrum of manufacturing processes from the ever-larger continuous plants at the source of feedstock through to the distributed, intensified and small plants that work on a made to order basis at the point of use. Throughout the spectrum the requirements will be for “smart operations” where the control, and the knowledge, must be used to match the process output and quality to an ever more variable demand. Concepts like intensification at the University of Newcastle, the flexible batch plant at the University of Imperial College and pipe less plant built by ICI and Mitsubishi provide further options for tomorrow’s processes. Hence, it is possible now to design a process for chemical manufacture that is agile. Note that the closer you are to the final consumer the greater the need for agility. The converse is that the farther away you are from the consumer in companies such as oil supply and raw materials processing the less the need for agility and the more the processes such as cat crackers and olefin plants will remain unchanged. There is however and interesting development occurring in the concept of gas to liquids technologies which would allow the hydrocarbon liquids to be made from gas, potentially in the long term at the point of use which could significantly change the nature of the supply chain. The rate of adoption is presently inhibited by a belief that the process industries in the future will look like the process industries of the past. This is difficult to accept given the pressures that are coming from the supply chain. Driving down supply chain costs as a % of sales from 15% to 5 to 7% is just too large an incentive. The pressure for tomorrow’s processes to be agile will require that they have to be designed to exploit the full potential of process control. That includes control of: The actual chemical processes The energy sources such as electricity Safety, health and environment Management of the maintenance Operation of the supply chain All the control will be in the context of multivariable statistical process control, as the products will go straight to the customers without any laboratory testing or final product storage. These “smart operations” will have the ability to make to order. This leads to the concept that the orders will arrive directly at the plant. The plant will purchase the raw materials as required, produce the products and ship it to the final customers. This basically says that the plant is managing the supply chain. Hence, no longer will you require this vast centralised supply chain software being developed by many well known names but the actual supply chain management will become a distributed supply chain management managed by the plant. This is a trend recognised by ABB and described as Real-Time Enterprise Integration. Shaping the Industry Trends 1995 Relationship Management Multiple, Proprietary Software Platforms 2000 200x IndustrialIT from ABB Collaborative eBusiness Enterprise Management Traditional ERP Systems Plant Management Manufacturing Execution Systems Automation and Control Traditional Control & Instrumentation Devices Wired Connections Integrated Business Processes Real-Time, Plant Automation Enterprise Device to Integration Intelligent Devices © ABB Eutech 2001 Smart sensors Totally accurate mathematical models Application of multi-variable statistical process control to monitor the operational process. Direct link between the real time plant and the business systems. Given what has been said earlier, the ability to provide a totally accurate dynamic model will be possible with developments such as g-proms. - HW / SW Islands Gateway Integration Full Integration! This has major consequences for the costs of the supply chain in that it is no longer necessary to have large IT departments, HR departments, Accounts departments etc at some central location and incurring overheads, the whole supply chain will become green. ACKNOWLEDGEMENTS The supply chain is a dynamic system where the capacities are warehouses, distribution, order processing times etc. It is possible to develop a dynamic model of the supply chain. In other words, control over the supply chain is a process control problem. Hence, one would anticipate that tomorrow’s smart control would be applying all the techniques of single loop; multi-variable model based predictive and multivariable statistical process control to the concept of the supply chain. One consequence will be to raise the benchmarks of world-class process plants closer to those of the leading software companies of today. Suggested targets are given below. (Reference 7) Tel: +44 (0) 1642 372379 Fax: +44 (0) 1642 372111 Benchmarks for a flexible Chemical manufacturing Poor m hrs / Reportable injuries 0.01 Good 0.1 W orld class Today OTIF % Custom er C om plaints ( % of orders ) Production rate Quality rate Availability % OEE Process capability ( CpK ) Stock turn Manufacturing velocity Supply chain costs as % of sales World class Tomorrow >1 >10 Environm ental incidents Professor Roger Benson FREng is Technology Director of ABB UK and Program Manager for Refineries and Petrochemicals. He has been the DTI nominated Judge of the UK Best Factory Award for the last 6 years. He is Visiting Professor at Imperial College, London, and the Universities of Newcastle and Teesside. He wishes to acknowledge the contribution of all his colleagues in ABB, in particular Sharon Golightly who prepared the manuscript. 40% 6% 60% 45% 70% 20% 99.9% 0.01% 99% 99% 96% 94% >99% <0.1% >90% >99% >95% >85% 0 >99.9 % <0.0004% >99% 100% 100% >99% 0.6 4 0.1% 22% 1.5 19 1% 12% >2 >25 >8% <9% >6 >50 >25% <6% 10% 0.8% <1% <1% Added value per em ployee £10k £200k £400k > £2000k © ABB Eutech 2001 Absenteeism This presents a very interesting research challenge for the process control community. ABB are already researching all these areas as a leading first tier supplier. Internet: roger.benson@gb.abb.com, References 1 INTEGRATED DESIGN AND OPTIMISATION OF PROCESSES, Prof R W H Sargent, The Chemical Engineer, 46,12, CE424 (1968) 2 “SPEED-UP” IN CHEMICAL ENGINEERING DESIGN, Prof R W H Sargent, A W Westerberg, Trans. Instn.Chem. Engrs, 42,T190 3 Process Engineering Library, www.abb.com 4 PSE, www.pse.com 5 BENCHMARKING IN THE PROCESS INDUSTRIES Prof. M Ahmed, Prof. R .S. Benson. Published by the I Chem E in June 1999, ISBN 0 85295 411 5 6 MANUFACTURING 2020: WE CAN MAKE IT; http://www.foresight.gov.uk/ 7 FLEXIBLE MANUFACTURING IN THE CHEMICAL INDUSTRY, Invited paper to be presented at the 6th World Congress for Chemical Engineers, Melbourne, Australia, 23 - 27 September 2001 CONCLUSIONS Tomorrow’s processes will be agile. The technology exists to develop, control and manage these processes. It will be a form of smart control that not only applies to the processes but also applies to the electrical/energy supplies and to the whole supply chain. This is an interesting challenge, which ABB is vigorously taking on at this time based on its unique IndustrialIT platform.