This paper summarizes Sigurd Skogestad's struggles in the plantwide control field.
A chemical plant may have thousands of measurements and control loops. By the term plantwide control it is not meant the tuning and behavior of each of these loops, but rather the control philosophy of the overall plant with emphasis on the structural decisions. In practice, the control system is usually divided into several layers, separated by time scale.
My interest in this field of plantwide control dates back to 1983 when I started my PhD work at Caltech. As an application, I worked on distillation column control, which is excellent example of a plantwide control problem. I was inspired by Greg Shinskey's book on Distillation Control, which came out with a second edition in 1984 (Shinskey, 1984). In particular, I liked his systematic procedure, which involved computing the steady-state relative gain array (RGA) for 12 different control structures ("configurations"); the DV-configuration, LV-configuration, ratio configuration, and so on. However, when I looked in more detail on the procedure I discovered that its theoretical basis was weak. First, it did not actually include all structures, and it even eliminated the DB-configuration as "impossible" even through it is workable in practise (Luyben, 1989). Second, controllability theory tells that the steady-state RGA by itself is actually not useful, except that one should avoid pairing on negative gains. Third, the procedure focused on dual composition control, while one in practise uses only single end control, for example, because it may be optimal economically to use maximum heating to maximize the recovery of the valuable product.01/25/2011
A Complete Precision Pressure Measurement Handbook Covering the Fundamentals of Pressure Measurement, Deadweight Pressure Testers, Calibration of Deadweight Testers, AMETEK's Deadweight Testers, Manometers, Secondary Comparison Pressure Standards and the Selection of a Pressure Measurement Standard.02/24/2009
The benefits of applying the S88.01 standard have been well proven in the industry, although most users have only scratched the surface on achieving these benefits. Some of this dilemma can be attributed to poor application of the standard by users; much can be traced to deficiencies in current tools that are available to the user. The S88.01 batch control standard has been around for five years. Ample time has been available to allow the appropriate tools to be developed that will allow users to take full advantage of the S88.01 standard. Most tools still do not provide enough needed features and flexibility. This paper will discuss ways of improving user application of the S88.01 standard and some of the deficiencies of currently available tools.08/26/2008
The Automation and Power World event highlighted ABBs increasing focus on integrating the worlds of power and automation. ARC believes that the cost saving potential of an integrated approach to power and automation is quite high and should provide a strong stimulus for automation project justification in a time of tight budgets and demand for substantial and quick returns.06/03/2009
Communication is more than exchanging data; it means globally understandable information based on syntax and semantics. This is the theory behind IEC 61850, the topic of this issue of ABB Review Special Report.10/08/2012
Manufacturers are under extreme pressure to increase operational efficiency as a means to increase reliability and maintain margins. Six Sigma is providing a powerful means for companies to improve performance. The use of this methodical, statistics-based approach is increasing across a range of industries. Those in the process industries are discovering the PI System can provide critical support to Six Sigma teams at every step of their effort. This paper discusses how to the PI System can support a Six Sigma initiative. QNI, an Australian minerals resource company, serves as an example.03/12/2009
This technical white paper will discuss Yokogawa's CENTUM VP DCS (Distributed Control System) product, hereafter referred to as "CENTUM VP", and the extent of its compliance with Part 11 of Title 21 of the Code of Federal Regulations, (21 CFR Part 11), the Electronic Records / Electronic Signatures Rule.
CENTUM VP Batch Management is the optional Batch control function for CENTUM VP, which provides recipe management and process management functionality based upon the ISA-88 Batch Control System standard. This whitepaper addresses the use of CENTUM VP and the Batch Management function.
A detailed analysis of Part 11 was performed, the results of which are listed in the Detailed Part 11 Compliance section (section 5) of this document, which supports the compliance of the CENTUM VP system to Part 11.
CENTUM VP is a comprehensive software package containing configurable functions that support Part 11 compliance (audit trails, electronic signatures and electronic records). The system capitalizes on its Part 11 compliance attributes in the marketing strategy of supplying FDA regulated industries with state of the art automation capabilities.
User training and education as well as the development and utilization of policies and procedures are key components of Part 11 compliance which must be established by the user.04/15/2010
Drive Improved Performance and Security Within Your Industrial Operation. Read the White Paper.07/31/2014
Lehigh Cement Company's complete modernization of its cement manufacturing facility in Union Bridge, Maryland has helped them conserve energy and improve production processes.10/09/2009
Industrial-strength Ethernet, bolstered by its wireless component, is giving facilities the tools they need to operate lean and mean and succeed in an uncertain economy. As companies seek to identify and eliminate waste, continually improve processes, and respond to the increasing product demands of its customers, they are learning to do more with less, whether it is resources, staff, or money. This white paper examines some reasons and factors influencing the success of the Ethernet infrastructure, while looking at the accelerating presence of its wireless component.04/06/2010
This White Paper examines a five step process that transforms average utilities into performance leaders by clearly defining a roadmap to pacesetter status.04/20/2005
With the advancement of computer and data transmission technologies, systems formerly reserved for the office environment are now critical components of the manufacturing floor. The demands of factory automation, in addition to computer hardware and software, have brought the wire and cable networking products that interconnect these technologies into the industrial setting as well.
With the vast differences between an office and an industrial environment, networking cables such as gigabit Ethernet have had to adapt to these harsh new surroundings, not only from a physical perspective but from a performance perspective as well, in order to function reliably.
This white paper discusses the constructional differences between standard Gigabit Ethernet and the specifications required for similar cables utilized in an industrial manufacturing environment. Additionally applications for these ruggedized designs are also reviewed.09/26/2012
This paper describes the application of an advanced model predictive adaptive controller to the problem of batch reactor temperature control. Although a great deal of work has been done to improve reactor throughput using batch sequence control, the control of the actual reactor temperature remains a difficult problem for many operators of these processes. Temperature control on these systems is difficult for conventional Proportional-Integral-Derivative (PID) controllers because the response is characterized bynan open loop integrator with long delay and time constant. Temperature control is important as many chemical reactions are sensitive to temperature for formation of desired products and reaction rates can be highly temperature dependent. The applications discussed in this paper include a PVC reactor and an Ethoxylated fatty acid reactor. In each case, the variability of the reactor temperature was reduced by 60% or more. Improved temperature control permitted operation at higher reaction temperatures with higher sustained feed rates of reactants and catalysts while remaining within product temperature limits. Batch cycle times were reduced by as much as 35% due to the higher sustained reaction rates. The applications demonstrate the attractive economics for optimization of batch reactors with model predictive controls and highlight the opportunity for tremendous improvements in batch consistency, reduced batch cycle times, and improved productivity.08/25/2008
This paper considers the features and benefits of an alternative performance supervision software approach to fieldbus diagnostics.01/23/2005
In today's manufacturing environment, there is an urgency to increase operating efficiencies, and to do it quickly. One area of improvement that can produce immediate results is reducing energy consumption. It's good for the environment and it's good for the bottom line. "Energy management," therefore, has become a common best practice, but there is more there than meets the eye. Typically it implies rigorously modeling all or a major portion of the plant, coupled with the use of real-time optimization technology. While this approach has been used successfully, there are other simpler, faster options for reducing energy consumption in a manufacturing plant. Learn what these options are.03/25/2010
Advances in Low Voltage Motor Control Center (MCC) Technology Help Reduce Arc-Flash Hazards and Minimize Risks
Selecting the right MCC equipment leads to improved plant safety, helping protect people and capital investments.
Measures to increase equipment and personnel safety in manufacturing are reflected in new approaches and technologies designed to help minimize the risk of workplace dangers. One rapidly growing area of focus is reducing the potentially serious hazards associated with arc-flash events. This white paper examines the causes of arc flash, discusses the standards guiding arc-flash safety and details the role arc-resistant motor control centers (MCCs) play in helping contain arc energy. It also highlights the key features of an effective arc-resistant MCC design.
Managing safety hazards and reducing risks are top priorities for manufacturers across all sectors of industry. With a multitude of potential dangers and new ones continuously emerging, companies must be diligent in their ongoing efforts while considering new approaches and technologies to improve plant safety. One rapidly growing area of focus is implementing techniques and practices designed to reduce hazards and minimize risk for workers who must enter an area with an electrical arc-flash potential.04/07/2010