Authors: Chang, Chuei-Tin; Chen, Jung-Yang

Abstract: A SDG-based simulation procedure is presented in this study to qualitatively predict all possible effects of one or more fault propagating in a given process system. All possible state evolution behaviors are characterized with an automaton model. By selecting a set of on-line sensors, the corresponding diagnoser can be constructed and the diagnosability of every fault origin can be determined accordingly. Furthermore, it is also possible to construct a formal diagnostic language on the basis of this diagnoser. Every string (word) in the language is then encoded into an IF-THEN rule and, consequently, a comprehensive fuzzy inference system can be synthesized for on-line diagnosis. The feasibility of this approach is demonstrated with a simple example in this paper.

Keywords: fault diagnosis,automata,signed directed graph,formal language,fuzzy logic

Identifier: 10.3182/20090712-4-TR-2008.00047

Conference: 7th IFAC International Symposium on Advanced Control of Chemical Processes (2009)

Location: Koç University Campus, Turkey

Start Date: Sun Jul 12 2009 - End Date: Wed Jul 15 2009

Authors: Dwivedi, Deeptanshu; Kaistha, Nitin

Abstract: Two-temperature inferential control of the ideal and the methyl acetate double feed reactive distillation (RD) systems operated neat is evaluated using constrained dynamic matrix control (CDMC) and traditional decentralized control. For the ideal RD system, significant improvement in the stripping tray temperature control and the transient deviation in the bottoms purity is observed using CDMC. For the methyl acetate system, CDMC results in significant improvement in the control of the two tray temperatures as well as transient deviations in both the distillate and bottoms purity. Results also show that the magnitude of the maximum through-put change for which the control system fails is noticeably higher using CDMC.

Keywords: reactive distillation control,dynamic matrix control,temperature inferential control

Identifier: 10.3182/20090712-4-TR-2008.00069

Conference: 7th IFAC International Symposium on Advanced Control of Chemical Processes (2009)

Location: Koç University Campus, Turkey

Start Date: Sun Jul 12 2009 - End Date: Wed Jul 15 2009

Authors: Peymani, Ehsan; Fatehi, Alireza; Sedigh, Ali Khaki

Abstract: In this paper, two types of multiple-model adaptive controllers are practically evaluated on a laboratory-scale pH neutralization process. The first one is supervisory switching multiple-model adaptive controller (SMMAC) whose model bank is fixed and selected a priori, and another one is a controller based on multiple models, switching, and tuning strategy (MMST) which uses the possibility of model bank tuning. In addition to investigation of the effect of tuning, the advantage of a disturbance rejection supervisor is studied. Various experiments and exhaustive numerical analyses are provided to assess the abilities of the proposed algorithms.

Keywords: multiple models,adaptive control,pH control,switching control,pole-placement control

Identifier: 10.3182/20090712-4-TR-2008.00090

Conference: 7th IFAC International Symposium on Advanced Control of Chemical Processes (2009)

Location: Koç University Campus, Turkey

Start Date: Sun Jul 12 2009 - End Date: Wed Jul 15 2009

Authors: Kano, Manabu; Ogawa, Morimasa

Abstract: In this age of globalization, the realization of production innovation and highly stable operation is the chief objective of the process industry in Japan. Obviously, modern advanced control plays an important role to achieve this target; but it is emphasized here that a key to success is the maximum utilization of PID control and conventional advanced control. This paper surveys how the three central pillars of process control - PID control, conventional advanced control, and linear/nonlinear model predictive control - have been used and how they have contributed toward increasing productivity. In addition to introducing eminently practical methods, emerging methods, and their applications, the authors point out challenging problems. In Japan, industry and academia are working in close cooperation to share their important problems and develop new technologies for solving them. Several methods introduced in this paper are results of such industry-academia collaboration among engineers and researchers in various companies and universities. Furthermore, soft-sensor or virtual sensor design is treated with emphasis on its maintenance, because soft-sensors must cope with changes in process characteristics for their continuous utilization. Maintenance is a key issue not only for soft-sensors but also for controllers. Finally, we will expand our scope and briefly introduce recent activities in tracking simulation and alarm management. A part of the results of our recent questionnaire survey of process control are also introduced; the results are extremely helpful in clarifying the state of the art in process control in Japan.

Keywords: advanced process control,alarm management,industrial application,model-based control,model predictive control,PID control,process control,production innovation,soft-sensor,tracking simulator

Identifier: 10.3182/20090712-4-TR-2008.00005

Conference: 7th IFAC International Symposium on Advanced Control of Chemical Processes (2009)

Location: Koç University Campus, Turkey

Start Date: Sun Jul 12 2009 - End Date: Wed Jul 15 2009

Authors: Hoang, H.; Couenne, F.; Jallut, C.; Le Gorrec, Y.

Abstract: This paper focuses on non linear control of non isothermal Continuous Stirred Tank Reactors (CSTRs). The model of the CSTR is thermodynamically consistent in order to apply the control strategy based on the concavity of the entropy function and the use of thermodynamic availability as Lyapunov function. More precisely the stabilization problem of continuous chemical reactors is addressed operated at an unstable open loop equilibrium point. The chosen control variable is the jacket temperature. In this paper we propose a state feedback strategy to insure asymptotic stability with physically admissible control variable solicitations. Theoretical developments are illustrated on a first order chemical reaction.

Keywords: Lyapunov based control,irreversible thermodynamics,non isothermal CSTR,multiple steady states,entropy

Identifier: 10.3182/20090712-4-TR-2008.00056

Conference: 7th IFAC International Symposium on Advanced Control of Chemical Processes (2009)

Location: Koç University Campus, Turkey

Start Date: Sun Jul 12 2009 - End Date: Wed Jul 15 2009

Authors: Kiran, K. Lakshmi; Lakshminarayanan, S.

Abstract: Cancer immunotherapy is one of the emerging therapies for cancer treatment where immune cells are guided to fight against cancer. Clinical immunologists are proposing different ideas to stimulate the immune cells and dendritic cell therapy is one among them. Like, other treatment modalities, the challenge in dendritic cell therapy is when and how much dendritic cells should be administered. In this work we use a mathematical model which elucidates the activation of the helper T-cells and cytotoxic T-cells by the intervention of dendritic cells. The objective is to minimize the tumor cells for a given input of dendritic cells. Then multi-objective optimization is applied on the model to design the treatment planning in order to achieve the objective.

Keywords: cancer,immune system,dendritic cell therapy,mathematical model,multi-objective optimization

Identifier: 10.3182/20090712-4-TR-2008.00016

Conference: 7th IFAC International Symposium on Advanced Control of Chemical Processes (2009)

Location: Koç University Campus, Turkey

Start Date: Sun Jul 12 2009 - End Date: Wed Jul 15 2009

Authors: Marafioti, Giancarlo; Tebbani, Sihem; Beauvois, Dominique; Becerra, Giuliana; Isambert, Arsene; Hovd, Morten

Abstract: Microalgae have many applications such as the production of high value compounds (source of long-chain polyunsaturated fatty acids, vitamins, and pigments), in energy production (e.g. photobiological hydrogen, biofuel, methane) or in environmental remediation (especially carbon dioxide fixation and greenhouse gas emissions reduction). However, the photobioreactor microalgae process needs complex and costly hardware sensors, especially for biomass measurement. Thus, state and parameter estimation seems to be a critical issue and is studied in this paper in the case of a culture of the microalga Porphyridium purpureum. This paper is an extension of the previous work of Becerra-Celis et al. (2008) where the principal objective is to design a biomass estimator of this microalga production in a photobioreactor based on the total inorganic carbon measurement. Unscented Kalman filtering is applied to estimation of states and model parameters, producing better performances in comparison with Extented Kalman filtering. Numerical simulations in batch mode, and real-life experiments in continuous mode have been carried out. Corresponding results are given in order to highlight the performance of the proposed estimator.

Keywords: unscented Kalman filter,state and parameter estimation,microalgae photobioreactor

Identifier: 10.3182/20090712-4-TR-2008.00131

Conference: 7th IFAC International Symposium on Advanced Control of Chemical Processes (2009)

Location: Koç University Campus, Turkey

Start Date: Sun Jul 12 2009 - End Date: Wed Jul 15 2009

Authors: Romano, Rodrigo A.; Garcia, Claudio

Abstract: Friction in control valves and inadequate controller tuning are two of the major sources of control loop performance degradation. As friction models are needed to diagnose abnormal valve operation or to compensate such undesirable effects, process models play an essential role in controller design. This paper extends existing optimization-based methods that jointly identify the process and friction model parameters, so that a nonlinear process model structure is considered. The procedure is based on data generated from closed-loop experiments with an external test signal. A simulation example indicates that the method accurately quantifies the valve friction, the process dynamics and the nonlinear steady state characteristics, even when the system is subjected to different level of disturbances.

Keywords: control valves,nonlinear models,identification algorithms,friction

Identifier: 10.3182/20090712-4-TR-2008.00078

Conference: 7th IFAC International Symposium on Advanced Control of Chemical Processes (2009)

Location: Koç University Campus, Turkey

Start Date: Sun Jul 12 2009 - End Date: Wed Jul 15 2009

Authors: Farenzena, M.; Trierweiler, J. O.

Abstract: Valve stiction is a well known villain in process industry. Quantifying this valve damage is essential to ensure plant stability and profitability. The scope of this work is to propose a new method to compute valve stiction parameters, using a two parameter model, using only routine operating data. The proposed method uses global optimization to evaluate loop and plant parameters. Combining the proposed procedure with an efficient global optimization algorithm, the mean computation time for each valve was about 5 minutes. The method was applied in both simulation and industrial valves, providing reliable results, with relative errors smaller than 3% in all parameters.

Keywords: performance monitoring,valve,static friction,hysteresis,global optimization

Identifier: 10.3182/20090712-4-TR-2008.00082

Conference: 7th IFAC International Symposium on Advanced Control of Chemical Processes (2009)

Location: Koç University Campus, Turkey

Start Date: Sun Jul 12 2009 - End Date: Wed Jul 15 2009

Authors: Farenzena, Marcelo; Trierweiler, Jorge O.; Shah, Sirish L.

Abstract: It is now common knowledge that as many as 40% of the control loops in most industrial processes have considerable potential for improving control performance by reducing variability. Because of the large number of control loops in an industrial plant, controller performance monitoring is indispensable, but equally important is how to prioritize their maintenance. It is well known that variance reduction in a loop occurs by transferring variability to other variables or loops. The focus of this study is to propose a methodology to prioritize loop maintenance based on the potential improvement of each loop and the variability transfer among them. The central point of this work is the Variability Matrix (VM), an array that shows the impact of performance improvement of a given loop on the whole plant. Based on the VM, a methodology to translate this array into a potential loop economic benefit metric is also introduced. The VM can be quantified in the ideal scenario where plant model and controller are available and also when they are not, thus allowing the application of these ideas in industry. The efficacy of proposed methodology is illustrated by successful application to two case studies.

Keywords:

Identifier: 10.3182/20090712-4-TR-2008.00109

Conference: 7th IFAC International Symposium on Advanced Control of Chemical Processes (2009)

Location: Koç University Campus, Turkey

Start Date: Sun Jul 12 2009 - End Date: Wed Jul 15 2009