One of the major problems in distillation column control is obtaining a suitable linear transfer function model for columns that are highly nonlinear and complex. Neither analytical nor numerical linearization methods...
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Much of the work in multivariable processcontrol has been directed at finding control structures that minimize interaction among loops and decouple the system. This paper claims that this approach is flawed. What is ...
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The values of the Relative Gain Array (RGA) for a 2 x 2 binary distillation column system are shown to be extremely sensitive to the size of the manipulated variable increment that is used to calculate the steady-stat...
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A multivariable closed-loop process may become unstable for small changes in steady-state gains if integral action is used. The results of this work show that the Relative Gain Array (RGA) is related quantitatively to...
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The sizing of control valves usually involves a trade-off between pump head and control valve size: the bigger the valve, the smaller the pressure drop across the valve and the lower the pump head. Thus, large valves ...
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作者：
LUYBEN, WLProcess Modeling and Control Center
Department of Chemical Engineering Mountaintop Campus Lehigh University Bethlehem Pennsylvania 18015 111 Research Drive United States
The capacity factor methodology developed by Luyben for binary batch distillation is extended to the separation of ternary mixtures. The processing strategy of recycling the two slop cuts back into the next batch is u...
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Industrial interest in batch distillation has increased significantly in recent years as more batch processing is being used for low-volume high-value specialty chemicals. Most studies have concentrated on the determi...
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Industrial interest in batch distillation has increased significantly in recent years as more batch processing is being used for low-volume high-value specialty chemicals. Most studies have concentrated on the determination of optimum operating strategies: optimum trajectories of reflux ratio and pressure during the batch and processing of the slop cuts that are produced. Little attention has been paid to the problems of control. If instantaneous and perfect analyzers were available, the control of batch distillation would be straightforward once the optimum policies are available. Switching from total-reflux operation to producing product and from this to slop-cut production could be performed when compositions in the reflux drum or in product tankage reached the desired values. However, in most industrial applications of batch distillation, perfect composition measurements are not available. This means that an inferential control system that relies on temperature and flow measurements must be used. Models of the batch distillation process can be used to provide estimates of the required compositions. This paper presents the results of a study of two types of model-based inferential control systems for multicomponent batch distillation. The results showed that both steady-state and dynamic estimators provide good estimation of the distillate compositions using only one temperature measurement.
Cyclic processes can be characterized by two time variables, viz, the time within a cycle and the cycle index, each carrying a distinct connotation of time. Conventional optimal control theory does not explicitly acco...
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ISBN:
(纸本)9780816910229
Cyclic processes can be characterized by two time variables, viz, the time within a cycle and the cycle index, each carrying a distinct connotation of time. Conventional optimal control theory does not explicitly account for these two dimensions (2D) of time that characterize cyclic systems. In this paper, we study the control of cyclic process using Model Predictive control (MPC). The proposed approach uses a 2D Lyapunov function and the stability requirements are established along each time dimension of the system. The resulting controller synthesis problem is expressed in convex form using Linear Matrix Inequalities (LMIs). The approach allows incorporation of input/output constraints in the proposed 2D MPC framework. An example of a cyclic process is presented to establish the applicability of the proposed approach.
There are significant incentives in controlling the end-use properties in batch reactors to reduce the variability in the final product quality specifications. Here we define an approach for controlling the properties...
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We present a stabilizing scheduled output feedback Model Predictive control (MPC) algorithm for constrained nonlinear systems with large operating regions. We design a set of local output feedback predictive controlle...
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