Plant Dynamics and Control

Based on the above performance concerns, Eqs. (22.22) and (22.24), an L2-gain robust controller is designed such that the plant disturbance d and sensor noise 6 have minimum effect on the plant dynamics and control actions. In an energy sense, this can be specified by... 

VI-5] TANI, A., et al.. Plant dynamics and Controllability of IMR, ICAPP05-5181 (2005X... 

This chapter is an introduction to process dynamics and control for those students who have had little or no contact or experience with real chemical engineering processes. The objective is to illustrate where process control fits into the picture and to indicate its relative importance in the operation, design, and development of a chemical engineering plant. 

Probably the best way to illustrate what we mean by process dynamics and control is to take a few real examples. The first example describes a simple process where dynamic response, the time-dependent behavior, is important. The second example illustrates the use of a single feedback controller. The third example discusses a simple but reasonably typical chemical engineering plant and its conventional control system involving several controllers. 

A comprehensive framework of robust feedback control of combustion instabilities in propulsion systems has been established. The model appears to be the most complete of its kind to date, and accommodates various unique phenomena commonly observed in practical combustion devices. Several important aspects of distributed control process (including time delay, plant disturbance, sensor noise, model uncertainty, and performance specification) are treated systematically, with emphasis placed on the optimization of control robustness and system performance. In addition, a robust observer is established to estimate the instantaneous plant dynamics and consequently to determine control gains. Implementation of the controller in a generic dump combustor has been successfully demonstrated. 

Morud, J. and Skogestad, S. (1994). Effects of recycle on dynamics and control of chemical processing plants. Cornput. Chem. Eng., 18, S529-S534. 

During recent years there has been an increasing demand for better operation of wastewater treatment plants in order to guarantee satisfactory effluent quality at minimal cost. The renewed interest in instrumentation and control comes after a period of huge investments in sewer networks and treatment plants. Several factors have contributed to the potential for better operation and control, such as cheap computing power, improving sensors and better knowledge of process dynamics and control. 

The project deals with a VAM plant capacity of lOOkton per year for an effective operation time of8400 h. The process will be based on the acetoxylation of ethylene conducted in gas phase in the presence of a palladium-based solid catalyst. The case study will tackle the problem of process synthesis and energy integration, as well as the dynamics and control for ensuring flexibility in production rate of 10%, while preserving safety and environment protection. 

The structure in Fig. 1 is essentially a cascade design. This structure is appropriate because of the differences in the plant dynamics and disturbance frequencies associated with the decisions at each level. Control responds to rapid disturbances and requires execution periods on the order of 1 sec. Real time optimization typically responds to disturbances occurring every few hours or slower, and it requires tens of minutes to compute. The higher levels respond to disturbances occurring every few days. While the cascade... 

The recycle of mass and energy have important effects on the dynamics and control of complex plants. Positive feedback increases the time constant of units placed in recycle, the effect depending on the recycle gain. Larger gains can lead even to unstable behaviour. On the contrary, negative feedback has always a stabilising effect. 

For buildings and elements of building structures, current design practice for explosion and blast is to use the quasi-static approach to dynamic response of the structure adopted in the CIA document Process Plant Hazard and Control Building Design , This is, in turn, based on ASCE Manual 42 Design of Structures to Resist Nuclear Weapon Effects . 

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