Control systems design and simulation

Various levels of models can be used to describe the behavior of pilot-scale jacketed batch reactors. For online reaction calorimetry and for rapid scale-up, a simple model characterizing the heat transfer from the reactor to the jacket can be used. Another level of modeling detail includes both the jacket and reactor dynamics. Finally, the complete set of equations simultaneously describing the integrated reactor/jacket and recirculating system dynamics can be used for feedback control system design and simulation. The complete model can more accurately assess the operability and safety of the pilot-scale system and can be used for more accurate process scale-up. 

Modelling of solar radiation components (diffuse and direct) in clear sky conditions is necessary in many solar energy applications (systems design and simulation, radiometers accuracy control procedures, quality control of data, recovering of observational missing data, etc) as well as in routine procedures in engineering. 

The book is divided into five parts. Part I provides an introduction to process control and an in-depth discussion of process modeling. Control system design and analysis increasingly rely on the availabihty of a process model. Consequently, the third edition includes additional material on process modeling based on first principles, such as conservation equations and thermodynamics. Exercises have been added to several chapters based on MATLAB simulations of two physical models, a distillation column and a furnace. These simulations are based on the book. Process Control Modules, by Frank Doyle, Ed Gatzke, and Bob Parker. Both the book and the MATLAB simulations are available on the book Web site (www.wiley.com/college/seborg). National Instruments has provided multimedia modules for a number of examples in the book based on their Lab VIEW software. 

The GHH Borsig Turbolog DSP control system used for controlling the machine train is designed to enable dynamic system simulation using the control system hardware and software. Tliis offers two major benefits ... 

Fritz, M., Liefeldt, A. and Engell, S. (1999) Recipe-driven batch processes Event handling in hybrid system simulation. Proceedings of 1999 IEEE International Symposium on Computer Aided Control System Design (CACSD 99), Hawaii, USA, pp. 138-143. 

The real power of the model developed in this work lies in the transient or dynamic simulations such as those necessary for control system design. The model we have developed can be used to simulate the effects on the reactor of various process disturbances and input changes. Under normal reactor operating conditions, step or pulse changes in inlet gas temperatures, concentrations, or velocity or changes in cooling rates can significantly affect... 

Simulations show negligible differences in the transient temperature and concentration profiles as a result of this quasi-steady-state approximation. The major advantage of this assumption should be apparent in control system design, where a reduction in the size of the state vector is computationally beneficial or in the time-consuming simulations of the full nonlinear model. 

Some special requirements of continuous systems are (1) Metering the feed. A continuous system must be fed at a precise, uniform rate. (See Sec. 21.) (2) Dust collection. This is a necessary part of most dryprocessing systems. Filters are available that can effectively remove dust down to 10 mg/m or less, and operate automatically. (Dust collection is covered in Sec. 17.) (3) On-line analysis. For more precise operation, on-line analysis of product particle size and composition may be desirable. (4) Computer control. Simulation can aid in optimizing system design and computer control. 

In the development of the process automation and control system, the required testing of that control system and the factory-assembled components, and the process simulation program must be established with the general functional specifications. In an API facility, many of the control systems perform process functions that require strict validation. The functional description for the automation system should require a complete factory acceptance test (FAT). This test should simulate the entire process and process failures and alarms. The FAT should also check and verify that the control system cabinets and controllers operate as designed. The factory acceptance testing of the process automation system prior to shipment and installation in the field is a critical step in the validation and start-up of the facility. 

Khang, G. and Zajac, F.E., Paraplegic standing controUed by functional electrical stimulation part I — computer model and control-system design part II —computer simulation studies, IEEE Trans. Biomed. Eng. BME-36 873-893,1989. 

For the implementation of advanced model-based controllers suitable models and suitable hardware is required including a computer for real-time simulation linked to the control system. In practice, this effort is only justified for a limited number of applications. For many applications standard PI controllers will suffice. Hence, finding a suitable control structure is often the dominating issue during control system design. Certainly, dynamics have to be considered for this and one should not only rely on steady state measures for comparing different control... 

Helget, A., Groebel, M., und Gilles, E. D. Dynamic simulation for plant and control system design. Proc. 5 International Symposium on Process System Engineering, PSE 94, Kyongju, Korea 1994, S. 1111-1116. 

This work investigates the use of reduced order RAP models for the purpose of dynamic simulation, controllability analysis and control system design. Three different discretization methods, namely orthogonal collocation (OC), finite difference (FD) and orthogonal collocation on finite elements (OCFE), are compared. All three methods are able to accurately describe the steady state behaviour. However, the predicted dynamic... 

Kurooka T., Y. Yamahsita, H. Nishitani, Y. Hashimoto, M. Yoshida, and M. Numata, Dynamic simulation and nonlinear control system design of a heterogeneous azeotropic distillation column, Comput. Chem. Engng., 24, 887-892 (2000). 

Another ALMR control system design task is to develop a control and communications architecture simulation capability to provide a software-based approach to test the ALMR control system architecture designs before implementation. The implementation of a plant architecture can be very costly. Therefore, it is important that the architecture implemented will support the plant s needs under all conditions. This simulator will allow potential architecture designs to be modeled. These models can then be tested under a variety of plant and information-flow conditions to assure that a vehicle for testing modifications to the architecture and new systems being implemented. This capability will discover architecture problems and facilitate fixing them before costly implementation expenditures. 

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