Design and controllability

A. J. Lynch, Developments in Mineral Processing, Vol. 1, Crushing and Grinding Circuits Their Simulation, Optimisation, Design, and Control, Elsevier, Amsterdam, the Netherlands, 1977, 342 pp. 

All these methods require careful design and control of fabrication methods to assure success. 

There are four overall guidehnes that analysts should keep in mind. They must recognize the difficulties associated with the limited number and accuracy of the data, overcome the plant operation mythologies, overcome the designers and controllers biases and, finally, override the analysts own prejudices. The following four overall guidelines assist in overcoming the hurdles to proper plant performance. 

Plant-performance analysis reqmres the proper analysis of limited, uncertain plant measurements to develop a model of plant operations for troubleshooting, design, and control. 

A variation for one vendor is shown in Figure 26. The design and control of the system takes into consideration the following parameters flow rate, water temperature, waste characteristics, chemical pretreatment options, solids loading, hydraulic loading, the air to solids ratio. Units are designed on the basis of peak flow rate expected. 

Huang, Y. L., and Fan, L. T. (1995). Intelligent process design and control for in-plant waste minimization. In Waste Minimization Through Process Design (A. P. Rossiter, eds.), pp. 165-180. McGraw Hill, New York. 

Tolerance The penalty for having an unbalanced wall is the reduction of tolerance control. Tolerance limits are usually at least doubled. Also, with certain plastics it is more difficult to process them, such as those with low melt strength. Although the balanced wall is the ideal, having it is not always possible. Recognize that the unbalanced wall can be extruded with proper die design and control of the extruder line from upstream to downstream equipment. 

Refining and applying chemical engineering principles to the design and control of the chemical reactors in which devices are fabricated. 

Emphasizing process design and control for enviroinnental protection and process safety. Microstructured Materials (Chapters 5 and 9)... 

Future computer aids will allow design and control engineers to examine many more alternatives much more thoroughly and thus produce better solutions to problems within the known technology. 

A second important need in the curriculum is for a far greater emphasis on design and control for process safety, waste minimization, and minimal adverse enviroiunental impact. These themes need to be woven into the curriculum wherever possible. The AIChE Center for Chemical Process Safety is attempting to provide curricular material in this area, but a larger effort than this project is needed. Several large chemical companies have significant expertise in this area. Closer interaction between academic researchers and educators and industry is required to disseminate this expertise. 

As chemical engineering research develops new design and control tools to deal with these factors, these tools should be integrated into the curriculum. Process safety research is generally more advanced in industry than it is in... 

Design and control have traditionally been treated separately for the following reasons ... 

The computational requirements of an integrated approach to design and control have been beyond the capability of available hardware and software. 

How does local stmcture depend on the starting materials and processing conditions by which the system or product was created How should the process be designed and controlled to achieve reliably the desired stmcturing ... 

Although there are a few exceptions, the prediction on the basis of the orbital mixing rule was not only well consistent with the observed selectivities but also can give a direction for designing and controlling tr-facial selectivity overwhelming steric hindrance. 

In the past three decades, industrial polymerization research and development aimed at controlling average polymer properties such as molecular weight averages, melt flow index and copolymer composition. These properties were modeled using either first principle models or empirical models represented by differential equations or statistical model equations. However, recent advances in polymerization chemistry, polymerization catalysis, polymer characterization techniques, and computational tools are making the molecular level design and control of polymer microstructure a reality. 

Chemical vapor deposition (CVD) of carbon from propane is the main reaction in the fabrication of the C/C composites [1,2] and the C-SiC functionally graded material [3,4,5]. The carbon deposition rate from propane is high compared with those from other aliphatic hydrocarbons [4]. Propane is rapidly decomposed in the gas phase and various hydrocarbons are formed independently of the film growth in the CVD reactor. The propane concentration distribution is determined by the gas-phase kinetics. The gas-phase reaction model, in addition to the film growth reaction model, is required for the numerical simulation of the CVD reactor for designing and controlling purposes. Therefore, a compact gas-phase reaction model is preferred. The authors proposed the procedure to reduce an elementary reaction model consisting of hundreds of reactions to a compact model objectively [6]. In this study, the procedure is applied to propane pyrolysis for carbon CVD and a compact gas-phase reaction model is built by the proposed procedure and the kinetic parameters are determined from the experimental results. 

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