Control on-line

The process monitors and controllers typically also have the capabiUty for data logging, analysis, and display. This capabiUty has made on-line control of pilot plants, as well as commercial-scale processes, desirable. Pilot-plant appHcations for on-line control have been described (106), and the use of such systems for both monitoring and process diagnosis has been discussed (107). A number of commercially available process control programs that mn on microprocessors have been reviewed (108). Virtually all of them incorporate graphic display as an integral part of the interactive capabiUty of the program. 

The recent availability of low cost microprocessors has brought the possibility of on-line control of all elements of the spectrophotometer, plus on-line data reduction into the realm of practicality. 

Automatic zero shift compensation by previously setting the isopotential values of pHi(electrodes) or even pHi(overaii, may be especially attractive for on-line control of process streams. 

Hub, L., "On-Line Uberwachung von Exothermen Chemischen Prozessen mit dem OLIWA System" ("On-Line Control of Exothermic Processes by the OLIWA System"), Chem. Eng. Tech., 54,181 (1982). 

As for normal liquids, modeling of droplet processes of melts provides tremendous opportunities to improve the understanding of the fundamental phenomena and underlying physics in the processes. It also provides basic guidelines for optimization and on-line control of the processes. This section is devoted to a comprehensive review of process models, computational methods, and numerical modeling results of the droplet processes of melts. The emphasis of this section will be placed on the droplet processes in spray atomization for metal powder production, and spray forming for near-net shape materials synthesis and manufacturing. Details of these processes have been described in Ref. 3. 

The design and operation of industrial crystallizers is where developments in the laboratory are confirmed and their practical significance determined. In recent years, crystallization processes involving specialty chemicals and pharmaceuticals have increased. This has led increased interest in batch crystallization operation, optimization and desigrt At the same time, the advent of powerful computers and their routine avaUabilily has stimulated interest in the area of on-line control of crystallization process (both batch and continuous). Progress in batch crystallization is surrunarized in a number of recent papers and reviews 173-801. In this section I will discuss two areas which I think will have an impact in the next decade. 

The future of on-line control of crystallization should see the use of parameter estimation for estimation and correction of model parameters along with higher level nonlinear control schemes. The major chtdlenge continues to be realistic measurement of the necessary variables such as the CSD or its moments. 

High cell densities are not only a prerequisite for high productivity additionally an effective on-line control and modeling of the bioprocesses is necessary. For industrial applications, optical measurement methods are more attractive because they are non-invasive and more robust. The potential of the BioView sensor for on-line bioprocess monitoring and control was tested. For high-cell-density cultivation of Escherichia coli, maintaining aerobic conditions and removal of inhibitory by-products are essential. Acetic acid is known to be one of the critical metabolites. Information about changes in the cell metabolism and the time of important process operations is accessible on-line for optimization... 

Of course, the pharmaceutical industry is not the only sector in which process engineering is needed to enhance national security and homeland defense. Also, other areas of process engineering such as model development, optimization schemes, on-line control, catalyst development, new separation methods, biomass conversion, and models using multiple length scales are equally important to include in research efforts. 

Accelerator engineering. Full, reliable, and on-line control of the electron accelerator, beam delivery system, and multileaf collimator is the basis of the new conformal treatment and IMRT approaches. Patient-beam positioning became more accurate and fully reliable. 

In addition, out-of-limit conditions are flagged on the screen, trends can be indicated, and operating conditions reviewed to pinpoint problems early on and provide support for corrective measures. Data can even be imported from on-line controllers, which provides preventative rather than reactive control. 

In order to make the GMC control law available for an on-line control implementation, the integral term in Eq. (22) is approximated by numerical integration. This leads to the discrete-time form of the GMC algorithm as given in the following equation. 

H. Herrmann, H. J. Nettelnbrecker, and A. Dreiblatt, Quality Assurance and Improvement in On-line Controlled Compounding, SPE ANTEC Tech. Papers, 33, 157 (1987). 

Based on current knowledge of the process and its disturbance characteristics, one may know or choose a reasonable difference equation structure for the controller algorithm. Starting with some assumed initial parameter values in the controller equation, the controller can be implemented on the process as shown. The control algorithm is coupled with an on-line recursive estimation algorithm which receives information on the inputs and outputs at each sampling interval and uses this to recursively estimate the optimal controller parameters on-line and to update the controller accordingly. The idea is to use the data collected from the on-line control manipulations to tune the controller directly. 

Utilization of a Computer in On-Line Control and Optimization of a Batch Process for Microbial Conversion of Ethanol to Protein... 

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