Continuous process control

A recent trend in particle analysis has been the introduction of personal computer-based automation (3). Sophisticated software packages can be used to automate and speed up the analysis. In some cases these computers can even carry out continuous process control (qv) (see Computer technology). The latest machines also allow the measurements of smaller particles and can detect a wider range of sizes. Machines based on light-scattering principles are being more widely accepted by the industry because of speed. An average analysis takes from 1—2 min, whereas those based on sedimentation principles require from 10—120 min. 

Development of automated batch process control systems has lagged behind that of continuous process control. Flexible factory scale commercial systems have only begun to appear in the last five years (1-4). Increases in the performance/price ratio of small computers are now making automation of laboratory scale batch processes more practical. 

Contaminated soil is excavated and stockpiled prior to treatment. Because the composition of the stockpiled soil is not monitored continuously, process control problems can occur if moisture and hydrocarbon contents vary over extreme ranges. Clay soils, to which hydrocarbons tend to be more tightly adsorbed, are typically more difficult to treat than sandy soils. 

A new program at FDA called process analytical technology (PAT) allows the use of continuous process control systems that measure and assess quality during the manufacturing process rather than between batches. The framework specifies the development of manufacturing processes that can consistently ensure a predefined quality at the end of the manufacturing run. Such procedures would be consistent with the basic tenet for quality by design inherent in currently available commercial control systems. 

An important feature of the distributed control system chosen is that the PCMs can communicate over a microwave link, thus allowing the well pad manifold modules to be included in the GC control system the hardwire data highway is limited to a distance of 5000 ft. (1524m) from the Host. The well chokes and manifold controls will remain on the SCAOA system, but the well pad will require continuous process control of the test separator, water injection flow control, and artificial lift gas flow control. 

Data collected for each process phase may also be evaluated statistically to evaluate objectively whether a process change was better or worse than the preceding one. For example, through analysis of variance, it would be possible to determine whether each process phase had demonstrated continued process control or clear improvement. The revalidation approach would thus allow the QA (or production technical services) group to proactively manage its responsi-... 

Faix O, Patt R, Beinhoff O (1987) Grundlagen und Anwendung von FTIR-Spektroskopie bei der Herstellung und Analyse von Zellstoffen Papier 41(12) 657-667 Faix O, Schubert HL, Patt R (1989) Continuous process control of pulping by FTIR spectra scopy, In Proc 5th Int Symp Wood Pulp Chem, Raleigh NC, 1-8 Tappi Press, Atlanta, GA... 

The pyrolysis of mixed waste thermoplastics in a pilot plant of 360 ton/year at the Korea Institute of Energy Research (KIER), as shown in Figure 5.6, has an oil yield of about 82% for continuous process control over two days. The distribution of oil product is 27% gasoline product and 73% heavy oil product. Also the yield, of gas product is 10-15% and consists of about 18.1% Ci, 15.2% C2, 30.3% C3, 21.9% C4 and 14.3% C5 components. Similar results were obtained by other researchers, as shown in Table 5.1. 

Smith, C. A., Automated Continuous Process Control, Wiley, New York, 2002. 

Continuous-process control instruments may make measurements directly in a flowing stream or a batch process reactor such as a fermentor. This generally precludes any analytical operation on the sample, and direct sensing devices such as electrodes must be used. If a sample dilution, temperature control, or reagent addition is required, or measurements are made with nonprobe-type instruments, then a small fraction of the stream is diverted into a test stream where reagents may be mixed continuously and automatically with the sample, and the test measurement is made. The sample may be passed through a filter prior to measurement. 

For smaller production quantities (mle of thumb 10 000 t/a) and/or frequent product changes, it has advantages over the tubular reactor. Very long residence times can readily be achieved, and reaction conditions such as temperature, pH value, and catalyst concentration can be changed and optimized during the reaction time. In batch mode, product quality is subject to certain variations, and hence continuous process control is necessary. 

Jacob, M., Rumpler, K., and Waskow, M. (2007). Fluidized bed apparatus for batch-by-batch or continuous process control and method for operating a fluidized bed apparatus. US Patent No 7,241,425 to Glatt Ingenieurtechnik GmbH, Weimar, Germany. 

Filament winding continuous process, control of fibre orientation, automation Expensive tooling, slow production rate, shape restriction Epoxy, polyester... 

Continuous process control that produces products within narrow specifications, with low color, and with minimal formation of impurities such as 1,4-dioxane in alcohol ether sulfates and sultones in AOS... 

Solvents are sometimes recovered in a reusable and recyclable form. Condensation is a very safe system and presents little or no fire hazard. It is an excellent system for continuous process control and has a fairly low operating and maintenance cost. Systems are available for airflows of less than 28 mVmin (708 cu.ft./min), which is well within the range needed for tape casting and drying. 

Smith, Garlos A. Automated Continuous Process Control. New York John Wiley Sons, 2002. A comprehensive discussion of process control systems in chemical engineering applications. 

Seborg, D.E., Edgar, T.E. and Mellichamp, D.A. Process Dynamics and Control, Wiley, New York, 1989. Smith, C.A. Automated Continuous Process Control, Wiley, New York, 2002. 

From this description, drying is not a continuous process controlled by one varying transport mechanism but that of several different mechanisms. The changing water distributions and operable transport mechanisms develop significantly different stresses. An efficient process would be one that maximizes the drying rate as the body transitions from state-to-state such that the stress on the body is not sufficient for fracture. In order to... 

FTI Mini and Mv Modular, compact (3 lbs) units featuring uncooled 160 x 120 element microbolometric FPA detectors, 7-14 pm for continuous process control and plant monitoring extensive diagnostic software. 

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