On-line monitoring and control

The one feature that distinguishes this instrument group from the others is dedicated use. The instrument is generally mounted where it can measure the temperature of one specific target and remains there for the life of the instrument or the process. With few exceptions, these instruments operate on line power. The output signal of the instrument can be observed on a meter, used to operate a switch or relay, feed a simple or sophisticated process control loop, or be used in any combination of these functions. 

Because a customer selects an instrument in this group to perform a specific task, the manufacturer usually provides a shopping list to the customer so that all required features can be purchased. 

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ATR-IR spectroscopy can be used as a spy inside a reactor for on-line monitoring and control of a reaction. The emphasis in this kind of application of ATR spectroscopy is on the detection of reactants and products in the bulk fluid phase. Such applications benefit from the excellent time resolution of FTIR instruments compared to other analytical tools, such as chromatographs. The method can be used in investigations of kinetics of reactions in batch reactors instrumentation has been developed and even commercialized that allows measurements at elevated temperatures and pressures. 

The Fitzpatrick Co. roller compactor (Fig. 20) features two feed screws in series one horizontal and the second vertical. This system is designed to transfer powder bulk into a set of cantilevered rolls positioned in the horizontal mode one is fixed, the other floats. Operator interface allows for on-line monitoring and controlling feed screw speeds, roll pressure, and roll gap. Features such as on-line help and diagnostic functions, maintenance, and calibration screens are displayed. All functions are interfaced and adjustable by PLC for process control and report generating. The machines have vacuum deaeration and roll cooling capabilities. The sizing unit is separate from the compactor and is either a rotor bar or a hammer mill. 

These results suggest that further refinement of this important fermentation can be achieved through the use of on-line monitoring and control. 

On-line monitoring and control of chemical reactions helps to... 

This volume presents a cross section of recent advances in the development of novel chemical and biochemical sensors for on-line monitoring and control applications in the environmental, clinical, and bioprocess areas. These chapters illustrate how many of the key challenges for continuous monitoring are being addressed. The methods discussed include optical techniques ranging from near-infrared spectroscopy to lifetime-based phase fluorometry biosensors ranging from optical immu-nosensors to enzyme-electrodes as well as electrochemical, acoustic, and plasmon resonance techniques. 

Chapters 9-16 cover the application of optical and biosensor methods for on-line monitoring and control of bioprocesses. Topics include the use of expert systems for controlling flow injection analysis systems and hybrid process modeling for bioprocess control. 

On-Line Monitoring and Control of a Biological Denitrification Process for Drinking-Water Treatment... 

The decisions involved in retrofitting projects may be of the discrete type, the continuous type, or a combination of both. An example of a discrete decision is whether to add an on-line monitoring and control system to a waste water stream The decision is a sinple yes or no. An exanple of a continuous decision is to determine what size of heat recovery system should be added to an existing process heater to inprove fuel efficiency. This type of decision would involve sizing the optimum heat exchanger, where the variable of interest (heat-exchanger area) is continuous. 

Forman, L. W., Thomas, B. D., and F. S. Jacobson. 1991. On-line monitoring and control of fermentation processes by flow injection analysis. Anal. Chim. Acta 249 101-111. 

Since 1975 there has been a movement toward the in situ analysis of specific species in complex mixtures without initial application of separation science to simplify the problem. The possible applications of such chemically selective devices, particularly those designed to quantitatively monitor organic compounds, cover a wide range of situations, including on-line monitoring and control of... 

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