Measurement in-line

Continuous in-line measurements and control of the mass material balance in the process, with automatic feedback to the reactants dosing devices (performed either by computerized system or by traditional flow control loops). 

To control the CCD, the anthors chose a closed-loop control strategy with in-line NIR used to measure the monomer concentrations. The closed-loop control strategy nses the NIR in-line measurement to provide close to real-time information abont the concentration of both reactants and prodncts in the reactor. One prerequisite of this control strategy is that the sampling rate be faster than the kinetics of the reaction. 

In-line measurements are frequently used to perform kinetic studies to follow chemical reactions or to visualize emerging physical and chemical properties like quantities of analytes, particle, or pore size. 

The efficiency of these steps can be conveniently monitored by continuous in-line measurement of the resistivity of the water (deionization results in increased resistivity, typically to levels of 1-10 MQ). If the resistivity of the deionized water falls below a value of approximately 1 MQ, automatic system shut-off, followed by regeneration of the anion and cation exchange beds (with NaOH and HCl respectively), is initiated. 

R. Weinekotter, L. Reh, Characterization of particulate mixtures by in-line measurements, Part. Part. Syst. Charact. 11 (1994) 284—290. 

Concentration profiting uses on- or in-line measurements of optical properties, typically not done for the whole volume, but along lines such as the channel cross-section (see e.g. [20]). Concentrations are accessible by photometric, electric or fluorescence measurements. Furthermore, vibrational analysis such as IR and Raman spectroscopy can be used for the same task [80,81]. Concentration profiling can also be achieved simply by gray-scale or comparable image analysis for quantitative data extraction from microscopy images of colored flows [20, 37, 68],... 

Measurement techniques, including process in-line measurements, at the molecular and micro-scale levels to verify theories and predictions. 

Development of fundamental kinetics for improved understanding of complex reaction systems is another frontier. More advanced catalyst characterization tools, including on-line and in-line measurements, need to be developed to provide better understanding of critical catalyst parameters. This should involve application of predictive chemistry capability to design better catalysts which carry out desired conversions in complex reaction systems. 

Figure. 10.8. Dependence of ultrasonic velocity on temperature In (A) Aipechfn under various experimental vacuum conditions and agitation. (B) Water, oil and aipechfn. (C) Aipechfn with variable oil contents as determined from In-line measurements. (Reproduced with permission of Elsevier, Ref. [80]).

Lieser KH Technische Hochschule Darmstadt, Germany In-line measurement of U, Pu, and Np in process currents using energy-dispersive X-ray fluorescence analysis. National Ministry for Research and Technology Bonn, Germany... 

In-line measurements of particle size distributions are essential in order to maximize production capacity and product quality. Ultrasonic attenuation is emerging as a technique, with capabilities beyond those of light scattering. In addition to the needs of industry for compact, robust instrumentation, this method is capable of operating at high concentrations, thus eliminating the need for an expensive dilution step, which may alter the very properties one wishes to measure [225,226]. 

Lecotrac LTU-25I Coupled to an external probe, this analyzer allows fast in-line measurement. The external probe is constructed of rugged, flexible steel and can be attached to a process line via a 3/8-inch NPT pipe-thread mounting hardware. The probe tip consists of a sapphire window embedded in a stainless steel sleeve using Teflon seals. 

It is very important to be able to measure the pressure in a vacuum system, particularly when carrying out a distillation. For low vacuum measurement a simple manometer, such as that shown in Fig. 8.3a, is commonly used and the pressure is taken by subtracting the heights of the mercury levels. Dial gauges are also useful for in-line measurements and they are particularly valuable when used with rotary evaporators. For high vacuum... 

An in-line measurement is performed in a process line an on-line measurement is performed in a bypass loop from the main process line and the food may be returned to the main process line after measurement is performed. A near-line measurement is performed on a sample taken from a process line which is often discarded after measurement. Because foods are complex materials (e.g., suspensions, emulsions, gels), stmctural changes may take place during sampling (e.g., flow through a valve) for on-line and near-line measurements (Roberts, 2003). Nevertheless, in principle, the previously described capillary flow, and rotational concentric cylinder, plate-cone, and mixer viscometers may be used for in-line, on-line, and near-line measurements. In this respect, Tamura et al. (1989) proposed a helical screw rheometer as an on-line viscometer. The empirical measurement methods described previously are used primarily in near-line measurements. 

Some, if not all, of the requirements of in-line measurement techniques are satisfied in tomographic techniques that provide spatially and temporally resolved data. The techniques utilize the inherent properties of the food material and include those based on magnetic, acoustic, optical, and electrical signals (Choi et al., 2002). These... 

Figure 3-24 A Schematic Diagram of In-Line Measurement of Flow Properties with an Ultrasonic Doppler Velocity Meter.

Dogan, N., McCarthy, M. J., and Powell, R. L. 2002. In-line measurement of theological parameters and modeling of apparent wall slip in diced tomato suspensions using ultrasonics. J. Food Scl 67(6) 2235-2240. 

For the processing of furfural in general, and for the control of furfural reactors in particular, it is desirable to have a continuous in-line measurement of the furfural concentration. For batchwise operation, this shows when the charge is exhausted, and for both batchwise and continuous operation it can show the response of the furfural concentration to the steam input, thus permitting an optimization of the furfural output. This is especially important for the ROSENLEW process, where an excess steam input blows out the acetic acid catalyst, so that there is a critical steam input beyond which the furfural output diminishes sharply. In addition, it is profitable to have a continuous record of the reactor operation, to pinpoint mistakes by the operators or other irregularities. 

A common practical approach to achieving growth while minimizing concern for seed dissolution is shown in curve B -F-C. The addition of antisolvent is stopped, and seed is added at point B, where the system is slightly supersaturated. As discussed in Chapter 2, in-line measurement by Fourier transform infrared (FTIR) or ultraviolet (U V) can be utilized to determine when the concentration reaches point B. Alternatively, the seed may be added in a sluiTy with the antisolvent starting before point B is reached, as discussed in Chapter 5 and below in Section 9.1.4. 

Measurement of chemical parameters is best accomplished with an in-line closed measurement cell (25). When the values of the indicator parameters are observed to vary less than +10% over three consecutive well-bore storage volumes, the well may be presumed to have been adequately flushed for representative sampling. When in-line measurement cells are not practical, standard pH and conductivity meters and thermometers are used. 

MCFARLANE, I. (1988) In-line measurement and closed loop control of the color of breakfast cereals. Cereal Foods World, 33 (12), 978-980. 

NIR is increasingly used in process and environmental analysis, the food industry, agriculture, the pharmaceutical industry and polymer analysis. In-line measurement with fiber optics and rapid multi-component quantification are the most important advantages of NIR spectroscopy. In comparison to mid-infrared, NIR analysis is much faster and more versatile. Most samples are analysed in one minute or less. Often chemometric methods must be applied to determine the parameter of interest... 

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