Process monitoring tools

Dne to their inherent simplicity, small size, efficiency and speed, the CE and CEC techniques are well suited for adoption as miniaturized process monitoring tools. Efforts have been made for such applications, conpled with continuous sampling from reaction mixtures. The CE lab on a chip has been shown to be a viable tool for real-time quantitation of a reacting system. 

Real-time process supervision is performed by means of a set of tools and methods, which ensure safe process operation in normal situation as well as in the presence of failures or undesired disturbances. Process supervision is conducted by integrating several tools, each specifically designed for a specific activity. These activities are fault detection, fault isolation, diagnosis (root cause analysis), fault quantification (determination of the severity of the fault), and the decision making to accommodate the fault. The presence of a fault is detected at the monitoring level, which determines whether the process is in normal operation or not. Other tools for fault isolation, diagnosis, etc., are executed when an abnormal process state is detected by the process monitoring tool. 

In Figure 2.6, the most important aspects for the implementation of the individual spectroscopies as process-monitoring tools are addressed. The very small, representative sample volume or thickness in Raman and MIR/ATR spectroscopy may certainly lead to problems if special care is not taken to avoid the formation of a stationary layer on the reactor window or on the ATR crystal. In this respect, NIR spectroscopy is the method of choice in view of the comparatively large sample volume/thickness involved in these measurements. The ability to separate the spectrometer from the point of sampling is certainly a great advantage for Raman and NIR spectroscopy. 

It should be noted that Figure 20.1 deals with chemical analysis - as does the remainder of this chapter. Physical measurements of, for example, the melt viscosity of a polymeric product are very common (at-line) process monitoring tools, but they are beyond the scope of the present chapter. 

Melt temperature and fill rates have been demonstrated to be very important process variables for microcellular injection molding. Recent work has studied the use of fast response thermocouples along with traditional pressure transducers to determine their effectiveness in providing practical process monitoring tools for the microcellular molding process [7]. Behind the ejector pin, pressure transducers and fast... 

Fig. 4. Examples of emission spectrometry as a diagnostic monitoring tool for plasma processing, (a) The removal of chlorine contamination from copper diode leads using a hydrogen—nitrogen plasma. Emissions are added together from several wavelengths, (b) The etching and eventual removal of a 50-p.m thick polyimide layer from an aluminum substrate, where (x ) and (° ) correspond to wavelengths (519.82 and 561.02 nm, respectively) for molecular CO2...

The information to be compiled about the chemicals, including process intermediates, needs to be comprehensive enough for an accurate assessment of the fire and explosion characteristics, reactivity hazards, the safety and health hazards to workers, and the corrosion and erosion effects on the process equipment and monitoring tools. Current material safety data sheet (MSDS) information can be used to help meet this requirement but must be supplemented with process chemistry information, including runaway reaction and over-pressure hazards, if applicable. 

HPLC as a purification technique and as a tool for process monitoring has become increasingly attractive and will find many new applications in the future. Low pressure LC, probe LC, and micro-LC are techniques important to the future of process chromatography. Specialized detectors and multidimensional chromatographic approaches are also of increasing use. Additional literature is available.22 33-36... 

In the area of process monitoring TLC has been used for the study of the thermal decomposition of zinc di-isopropyl dithiophosphate (antiwear additive in lubricating oils) [458]. TLC analysis has been reported as a quality control tool for analysis of dispersing agents (alkylsalicylates, thioalkylphenolates), AOs (dithiophosphates, dialkyldithiophosphates) and their intermediates in lubricating oil (UV detection,... 

Table II demonstrates how NPV would be calculated for a hypothetical LIMS, purchased as a package with negligible site preparation and with installation costs included in the purchase. It is to be acquired for a service laboratory primarily supporting R D activities but with some minimal process monitoring responsibilities. The IRR for this project could be found by trial and error determination of the yearly discount rate which results in a zero NPV. A succinct discussion of these financial management analysis tools can be found in two works by Weston and Brigham. The first (9) presents theoretical and detailed analytical expositions the second OO) is a more practical, applications oriented presentation.

While we recommend the application of control cell fines as reagent, assay, and EQA monitoring tools, it is important to emphasize that appropriate tissue controls are also continued to be used in parallel, as tissue is still considered the gold standard in laboratory assay control. For reliable results, it is also important that tissue or cell line controls are fixed and processed in the same manner as diagnostic material submitted for evaluation. 

A miniaturized MB spectrometer MIMOS II was developed for the robotic exploration of Mars, where it provided fundamental information about mineralogical composition and alteration processes, helped to classify rocks and soils, aided geologic mapping, was instrumental in assessing habitability of past and present environments, and identified potential construction resources for future human explorers. The applicability of the instrument as a process monitor for oxygen production and prospecting tool for lunar ISRU has been demonstrated. The characterization of air pollution sources and the study of mixed-valence materials as a function of depth in soil are examples of terrestrial in situ applications. MIMOS lla with additional XRF capability will open up new applications. 

Mass spectrometry is also extremely useful as a process monitor. Less sophisticated residual gas analyzers (RGA) operating on the principles of mass spectrometry are available for these purposes and for end point detection. For the etching of Si 128-130), poly-Si 130), silicon nitride 130), and Si02 (729), SiF (m/e=85) has been shown to be effective for end-point detection. In addition, (m/e=14) is useful for nitride 129,130) in leak tight systems, while O (m/e =16), CO (m/e =44) and Si" " (m/e=29) are useful for oxide (757). Because of the general nature of mass spectrometry as a diagnostic tool, it should be applicable to etching studies of metals and other semiconductor materials. 

As will become obvious in this chapter, UV-vis spectroscopy is a valuable tool for process analytics in a wide range of industrial applications, be it in production-related R D or in actual process monitoring and control. An overview of reviews for the various fields is given in Table 4.1. 

The acoustic chemometric approach can also be used to monitor industrial production processes involving particles and powders and to provide a complementary tool for process operators for more efficient process control, or to monitor particle movement in a fluidized bed [7] for example. Below we illustrate the application potential by focusing on two applications process monitoring of a granulation process and monitoring of ammonia concentration. 

K. Pollanen, A. Hakkinen, S-P. Reinikinen, J. Rantanen, M. Kaijalainen, M. Louhi-Kultanen and L. Nystrom, IR spectroscopy together with multivariate data analysis as a process analytical tool for in-hne monitoring of crystallization process and solid-state analysis of crystalline product, J. Pharm. Biomed. Anal., 38, 275-284 (2005). 

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