Online monitoring, industrial applications

In comparison to previous summaries of industrial applications of IMS, the discussion here illustrated a wide breadth of applications in the past decade. In addition, significant depth is seen, with methods applied in actual online process control, monitoring of stacks, ambient air monitoring, and measurements with authentic samples, not only standard laboratory solutions. The versatility and capability of IMS are now proven in the range of chanicals monitored, the complex matrices for some samples, and the demands on instruments. The advantages of IMS include reliability and quantitative performance, speed of response, durability in accepting sample with little preparation, and low detection limits. When samples are complex enough to create complications from competitive reactions in the ion source, remedies have been found with fast GC or temperature-ramped desorption of sorbent traps. 

Figure 2 illustrates several cells with contacting electrodes. Cell designs are available for a variety of research, routine, and industrial applications. Routine measurements use conductivity cells of suitable size that may be directly immersed in beakers, flasks, etc. Water analysis and online industrial measurements may require immersion or flow-through cells for continuous monitoring. Precision measurements... 

A Joint Industry Project was launched in 2005 with support from six industrial sponsors. A number of techniques were tested and finally a technique was chosen for further investigation and industrial application. The laboratory results under simulated pipeline conditions are very promising. The technique which is based on online downstream monitoring is able to detect early signs of hydrate formation. The information can be transferred to the control room or used as feedback to the inhibition facilities for planning remedial actions. In collaboration with the project sponsors a field evaluation is being planned. 

Process GC has developed into one of the most widely used online monitoring techniques in the petrochemical industry. Its popularity is due to the abiUty of GC to quickly analyze hydrocarbon streams for process control. As is the case for aU on-line analyzers, process chromatographs are capable of safe, continuous, unattended, in-plant operation. Because of the need for fast and specific analyses to provide feedback for process control, these chromatographs are usually designed for each specific application. The ideal process gas chromatograph (PGC) has the following characteristics ... 

While H NMR and NMR spectroscopy were proved to be useful tools for the online monitoring of polymerization reactions, their limitations, such as the intrinsic low sensitivity of the measurements and the time-consuming signal averaging, the use of expensive deuterated solvents ( H NMR) that limits their application in industrial processes, led to the development of the so-called hyperpolarization methods which overcome the lack of sensitivity of NMR... 

When an ultra-microelectrode is used as an electroanalytical tool, the diffusion-limited current density is not affected by the rate of flow, which typically creates a diffusion layer thickness of the order of50-100 pm. This can be a great asset for online monitoring in industrial applications, where the flow rate may fluctuate and would otherwise have to be measured and corrected for. 

The measurement of analyte concentration is a critical part of successful bioreactor monitoring. Although strategies exist for measuring the majority of relevant analytes, industrial online bioreactor control is carried out primarily by measurement and control of temperature, pH, d02, CO2, and, in some cases, cell density. This is because the available technology cannot be easily and inexpensively adapted to measure the analyte in an aseptic manner and measurement is not often achieved in real time so that online control is challenging. Biosensors for a variety of applications for... 

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On-line mass spectrometry has been implemented in pharmaceutical processes for monitoring raw materials andproducts ". In this particular application, dilution of the samples is carried out by a membrane interface coupled directly to the atmospheric pressure chemical ionisation source of a quadrupole mass spectrometer for real-time analysis. Continuous online MS has also been used for monitoring fermentation processes in the brewing industry. ... 

Infrared spectroscopy is widely used in industry. The applications range from quality control and quality assurance of raw materials to customer complaints (troubleshooting) to quantitative analysis and online process monitoring and control. Most of the instrumentation is based on a Fourier transform infrared (FTIR) spectrometer but specialist applications use instruments as diverse as a nondispersive infrared detector through to mid-infrared diode lasers. 

The use of analytical instrumentation for continuous online measurement of industrial process streams for real-time information gained popularity in the late 1950s and early 1960s. This information has met various demands, the most notable of which include process control, safety, waste reduction, environmental emission monitoring and control, and product quality assurance. With the application of computers and electronics to analyzer technology in recent decades, online analyzers have become even more sophisticated and widely used. In many instances, the application of online analysis has become a necessity for survival in the face of the economic pressures of globalization in chemical manufacturing. 

NIR-Raman has found applications in the pharmaceutical industry. McCreery and colleagues reported the use of the technique for identification of pharmaceuticals inside amber vials. Even with the signal attenuation through the glass, adequate spectra were obtained for determination of vial content with 1-60 s integration times. Using a library of spectra, identification of the pharmaceuticals in the vials was performed and identification was found to display accuracy between 88% and 96%. This work demonstrated the potential of NIR-Raman for online process monitoring. 

Spectrophotometry in the ultraviolet (UV) range has repeatedly proven to be a fast, inexpensive and reliable method for the monitoring of many compounds in urban and industrial wastewaters (Narayana and Sunil 2009 Pinheiro et al. 2004). Through the application of spectral analysis, quantitative and qualitative wastewater parameters can be estimated on direct samples in just a few minutes, using portable or online field instrumentation. Perez (2001) has successfully applied UV spectral deconvolution on wastewater monitoring in a chemical industry, for the estimation of aniline derivative concentrations. In the case of textile effluents, the use of the UV range of the spectra (200-350 nm) for aromatic amine determination is particularly useful to avoid interference by visible colour of dyes. The characteristic... 

Considering the need for them in the food industry, reliable methods for the determination of acetic acid and acetate, mainly for continuous monitoring, such as online methods, are highly desirable. In this context, flow injection analysis (FIA) has been used extensively for various applications because this technique offers a number of important benefits, including reduced disposal costs and high sample throughput. 

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