Online monitoring, industrial

In membrane extraction, the treated solution and the extractant/solvent are separated from each other by means of a solid or liquid membrane. The technique is applied primarily in three areas wastewater treatment (e.g., removal of pollutants or recovery of trace components), biotechnology (e.g., removal of products from fermentation broths or separation of enantiomers), and analytical chemistry (e.g., online monitoring of pollutant concentrations in wastewater). Figure 18a shows schematically an industrial hollow fiber-based pertraction unit for water treatment, according to the TNO technology (263). The unit can be integrated with a him evaporator to enable the release of pollutants in pure form (Figure 18b). 

Keywords advanced control monitoring, industrial automation, refining industry, online optimization... 

Wortberg, M., Ziemer, W., Kugel, M. et al. (2006) Monitoring industrial wastewater by online GC-MS with direct aqueous injection. Anal Bioanal Chem, 384 (5), 1113-1122. 

The various oxygen sensors have not only gained wider use in laboratory and in-field analysis, they have also become popular for online monitoring of industrial processes. 

Spectroscopy is the measurement of light intensity versus frequency. Remote high-temperature measurement systems often use some form of spectroscopy to measure temperatures. In the laboratory, high-temperature salt properties (purity, composition, etc.) can be measured by spectroscopy. This is a standard technique used in the chemical industry for online monitoring of the chemical composition of flowing streams in chemical plants. Properties that can be measured include the following. 

In Figure 7.53 a flow-injection interface for fluorometric monitoring of focused microwave-assisted Soxhlet extraction is represented [195]. This assembly allows real-time online monitoring of the PAHs extracted from solid samples in each Soxhlet cycle and provides qualitative and semi-quantitative information from natural and spiked samples. The method has been applied to a certified reference material (CRM 524, BCR, industrial soil/organics) for quality assurance/validation. The proposed technique is as efficient as conventional Soxhlet to extract PAHs from soils but with a drastic reduction of both extraction time and organic solvent disposal. 

Online monitoring and control of the biological denitrification process in a cell recyle membrane reactor has been developed and implemented at laboratory scale. The system has been tested with a real groundwater contaminated with nitrate. The results presented in this study show that the C7N ratio is the key parameter to guarantee an efficient denitrification process. A simple feedforward control strategy that adjusts the feed rate of the carbon source to maintain an inlet C/N ratio value of 1.39 is effective at reducing both nitrate and nitrite concentrations in the treated water below the maximum admissible values. Moreover, this control strategy based on the C/N ratio is easy to implement in a water treatment plant and does not increase the complexity of its operation at industrial scale. 

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 ... 

The possible tools today to make this come true are cleaning the membrane and running the process at constant flux and, in order to avoid fouling, running at a subcritical flux [4]. To find the best long-term conditions some online monitoring is needed. It has been noticed that in many discussions with industry one of the most important items on their wish list is to monitor the membrane process and characterize the membrane, possibly on-/inline. 

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... 

Overview of Current Industrial Online Monitoring Technologies... 

Several online monitoring methods for polymerization have been reviewed [63, 64]. While some of these methods are still in development or suited for laboratory use, many monitoring techniques, in particular spectroscopic techniques, have found their way into industrial processes. There are several reaction features that could be addressed through improved online monitoring techniques in the production of water-soluble polymers. These techniques are used to... 

A spectrum of synthetic water-soluble polymers is available and utilized daily in areas such as the production of energy, clean water, and industrial and personal care products that enhance our quality of life. It is hard to imagine what our world would be like without than. Advances continue to be made in the areas of new polyma design, production, and in the instrumentation and methods utilized for monitoring polymerizations. There is unlimited opportunity for researchers in academia and industry alike to develop and utilize cost-effective monitoring tools in water-soluble polyma production. Increased use of online monitoring tools at the commercial-scale will allow for improved production efficiency, reduced product variability, and the accommodation and tighter control of more complex processes. 

Online monitoring of viscosity is currently used in industry. Despite the fact that useful rheological characterization of materials requires a wide range of shear rate measurements. 

These may include, for example, a framework to analyze the flow and transport behavior in relation to tissue and nutrient (solute) properties and the reaction rates in a changing tissue environment. This can then help to interpret the obtained results and direct further experimental work in an appropriate manner. It should also be noted that due to the nature of the HFMB system used for growing tissue (i.e., sterile operating conditions and the relatively small dimension compared to industrial processes), it does not allow precise online monitoring of most variables of interest. Instead, a mathematical model can be used to determine these variables. 

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. 

Until progress can be made in development of practical and affordable online contaminant monitoring and surveillance systems, most chemical industrial facilities must use other approaches to contaminant monitoring and surveillance. This includes monitoring data of physical and chemical contamination surrogates, pressure change abnormalities, free and total chlorine residual, temperature, dissolved oxygen, and conductivity. 

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