Industrial Processes
Process monitoring and control is one of the chief fields of interest in modern analytical chemistry. In spite of the advantage to be gained by using FIA for online process monitoring and control, the number of applications proposed so far is very low, given the technique's potential. Until the mid-1980s hardly any reference could be found to the industrial application of FIA for real process monitoring. This was at least partly due to problems associated with the design and construction of adequate sampling and sample conditioning systems. The use of membranes for dialysis, gas diffusion, and other separative and preconcentration techniques merits more attention for online process analysis. Several novel process FIA instruments have come into the market in the past few years, and other companies working in this area expected to introduce systems in the near future. In some cases the interested companies have built their own FIA instruments devoted to process monitoring. Many FIA process control applications have not yet been published, to avoid divulging proprietary data. The FIA analyzers available for online process monitoring are sturdy and have been field tested, with proven design of components.
Physical redundancy vs analytical redundancy
Process monitoring is essentially based on the exploitation of redundant sources of information. There are two types of redundancy in the process: physical redundancy and analytical redundancy (Fig. 1.4A–B). The essence of hardware or physical redundancy, which is a traditional method in process monitoring, consists of measuring a particular process variable using several sensors (e.g., two or more sensors). To detect and isolate simple faults, the number of sensors to use should be doubled. Specifically, under normal conditions, one sensor is sufficient to monitor a particular variable, but adding at least two extra sensors is generally needed to guarantee reliable measurements and monitoring under faulty conditions. Typically, fault detection and isolation are achieved by a majority vote between all the redundant sensors. This strategy has been widely used in the industry because of its reliability and simplicity of implementation. In practice, the main disadvantage of hardware redundancy is the additional cost of equipment and maintenance, as well as the space needed to install the equipment that increases complexity considerably in the already very complex systems.
Industrial Processes
Process monitoring and control is one of the chief fields of interest in modern analytical chemistry. In spite of the advantage to be gained by using FIA for online process monitoring and control, the number of applications proposed so far is very low, given the technique's potential. Until the mid-1980s hardly any reference could be found to the industrial application of FIA for real process monitoring. This was at least partly due to problems associated with the design and construction of adequate sampling and sample conditioning systems. The use of membranes for dialysis, gas diffusion, and other separative and preconcentration techniques merits more attention for online process analysis. Several novel process FIA instruments have come into the market in the past few years, and other companies working in this area expected to introduce systems in the near future. In some cases the interested companies have built their own FIA instruments devoted to process monitoring. Many FIA process control applications have not yet been published, to avoid divulging proprietary data. The FIA analyzers available for online process monitoring are sturdy and have been field tested, with proven design of components.
