Monitoring of process

Many plants do not consider machine or systems efficiency as part of the maintenance responsibility. However, machinery that is not operating within acceptable efficiency parameters severely limits the productivity of many plants. Therefore a comprehensive predictive maintenance program should include routine monitoring of process parameters. 

Process inefficiencies, like the example, are often the most serious limiting factor in a plant. Their negative impact on plant productivity and profitability is often greater than the total cost of the maintenance operation. However, without regular monitoring of process parameters, many plants do not recognize this unfortunate fact. 

Neufeld, P. and Queenan, E. D., Frequency Dependence of Polarisation Resistance Measured with Square Wave Alternating Potential , Br. Corros. J., 5, 72-75, March (1970) Fontana, M. G., Corrosion Engineering, 3rd edn., McGraw-Hill, pp 194-8 (1986) Dawson, J. L., Callow, L. M., Hlady, K. and Richardson, J. A., Corrosion Rate Determination By Electrochemical Impedance Measurement , Conf. On-Line Surveillance and Monitoring of Process Plant, London, Society of Chemical Industry (1977)... 

Seminar, London, March 1987, Global Corrosion Consultants, Telford, UK On-Line Surveillance and Monitoring of Process Plant , Proc. Symposium, London, September 1977, Society of Chemical Industry, London Inspection of Chemical Plant, (Pilborough), Leonard Hill Books, London (1971)... 

Flow injection analysis is a fast-developing technique with many potentialities. Particular attractions are the relative simplicity of operation and automation, together with sample throughputs which may exceed 100 per hour. Thus routine monitoring of process streams and pollution control are obvious areas for application. 

The temperature below which fouling can be prevented varies with each process, compressor, and application. Monitoring of process conditions is necessary to establish a threshold temperature in each case. In some cases, fouling cannot be prevented with an existing compressor. It may be necessary to modify the aerodynamic design and/or add cooling. 

One approach for using DOE on more complex processes is to do the majority of the process development on smaller, representative sections of material, such as test panels, rather than on full-scale parts, and then to scale up with a more limited experimental matrix. There is no guarantee that experience on small-scale test panels will directly translate to large parts because dimensions and thickness of the part are important variables in their own right. Another way to save on costs is to start with a satisfactory process and to continue, via careful monitoring of process variations and results, to extend the range of experience. This method is variously called statistical process control or statistical quality control. 

Process verification, by the coordination of routine dosimetry and the monitoring of process parameters... 

Quality control experts, such as Shewhart and Deming, decades ago called attention to the importance of minimizing measurement errors in achieving quality control in manufacturing and the importance of statistical monitoring of process data. But tying these concepts to equipment calibration in a statistically rigorous way did not occur until the second half of the twentieth century. 

PAT is an automated quality-assurance process originally developed in the petrochemical industries. It is defined by three general principles continuous, cybernetic, and potentially remote monitoring of processes. 

Combined spectroscopic monitoring of processes is expected to be of value during industrial operations to keep the catalysts in their best working state and to regenerate them at appropriate stages of deactivation. 

An effective control system provides detection and rejection of unanticipated disturbances which might cause deterioration of the product, continuous monitoring of process state and product quality, and improved and reproducibility (Mattiason and Hakanson,1 p. 221), all of which lead to a more efficient, productive process system. 

The demonstrations cited above illustrate how AW devices can be used to probe intrinsic and extrinsic fluid properties. This capability can be useful for providing in-situ probes of critical solution properties such as viscosity, density, and conductivity. This capability should prove useful in the monitoring of process streams or critical fluids (e.g., automotive oil condition monitoring [41]). 

Fig. 9.11 Particle Measuring Systems Liquid Volumetric Probe, designed for continuous monitoring of process waters, product liquids and semiconductor chemicals.

The use of instruments that log and archive data facilitates remote monitoring of process performance and can improve plant troubleshooting and optimization and provide high-level data for enterprise-wide supply chain management. 

Husain, S. and Nageswara R. R. High performance liquid chromatographic monitoring of process impurities in bulk drugs and formulations. Process Control Qual. 10 41-57, 1997. 

Monitoring of process execution. The contractor is informed continuously about the state of execution of the subprocess delegated to the subcontractor. In this way, the contractor may monitor execution and control whether set deadlines are met. 

JV Kresta, JF MacGregor, and TE Marlin. Multivariate statistical monitoring of process operating performance. Canadian J. Chem. Engg., 69 35-47, 1991. 

A Negiz and A Cinar. A parametric approach to statistical monitoring of processes with autocorrelated observations. In AIChE Annual Meeting, Miami, FL, 1995. 

SJ Zhao, J Zhang, and YM Xu. Monitoring of processes with multiple operating modes through multiple principal components analysis models. Ind. Engg. Chem. Research, 43 7025-7035, 2004. 

The industrial application of the sensor technologies described earlier (Chapter 3) is the basis for real-time monitoring of processing of reactive polymers. The critical parameters to be monitored may be seen from an examination of the chemorheological process-control equations described in the previous sections ... 

The cyclic voltammetric experiment is an interfacial electrochemical technique (i.e. monitoring of processes occurring near the electrode surface) that involves measurement of current flow as a function of applied potential. The potential is swept from a resting potential, (measured against a reference such as the saturated calomel electrode or the potential of the Fe(II)/Fe(III) couple in ferrocene), at a constant rate (usually... 

Process validation, in-process controls and monitoring of process parameters and environment assume particular importance in cases where it is necessary to take the decision to release or reject a batch or a product before all tests are completed. 

Process validation, in-process controls and monitoring of process parameters and environment assume particular... 

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