Process control monitoring

When data of a single type accumulate, new forms of statistical analysis become possible. In the following, conventional control and Cusum charts will be presented. In the authors opinion, newer developments in the form of tight (multiple) specifications and the proliferation of PCs have increased the value of control charts especially in the case of on-line in-process controlling, monitors depicting several stacked charts allow floor supervi-... 

Improved process control (monitoring and instrumentation) more automation... 

Acoustic chemometrics can be used for monitoring of both process state and product quality/quantity for better process control. Monitoring process states can provide early warnings which trigger the process operator to change relevant process parameters to prevent critical shutdown situations. 

In summary, the results from this and other studies (30, 31, 32) unambiguously demonstrate that simple solvent extraction of coal liquids does not yield chemically well-defined fractions. Consequently, detailed molecular analysis is a prerequisite for an in-depth analysis/prediction of the production and/or upgrading of coal liquids and for the correct evaluation of process effectiveness. In addition, implementation of routine process control/monitoring schemes employing fractions obtained from separation of products/reactants necessarily requires calibration by detailed molecular analysis. Finally, the separation method(s) should produce fractions possessing chemical significance. 

Process Control Monitors. Deposition kinetics were investigated by accurately measuring RF power, monomer pressure, and monomer flow. The actual RF power dissipated in the gas discharge was determined by taking the difference between the net power delivered to the gas discharge and the net power delivered to the system under vacuum. Pressure was measured to a precision of 1 millitorr with a capacitance manometer. Gas flow was reproduced to a precision of 0.1 SCCM with a Hastings Mass Flow Meter. 

Electrical evaluation. Electrical process-control monitors that are included at critical steps in the manufacturing as a means of evaluating the process steps are an important component of surface micromachining. The diffusion profiles and semiconductor junctions, as well as the quality of the oxides and contacts, can all be... 

The PCM (process control monitor) 5000 is an FTIR instrument from Analect/Applied Instrument Technologies that measures the physical and chemical properties of liquid, solid and gaseous in-process samples. The heart of the system is a rugged optical head coupled with a patented fibre optic system. The system is configured for continuous, unattended operation in harsh and hazardous environments. The PCM 5000 FTIR uses close-coupled sample cells (7000-450 cm ). The instrument is configured with a selfdiagnostic module to monitor the critical parameters of its own operation. 

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 40.17 Different parameters that are subjects of process control monitoring for SiGe. Reprinted from Maul, J.L., Chou, E-F., Lu, Y.H. (2004) Use of SIMS in SiGe process control. Applied Surface Science, 231-232,713-715. Copyright (2004), with permission from Elsevier. 

Process control. Chemical engineers will develop and implement better sensors for temperature, pressure, and chemical composition. Processes will be designed to integrate artificial intelligence for process control, monitoring, and safety. 

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