Advance process control

Economic Incentives for Automation Projects Industrial applications of advanced process control strategies such as MFC are... 

In the pressure balance section, the significance of the pressure balance in debottlenecking the unit is discussed. Finally, fundamentals of both basic and advanced process controls are presented. 

To maximize the unit s profit, one must operate the unit simultaneously against as many constraints as possible. Examples of these constraints are limits on the air blower, the wet gas compresst>r. reactor/regenerator temperatures, slide valve differentials, etc. The conventional regulatory controllers work only one loop at a time and they do not talk to one another. A skilled operator can push the unit against more than one constraint at a time, but the constraints change often. To operate closer to multiple constraints, a number of refiners have installed an advanced process control (APC) package either within their DCS or in a host computer. 

A properly configured advanced process control (APC) system could allow for on-line, continuous optimal unit operation and push the FCC operations to multiple constraints simultaneously. 

Advance Process Control (APC) is a mechanism which manipulates regulatory controls toward more optimum unit operation. 

W.H. Ray. Advanced process control. McGraw-Hill, New York, 1981. 

J. C. Edwards and P. J. Giammatteo, Detailed hydrocarbon analysis of naphtha by on-line NMR integration of real-time NMR Feed analysis with advanced process control and optimization, Presented at Eastern Analytical Symposium, Somerset, NJ, November 18-21, 2002. 

G. Dishon, D. Eylon, M. Finarov, A. Shulman, Dielectric CMP Advanced Process Control Based on Integrated Thickness Monitoring, Third International CMP for ULSI Multilevel Interconnection Conference, Santa Clara, CA, pp. 267-274, Feb. 19-20, 1998. 

L. Kane, ed., Advanced Process Control Handbook, Hydrocarbon Process., Sept. 1991. 

Economic Incentives for Automation Projects Industrial applications of advanced process control strategies such as MPC are motivated by the need for improvements regarding safety, product quality, environmental standards, and economic operation of the process. One view of the economics incentives for advanced automation techniques is illustrated in Fig. 8-41. Distributed control systems (DCS) are widely used for data acquisition and conventional singleloop (PID) control. The addition of advanced regulatory control systems such as selective controls, gain scheduling, and time-delay compensation can provide benefits for a modest incremental cost. But... 

Mechanical pulping has higher yields but lower-strength pulps when compared to full chemical pulps. Improvements are constantly being made, and considerable gains have been made in adapting different types of wood and different forms of wood (sawdust versus chips) to mechanical pulping via advanced process control techniques. 

The advanced process control strategies that are most applicable to the optimization of the distillation process are usually based on white-box modeling, where the theoretical dynamic models are derived on the basis of the mass, energy, and momentum balances of this well-understood process. Although the optimization techniques described here can improve productivity and profitability by 25%, this goal will only be achieved if the distillation process is treated as a single and integrated unit operation and the variables, such as flows, levels, pressures, etc., become only constraints, and the controlled and optimized variables are productivity and profitability. 

DOW in Midland, USA, performed metallocene-catalyzed polymerization of ethylene using a homebuilt tube reactor setup with advanced microflow tailored plant peripherals for heating, temperature monitoring, pressure control and dosing via smart valves and injectors. Screening of process conditions was a driver [19]. Also, flexibility with regard to temperature and pressure at low sample consumption was an issue. Quality of the information is another motivation due to the advanced process control and sensing. 

Peters and Timmerhaus Plant Design and Economics for Chemical Engineers Probstein and Hicks Synthetic Fuels Ray Advanced Process Control... 

FIGURE 3.5 Schematic illustration of the evolution of CMP tools from stand-alone, dry-in/dry-out to those with advanced process control (APC). 

Manens et al. [27] reported that charge-based end-point detection coupled with advanced process control (APC) can be used to adjust the amount of copper removed and compensate for the large variations in incoming Cu thickness. Figure 11.13 shows wafers with various incoming Cu thicknesses ranging from 3500 A to more than 6000 A, which simulates, in an extreme fashion, the variations that can be observed from wafer-to-wafer and lot-to-lot... 

Manens A, Miller P, Kollata E, Duboust A. Advanced process control extends ECMP process consistency. Solid State Technol Feb 2006. 

WTW and RTR control of thickness are improved by the use of end-point detection systems and advanced process control. End-point detection, whether mechanical or optical, monitor the state of the wafer surface (film thickness, reflectivity, etc.) or of the entire polishing system (friction, slurry by products, etc.) in an attempt to predict when the desired amount of material has been removed (i.e., the end of process). End-point detection is most successful in processes where a change in the films on the wafer surface leads to an abrupt change in the optical or mechanical properties of the wafer surface. For example, copper CMP end point is easy to detect by optical means due to the large difference in reflectivity of the copper film compared to the barrier films. In contrast, end-point detection for small amounts of ILD removal is difficult due to the lack of change in the wafer surface or the wafer-pad interface. 

Birchfleld, G. S., Trends in optimization and advanced process control in the refinery industry. Chemical Process Control V, Tahoe City, CA (1996). 

Advanced Process Control Handbook 2, Hydrocarbon Processing, March (1987). 

New tools have been recently developed allowing a thorough analysis of each application in terms of statistical distribution of active variables and of process variability. The last Solomon APC Study has evidenced the fact that the company has a good position among the leading oil companies with respect of advanced process control and automation performance in general. 

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