Improve Process Control

J. W. Carson and T. A. Royal, "In-Bin Blending Improves Process Control," Powder Handl Proc. (Sept. 1992). 

The LIMS software is essentially a database for tracking, reporting, and archiving lab data as well as scheduling and guiding lab activities. Graphical and statistical treatment of data for improved process control (qv) as well as preparation of certificates of analysis (COA) for the customer are some of the other features of a comprehensive LIMS package (30). 

Some tvpical examples of where the dvnarnics of the positioner are siifficientlv fast to improve process control are the following ... 

Valve Application Technology Functional requirements and the properties of the controlled fluid determine which valve and actuator types are best for a specific apphcation. If demands are modest and no unique valve features are required, the valve-design style selection may be determined solely by cost. If so, general-purpose globe or angle valves provide exceptional value, especially in sizes less than 3-inch NFS and hence are very popular. Beyond type selection, there are many other valve specifications that must be determined properly in order to ultimately yield-improved process control. 

Just as in offices, energy efficiency improvements in manufacturing can generate increases in overall productivity far in excess of the gains in output per unit energy. This occurs in two principal ways improved process control and systemic process redesign. 

Identify opportunities for improvements in material and water transfer and handling Identify opportunities for improved process control Identify opportunities for improved cleaning procedures... 

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

I have discussed some of the history of PAC, and some early approaches to its implementation in the petrochemical industry. So, what does it take to Do Process Analysis It takes freedom to try new things with an eye on how it can improve process control in order to make the plant more economical. The dollars drive the technology. Someone, preferably a group, needs to have the freedom to fail because not everything is going to work. This freedom means one tries various approaches looking for the best, most viable solution. Sometimes that solution is the one with which the plant is most... 

In this section, possible applications of the theory presented in the previous section are highlighted. It was shown that the equilibrium theory and nonlinear waves provide a simple means for understanding the dynamic behavior of many integrated processes. It thereby often directly guides the way to improved process operation and improved process control. Several examples will be discussed subsequently. 

The electric furnace melting of steel scrap rather than cupola melting is a trend that will probably continue resulting in increasing need for recarburisers. And as the ductile iron segment of the foundry industry grows, so will the demand for consistent materials that allow improved process control. 

Cassens (1997) has reported a dramatic decline in the residual nitrite levels in cured meat products in the United States. The current residual nitrite content of cured meat products is about 10 ppm. In 1975 an average residual nitrite content in cured meats was reported as 52.5 ppm. This reduction of nitrite levels by about 80 percent has been attributed to lower ingoing nitrite, increased use of ascorbates, improved process control, and altered formulations. 

In addition to discussing phase separators, it is also appropriate to eonsider the apphcation of accumulators in processes. Accumulators or surge vessels are necessary to reduce fluctuations in flow rate, pressure and composition and thereby improve process control. Although accumulators are not phase separators, they are discussed here because they are sometimes contained in the same vessel as a phase separator. For example, in a gas-liquid separator, the volume of liquid at the bottom of the separator is determined by the need to dampen fluctuations in flow rate. 

Validation should be viewed as an integral part of the overall computer system s life cycle. It should promote improved process control and not bureaucracy. Good practice and common sense should prevail. 

Perform on-line sampling to improve process control... 

With a proven process and time-tested reliable equipment, recent innovations have been directed toward improved process control and automation. Shortening lines are now available with semiautomated or completely automated screen-based control systems. 

In summary the use of motor-current endpoint versus timed WCMP recipes provides improved process control for production worthy applications. 

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