Troubleshooting separation problems

Using this or similar mixtures, inject a sample into an equilibrated column, elute the resolved bands, and record them on the recorder. Calculate plate counts for the first and last peak using the 5 [Pg.38]

Consistent with the theme of thehandbook, this chapter has a practice-oriented focus, with the presentation of select theoretical aspects of CE limited to the basic principles needed for understanding how molecules separate in an applied voltage, and the factors that affect the separation. Appendix 2 provides the reader with a guide to troubleshooting typical problems that may be encountered with CE. 

TROUBLESHOOTING CHECKLIST for Vapor-Liquid Separation Problems... 

When there is a problem with process operation, the cause of the problem must be identified. The problem may or may not be located at the unit where poor operation is observed. For example, the output from the separator may be off spec due to lower-quality product exiting the reactor rather than due to poor separator operation. In troubleshooting plant problems, a vast amount of data exists that can be used to help identify the problem These data would likely include current and historical operating conditions. In... 

Ascertain the depth of technical knowledge available in a company to support their bonded phase products. This knowledge is usually found in their customer service department, technical sales or marketing specialists, and research and development scientists. The name of the marketing people or scientists of most value in this respect, will be found on papers published on the products in which you are interested. These people will be able to give detailed information on column use and care, applications, and in most cases, can help in solving new separation problems and troubleshooting... 

Stand-alone computer systems, usually based on a personal computer (PC) or programmable logic controller (PLC), provide a separate computer system for each pilot plant. This allows for economical expansion for new units, separates pilot plants completely for maintenance and troubleshooting, and often has the lowest initial cost. Standardization can be a problem and software control, data gathering, and storage packages can be limited in size, scope, and capabiUty these are usually acceptable trade-offs. 

Since the response of the detector (and the separation) is a function of a flow rate, it is essential that the standard response curve be determined at the same flow rate as the tablet assay. If retention times differ significantly from the runs of the standards, there is a need to troubleshoot the HPLC to determine where the problem resides. Refer to Chapter 3 for a discussion of retention time precision. 

Would more data Kelp clarify the relationships among frequency, speet and temperature If so. in what temperature should the data be obtained Pick an insect, and explain how you would carry out the experiment t obtain more data. [For an alternative to this problem, see CDP3-Ab.] Troubleshooting, Corrosion of high-nickel stainless steel plates was found t occur in a distillation column used at DuPont to. separate HCN and water. Su furic acid is always added at the top of the column to prevent poly men zatio of HCN. Water collects at the bottom of the column and HCN at the top. Tit amount of corrosion on each tray is shown in Figure P3-5 as a function c plate location in the column. 

This appendix follows the instructions in the appendices to Chapters 2 and 6. Although the Aspen Plus simulator is referred to, other process simulators can be used. The three problems in this appendix all employ recycle streams in distillation columns. The procedures shown here to obtain convergence are all forms of stream tearing. Since these are not the only methods that will work, you are encouraged to experiment with other approaches. If problems persist while running the simulator, see Appendix A Aspen Plus Separations Troubleshooting Guide, at the end of the book. 

Troubleshooting is often the most critical element of extrusion engineering because of the huge financial impact that extrusion problems can have. As a result, this topic may be the most important in the whole book. For that reason it was decided to devote a separate publication to this subject. The book Troubleshooting the Extrusion Process [159] is an expanded text of this chapter, with many detailed case studies. Therefore, for more details on troubleshooting the reader is referred to that book. 

Troubleshooting models are literal, physical demonstrations of the equipment and systems presently being taught in community colleges and universities. Some of these models are the reaction model, the absorption and stripping model, the separation model, and the distillation model. These models are completely outfitted with alarms, analyzers, interlocks, permissives, video trends, recorders, and control instrumentation. Process problems can be simulated using these models. 

I have written a separate book pertaining to a wide variety of vacuum system problems Troubleshooting Vacuum Systems (Wiley, 2012). And my chapter on steam surface condensers also deals with pertinent vacuum system malfunctions. 

---