Process Troubleshooting

An additional series of process tests and plots can be helpful. The Delta-P over each section should be monitored and the reflux increased/decreased at constant bottom temperature. The composition of the heavy key in the overhead should be monitored. Plots should then be made of both Delta-P and of composition vs. reflux. Additional information concerning these tests can be found in Norman Lieberman s book entitled Troubleshooting Process Operations. ... 

Since 1977, Reza Sadeghbeigi has been involved in various aspects of cat cracking at major and independent oil companies focusing on technical services, troubleshooting, process design, and project management—including major FCC revamps. 

Three examples are presented that introduce the use of the equations developed in this chapter. These calculations should be used at the start of the performance analysis of all troubleshooting problems. This analysis will be expanded in subsequent chapters through Chapter 7 using additional tools and understandings to complete the troubleshooting process. 

Often troubleshooting guides are provided by equipment manufacturers for common problems. These guides are helpful for many of the simpler problems associated with the equipment. Some resin manufacturers are an excellent resource for troubleshooting processing problems that are specific to a resin. Subject matter experts or extrusion consultants are also resources for troubleshooting an extrusion process. 

Performance information for the incumbent resin was missing from the early parts of the decision-making process. The decision that the technical problem was the performance of the new resin was based on anecdotal information from plant personnel on the performance of the incumbent resin. That is, the plant personnel believed that the reject level for parts made from the incumbent resin was less than 5 %. A statistical analysis of the part defect rates was not performed. This lack of information early in the process allowed the plant manager to propose a poor technical solution without understanding the root cause for the defect. Later in the troubleshooting process, a statistical analysis of the defect rate indicated that the incumbent resin had a defect rate that was statistically equivalent to the new resin. 

This example clearly shows that developing and accepting a hypothesis based on accurate and complete information is necessary for setting an acceptable technical solution. If the plant manager could have persuaded the resin manufacturer to develop a new resin that was similar to the incumbent resin, then the defect would still be there, the cost of the troubleshooting process would have been extremely high, the supplier would have incurred unnecessary development costs, and a high level of defective parts would still have occurred because the root cause would not have been removed. 

The Norm Lieberman Video Library of Troubleshooting Process Operations... 

After the plant is constmcted, the operations phase of the project begins, which includes plant startup. Rarely does this operation proceed smoothly. Troubleshooting, process modifications, and repairs are generally required. 

These examples are used for illustration purposes only, and we do not mean to imply that the explanations given will always fit scenarios you will see in your own processes. Certainly, as stated earlier, process changes could have resulted ill the time plots shown. However, the point we wish to make emphatically is that sampling should be on any checklist for troubleshooting process problems and should be taken seriously as a possible cause for problems. 

Finally, we presented our top 10 troubleshooting steps. Following the steps should lead you to a satisfactory conclusion of your troubleshooting process. 

A. The first step in the troubleshooting process is to talk to the customer. It is best to obtain as much information as possible from the user so you have an idea of where to begin your troubleshooting. 

By closely following the introduction of the optimized steps at the site where the problem occurred, one can monitor the results immediately and quickly make any further adjustments that are needed. If the modified operations did not solve the problem, it is necessary to begin the troubleshooting process again. 

Lieberman, N. Troubleshooting Process Operations 3rd Ed Pennwell Publishing Company, 1985. 

Lieberman, N. R, Troubleshooting Process Operations, 2nd. Ed., Penn Well Books, Oklahoma, 1985. 

The following is a step-by-step troubleshooting process along with intermediate results for a temperature controller that was observed to result in sluggish closed-loop performance. 

It is recommended that all instalments (including microplate readers and washers) undergo validation, calibration, and routine maintenance programs established and documented to meet regulatory requirements. This eliminates instruments as a cause of poor assay performance and streamlines the assay troubleshooting process. 

Immunoassay troubleshooting is a sequential, cumulative process whereby one first looks at the calibration curve, then QC s, and finally the sample results. If the curve is not acceptable, the assay fails. If the curve is acceptable, then one reviews QC performance if QC performance is unacceptable, the assay fails. If QCs are acceptable, then one examines individual sample results. If the assay fails as the result of an apparent technical error, the error is corrected and the assay is repeated. If the cause for the failure is not apparent or the assay has failed consistently, then a troubleshooting process should be initiated prior to further analysis (and depletion) of study samples. A summary of the calibrator/QC/sample result troubleshooting process is depicted in Fig. 3.14. 

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