Troubleshooting - Requirements

Troubleshooting requires time. What one individual views as a problem may not be a significant barrier to achieving the overall goal. It may be appropriate to check with management or someone who has an overview of the situation before investing time and resources to identify the cause of a problem and resolve the difficulty. 

The existing IPC method may serve to quickly monitor key processing steps. It may be necessary to develop a new assay if the existing one does not enable the type of investigations that troubleshooting requires. The accuracy and reliability of the new method are more important than convenience. 

In addition to difficulties related to alkylation chemistry, acid may be physically carried out of the reactor due to poor level or pressure control. Troubleshooting requires the engineer to differentiate between physical-and chemical-initiated carry-overs. 

A voltmeter measures the electrical potential (voltage) between two points of a circuit. Depending on the apphcation, voltmeters may be used to read fractions of a volt in a solid-state circuit one day and a 440-V power line the next. Applications such as cathode-ray tube troubleshooting require measurements in the kilovolt range. 

Because of its small size and portabiHty, the hot-wire anemometer is ideally suited to measure gas velocities either continuously or on a troubleshooting basis in systems where excess pressure drop cannot be tolerated. Furnaces, smokestacks, electrostatic precipitators, and air ducts are typical areas of appHcation. Its fast response to velocity or temperature fluctuations in the surrounding gas makes it particularly useful in studying the turbulence characteristics and rapidity of mixing in gas streams. The constant current mode of operation has a wide frequency response and relatively lower noise level, provided a sufficiently small wire can be used. Where a more mgged wire is required, the constant temperature mode is employed because of its insensitivity to sensor heat capacity. In Hquids, hot-film sensors are employed instead of wires. The sensor consists of a thin metallic film mounted on the surface of a thermally and electrically insulated probe. 

A silver stain is used when proteins exist in a very small quantity or when analysis of as many bands as possible created by separation techniques is desired. One positive apphcation of silver stain is its sensitivity. A drawback of the silver stain, however, is that it is more complex and often requires more troubleshooting to obtain the desired results. 

Extended Plant-Performance Triangle The historical representation of plant-performance analysis in Fig. 30-1 misses one of the principal a ects identification. Identification establishes troubleshooting hypotheses and measurements that will support the level of confidence required in the resultant model (i.e., which measurements will be most beneficial). Unfortunately, the relative impact of the measurements on the desired end use of the analysis is frequently overlooked. The most important technical step in the analysis procedures is to identify which measurements should be made. This is one of the roles of the plant-performance engineer. Figure 30-3 includes identification in the plant-performance triangle. 

Design In this context, design embodies all aspec ts requiring a model of the plant operations. Examples can include troubleshooting, fault detection, control corrections, and design development. 

Limitations Identifying the appropriate test to troubleshoot a unit problem requires hypothesis development and testing. Hypothe-... 

A change in the measurements or parameters indicates a change in the unit operation. The diagnosis (interpretation) of the cause for the change requires troubleshooting skills. 

Not surprisingly, the same strategies and philosophy that govern turboexpander seleetion play a key role in defining maintenanee requirements. Unfortunately, a number of operators never link maintenanee philosophy and troubleshooting to an appropriate extent. They either leave themselves wide open for disastrous repair bills or spend more than they need to on maintenanee. 

To ensure the required eonstant pressure, a loeal pressure eontrol loop is provided on eaeh system—turbine lube oil, eompressor lube oil, and eontrol oil. Eaeh oil pressure system should be reeorded in the eontrol room to provide troubleshooting information. The sueeess of the oil system depends upon not only the instrumentation, but upon proper instrument loeation. 

Table 44.6 is a vibration troubleshooting chart that identifies some of the common failure modes. This table provides general guidelines for interpreting the most common abnormal vibration profiles. These guidelines, however, do not provide positive verification or identification of machine-train problems. Verification requires an understanding of the failure mode and how it appears in the vibration signature. 

Several causes of V-belt failure and the action required to correct the problem are described in this section. Table 58.6 provides a troubleshooting overview. 

The cat cracker plays a key role in the overall profitability of the refinery. It must operate reliably and efficiently. It must also operate safely and comply with federal, state, and local environmental requirements. A typical FCC unit circulates tons of catalyst per minute, processes various types of feedstock and uses hundreds of control loops, any of which can make operation difficult. Proper troubleshooting will ensure that the unit operates at maximum reliability and efficiency while complying with environmental concerns. 

A successful troubleshooting assignment will require someone to ... 

Catalyst circulation is like blood circulation to the human body. Without proper catalyst circulation, the unit is dead. Troubleshooting circulation problems requires a good understanding of the pressure balance around the reactor-regenerator circuit and the factors affecting catalyst fluidization. The fundamentals of fluidization and catalyst circulation are discussed in Chapter 5. 

There are two types of circulation problems in the FCC unit that require troubleshooting. The first occurs when the apparent maximum circulation has been reached, and the second occurs when the unit is experiencing erratic circulation. 

Often, the feed rate or the conversion cannot be increased because the unit is circulation-limited. Effective troubleshooting of this limitation requires having in place a methodology such as the one shown in Figure 8-1. 

Effective troubleshooting of the circulation system requires a methodology similar to the procedures outlined in Figure 8-1. Some of the key steps are as follows ... 

With all types of plastic processes, troubleshooting guides are set up to take fast, corrective action when products do not meet their performance requirements. This problem-solving approach fits into the overall fabricating-design interface. One brief example of troubleshooting an RP/composite is in Table 8-44. 

Bioinformatics requires people. It always has, and probably always will. To expect informatics to behave differently from experimental science is, at best, hopeful and overly optimistic and, at worse, naive or disingenuous. Experimental science is becoming ever more reliant on instrumental analysis and robotics, yet people are still required to troubleshoot and to make sense of the results. Much the same holds for bioinformatics We can devolve work that is routine to automation—scanning genomes, etc.— but people are still needed to ensure such automation works and to assess the results. New methods need to be developed and their results used and applied. There is... 

Establish control charts of instrumental performance. Day-to-day variations in pump flow rate, relative response factors, absolute response to a standard, column plate counts, and standard retention times or capacity factors are all useful monitors of the performance of a system. By requiring that operators maintain control charts, troubleshooting is made much easier. The maintenance of control charts should be limited to a few minutes per day. 

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