Troubleshooting Models

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. 

A good college curriculum includes the use of advanced computer system software that closely simulates console operations. Software companies like Advanced Training Resources (ATR ) are leading the way in the development of this type of software and computer systems. Some college 

Pump and tank model Compressor model Heat exchanger model Cooling-tower model Steam-generation model Furnace model Distillation model Reaction model Separation model Absorption and stripping model Combination of the preceding models 

---

The vertices are connected with hues indicating information flow. Measurements from the plant flow to plant data, where raw measurements are converted to typical engineering units. The plant data information flows via reconciliation, rec tification, and interpretation to the plant model. The results of the model (i.e., troubleshooting, model building, or parameter estimation) are then used to improve plant operation through remedial action, control, and design. 

The above assumes that the measurement statistics are known. This is rarely the case. Typically a normal distribution is assumed for the plant and the measurements. Since these distributions are used in the analysis of the data, an incorrect assumption will lead to further bias in the resultant troubleshooting, model, and parameter estimation conclusions. 

Overview Reconciliation adjusts the measurements to close constraints subject to their uncertainty. The numerical methods for reconciliation are based on the restriction that the measurements are only subject to random errors. Since all measurements have some unknown bias, this restriction is violated. The resultant adjusted measurements propagate these biases. Since troubleshooting, model development, ana parameter estimation will ultimately be based on these adjusted measurements, the biases will be incorporated into the conclusions, models, and parameter estimates. This potentially leads to errors in operation, control, and design. 

Troubleshooting models are attached to equipment and systems presently being studied at every community college and university that teaches process technology. The 10 models commonly used to teach process troubleshooting include ... 

Troubleshooting models—tools used to teach troubleshooting techniques. Basic models include distillation, reaction, and absorption and stripping, or combinations of these three. 

A number of troubleshooting methods can be used with any of the troubleshooting models. Methods employed vary depending on the individual educational faculty, consultants, and industry. The basic approach to most methods includes the development of a good educational foundation. 

Apprentice technicians typically study the various compressors found in industry and should be able to identify critical components. Included in this study are discussions on the scientific principles associated with the operation of a compressor, however, operating a compressor system is a much more complex undertaking. Very few colleges actually have a complete compressor system on which each apprentice technician has an opportunity to train and qualify for start-up, maintenance, data collection, troubleshooting, and shutdown. This is a gap in the system, but the troubleshooting model allows instructors some flexibility to discuss and illustrate operational techniques. 

The purpose of the multiple-variable model is to provide an apprentice technician with a comprehensive view of the large scope of operations he or she will be exposed to in the chemical processing industry. When all of the equipment pieces are combined into a full-scale plant, it is easier to see how each system operates and the potential problems that troubleshooters will encounter. Nine of the troubleshooting models have been combined to make the multivariable model shown in Figure 17-15. 

Compare and contrast troubleshooting methods with troubleshooting models. 

---