Many power generation steam turbine generators today are required in service well beyond their intended lifetimes. Dismantling for inspection is expensive, and owners need to consider all relevant information in making the decision. Application of condition monitoring in all the applicable methods is justified, with each showing different degradation modes. Performance analysis is less well publicised, yet unlike vibration analysis and oil debris analysis, it will show conditions which reduce machine efficiency and output, such as deposits on blades and erosion of internal clearances. The paper outlines, with examples, some condition monitoring techniques that have contributed to retaining some large fossil machines in service for up to 17 years without opening high-pressure sections.
A common approach to looking at vibration spectra is to display the graphs and then ask “What is wrong with this machine?” Another common approach to analyzing vibration spectra is to display the graphs and then ask “What is this peak?” and “what is that peak” A better approach to analyzing data is to first ask “What faults can this machine have?”, “Which of these are most common for this machine?” and finally…
A vibration test and analysis guide is a simple book or electronic document that contains a variety of information about the machine. Information should include: A simple schematic of the machine with test points identified, instructions for testing the machine (especially if loads and speeds must be manipulated or verified), name plate information and a simple schematic of internal components. This information is invaluable for conducting a proper diagnosis of the machine.
When troubleshooting or using vibration in a Predictive Maintenance program comparing identical machines to each other is often the best method to diagnose a problem – especially if you suspect a problem exists in one or more of the machines. When vibration data is collected on a bearing housing using an accelerometer, one is not only measuring vibration forces, but also the effect of the structure on these forces.
Westar is currently evaluating the implementation of a new database and route collection system. This new component to the infrared program will allow for Web-based tracking and trending of all infrared projects and will greatly enhance the efficiency of our program. It will also allow for simultaneous imbedding, reporting, tracking, and trending of the ultrasonic technology being brought into the thermography program.
Accept that you will sometimes be wrong and do whatever it takes to find out the “as found” condition. This is often difficult to accomplish but it is well worth the effort and in the best circumstances this should be implemented as a normal procedure.
Before bearings, valves and other mechanical parts fail, they usually scream for help. But their piercing wails usually fall on deaf ears because the sound frequencies are far too high for humans to hear. No wonder deteriorating components may go undetected until they break down completely. Now, however, a variety of tools using ultrasonic technology—ultrasound, as it is commonly known—are helping companies in a wide range of industries avoid wasteful replacements or costly breakdowns.
There are four primary components to precision grease lubrication for bearings: lubricant selection, application method, the volume of lubricant to be delivered, and the frequency with which it is applied. There are, of course, many different methods for specifying these values, and opinions can vary significantly as to which approach is best. Due to the variability of operating conditions and machine design, it can be very difficult to be truly precise without introducing the “condition-based” component to the formula.