Vibration measurement monitoring system

Most computer-based systems require data-acquisition routes to be established as part of the database setup. These routes specifically define the sequence of measurement points and, typically, a route is developed for each area or section of the plant. With the exception of limitations imposed by some of the vibration monitoring systems, these routes should define a logical walking route within a specific plant area. A typical measurement is shown in Figure 44.15. 

The method of establishing and using alert/alarm limits varies depending on the particular vibration monitoring system that you select. Normally these systems will use either static or dynamic limits to monitor, trend and alarm measured vibration. We will not attempt to define the different dynamic methods of monitoring vibration severity in this book. We will however provide a guideline for the maximum limits that should be considered acceptable for most plant mechanical equipment. 

A system for evaluating the physical state of machinery and equipment over time, to prevent a failure that could lead to an incident Readings and parameters are plotted to give a characteristic trend. The objective is to identify evidence of deterioration at an early stage so that corrective maintenance can be undertaken before failure. There are a range of techniques that may be employed that include strain measurement, corrosion monitoring, vibration measurement, and acoustic emission monitoring. It is considered a type of preventive maintenance or predictive maintenance. 

In this paper, we have presented a new on-line monitoring system to help oil and gas companies monitor the performance and availability of their machines. This helps in reducing down time and preventing trips. The article presents rules to monitor the performance of the axial compressor and output of the machine, as well as a rule to monitor fuel consumption, which is also applicable at part load conditions. Physics-based availability rules to monitor the wheelspace temperatures and combustion process were also shown. Vibration rules based on a correlation with key parameters as well as a new rule to measure natural frequencies were also introduced. 

Process condition monitoring system (sometimes also called technological monitoring system) These systems collect information from QCS sensors, vibration sensors, pressure sensors, triggers at rolls and fabrics, etc. to analyse the reasons for periodic quahty disturbances. AU collected signals are taken simultaneously with sample rates from 100 Hz to 4 kHz, depending on sensor type and application. The required measurement frequency is given by the revolution time of the machine elements which can cause quality variations, like felts, rolls, pumps, etc. 

Monitoring should include the usual parameters worthy of surveillance in high-speed turbo machinery the temperature of journal bearings, vibration and axial position of the pinions, inlet and discharge temperatures combined with discharge pressure from the individual compressor stages, and various lube oil system devices. Competent manufacturers make sure all measurement locations are completely prewired on the machine and made available at predefined interfaces or in terminal boxes for connection at the plant site. 

This is especially true in applications that use microprocessor/computer-based systems. These systems require a database that specifies the monitoring parameters, measurement routes, analysis parameters, and a variety of other information. This input is needed to acquire, trend, store, and report what is referred to as conditioned vibration data. 

This obviously has a physical reason. Since condensed systems are investigated, interaction with the environment is involved in the transition. The chromophore is an open system which dissipates vibrational energy into the surrounding medium by irreversible processes. This phenomenon can be used for detecting fine structure from the time resolved measurements of photon events, by monitoring the correlations between successively emitted photons. This new technique will be reported in the second part of this article. 

Various monitoring methods are used in practice. The method most commonly used in large systems is vibration analysis. With this method, any defects can be assigned to particular bearings or gearwheels and targeted measures can be initiated at an early stage. 

---