Monitoring Malfunctions

If a plant leaves its range of specified operation because one or several process variables have left their nominal range the PCE equipment intervenes at the limit between specified operation and tolerable fault conditions, unless there is a reason for plant shut-down. 

Alarms are generated to arouse the attention of the plant personnel or prompt a direct intervention. Automatic action of the PCE equipment aimed at returning the process variables to their permissible range are also provided for. 

Additionally provisions exist to prevent the triggering of safety systems unless this is definitely required. 

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Operation Inspection, testing Nondestructive testing, condition monitoring, corrosion monitoring, malfunction detection, plant degradation audits Plant safety audits... 

For example, in rotary vacuum dryers it is possible to prevent the formation of explosible dust-air mixtures by setting and monitoring a certain partial vacuum (negative pressure). This pressure value must be determined by experiment for each type of dust. With pressures of less than O.I bar, in general, hazardous effects of dust explosions need not be anticipated. If the vacuum system malfunctions, the partial vacuum must be released by inert gas and the instaUation shut down. 

Critical Equipment Equipment, instrumentation, controls, or systems whose malfunction or failure would likely result in a catastrophic release of highly hazardous chemicals, or whose proper operation is required to mitigate the consequences of such release. (Examples are most safety systems, such as area LEL monitors, fire protection systems such as deluge or underground systems, and key operational equipment usually handling high pressures or large volumes.)... 

Borhaug, J.E., and Mitchell, J.S., Applications of Spectrum Analysis to Onstream Condition Monitoring and Malfunction Diagnosis of Process Machinery, Proceedings of the 1st Turbomachinery Symposium, Texas A M University, 1972, pp. 150-162. 

Maintenance "indicators" are available to help facility staff determine when routine maintenance is required. For example, air filters are often neglected (sometimes due to reasons such as difficult access) and fail to receive maintenance at proper intervals. Installation of an inexpensive manometer, an instrument used to monitor the pressure loss across a filter bank, can give an immediate indication of filter condition without having to open the unit to visually observe the actual filter. Computerized systems are available that can prompt staff to carry out maintenance activities at the proper intervals. Some of these programs can be connected to building equipment so that a signal is transmitted to staff if a piece of equipment malfunctions. Individual areas can be monitored for temperature, air movement, humidity, and carbon dioxide, and new sensors are constantly entering the market. 

The CRC is an important parameter for a unit operator to monitor periodically. Most FCC units check for CRC on their own, usually daily. The CRC is an indicator of regenerator performance. If the CRC shows signs of increasing, this could reveal malfunction of the regenerator s air/spent catalyst distributors. It should be noted that the MAT numbers reported on the E-cat sheet are determined after the CRC has been completely burned off. 

Within these tortuous systems there exists considerable opportunity for process contamination, corrosion, and equipment malfunction to occur, with cause-and-effect problems creating further impact downstream and placing additional demands on monitoring and control efforts. 

These various problems may arise under several different circumstances. For example, difficulties may result from consistently poor operational control of the boiler plant or from enforced operating conditions that fall outside generally accepted procedures. Alternatively, problems may stem from malfunctioning equipment, from equipment design flaws, from inadequate water treatment programs, or even as a result of poor interpretation of monitored results and bad water treatment advice. 

The parameters of this category should be recorded automatically using monitor channels of the data acquisition system (cf. Sect. 4.3). The value of the experiment is strongly resting on these data. In case of a malfunction or unavailability of the monitor channel module of the data acquisition system at least the most important parameter must be collected using paper and pencil. These parameters are the main process parameter6, the exposure times, and the readings of the ionization chambers. 

At least in the power industry, the terms "monitoring" and "diagnostics" are often used interchangeably or without careful definition. Much confusion can arise when these terms are used. For purposes of this paper, these terms and the terms "expert system" and "malfunction" will be defined here. 

An artificial intelligence system for the chemistry of a fossil once-through steam system has been constructed. It is based on on-line monitors. It diagnoses both sensor and plant malfunction and removes malfunctioning sensors from diagnosis of plant malfunctions. The system has been tested off-line using real and synthesized power plant data and is now ready for testing in a plant. 

The heart of the system comprises the automatic units that carry out the basic operations. The individual steps of the operations are specified in a set of execution parameters, which are controlled and monitored by a microprocessor that also calculates the basic results. Apart from monitoring all operations for correct action, it is necessary to avoid the generation of incorrect analytical results and to signal the malfunctioning of any subsystem. The machine operation should allow the state of any procedure or module to be readily and easily visible. 

While still preliminary, this study demonstrates the feasibility of evaluating the renal status in real-time by optical modality. This continuous renal function monitoring by the optical modality represents a new and minimally invasive method to detect kidney malfunctions. In addition to using relatively harmless radiation, the simplicity and portability of the equipment make this approach compatible for use in ambulatory and critical care. However, further studies... 

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