Jean-Luc Goutagny from Emerson Process Management explains how a system incorporating protection monitoring, prediction monitoring, performance monitoring, and integration with process control is the most effective way to protect critical assets.
Within process plants, it is unusual for rotating equipment to fail without offering some sort of notice. By detecting the signs of imminent failure, breakdowns can usually be predicted and avoided. An effective way to track the health of production machinery is by using vibration monitoring, accompanied by machine diagnostics.
By using the best maintenance practices equipment life can be extended – helping to avoid any unplanned downtime. In particular, it is important to have access to reliable information about the operating condition of critical production equipment, not just a “trip” signal that arrives after internal damage has already occurred.
Machinery shutdown protection systems guard against events that occur with little or no apparent warning. However these should form only part of a complete monitoring strategy. With the right monitoring equipment, trained personnel and software package, the signs of failure can be detected long before a key compressor, turbine, gearbox, pump, coupling or air induction fan fails “unexpectedly”. In any business, timely maintenance is far better than catastrophic failure and the costly repairs that follow.
Even so, recent studies indicate that more than 50 per cent of industrial maintenance man-hours are spent fixing equipment after a failure has occurred, whereas less than 18 per cent of the time is spent determining when equipment might fail and responding accordingly. It is expected that these numbers will improve as maintenance departments recognise the benefits of machinery health monitoring.
One way to ensure high reliability production is to monitor the health of rotating machinery. This can be achieved by integrating advanced in-the-field vibration analysis and online and wireless vibration monitoring, with process control systems.
The traditional method of collecting vibration data from rotating machinery is based on a technician with a hand-held data collector attaching this to predetermined points on a machine or connecting to permanently installed sensors. The technician follows an expeditious route through the plant to obtain detailed vibration information on different rotating assets. By uploading this data to a computer software package, it can be analysed and compared with earlier measurements taken on the same machine.
Data collection equipment (such as Emerson’s CSI 2130 Machinery Health Analyser) accurately identifies the earliest signs of faults, such as bearing and gear wear. The analyser can detect many other potential machine faults, and provide an indication of severity of the problem, while the technician is still at the machine. This enables real-time decisions to be made on whether to collect more detailed data or move on to the next machine.
In every process plant, certain rotating machinery must perform continuously to maintain a high level of production. This means that some critical situations can only be averted by making available a stream of data regarding the real-time condition of that equipment. To ensure a flow of information regarding the health of a whole range of machinery, online monitoring systems provide a solution beyond route-based monitors that provide only snapshots of an operation. Essential equipment, such as gas turbines, steam turbines, generators, compressors, fans, motors, pumps and the like, can be monitored for changing vibration patterns and rising temperatures – sure signs of impending trouble.
Data received directly from a machine is presented in a variety of plots that depict exactly what is occurring. Maintenance engineers and machine specialists are given real-time information for use in analysing changes in the machine’s operation.
These signals enable analysts to pinpoint the location, nature and even the severity of developing problems. By using information from these automated monitoring systems, plant personnel can predict with greater accuracy when a machine will need maintenance to prevent damage, averting unscheduled downtime and avoiding lost production. Machinery health management software categorises the significance of each machine in a production environment, focusing greater attention on those machines that would most likely shut down all or a major section of the plant if they fail. Online monitoring ensures that the condition of these machines is being assessed continuously.
For example, Emerson’s CSI 6500 Machinery Health Monitor is designed for process automation applications and is ideally suited to protecting new installations and upgrade projects, combining prediction and protection in a single chassis. Fully compliant with API 670, this online monitoring solution delivers real-time information necessary for immediate decision-making. Additionally, the AMS Suite predictive maintenance software captures vibration data continuously from a range of plant equipment, processing it and displaying the results graphically to give machinery analysts a better understanding of what is going on inside a machine. This software also uses ASME PTC performance calculation techniques to monitor the thermodynamic performance relevant to design to show how the equipment is performing versus expected or original design conditions.
This combination of machinery health and process status/health gives operators a much greater ability to recognise and manage controllable scenarios in order to avoid problems that might otherwise lead to degraded machinery health. Such controllable events represent the best opportunity for plant personnel to optimise processes and performance, and make a positive contribution to return on investment.
For assets that have been considered either technically or economically unreachable with conventional wiring – the latest wireless communications eliminate “blind spot” areas. Wireless has the potential to improve communications with a wide range of assets, including field instruments, valves and safety showers. Wireless vibration monitors, for example, can be adapted to many types of rotary equipment that are critical to the process. These devices provide convenient access to information that was previously not available, but may be essential to the overall performance and safety of each process unit.
The IEC62591 (WirelessHART®) standard is based on a self-organising mesh network in which transmissions are unaffected by the metal structures that define most large process industry plants. With this technology, each wireless device is a transceiver, so a direct, line-of-sight connection between an instrument and the data gateway is not required. In the event of one transmission path being blocked, the network automatically directs the signal to an adjacent device, which then relays it to the gateway, ensuring transmission reliability and data integrity.
With a wireless vibration transmitter (such as Emerson’s CSI 9420), vibration data from essential equipment can be transmitted simultaneously to control room operators and a machinery health monitoring application, ensuring that the right kind of data gets to the right person at the right time. By using this information to initiate predictive maintenance, unexpected failures which could lead to an expensive unplanned shutdown are avoided. This means that many potentially disastrous conditions can be resolved before they are even recognised as problems in the control room.
Plants that are being operated efficiently utilise every means of monitoring to obtain early indications of failing equipment, so appropriate action can be taken. A system incorporating protection monitoring, prediction monitoring, performance monitoring, and integration with process control is the most effective way to achieve a complete maintenance solution.
Tracking the health of production machinery in this way is a best practice, leading to extended equipment longevity and avoidance of downtime.
Emerson Process Management
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