Increasing machine reliability and protection in plants with hazardous areas.
A recent ARC study identified the growing need for integrated predictive health solutions to complement the core protection functionality required for high-end equipment.
The process manufacturing industries have used dedicated machinery protection systems for high-end equipment for quite awhile. These systems consist of many components, including sensors that require a large nest of wires that connect to a bank of rack-mounted electronic control equipment. These racks are often located in environmentally protected rooms or the plant control room. In plants with hazardous (explosive) areas, this can be particularly problematic, since special work permits are often required to perform repairs, upgrades, or even routine maintenance on the equipment.
Most legacy machinery protection systems installed in existing plants have point-to-point connections that require many separate wiring runs between hazardous and safe areas of the plant. As plants increase in size, all free space for new components has long since been filled and cable trays are overloaded. This makes upgrading to new equipment of any kind increasingly difficult; there simply is no extra space. Even replacing older equipment with newer units is a chore, due to the increasing probability of damaging equipment and connections adjacent to or close to the slot being worked on.
In the past, machinery protection systems had not taken advantage of intrinsically safe (IS) communications networks, despite the widespread acceptance of these for process control networks in Europe, Africa, and, increasingly, also in North America. And unlike the plant asset management (PAM) systems for other classes of process assets, legacy machinery protection systems rarely include much, if any, predictive asset management functionality, which could alert operators well before a costly protection system shutdown is required.
As most readers know, the intrinsic safety approach, which limits the amount of electrical energy allowed to enter industrial areas with potentially explosive environments (due to the presence of explosive gasses, such as methane, and/or dust concentrations), was developed in response to a series of mining accidents in the early 19th century. Intrinsic safety is particularly relevant in South Africa, where a relatively high percentage of goods and materials are produced in above- or below-ground facilities with hazardous locations.
Recently, new, jointly developed solutions have emerged that combine sophisticated machinery protection and predictive condition monitoring capabilities in intrinsically safe configurations. These solutions accept inputs from the sensors that measure vibration, acceleration, velocity, displacement and other process variables, using digital communications that require only a single or dual-pair cable set, reducing installation costs and start-up time. This simplifies field installation in hazardous areas, particularly for legacy equipment retrofits, reducing the number of cabinets and isolation barriers required.
Successful applications to date include critical and non-critical turbo machinery and pumps in pipelines, refineries, and chemical and water and wastewater plants. In many cases, end users can easily migrate old legacy systems to the new technology without disrupting plant operation. The intrinsically safe design allows installation without special authorisation. Current agency approvals include ATEX, CE, and UL. Additionally, the ability to use an RS-485 signal to connect operators in the control room to the intelligence embedded in the equipment protection devices provides insight into equipment health that was not previously available for this type of machinery protection system.
This innovative solution is the product of close collaboration between companies that specialise in machinery protection and intrinsically safe interfaces for field devices. It provides refineries, petrochemical plants, oil and gas pipelines, mineral processing plants, water and wastewater plants and other process plants with both heavy machinery (pumps, turbines, compressors, etc.) and hazardous areas with a practical option for replacing ageing, legacy, hard-wired machinery protection systems with the latest digital technology.
For more information contact Larry O’Brien, ARC Advisory Group, (+1) 781 471 1126, [email protected], www.arcweb.com
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