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As collective interest in wireless gathers momentum, a growing number of process manufacturers are seeking that first, relatively low-risk application that will allow them to validate the technology within their own cultures and operating environments.
And while the reasoning and justification varies widely, many process manufacturers continue to choose a field-level network of measurement devices as their first foray into the wireless world, according to Emerson Process Management, which today has several years and hundreds of wireless implementations under its corporate belt.
Indeed, while most current application requests are for field-network applications, says Jane Lansing, vice president of marketing for Emerson Process Management, “we’re increasingly working with customers on plant-level applications, such as for mobile workers and the location of assets and people.”
And while none of the applications surveyed in this article may apply directly to your plant’s situation, it’s likely there’s one that has much in common with them. (See figure for application categories.)
Heat exchangers, which often are run until fouling adversely affects unit performance, represent an excellent application for wireless. They rarely are instrumented, even in newer plants, but wireless monitors enable personnel to determine when maintenance is needed.
For example, a major refiner in Europe developed an equipment health system for keeping an eye on its heat exchangers. One of the company’s engineers explains, “Monitoring heat exchangers for fouling allowed us to establish which heat exchanger was the most fouled. This knowledge gives us the opportunity to compare increases in the throughput with cleaning cost and to make better economic decisions.”
Filters present another application opportunity. Many filters are run until they clog, but users can improve their performance significantly and save energy by using wireless monitors. One major refinery uses wireless to detect plugged filters on coker unit pumps, which is critical to prevent damage to the pump on loss of suction.
Tank farms pose a unique instrumentation problem: Each of dozens of storage tanks may have to be monitored for level, temperature, pressure and so on. Because of the cost of running wiring underground over the vast distances involved, tank farms often are not instrumented.
Hunt Refining Company in Tuscaloosa, Ala., U.S., uses wireless temperature transmitters to monitor hot asphalt tanks. When very hot asphalt is added to a tank, the hot fluid can “melt through” the stored asphalt and reach cold pockets, where any moisture present can flash off violently. This can cause a tank roof failure, which costs $200,000 to repair. Wireless temperature transmitters are spaced around each tank to monitor for cold pockets.
When a vital pump or motor fails, it can cause a very expensive process shutdown, a leak or other problems.
Installing wireless vibration monitors on key pumps and motors is proving a wise investment for process plants. Vibration data is transmitted wirelessly to a control system that detects and diagnoses problems long before the pump or motor fails, allowing the plant to schedule maintenance or replacement at its convenience.
Some process units, such as skids, pumps, compressors, portable laboratories and test equipment, are mobile. A major life-sciences company installed wireless on its moving skid platforms, which included pumps, filtration and milling equipment. The skids can be moved anywhere in the five-story building, and successfully communicate through 12-in. reinforced concrete floors.
Installing instrumentation in extreme environments causes problems for both the instrumentation and personnel. Extreme environments can mean temperature extremes, wet or dusty conditions or hazardous, explosive conditions.
At Usiminas (Usinas Siderúrgicas de Minas Gerais S.A.), one of the world’s top steel producers, wireless temperature transmitters are being used to monitor roll bearing oil temperature at the company’s heavy plate steel mill in Ipatinga, Brazil. “This more accurate and redundant data allows us to better maintain the roll bearings and to avoid unscheduled shut downs,” says Carlos Augusto Souza de Oliveira, Usiminas instrumentation supervisor.
Wireless analyzers increasingly are used to monitor rotating equipment, such as turbines, generator sets, reciprocating engines, compressors and other motor-driven systems. Since such machines are often very large and expensive, diagnostic equipment that can predict pending problems allows users to fix small problems before they become very large problems.
Rotating process equipment is also difficult to monitor with wired instruments. At Coogee Chemicals in Australia, wired instruments failed frequently on a rotating reactor, so Coogee installed wireless pressure and temperature transmitters.
Monitoring energy usage is vital, but often difficult to do with wired instruments. When a plant is first built, many measurement points are considered, but not installed because of time or cost. Now, when the measurements are needed, the cost of wiring new sensors is prohibitive.
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