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More than 30 million HART-enabled devices have been installed in process plants around the world. In fact, according to a recent market study released by ARC Advisory Group, there were 32 million installed HART devices, growing to 35 million in 2011, and the report projects growth to continue to 37.3 million devices in 2012. Many, if not most, of the instrumentation and final control element vendors in the world provide HART connectivity with their field devices. The HART protocol has become the standard for fieldbus communication in the world.
More and more, companies are seeing the benefit of doing more than being temporarily connected to the instrument or valve with HART communicator or PC communicator software for commissioning or calibration. They have seen that using HART to its fullest capabilities is an area of optimization, lowered cost and increased profitability.
For the past 15 years, manufacturing theorists such as ARC Advisory Group have been talking about the benefits of implementing real-time decision making from the plant to the executive suite. Especially in the "high-cost" manufacturing countries, such as the United States, Canada and all of Western Europe, keeping plants open means showing increasing ROI to corporate planners. There are really few ways to do this. The two increasingly useful approaches are both about increasing productivity. The first is asset management. The second is advanced process optimization.
"Collaborative process automation and a continuous improvement plan utilizing performance feedback and the benefits associated with automation are the keys to automation's contribution to increasing manufacturing productivity, not the latest and the greatest technology," an ARC study reports.
Performance feedback is the key. Most plants have HART-enabled field instruments and final control elements. Simply connecting those instruments digitally to the control and computerized maintenance management systems (CMMS) provides much of the feedback that the ARC report is talking about.
Downtime is a key culprit. An ARC study done in 2007 reports that downtime still represents a significant percent of production lost. In oil refining, for example, downtime can be from 1% to 8%. In petrochemicals as a whole, downtime ranges from 2% to 5%, and in the food and pharmaceutical industries, downtime ranges from 1% to 10%.It is easy to tie ROI into reducing downtime. So how do you reduce downtime? The answer has been clear for years: better and more predictive maintenance systems. But no maintenance system is any better than the sensors that feed information to it. If you are collecting information from those sensors about their sensor health and the processes they are monitoring by hand, the maintenance system is always behind. The quality of that hand-collected data taken off operator and technician clipboards is usually poor to unreadable, and says things like "didn't work—fixed it." State-of-the-art asset management systems need real-time data—real-time sensor readings and real-time diagnostics.
Evonik Degussa Specialty Chemicals Company in Shanghai, P. R. China, decided that HART technology would be used to connect field instruments to the distributed control system (DCS) as well as to the asset management and safety systems. There are more than 2000 HART-enabled instruments connected to the central control system, while the remote HART connection simultaneously feeds data to the integrated asset management and safety instrumented systems.
"As a direct result of this implementation," says Luc Sterck, Project Manager Instrumentation for Evonik, "we cut loop check time and costs by 25 percent, and daily troubleshooting of instruments are now mainly done from the safety and convenience of the control room."
The plant's predictive maintenance program is expected to reduce the total number of hours spent by maintenance teams. "We strongly believe," Sterck says, "that our plant's commitment to implement predictive device diagnostics on all HART instruments will bring comprehensive and pertinent operating information to key personnel and therefore assure better plant availability by predicting unexpected failures and avoiding associated downtimes."
The logic solvers of Evonik Degussa's plant use HART technology to connect with the sensors for loop check and safety instrumented function (SIF) interlock validation. Some of the logic solvers are used in complex online flammability calculations (SIL3).
You don't need to radically revise your plant's instrumentation schemes. Operators and maintenance techs already have all the data they need—right in their HART devices. Each HART device is designed to be interoperable—it starts in the HART specification, using EDD in every device, and then it is tested and registered by the HART Communication Foundation.
Since 2007, there has been a new way to get connected with HART. In 2010, the IEC approved IEC62591-WirelessHART, the first international open standard for wireless field devices. As data gathering needs expand, both for asset management and plant optimization, new devices and new functions can be added to the control system without the major expense and downtime of pulling new wires. And WirelessHART is designed to be backward-compatible and interoperable with wired HART devices.
"Because IEC 62591-WirelessHART is completely backward-compatible with any registered installed HART devices, using adapters such as the MACTek Bullet can easily get the diagnostic and secondary process variable information from existing HART transmitters without the cost, expense and time associated with new wiring. And, since the Bullet can support up to eight devices in a HART multidrop application, it makes the case for the adapter even more cost-effective," says Thomas Holmes, CEO of MACTek Corporation.