The refinery’s decision was part of a plant-wide maintenance initiative designed to increase operational reliability. “We made the decision going forward to purchase intelligent field instruments that support the HART protocol, and then to develop and use the in-depth and sophisticated communication options embedded in those HART instruments,” says Gábor Bereznai, MOL instrumentation and electrical department head. “Our directive became, ‘Let’s get connected—off-line and on-line—and put these HART instruments to work.’”
More than 30,000 of the plant’s 50,000 instruments are HART-enabled and 3,700 of these—mostly control valves and instruments used in critical control loops—are connected directly into computerized maintenance management systems (CMMSs). The refinery uses Emerson’s AMS Suite predictive maintenance software, as well as a range of Rosemount measurement instruments, Fisher Fieldvue digital valve controllers, and other devices.
The decision has changed the way the MOL maintenance department runs. Refinery personnel are able to minimize downtime through early warning of field device issues, improving profitability by millions of dollars each year. Since the introduction of HART diagnostics, for example, the number of valves selected for repair during a planned shutdown has dropped from 60% to about 5%. In just one case, preventing the unnecessary removal of a functioning control valve avoided an unscheduled shutdown, saving the refinery US $840,000. Overall, the system has already saved an estimated US $2 million. Inaccurate control loops—often caused by valve detuning—also can be identified so process control can be improved, and instrument calibration costs are reduced.
Automation Engineer József Bartók says, “On-line diagnostics… does something more than preventive maintenance. It ensures the stable operation of the system and increases the precision of control.”