FOUNDATION Fieldbus instrument alarms are configured in the DCS with suitable priority according to EEMUA-191 guidelines so that early detection of instrument failures can be ensured. These FOUNDATION device alarms are available not only for real-time monitoring, but are also connected to the refinery’s Yokogawa Exaquantum Alarms & Reporting Analytics (ARA) server for proactively deciding maintenance actions to head off potential failures.
Analog 4-20mA HART instrumentation is also used in the FCC unit. For example, to realize three-element control logic of steam-drum level in the unit’s flue gas heat recovery boilers, which provide both economic and environmental benefits. In short, the required boiler feed water flow is calculated based on both steam demand and drum level setpoint.
Other units, such as for hexane recovery and liquified petroleum gas (LPG) treatment also run with FOUNDATION Fieldbus devices in closed-loop applications. “By following good maintenance practices and ensuring increased availability of FOUNDATION instruments, we are able to sustain refinery operations and are continually improving our refining capacity in a safe and clean manner,” Kansal says.
Benefits from execution through maintenance
The early decision to use FOUNDATION Fieldbus instruments when the refinery was first designed provided advantages in terms of execution schedule and project cost, according to Kansal. “With various good engineering practices and meritorious maintenance techniques, we at HMEL not only reduced capital expenditure by selecting FOUNDATION Fieldbus technology for complex process applications, but also increased availability of instruments and reduced maintenance costs.”
One tangible demonstration of the power of FOUNDATION Fieldbus data was in February 2021 when FCC throughput was restricted due to flooding issues in the debutanizer and depropanizer columns. Staff were able to diagnose and resolve the problem in short order owing to the higher availability plus higher accuracy, repeatability and response time of FOUNDATION Fieldbus instrumentation. Quickly resolving the column problems led to an incremental improvement in FCC throughput of 7%, which in turn translated to a $11.2M USD gain in annual output.
Some of the best practices and design improvements for FOUNDATION Fieldbus carried out at HMEL for increased availability of the refinery process include:
- Use of trunk/spur signal ground correction to avoid noise issues,
- Use of field barrier terminators for signal level improvement,
- Use of silica gel bags and canopies for FOUNDATION Fieldbus junction boxes and instruments to increase life of electronic components due to varying ambient conditions,
- Installation of spur-level protection barriers to protect FOUNDATION Fieldbus devices in same segment, and,
- Ensuring lightning protection device integrity for field junction boxes.
Field instruments with HART capabilities also offer high availability, accuracy, response time and repeatability. Further, the ability to digitally share HART diagnostics data facilitates real-time monitoring of field instruments and their performance.
For HMEL, the combination of FOUNDATION Fieldbus and 4-20mA HART technologies offered the following qualitative benefits: