Figure 1. For process plants, best practice operation means ensuring maximum yield, utmost efficiency, and minimum emissions.
At process plants, it’s important to support control engineers, optimization engineers, and operators who are implementing best practices for operational excellence aimed at meeting the plant’s business and safety goals. Personnel must monitor a wide range of measurements and key performance indicators (KPIs) from plant and equipment at a production site, as well as maintain the required values of variables to meet operating objectives such as maximum yield, utmost efficiency, and minimum emissions (Figure 1).
An operating envelope is a collection of constraints, boundaries, and operating limits in an industrial facility that, when exceeded, put the integrity of assets at risk and reduce the ability to meet production and efficiency goals. These limits are typically based on combinations of factors such as process unit capacity, equipment constraints, efficiency limits, and safety concerns. Depending on the urgency required to address a deviation from the limit, they will either be implemented in alarm systems or operating target monitoring systems. According to the Abnormal Situation Management (ASM) Consortium, ensuring that operations remain within correct limits is central to avoiding many of the root causes of abnormal situations.
To maximize the life of an asset in an industrial facility, it must be operated according to design parameters and not simply within process safety limits. That means extending operating strategies beyond operator visibility to the entire operations team and all those interacting with the process. Without a comprehensive limit management solution, operators lack the insight needed to run plants within operating envelope boundaries.
Industrial sites typically employ multiple types of process control applications, each of which can be used to independently enter and control respective targets, constraints, or limits. Although these applications may relate to the same process measurements, the limits they use are sometimes inconsistent or conflicting. This situation can result in inefficient operation, costly process upsets, and unplanned shutdowns.
Various groups within the plant are responsible for maintaining safe operating limit information. As these variables are often system configuration parameters entered by humans, there is the possibility values may fall outside of the safety and compliance envelope. Additionally, some processes have dynamic safe operating limits that are continually changing, which is challenging for plant operators to manage. As these limits are adjusted for safety, reliability, and optimization, staff across the facility must have current and updated exceedance reporting to effectively manage site performance.
Plant owners and operators are under continual pressure to optimize their facilities and processes. This means achieving greater productivity more efficiently with fewer resources. Data about plant performance is key to making smart operational decisions, but, in most cases, operators have access only to piecemeal information about their units and processes — examining performance often in a vacuum.
Process industry facilities typically devote considerable resources to rationalizing their alarm systems so operators can effectively manage the process and not just respond to alarms throughout the shift. Alarm rationalization involves reconciling individual alarms against the principles and requirements of the alarm philosophy. It is important that the relevant data for each alarm is documented to support the other stages of the lifecycle. This includes the alarm description, settings, causes of an alarm, consequence of no action, required operator action, response time, and consequence rating.
Figure 2. A properly designed and well-functioning alarm system is imperative to operational excellence initiatives.
Given the alarm rationalization process has the right people involved to capture all the necessary limit information to design proper alarm settings, this effort can capture limits that assist an operator to keep the process in the best operating zone. Thus, this effort should consider an operating philosophy that helps the rationalization process to identify the operating limits while setting alarm limits to avoid any rework that might occur if addressing operational monitoring after alarm management systems are redesigned. While a properly designed and well functioning alarm system is imperative to operational excellence initiatives, it isn’t enough to simply operate within alarm boundaries. Operations managers need to know if units are running in a range that will assure production plans are met while staying within limits, which include but are not limited to equipment constraints, economic targets, environmental standards, safety system regulations, and advanced process control strategies (Figure 2).
Many automated industrial plants have implemented some type of operations monitoring program. These programs provide the tools for an operations department to establish and manage engineering limits and constraints, monitor performance to plan and limits, and follow up on performance problems.