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Setting Operational Limits for Maximum Efficiency
Pankaj Deshmukh, Business Development Manager, Honeywell Process Solutions. Every manufacturing plant must possess the necessary tools to ensure optimum utilisation of resources and manpower with in prescribed limits. Boundary management involves setting and maintaining multi-dimensional process operating limits, while execution of operations in a consistent manner to achieve operational excellence.

Stop and think about control room alarms for a minute: How many alarms are currently configured in the systems or processes you manage? 25? 100? 1,000? How many of those alarms would go off in the first minute of a process disruption or a system shutdown? Would your facility’s operators know which alarms to address first?

When alarms proliferate, their value as tools for diagnosing and preventing problems declines. Managing alarms is a largely matter of correctly monitoring and managing operating envelopes. It is a process in which operators and process engineers ensure alarms, operations monitoring, operating instructions, and alerts are set consistently with process, and equipment limits that are imposed by equipment and process design and by environmental and safety constraints. In addition to managing these ‘operating envelopes’, the work process must include deployment of this information wherever it is needed in the plant.

The effective management of this information and its dissemination constitute operat ions excel lence and opt imum people effectiveness.

Plants require the necessary tools to achieving people effectiveness. Boundary management aids the operator to maintaining multi-dimensional process operating limits; applying these limits while executing operating plans, schedules and instructions in a consistent manner, and finally in reporting the results to their management. Figure 1 illustrates data retrieval and reporting framework of boundary management.

Capabilities of Boundary Management
a) Establish Limits

Variables and Boundaries: The first step in a safe and reliable work process is to establish limits or operating envelopes. In boundary management, the critical, standard, and target boundaries (limits) are captured for every process unit - variable or measurement and is subsequently stored in a database.

Along with these limits, supporting information for the variables and limits, such as purpose of the measurement; Piping and Instrumentation Diagram (P&ID) reference; and equipment constraints (e.g., corrosion control limit, safety limit, environmental limit), are also captured. The result is a single source or complete repository for all variable and boundary information (Figure 2).

Mode-Based Alarms: Nuisance alarms often occur when an operating unit’s mode is changed during shutdown or startup, or when the grade of the product being manufactured is changed. To avoid nuisance alarms, the system supports the definition of these various modes and the entry of multiple groups of alarm settings. At runtime, the desired alarm settings can be written to the control system based on the context of the operating environment.

Management of Change (MOC): Boundary management provides MOC process for variable, boundary and alarm information. This process uses change stages of in progress, proposed, approved and released to indicate the status of a change being considered for a particular point or parameter in the system. In addition, the database includes an audit trail of variable changes and a location to store an ‘official’ or site MOC reference number.

b) Validate: The next phase in the work process is the stage in which operating plans are validated against boundaries set in the Establish Limits phase.

Operating Instructions: In most process plants, a planning and scheduling group sets daily and weekly operating plans according to availability of feedstocks, committed product shipments and plant constraints. But before those plans can be executed, they must be translated from planning vernacular into operational terms. Boundary management provides an infrastructure for converting operating plans into operating instructions complete with all the details of the plan, but in operational terms, so that an operator can use to execute the plan as required.

Instruction Validation: A key element of this phase is the validation of targets entered in the operating instructions against the boundaries specified in the Establish Limits phase. These validation checks are performed when the instructions are created and again at runtime. This process reduces the possibility of targets being set outside the safe operating range.

c) Monitor and Control: The Monitoring and Control phase of the work process includes both automated monitoring as well as manual monitoring and control functions.

Production Monitoring: Systematic performance monitoring of the process against expected targets enables operators to spot problems as they occur and make necessary corrections as required. Deviations from operating boundaries and planning targets are automatically detected, recorded and retained for analysis. An economic impact can be triggered automatically complete with calculated deviations ranked based on their economic impact. This also helps operators to prioritise steps to alleviate costly problems.

Proactive Process Monitoring: Boundary management includes a proactive process monitoring function to monitor simple or complex process conditions and alert the operator when these conditions are detected. This capability can be used to monitor the process, environmental, equipment and other types of conditions that are either monitored by the alarm system today or are left up to the operator to monitor manually.

Operator Awareness: Control systems do not automatically monitor all operations; manual monitoring and operator awareness are essential to safe and reliable operations. To improve operator’s situational awareness, boundary management provides advanced trending tools to help operator with easy access to superior trending from operating graphics. Trending combines realtime and historical trending to allow operators to create trends dynamically as group trends. These are high density 48 trend displays and specially configured traces accessible via right click functionality from the operating graphic. Event Analysis can be used by the operator to decipher quickly when events are recorded in relation to changes in the process.

d) Report, Analyse and Improve: The Report and Analyse activities help users to maintain the benefits and make continuous improvements to their operations. This phase has a number of facets. Without this phase, the improvements made throughout the work process cannot be sustained or further improved. In this phase of the operations management process, the implemented system is monitored for improvement.

Alarm Metric Reporting: Boundary management provides analysis of system alarm configuration and performance. In addition to many pre-configured reports that can be scheduled and distributed via e-mail, it features an application that enables users to 'drill down' and analyse the alarm report information. Alarm metrics reporting tools, which provide reports on bad actors, standing alarms, etc, will facilitate a continuous improvement programme.

Electronic Shift Report: Operators, shift supervisors, planners and plant engineers must collaborate to optimise process operations. Getting the right information at the right time to make the right decision can be very challenging when data is not properly organised or widely accessible. An electronic shift log (operations logbook) helps users to optimise access and management of operations information by providing the operations staff with a common window to access operational information.

Give Me The Limits And I Will Stay Within Them!
Boundary management is the solution that enables a facility to achieve the previously incompatible goals of operating within their limits, thereby ensuring the safety and health of employees, equipment and the environment, while reducing costs and improving profits. Unfortunately, if the operator does not know these limits or if these boundaries are poorly communicated, documented, maintained or controlled then the operator will have little chance of success in this quest for excellence. Figure 3 shows how to depicts the work processes around boundraies through boundary management.

Operational excellence is the application of people, processes, and technology to consistently and reliably run at (or near) operating constraints while staying within the limits. The things that you need to provide across your operating teams are work practices, best practices and technologies that support:

• A clear view of operating plan and targets
• A clear view of operating constraints, limits and boundaries
• Optimised alarm system with priorities, alerts and associated help
• Alarm system management (configuration, monitoring and enforcement)
• Deviation monitoring and reporting (alarms, alerts and targets)
• Situational Awareness
• Operator guidance (alarm response and process automation)
• Deviation and Performance reporting and analysis

With these items in place the site will be poised to optimize production and achieve the economic targets as desired. By ensuring that operations are within prescribed limits this not only aids in the goal for maximum site efficiency, but alsoat the same time it safeguards plant equipment as well as safe, healthy and environmentally friendly production.