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Jul-2013

Manufacturing execution systems for the refining industry

Real-time data and decision support tools provide access to plant information to enable a timely response to production issues

MARTY MORAN
AspenTech
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Article Summary
Transforming data into meaningful business knowledge is vital to optimising production and maximising commercial potential. Today, a refinery business needs to be more agile and responsive to fluctuations within the market. Effective performance management involves integrating planning, scheduling, execution and the ability to respond to change immediately. This article explores the background to manufacturing execution systems (MES) and reveals how MES software technology delivers more efficient data management, improved production execution and enhanced operational performance, enabling refiners to quickly turn data into profit.

Milestones of MES
Delivering products that consistently meet customer expectations helps refiners remain competitive and achieve higher profitability. MES provides intelligence for optimising operations with rapid, accurate and transparent data in real time. With a better understanding of how their plants are performing in real time, refiners can positively impact the bottom line with timely, informed decisions about production performance.

There are three key milestones for MES, which form the pillars of profitability:
• More efficient data management (MES 1.0: integrating the past)
• Improved production execution (MES 2.0: the era of work process automation)
• Enhanced performance management (MES 3.0: technology on the move)

MES 1.0: integrating the past
MES emerged in the process industries over 30 years ago. Only in the late 1970s did minicomputers become affordable enough to be successfully used in the process industries. The earliest applications were primarily data historians (handling values such as temperatures and pressure levels) in the large continuous industries, such as refining and bulk chemicals. The primary need was “historising” time-series data for trending and later analysis. Over time, refiners began to generate significant volumes of data, but struggled to leverage information effectively.
During the era of MES 1.0, other new technologies, such as planning, scheduling and advanced process control (APC), also emerged to further enhance refinery profitability. For example, APC enables refiners to increase throughput, improve product quality, reduce energy and raw material usage, as well as enhance operational efficiency while keeping the process within safe limits of reliable operation. Today, many leading refiners have successfully adopted this technology using aspenONE APC software. Not only can it efficiently scale to any control problem size, it has also been successfully applied to virtually every control problem in refining, chemicals and petrochemicals processing. Significantly, this helps improve the financial performance of the plant, where companies have experienced benefits ranging from a 3-5% increase in capacity and a 3-5% reduction in energy usage.

Another significant technology development in the early to mid-1990s was refinery scheduling. This allowed a refiner to take the leading planning model (Aspen PIMS) and create a time-based schedule for either crude or unit scheduling. Crude scheduling involved informing operations of whatever oil movements were involved in the crude oil portion of the refinery, such as offloading a ship to a specific tank, or deciding what tank should charge the crude unit. 

As MES software continued to progress through this period, the foundations to greater manufacturing profitability were being laid. During the 1980s and through to the economically challenged early 1990s, an expert engineer was usually required to interface with a MES. However, new technology has emerged in recent years that has made it much easier for casual engineers to leverage today’s MES. For example, greater intelligent search functionalities and business intelligence (BI), such as Microsoft Suite, make it easier to find and leverage information in a MES. The Aspen InfoPlus.21 family, for example, was initially developed to aggregate process, production and business information into a cohesive context for understanding and improving performance. It is now the foundation for integrating and connecting plant control systems and the shop floor with business systems.

MES 2.0: the era of work process automation
Throughout the 1990s and into the new millennium, the petroleum industry began to recognise the importance of automated work processes. Simply relying on a data historian was not enough. During this period, software was introduced that allowed refiners to automate oil movements, order processing and monitoring. Normally, the scheduling function sends down orders that certain oil movements need to occur. However, the actual work process of oil movements had many manual steps and effective monitoring of oil movement operations was always a challenge. 
Software developed during this period automated oil movement monitoring. It calculated the gross volume in tanks using strapping tables based on real-time estimates of tank level and qualities. It also alerted the operator when a movement should occur, when 90% of the movement had been reached, if a tank was in double movement and whether unauthorised movements were taking place. Before the movement began, it ensured that there was enough source material and sufficient room at the destination to adequately complete the movement.   

In this era, software programs were introduced that allowed for operations reconciliation and accounting, providing an accurate and timely account of liquid flows and inventories on a daily basis and enabling more intelligent business decisions. The automated system could reconcile production on a daily rather than monthly basis, giving refiners improved confidence of actual inventory positions, including being able to tabulate the exact inventory in each tank.

Oil accounting is a business process of measuring, validating, reconciling and publishing all the work flows on, and inventories within and out of, a refinery. Its practice varies widely. Flows are normally imported from the refinery data historian and tank inventories from the tank gauging system. It boosts profitability by identifying product loss and consistently problematic instrumentation, and provides decision-makers throughout the plant with critical reconciled production data. Proper yield accounting, for example, must also take into account oil movements that occurred during a particular day (for instance, where automated oil movement software understands the amount of oil moved during a 12am to 12am period). This information can be used in the yield accounting software to more accurately reflect the final daily inventory positions. Companies can now closely track production and take timely corrective actions when deviations occur, ensuring that commitments are met and helping to avoid purchasing components or downgrading shipments.
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