August 2018

Special Focus: Fluid flow and rotating equipment

Six considerations for turbomachinery control upgrades

Increasing competitive pressures in process industries, including oil and gas, are driving dramatic changes in the operational needs of process plants, utilities and pipelines.

Egbuna, C., Rockwell Automation

Increasing competitive pressures in process industries, including oil and gas, are driving dramatic changes in the operational needs of process plants, utilities and pipelines. Facing the ongoing need to reduce startup time, increase turbomachinery availability and get the most out of assets, while also dealing with smaller workforces and lower budgets, can be an overwhelming challenge.

FIG. 1. The reliability of rotating equipment is a key concern in the successful operation of a system.
FIG. 1. The reliability of rotating equipment is a key concern in the successful operation of a system.

The need for control reliability is critical. Hence, for many producers, the need to upgrade their control platforms is of utmost importance. Specifically, when it comes to upgrading rotating equipment (Fig. 1), producers ask: How do I control my equipment in the safest and most efficient way possible, while also maintaining OEM-recommended operating parameters? The successful operation of a system typically encompasses two concerns: the reliability of the machinery, and the control of the equipment to meet recommended operating ranges.

As rotating machinery begins to operate beyond its life expectancy, it is important to have an optimized control system. These systems tend to age faster than the rotating equipment they are controlling; therefore, continuous upgrades are required. A myth exists in the market that OEM rotating equipment should be controlled only by OEM control systems. This is not the case.

Although OEMs provide best-in-class support for their rotating machines, the control platform for the equipment can be handled by a well-qualified control and automation vendor. When selecting a machine control system from a third-party automation vendor, the following considerations are recommended:

  1. High reliability and availability. To maintain competitiveness, end users know that new technologies should be introduced at a low risk level. Any upgrade to the existing control system should provide better performance and increase the uptime of rotating equipment. A general rule is that the net present value (NPV) of any investment should be greater than zero. With a new control system, the rotating machines should continue to perform their intended functions. The machines should always be in an operable state, regardless of the operating conditions of the rest of the plant. Therefore, the application and equipment knowledge of the control vendors should be carefully evaluated, and only providers with demonstrated domain expertise should be on a producer’s shortlist for a new control solution.
  2. Open architectures. Open and expandable system architectures are ideal for oil and gas control solutions. They provide end users with the flexibility to combine software and hardware to meet their unique needs and system requirements. An open architecture enables the collection of system data for use in multiple functions, through multiple communication protocols. With varying system operating dynamics, end users can easily add, upgrade or even swap components.
  3. Ease of integration. Rotating equipment does not run in isolation. These machines are typically part of a larger process or plant, so the control platform should easily integrate into other balance-of-plant equipment and auxiliary systems. A uniform platform is key to helping maintain reliability and decrease downtime. Additionally, a turbomachinery architecture requires a significant amount of hard-wiring and communications networks to aggregate control functions. These interactions must be carefully designed to help verify a communication fault from an auxiliary system so that it does not, for example, lead to a shutdown of the entire system.
  1. Scalability. End users are often challenged with adding I/O to meet specific functionalities. Due to constant changes in requirements and operability, scalability should also be considered when selecting a control platform. It is more cost-effective to have a system that supports these changes without changing the overall system architecture.
  2. Continuous monitoring. Many oil and gas producers are looking for ways to transition from a preventive maintenance strategy to a predictive maintenance approach. Today, new technologies and analytics tools enable comprehensive predictive maintenance programs that help optimize the cost and increase machinery uptime and yield, while positively impacting overall equipment effectiveness. Rotating equipment is more susceptible to mechanical failure than non-rotating equipment, requiring continuous monitoring to help improve productivity
    and extend its useful life.
  3. Analytics capabilities. Analytics allows producers to view operations differently, and provides the ability to capture data patterns to help understand historic trends, predict future occurrences and help operators make more informed decisions—many of which involve changing the way equipment is operated.

Many factors should be considered when upgrading a control system—however, basing a decision on the need to maintain an OEM presence onsite is not one of them. Although certain limitations may exist to duplicating OEM functionality and protective schemes, there should always be a fair comparison when deciding which company should perform an upgrade.

Many will claim to execute projects “at a fraction of the cost.” The correct responses should be: A fraction of what cost? Hardware, software, commissioning or all of the above? A scope of work should always be segmented, and control system features compared holistically, to find the right automation and control system provider. HP

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