June 2014, Vol. 241, No. 6


Distributed Condition Monitoring For Pipeline Compressor Stations

Tim Burgess, Bently Nevada, Minden, NV

The majority of the United States is dependent upon the Interstate Natural Gas Pipeline system for supplies of natural gas. Intelligent distributed condition monitoring solutions are now available for the compressor stations that maintain pressure on the natural gas pipeline network and ensure continuous forward movement of supplies.

These distributed condition monitoring solutions provide the full spectrum of asset support from individual asset protection to compressor station machine condition intelligence while also providing lower maintenance costs and increased production at a fraction of the installation cost of comparable rack-based condition monitoring solutions.

Machine Condition Intelligence
It is critical for system owners and operators to understand the health of production assets in order to meet production targets while keeping maintenance costs under control. Improved computing capabilities have allowed the creation of new decentralized, distributed condition monitoring and protection solutions closer to the skid.

These resources include those that acquire the signals from sensors and process and monitor those signals to provide foresight and insight into an asset’s health as well as provide actionable information for the management and maintenance of the equipment.

Original equipment manufacturers (OEM) provide calendar-based recommendations to maintain equipment. The calendar-based approach is generally effective but is expensive. It is based on a holistic approach to all operating conditions (ranging from minimal wear to severe) and does not take the unique operating profile for each individual machine into account.

Condition monitoring-based practices accommodate unique operating circumstances that apply to each asset and help avoid removing machinery from service that have components that are well within wear and operating limits. Through accurate determination of machine condition, the right maintenance regimen at the right time is employed, avoiding unnecessary work and risk.

This improved maintenance regimen also helps to avoid costly errors that can occur during machinery disassembly and assembly, thus avoiding the introduction of problems not previously present. Furthermore, the improved maintenance regimen from condition monitoring is an important contributor to extending the length of time between major outages.

Best-in-class performers typically manage critical assets as far up the potential failure (P-F) curve (Figure 1) as possible. This enables rigorous planning and scheduling programs with condition monitoring technologies as one of the key work identification systems driving those programs. Maintenance and reliability teams spend the right amount of time identifying failures earlier for each asset, enabling improved coordination of scheduled maintenance activities.

Distributed Condition Monitoring
Distributed means moving the configuration, analytics, diagnosis, quick access functions closer to the actual asset. It is self-contained, within in the same platform. The result is a less cumbersome, more intuitive and informative user interface for machinery specialists, test personnel, the maintenance team and the unit operator.

Distributed also means greater measurement density. A single physical measurement (or channel) is capable of sourcing a large number of complex measurements. For example, a single channel can produce 1x, 2x, to nx, multiple band pass measurements (representing fault frequencies and bearing/support resonance frequencies). The time domain and frequency domain waveforms provide detailed diagnostic analysis tools for post-event analysis.

Specific examples of channel count reduction that can be realized with these processing-intense distributed monitors include: aeroderivative gas turbine, 16 measurements are available from 11 channels which would otherwise require 15 channels in a non-distributed system.

Although not a gas turbine application, a similar distributed system is capable of delivering more than 140 measurements from six channels. These new systems bring a lot to condition monitoring and protection.

Specific OEM cost benefits are achieved by providing low-cost protection with their product, and easily adding condition monitoring as time and resources permit. Distributed protection and condition monitoring systems also include smart machine capability. A smart machine provides detailed knowledge of the asset being protected and monitored so it knows the machine instrumentation and set point configuration. It is simply a matter of confirming the desired alarm and shutdown values.

These easy-to-configure distributed systems make the asset smarter and further automate the analysis and decision-making process. In parallel with computing capacity, the Industrial Internet and cloud technology make it economically possible to move the big data from these emerging systems to where it can be best utilized.

The advent of the Industrial Internet is another aspect of big data that makes distributed systems even more attractive. The ability to move the right amount of data when, and as needed, is the enabler for this benefit. Whether the data is a simple “pulse check” notification for operations, or detailed data-intense diagnostics for event diagnosis and analysis, distributed systems and the Industrial Internet are value drivers.

The simple, but very important, fundamental benefits delivered by distributed systems are reduced wiring content along with lower installation and maintenance costs.

Considering the distance between sensors and a centralized system can reach hundreds of meters, considerable material and labor savings for these installations are realized by moving the system to the equipment skid. Less wire, shorter runs and fewer opportunities for inadvertent failures from destruction all contribute to lower installation and operating costs.

The continuing development of distributed condition monitoring and protection systems deliver greater value to rotating equipment OEMs by reducing assembly, configuration and testing costs.

Owners and operators achieve increased value through more intelligent machine condition notifications that can result in increased availability and lower maintenance and repair costs.

Machinery diagnostics and operations are able to manage more machines more intelligently with fewer resources. And, owners and operators can realize increased availability and production from reduced maintenance and operating expenses.
Author: Tim Burgess is a marketing manager for GE’s Bently Nevada asset condition monitoring product lines, including continuous, scanning and wireless condition monitoring systems, and distributed protection platforms.

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