Today’s flow metering systems for petroleum products must not only precisely monitor production and transfers; they also need to provide robust data to underpin digital intelligence for improved decision-making, says Honeywell Process Solutions’ Tim Vogel.
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Ultrasonic flowmeters are a preferred technology for demanding fiscal metering applications. Images from Honeywell Process Solutions. |
Custody transfer presents unique challenges for a flowmeter application since substantial sums of money change hands based on its measurements. When metering large volumes of product even a very small measurement uncertainties can cost millions of dollars a year.
Moreover, accurate and reliable fiscal measurement not only defines the point at which ownership changes hands based on regulatory standards, but also helps maximize overall production and movement efficiency.
Until recently, operators used disparate, bespoke systems for these measurements. A fast changing and cost-constrained environment, however, means many are adopting a new approach to metering, replacing old flow computers with new, integrated automation solutions. This provides the benefits of a centralized solution, such as commonality and scalability, with improved monitoring, management and reporting processes that deliver data to the entire operation.
Integrated solutions bring a number of benefits:
Most field measurement and metering units currently monitor a single process element and present it individually. Intelligent solutions, however, integrate disparate assets throughout the process, so data is fed into a central hub where it can be utilized for highly informed production and business decisions.
In upstream operations, particularly, this data opens opportunities for enhanced operations and increased reliability through condition based monitoring and increased visibility of the downstream supply chain.
Latest metering technology
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A key advantage of ultrasonic meters is the availability of robust diagnostic information and condition based monitoring capabilities. |
The flow meter remains the central piece in this intelligent revolution, with accurate measurements essential for safe and efficient operation.
Ultrasonic meters are increasingly a preferred technology for many upstream and offshore operators, being well suited to the dirty gases often encountered. Ultrasonic meters also have negligible pressure drop, have high turndown capability, and can handle a wide range of applications.
A key advantage of ultrasonic meters over other flow measurement solutions is the availability of diagnostic information beyond just delivering pulses or signals proportional to gas volume. New ultrasonic meter designs employ electronics that optimize internal diagnostics, flow velocity calculations, signal processing, data storage, interface to flow computers and supervisory control and data acquisition (SCADA) systems, and field service diagnostics tools.
Again, this diagnostic data is particularly valuable for upstream and offshore operators: The diagnostics help to better understand the process, keeping field maintenance work to a minimum to bring benefits to both efficiency and safety.
The most advanced ultrasonic flow meters today provide stability during flow perturbations due to innovative path designs, utilizing multiple measuring paths on different levels.
Finally, ultrasonic meter designers have developed detection algorithms extending signal amplitude to effectively create a higher signal-to-noise ratio (SNR). For example, by transmitting a predefined burst signal instead of a single pulse the tolerance to signal attenuation is improved. Such innovative detection algorithms enable greater insensitivity to the noise characterizing many upstream installations.
The value of integration
Once reliable measurement data is in place, fast, smart business decisions require streamlining the data collection, validation, surveillance, and notification processes from field assets such as the flow meters. An integrated operations platform delivering both operational intelligence and field system and engineering application integration is also required.
Traditional technology assumptions that accurate, safe and reliable measurements required a separate, closed system are no longer valid. Open systems technology now provide this, as well as a wide range of additional benefits. Integrated metering solutions are therefore increasingly replacing separate, higher-cost dedicated systems. A solution that integrates the metering function into the control system architecture provides the basic answer.
Such solutions are much more cost-effective in terms of their installation and configuration, as well as their support and upgradeability over the long-term. Flow computation in petroleum facilities, for example, is traditionally handled by disparate flow computer devices, and recently also by programmable logic controllers (PLCs) and, in non-fiscal applications, “virtual” flow computers. Solutions integrated with distributed control system (DCS) platforms, however, offer significantly greater cost efficiency, extended lifecycle support, improved control and can also be approved for custody transfer making them a real alternative for all applications.
Centralized metering technology enables users to better meet regulatory requirements for fiscal reporting of carbon emissions; simplifies integration of raw meter data in accounting and reporting systems; and improves optimization control of liquid, loading and proving systems where control and sequencing-type tasks are critical. They can also benefit from flexible reporting, Web-based access, and integration with wireless and fieldbus transmitters in the metering function.
With a DCS-embedded metering solution, fiscal and allocation metering functions are integrated in robust and sustainable controls, rather than held in flow computers or dedicated metering supervisory computers. This approach utilizes a redundant process controller as the fiscal point. Additional flow computing calculations are easily configured in software, which links new instrument inputs to results.
With more functions inside the control system there is no external system and custom interface to maintain. This eliminates a separate database, configuration and graphics building effort. Fewer systems to maintain also means less training is needed.
In addition, modern control processors, and therefore the metering solution, support a wide variety of I/O, including analogue, remote, FOUNDATION fieldbus and HART. Finally, users can load ISO, American Gas Association (AGA) and American Petroleum Institute (API) calculations into the controllers and upgrade them to easily keep up with changing business and regulatory requirements.
Conclusion
By integrating fiscal flow measurements and centralizing the calculations, data becomes more accurate, more manageable, and ultimately more transparent to operators, partners, and regulatory authorities. Integration with the DCS platform also allows for advanced database maintenance, graphics building, trending, management reporting and Web-based intranet access.
Petroleum-based products have always been precious commodities, but today’s business outlook makes accurate measurement of production values and product custody transfers all the more critical. For offshore, as for onshore, new ways to use digital intelligence from these fiscal metering systems will become increasingly central to the faster and smarter decisions businesses need to succeed.
Tim Vogel is product marketing manager – gas metering, Honeywell Process Solutions, and has been with Honeywell for nine years. He holds a Master of Science from the Technical University Mittelhessen, Germany, which focused on business process management and a Bachelor of Business Administration and engineering with a major in mechanical engineering.
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