By applying today’s improved hardware and software to process instrumentation, it is possible to collect enormous amounts of diagnostic data, providing insight into the instrument itself, but also the process in which it is installed. How this works with ultrasonic flow meters is the subject of my article in the February issue of Process Instrumentation, Sophisticated Diagnostics Improve Flow Meter Performance in Challenging Applications.
The challenging application in this case is custody transfer for natural gas, and there are few situations that are more difficult. Here we must provide exceptionally high accuracy and repeatability, with variability well below 1%, across a range of flows and pressures, and in pipe sizes from small to very large. Emerson’s Rosemount Gas and Liquid Ultrasonic Flow Meters (USMs) address these challenges and provide high accuracy, extended rangeability, and advanced flow meter diagnostics—all with no moving parts—while practically eliminating pressure loss common to other types of flow measurement devices.
This advanced ultrasonic measurement technology can be applied to custody transfer, allocation measurement, check metering, leak detection, inventory control, and other applications. As the article says:
USMs using the latest designs have extensive built-in internal diagnostic capabilities, capable of diagnosing not only internal parameters, but also inferring much about the process. These diagnostics go far beyond anything that traditional technologies can see or report, so Emerson has created solutions specifically for this purpose, namely Smart Meter Verification device and process diagnostics, and MeterLink software.
So what does this mean? Normally when we talk about instrumentation diagnostics, they’re used to monitor internal functions. In today’s advanced USMs, Emerson extends those into critical aspects into the process, such that problems with the flow itself can be detected. As mentioned, these features work especially well in natural gas custody applications.
Using MeterLink, operators can monitor many variables, such as flow velocity patterns like asymmetry, and even turbulence at each of the measuring chords. With an eight-path meter, that means measuring at four points across the pipe using eight chords across the pipe’s cross section in two opposing directions for cancellation of flow effects. When the path velocity ratios change significantly from the normal flow profile and turbulence is high on one or more of the chords, it suggests some localized cause is responsible, such as upstream impediment, which could potentially affect overall accuracy of the measurement.
This is only one example of what these designs can do. The article goes into more detail on how USMs streamline calibration, guide maintenance, and add connectivity options, especially valuable for the finicky demands of custody transfer applications.
Today’s ultrasonic flow meters, with their sophisticated diagnostic capabilities working in conjunction with support platforms such as Smart Meter Verification and MeterLink, can meet these requirements on a real-time, hourly, daily and/or monthly basis.
Visit the Advanced Flow Measurement pages at Emerson.com. You can also connect and interact with other engineers in the Oil & Gas and Chemical Processing Groups at the Emerson Exchange 365 community.
