Flow Metres: Taking out the guesswork
Temperature and flow meters play an important role in maintaining smooth operations throughout the refining and petrochemical cycle. We look at how smart design and automation can improve efficiency and lower operational cost
Fluctuations in gas pressure and temperature tend to be extremely problematic for refineries and petrochemical plants. According to some estimates, as little as 0.1% metering error in a single transfer line could cost operators a staggering $50,000 per year.
“Achieving an efficient and reliable measurement depends on several factors including measurement technology, fluid quality, rate of production, operating conditions and process complexity,” says David Fisher, flow solutions advisor at Emerson Process Management.
According to Fisher, most problems occur when wrong measurement instrumentation and flow meters are used for a particular application, since this impacts the accuracy and certainty of such technologies.
“In addition, poor maintenance practices, along with less skilled operators who execute them, lead to expensive operational costs,” he said.
Measurement inaccuracies and ambiguity over reserve volumes are growing concerns for brownfield operators in the Middle East, according to Jasmit Bhansali, divisional manager, Alderley Metering Solutions Middle East. “Since flow rates shift during a plant’s lifetime, original metering systems on brownfield sites may no longer be fit for purpose. Meters tend to perform better when dealing with flow rates at the higher end of the spectrum for which they are designed. So as production rates decline, they are likely to have diminishing performance from a metering uncertainty perspective.”
Good oilfield practice dictates that when the operating range changes, a review should be undertaken to ensure the existing metering system remains suitable, Bhansali says.
“Repeated system failure or poor performance in audits usually indicates that urgent attention is needed. However, selecting the most appropriate course of action is not a simple task. Practical challenges are compounded by the fact that original sales agreements need to be considered. These contracts often involve measurement principles that don’t dovetail with today’s best available technologies.”
“Intelligent, risk-based decision-making is the cornerstone of best practice in this scenario. This can be facilitated by a front-loaded strategy led by metering solutions experts. One way to mitigate the risks of measurement inaccuracies is by implementing flow metering systems with diagnostics and optimisation, specifically designed to help operators achieve accurate flow measurement and sustained meter performance,” Bhansali suggests.
Fisher agrees and claims advanced sensors, equipped with predictive intelligence, unlock more process information and therefore provide better insight into the operations. “Diagnostics enable operators to quickly identify measurement uncertainty and detect potential problems. Adopting best maintenance practices, including proving and calibration, ensures that the technologies are working within designed tolerances. This safeguards ongoing meter accuracy and repeatability, reduces operational cost, minimizes troubleshooting, and provides improved production visibility.”
More often than not there is a direct correlation between the smooth and uninterrupted functioning of equipment and unplanned shutdowns or plant downtime.
“The main objective of a measurement system is to provide precise, reliable, and traceable measurement of the product continuously,” advises Fisher.
“A well-performing flow metering system maintains its specified accuracy, is compliant with industry standards and regulations, provides fluid composition, and ensures sustainable measurement between proving and calibration cycles. Meters that cause downtime and unplanned shutdowns are those that do not provide insight into the system health, are not capable of issuing actionable alerts to operators, are not designed for fast troubleshooting, and cannot support Root Cause identification.
Among the latest trends in flow meter automation and remote control is the requirement for efficient and fast integration from multiple vendors, says Fisher.
“Customers are standardising and integrating their systems and work practices to lower project risk, meet aggressive targets, and improve capital efficiency. Moreover, many projects today involve the implementation of large-scale remote automation of flow metering systems. The goal of these projects is to have a production-wide access to critical information regarding field equipment health, process unit diagnostics, optimisation opportunities and resource utilisation.” With innovation and smart product development part of its DNA, Emerson has developed a number of new technologies to optimise instrumentation and measurement systems.
“We are seeing an ever increasing adoption of SMV or Smart Meter Verification, the unique technology in Emerson flow meters that can perform self-check on the integrity of the flow tubes, sensors, and components without the need to remove the meter or interrupt the flow measurement, significantly reducing maintenance costs,” said Fisher.
Safety is another crucial aspect of flow measurement, monitoring and control. Fisher explained: “An industry survey indicated more than 60% of all safety incidents occurred during reactive maintenance. Reliable flowmeters minimise the exposure of personnel to safety risks in doing manual checks in the field.”
On top of having the right technology, it is essential to implement a Best Practice Program that quantifies and optimises the performance of the installed meters, says Fisher. “This will not only help operators ensure measurement system accuracy, but reduce process variability as well.”