Coriolis Flowmeters An Italian Refinery Uses Emerson’s Micro Motion Coriolis Flowmeters for Fiscal Measurement
Oil and gas producers, processors and shippers need to accurately measure product flowing into and out of their operations. These measurements are critical because they have a direct impact on profitability. Under-measure and you could be giving away valuable product. Over-measure and you may short-change your customers, damaging your reputation. There may also be tax or accounting implications for improper or inaccurate measurement.
Because of this, measuring mass flow to obtain accurate results in fiscal metering applications is becoming more common. This is especially true for applications involving large quantities, such as the loading and unloading of road tankers and ships. Companies are adopting innovative metering solutions that not only help ensure accuracy, consistency and reliability, but also are fully compliant with current legislation.
To upgrade fiscal measurements at its Falconara Marittima refinery on Italy’s Adriatic coast, API SpA installed an Emerson Process Management metering system based on Coriolis mass flow measurement. The installation has greatly increased the fiscal metering accuracy at the tanker terminals, as well as improving the operation’s overall equipment effectiveness (OEE).
Measuring Level is Not Enough
The sea tanker loading terminal at the refinery discharges hydrocarbons from large storage tanks to waiting tankers. Quantities were previously calculated by using the latest level measurement technology to monitor tank levels. However, API calculated the average error at 0.5 percent — a figure deemed to be unacceptable given that it directly affected both taxes paid and profit margin.
API therefore asked Emerson Process Management to provide a turnkey metering solution that would increase the accuracy of fiscal measurement at the tanker terminal. Emerson provided a metering skid based on Micro Motion Coriolis mass flow meters. The skid was provided complete, requiring only that API construct a base and connect the inlet and outlet manifolds. Emerson provided the design paperwork and certification, plus technical support through every phase of the project. Emerson liaised directly with the Italian government’s Metric Office, who verified that the measurement accuracy complied with the relevant legislation.
Coriolis for Accuracy
The measurement system skid includes both a duty and a master meter. The master meter has a greater accuracy than the duty meter and is used as a reference point to calibrate and check the performance of the other measurements being taken. The master meter is a Micro Motion ELITE, which offers ±0.05 percent accuracy over a range of 20:1. An advantage of using Micro Motion meters is that they were certified by the Metric Office in 2001 and have subsequently been approved without reserve by the Customs and Excise department. The full range of Micro Motion ELITE meters are also certified under the EU’s new MID (Measurement Instrument Directive).
There are several advantages in using Coriolis flowmeters on a fiscal application. First, since they measure mass and not volume, the accuracy of the results is not affected by environmental influences such as temperature.
Using temperature measured by an external RTD, the Coriolis flowmeter can also convert the mass reading into a standardized volume. This is important when measuring gasoline, kerosene and other light products, which are often sold by volume.
Other advantages include the fact the meters perform better with entrained gas, which can reduce the apparent density of the liquid. The meter can also measure flow in both directions. Together, these characteristics eliminate the need for bidirectional manifolds, motor-operated valves, strainers, and air eliminators. Lastly, Coriolis flowmeters do not need any straight pipe runs to condition the flow before and after the meter. All these factors mean that the skid can be more compact.
Measuring the Benefits
- Availability: Micro Motion Coriolis devices are extremely reliable and require minimal maintenance. The presence of a master meter on the skid further increases availability by allowing the other meters to be calibrated without interrupting operations. Using valves, the skid can change to a “pay and check” mode for redundant measurement, or to a “duty and master” mode, where the master meter audits the duty meters. The master meter itself is calibrated periodically at one of Emerson’s calibration centers, but there is no need to halt operations whilst this takes place. These benefits increase availability by ten percent.
- Quality control: Micro Motion Coriolis devices provide an accurate measurement of density, which can be used to check the quality of the product. Contaminants such as water, if not identified before delivery, can lead to costly complaints from the buyer.
- Productivity: the increased accuracy of Micro Motion meters helps to ensure that the specified amount of product has been loaded or unloaded. For fiscal applications their accuracy is +0.2/–0.3 percent, so 20,000 t of diesel as measured could give rise to an error of 60 t. For the same operation, a traditional flowmeter with an accuracy of ±0.5 percent could produce a maximum error of 100 t.
As a result, API says its overall equipment effectiveness (OEE) — the product of availability, quality and productivity — has increased by around ten percent.
In addition, the reliability of the Micro Motion instruments and the integrated structure of the skid have helped to reduce the cost of maintenance to almost zero. The running costs, including power and utilities, spare parts management and personnel costs have also been minimized. Overall, operating costs have been reduced by at least 50 percent.
The solution is extremely user-friendly for operators and has simplified procedures for fiscal declaration. It has also made it much easier to create the documentation to accompany shipments.
API is extremely satisfied with the new metering system. The company is currently working on a project to rationalize its sea shipment procedures, and will soon install Emerson’s Micro Motion measurement systems to handle all load sizes. API is also considering Emerson for a future update of its loading bays. In this application API believes the new skid will not only reduce maintenance requirements, but lower error margins and reduce calibration requirements.