For an international oil company, KROHNE manufactured an unique, vertically constructed, fiscal metering system. The design of the metering system is unique due to vertical installation of the metering lines and due to the fact that the Ultrasonic flowmeters will be directly calibrated against a Small Volume Prover. The metering system is equipped with 4 highly accurate ultrasonic ALTOSONIC 5 flowmeters. They are used to perform fiscal measurement of crude oil during batch loading to tankers from an offshore submerged caisson of 48,000 m³ storage capacity. This project combines three unique features and capabilities:
1. Construction of a vertical custody transfer measuring skid with vertically installed ALTOSONIC 5 ultrasonic flowmeters,
2. Initial vertical calibration of the ALTOSONIC 5 ultrasonic flowmeters using Master Meters.
3. Vertical verification of the ALTOSONIC 5 ultrasonic flowmeter against a Small Volume Prover.
The custody transfer ALTOSONIC 5 ultrasonic flowmeters have been manufactured at the KROHNE production facility and are compliant with the NPD (Norwegian Petroleum Directorate) quality standards. To ensure and confirm equipment’s performance, the customer requested the flowmeters to be calibrated in a vertical position at the EUROLOOP facility in Rotterdam. The flowmeters were calibrated over the applicable Reynolds range of approximate 80.000 to 1.000.000 at 5 flowrates with 5 repeats using the EuroLoop Master Meters as a reference. The calibration results were compliant to the customer’s requirements defined as:
- Performance band : ± 0.15 percent over its full operational flow range
- Uncertainty: 0.027 % following API standards.
In the oil and gas industry, ultrasonic technology is adopted as an alternative for turbine- and positive displacement meters, offering additional features like viscosity independency and extended diagnostic features for continuous monitoring of the flowmeter and the process. In the last decade, KROHNE has tested various Small Volume Prover types and gather a lot of data which has helped to design enhanced electronics. The ultrasonic flowmeter equipped with modern UFC5 electronics has much faster sampling time, enhanced filtering and algorithms; these improvements have led to increase significant the repeatability performance.
During each batch loading the KROHNE ALTOSONIC 5 ultrasonic flowmeters will be offshore calibrated against the Small Volume Prover. For confirming the compatibility of the ALTOSONIC 5’s in combination with the specific used 151 liters Small Volume Prover, several proving runs were performed at the EuroLoop facility, using 5 runs with 3 to 5 passes per run. With astonishing pass times even up to 0.65 seconds at the maximum flow rate of 840 m³/h also API uncertainty of 0.027% was still made. The calibration results were concluded to be in compliance with the customer requirements.
From EuroLoop facility, the ALTOSONIC 5 ultrasonic flowmeters, the Small Volume Prover and the monitoring system cabinet have been transported to the KROHNE facility in Dordrecht, in the Netherlands. Here, a full system functional and accuracy flow test has been performed, witnessed by again the customer. To produce the flow through the metering skid two big water reservoirs in combination with a centrifugal pump were installed reaching a maximum flowrate of 850 m³/h.
After finishing the tests, the metering system was drained and thoroughly dried with warm dry air to protect the system against corrosion. For transportation the skid to the end destination, it has been disassembled in multiple large parts, wrapped in shrink foil to protect components against transport damages. From the Dordrecht KROHNE facility the skid parts was loaded on a barge/boot on its way to the customer for final installation.
All information about ALTOSONIC 5 at a glance: https://krohne.com/en/products/flow-measurement/flowmeters/ultrasonic-flowmeters/altosonic-5/