Laboratory and field validation of a new Coriolis metering concept for better measurement uncertainty, reliability and process insight

Coriolis mass flowmeters are widely accepted in various industries for their high performance measurement of density and mass flow rate. Not only do they play a critical role in O & G custody transfer applications, they are also increasingly important in addressing the new challenges and applications related to the energy transition where the highest accuracy and reliability is also required. Analogous to multi-beam Ultrasonic flowmeters, a new measuring concept based on the Coriolis principle has been developed with a metering system consisting of two individual Coriolis meters arranged in parallel to measure the incoming flow into the overall system. There are numerous advantages of this arrangement, among which reducing measurement uncertainty, increasing reliability and gaining greater process insights are the most significant addressed in this paper. Statistic theory suggests that for a total measurement equally divided by two sub-measurements of two independent measuring devices, the measurement uncertainty caused by random errors is reduced by a factor of the square root of 2 for the combined total measurement if the two sub-measurements are not correlated. This advantage applies to the zero-point and repeatability performance of the metering system. Taking advantage of independently measuring the same or similar fluid parameters twice, the measurement reliability is enhanced by cross-checking the two sets of measured parameters. For certain special cases, such as the transient disturbance caused by entrained gas that often exists under real process conditions, the corresponding negative impact can even be mitigated or eliminated by utilizing the undisturbed measured parameter set from the two. The spacial arrangement of the two Coriolis meters makes it useful to monitor the measured fluid parameters such as two sets of density, flow and temperature values to obtain additional knowledge of the spacial distribution of these fluid parameters, which can provide greater process insights.A critical step has been the validation of the theoretical advantages in third-party laboratories and in the field. A test was done for the zero-point stability of the metering system under various temperatures, pressures and viscosities at NEL using the EPAT facility. The measurement results suggested that the zero-point deviations of the two Coriolis meters followed a random probability and tended to cancel each other to certain degree, leading to a reduced zero-point deviation for the complete metering system. Repeatability and reproducibility tests conducted both at NEL EPAT and at Euroloop oil rigs with provers, showed good and consistent results. Recognizing most hydrocarbon markets trade on a volumetric basis rather than mass, the advantages the design brings towards density measurement are discussed and measurement data is presented across varying fluid densities and viscosities. In step with the growing importance of gaseous fluids associated with the evolving energy markets, the influence the novel design has on performance in gas applications is described and measurement data in gases is also presented. Furthermore, an interesting phenomenon has been captured during the flow stabilization phase before proving at Euroloop that transient disturbance of gas bubbles could be present, and very often disturbed only one of the two measuring systems at the same time, which enables the possibility to remediate the effect of transient disturbances. The same phenomenon was observed in field tests of this novel metering system, indicating the high probability of the occurrence. In this paper, the laboratories data from the NEL EPAT rig, Euroloop rig, pigsar rig, and H & D Fitzgerald as well as the data from field applications are pre-sented and analysed to validate the theoretical analysis.

Automated summary

Coriolis mass flowmeters are widely accepted for their high performance measurement of density and mass flow rate. A new measuring concept based on the Coriolis principle utilizing two parallel meters has advantages in reducing measurement uncertainty, increasing reliability, and gaining greater process insights.