Author: Khadra Helminski
Emerson’s Trilochan Gupta shared a case study with the readers of Hydrocarbon Processing magazine. The article, Major refinery uses reliable fiscal metering system, describes how Reliance refinery, the world’s largest refinery located in Jamnagar, India, employed 76 large engineered Rosemount flow metering systems from Emerson to monitor oil and gas valued at US$ 20 billion annually. These integrated systems were delivered in a short span of 12 months and included over 100 ultrasonic flow meters.
Ultrasonic flowmeters were selected as the accounting meters because they can handle a wide variety of process fluids including white oil, black oil, 20 types of crude oils, refinery intermediates and end products. These fluids vary in viscosity from 1 cP to 360 cP, and they also vary in temperature.
Ultrasonic flow meters, such as Rosemount Series 3410 and 3810 ultrasonic meters, have been used in custody transfer applications for measurement of gas and liquids. These meters use an electronics platform that detect changing flow dynamics in real time to ensure flow variables are communicated in a matter of seconds, providing low-flow accuracy and linearity throughout the calibrated flow range. This accuracy is an extremely important quality, particularly because of the significant financial risks in fiscal metering applications.
Custody transfer and allocation measurements are critical at a grass-roots refinery of the size and complexity of the Reliance refinery. Flow measurement errors of only 0.2% could cost the refinery upwards of US$50 million per year.
The complexity of any refinery is defined by its Nelson Complexity Index (CI). This index is a measure of secondary conversion capacity in comparison to the primary distillation capacity. It is also an indicator of not only the investment intensity or cost index of the refinery, but also the value-added potential of a refinery. Adding up the complexity values assigned to each piece of equipment, including crude distillation, determines a refinery’s complexity based on the Nelson CI.
The Nelson CI averages 9.5 for US refiners, and 6.5 for European refineries. The Jamnagar facility has a CI of 14, one of the highest in the world. One of the reasons for the high index value is the refinery’s ability to process 20 different crudes, plus intermediates and end products.
For this reason, successful proving methods were implemented to provide field verifiable and traceable metering data.
Because of the wide variety of incoming crude and outgoing products, ultrasonic flowmeters were chosen for the metering stations. To ensure transaction repeatability of 0.05%, master meters and provers were installed on each metering skid, and the skids were provided with mobile or fixed-compact provers. There are five compact provers at the Jamnagar facility.
Proving is done in accordance with API MPMS 4.2, 4.5, 4.8 and 5.8 recommendations. Field proving of master meters is done “in situ,” meaning the prover is placed in series with the accounting metering system.
In addition, the article highlights the critical aspects, beyond the hardware, that make for an optimal fiscal metering system and an accurate product flow. Custody transfer applications require more than simply an accurate flowmeter. A vast amount of specific application knowledge is needed, including an understanding of government regulations, flow characteristics, flowmeter specifications, metrology and mechanical installation standards, calibration, automation, quality control and testing, start-up and a commissioning, and a host of other factors.
For these reasons, one of the important key elements to reduce project risk was to have one automation supplier responsible for the complete fiscal metering solution and measurement sustainability throughout the lifecycle of the system. Performance results from the refinery show it has been operating at near 100% capacity with minimal downtime since it began operation in 2008.
Proven results. All key processing units are operating close to, or at, their respective design capacities. The support units and utilities are fully operational, and the refinery has been operating at near 100% capacity with minimal downtime since it began operation in December 2008.
Given the refinery’s unprecedented size and scope, high level of processing complexity, the various system design permutations and combinations, and the requirement to equate each option according to cost and value—this was a particularly difficult application for flowmetering. More than 100 ultrasonic flowmeters have proven their ability to measure a wide range of fluids across this refinery, and the fiscal metering skids have met all regulatory requirements.
For guidance on how to size an ultrasonic meter, download your complimentary copy of the gas and liquid ultrasonic meter sizing software. Designed with accuracy in mind, the software will indicate if a parameter is outside of the recommended range for the intended application. The software also provides a final report that can be used as a guide. In addition, the tool is designed for international use and includes local units of measure, as well as links to a variety of technical documentation.
If you have custody transfer applications in your plant and you’re not already an expert on the subject, you will want to also read this article highlighted in an earlier post, Custody Transfer Flow Measurement.