Custody transfer gas measurement: Modernization of the SGI gas pipeline interconnection point
Natural gas is a fundamental resource which plays a crucial role within Italian energy systems. It is for this reason that the modernization of the installations and infrastructures dedicated to its transport and distribution is becoming strategic. The Società Gasdotti Italia S.p.A. (SGI) partnered with SICK for the modernization project of the complete fiscal measuring system of the natural gas interconnection point of Castel Di Ieri (AQ) successfully.
Società Gasdotti Italia (SGI) is an important operator for the transport of natural gas through a grid of high-pressure methane pipelines with a length of approximately 1,550 km. The company was founded in December 2004 from the merger of the companies Edison T&S S.p.A. and its subsidiary SGM S.p.A.. In September 2016 it came under the ownership of Macquarie European Infrastructure Fund 4 and Swiss Life GIO II EUR Holding.
Technical innovation of the measuring system
The Castel di Ieri interconnection point at Avezzano, in the province of Aquila, is one of the entry points of the SGI grid which allows natural gas to be transported to various areas in the regions of central Italy such as Abruzzo, Marche and Lazio. The gas comes from the main ridge of the SRG pipeline and is fed into the Control and Measurement cabin of Castel di Ieri. Here the gas is first filtered, then measured fiscally and subsequently controlled with regard to pressure and flow rate in relation to the quantity of gas which the SGI dispatching service manages. The main requirement of SGI was to increase the flow capacity from 150,000 Sm3/h to 350,000 Sm3/h.
Conventional mechanical solutions (turbine meters) were replaced by ultrasonic flow meters. The new meters permit an improved measurement performance, especially at low flow rates, increasing the flow range from a Qmin/Qmax ratio of 1:20 (typical capacity of a turbine meter) to a Qmin/Qmax ratio of 1:185 (capacity of SICK ultrasonic meters).
SICK as technological partner
Although the project execution time was a very ambitious objective, SICK, thanks to the competence of the Customer Project Management division and close collaboration, ensured that the schedule required for the commissioning of the gas metering system was met. SGI’s interconnection point at Castel di Ieri now consists of a measuring system with two independent lines with a bypass. The measuring chain consists of a flow computer, a temperature transmitter, a pressure transmitter and the primary ultrasonic flowmeter for each line.
The innovative primary flow meter ist he FLOWSIC600-XT Forte. In addition to guaranteeing a very high level of accuracy, in accordance with the latest OIML R 137 2012, Class 0.5 standards, the meter is equipped with Power In Technology™. This sophisticated integrated backup battery system permits the fully autonomous measurement of gas in the event of a power failure for up to three weeks.
The uncompensated volumes (Vm) precisely totaled by the FLOWSIC600-XT Forte are transmitted by means of a high-precision, high-frequency pulse signal to the EVC (Electronic Volume Converter) flow computer. The EVC receives pressure and temperature values from the integrated sensors and converts the volume of gas into volume at base conditions (Vb). This is then returned to the thermodynamic reference conditions. The performance of the measuring system is constantly controlled by the advanced diagnostics of the FLOWSIC600-XT that allows operators to take prompt action in case of system issues.
SICK's solutions for fiscal measurement of natural gas include the supply of individual components or integrated solutions, depending on the customer's specific requirements. Thanks to its wide range of services, extensive knowledge of the application, product and associated system, project management competence and high level of technical support, SICK has proven to be a reliable partner at all times.