Monday 30 September 2013

Enhanced safety system for Oil & Gas

Yokogawa Electric Corporation has released an enhanced version of the ProSafe®-RS safety instrumented system and the addition of a new function to the DPharp EJX multivariable transmitter. The new ProSafe-RS version, R3.02.10, offers improved functions for upstream oil and gas, which is one of Yokogawa’s core markets. The DPharp EJX multivariable transmitter has been enhanced to improve connectivity with ProSafe-RS.

In upstream oil and gas processes, there is an ever-pressing need to prevent accidents and protect the environment. Accordingly, there is a growing demand for safety instrumented systems that can detect abnormal conditions and safely initiate emergency shutdowns. However, wells and pipelines are typically distributed over a wide area and often have limited space for the installation of equipment. To improve operational efficiency and reduce hardware costs, there is a need to consolidate the functions performed by control and safety instrumented systems. In response to these needs, Yokogawa is releasing a new version of the ProSafe-RS safety instrumented system and has enhanced the DPharp EJX multivariable transmitter.

New developments and enhancements include AGA (American Gas Association) gas flow rate calculation, Modbus communications between DPharp EJX and ProSafe-RS for gas flow rate calculation, and support for the wide variety of networks used in oil and gas upstream applications.

To monitor and control gas wells and pipelines, gas flow rate compensation is required. The in-situ gas volume needs to be compensated to a standard volume because the gas volume rises or falls significantly depending on the process temperature and pressure. This compensation is usually carried out by a control device or dedicated flow computer. For customers in regions such as the Americas and the Middle East who wish to eliminate the need for such dedicated devices, Yokogawa has incorporated a gas flow rate calculation function in ProSafe-RS R3.02.10. Thus ProSafe-RS, which is certified for use in SIL3 applications, is now suitable for use both in safety instrumentation and monitoring & control. SIL is a standard relating to the functional safety of electrical and electronic equipment that was established by the International Electrotechnical Commission (IEC). Safety integrity levels (SIL) are defined by the IEC61508. At SIL3, the risk factor for a plant where safety measures are not in place has been reduced to a range from 1/1000 to 1/10000.

To compensate the gas flow rate, differential pressure, static pressure, and temperature must be measured. The DPharp EJX multivariable transmitter is a sensor that can measure all three of these variables. As the Modbus protocol - an industrial communications protocol developed by the US company Modicon (now owned by Schneider Electric) - is widely used in upstream oil and gas processes for communications between sensors and gas flow rate compensation devices, Yokogawa has added Modbus protocol support to the DPharp EJX multivariable transmitter. This sensor can thus be used together with ProSafe-RS to perform highly reliable and accurate gas flow rate calculations.

A variety of networks are used to link ProSafe-RS at the site to the Yokogawa FAST/TOOLS SCADA system. Some networks use high-bandwidth optical fibre, while others rely on low-bandwidth wireless links. By optimising the frequency of data collection and the volume of transmitted data, ProSafe-RS R3.02.10 can now link up with other systems using low-bandwidth media. This improves maintenance efficiency by enabling remote engineering. Essential data is stored on the ProSafe-RS controller, ensuring continuity in the event of a network failure.

Major target markets and applications include emergency shutdown and fire prevention/suppression, production, and other applications in process industries such as oil, natural gas, and petrochemicals.

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