Vortex meters on steam eliminate need for cleaning

Rosemount vortex flowmeters installed for steam line monitoring at major Shell Chemicals ethylene plant eliminate need for monthly cleaning, and demonstrate improved measurement reliability

Vortex flowmeters from Emerson Process Management have improved the reliability of steam measurement for the Shell Chemicals ethylene plant in The Netherlands.

The Rosemount 8800CD dual vortex meters provide two flow measurements on the main steam lines, one for plant process control plus another separated measurement for the plant safety instrumented system (SIS).

For Shell, the Rosemount vortex metering technology delivers more reliable steam flow measurement, enabling better operation and helping to increase plant uptime.

Further, the plant operators have a better, more accurate steam flow measurement, which allows them to optimise production performance.

Shell Chemicals at Moerdijk has one of the largest ethylene plants in Europe: this naphtha cracker process mixes accurate proportions of Light Distillate Feedstock (LDF) - such as naphtha or ethane - and steam, and heats these to a high temperature in a furnace: this cracks the LDF into basic feedstocks like ethylene for use in downstream processes, but also creates some carbon and coke deposits which are re-circulated with the process water.

Such particles, when recycled in the steam, had created a maintenance requirement for the previous DP based steam flow measurement systems, by blocking the impulse lines to the transmitters.

A monthly schedule of cleaning each flowmeter had been established to overcome this problem, to remove these deposits to ensure measurement reliability.

The Rosemount 8800CD vortex meter sensor has an all-welded body design, with no crevices, process seals or pockets where particles might collect.

In addition, as a dual sensor unit, the 8800CD provides two separate flow measurements, enabling one sensor to provide the process control signal, and the other to be used in the SIS loops, based on the FMEDA assessment of the Rosemount vortex sensor technology.

Shell engineers undertook a three month trial with a Rosemount 8800CD on one furnace line, which provided reliable measurement with no problems and no cleaning required.

Following the success of this trial all twenty furnaces were scheduled to be equipped with the Rosemount dual vortex measurement systems.

The first eight furnaces have now been in operation for over two years.

During this time none of the units have had to be removed as a result of any need for cleaning.

The Rosemount vortex flowmeters are part of the Emerson broad range of intelligent, digital field devices that power the PlantWeb digital plant architecture to improve plant efficiency by 2% and more through delivering asset optimisation, process automation, and management execution.

Further cost savings, increased plant availability, and enhanced safety and environmental compliance are achieved when the level transmitters are integrated into the PlantWeb architecture.

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