Safety controllers added to ethylene plant

Shell's Moerdijk has been revamped, which involved replacing the old safety equipment with 17 safety-related H51q controllers made by HIMA Paul Hildebrandt.

Shell's Moerdijk facility in the Netherlands is one of Europe's most important production sites for ethylene and related products.

The plant has been revamped, which involved replacing the old safety equipment with 17 safety-related H51q controllers made by HIMA Paul Hildebrandt.

The HIMA safety systems are coupled to the Yokogawa process control system via Modbus TCP, providing extremely fast data transfer.

The great benefit of this method of communication is that it enables the use of network components that are now standard, such as switches and Ethernet network cards.

These in turn allow data rates around twenty times higher than previously possible (10 MBit/s).

The HIMA delivery included safety-related controllers, project management for the systems, the engineering of the hardware and software, and on-site support.

The failsafe, SIL 3-certified H51q systems meet Shell's high standards of reliability and availability.

The primary task of the redundant SIL 3 controllers is to shut down critical sections of the plant (ESD = Emergency Shut Down).

They are also used in FandG (fire and gas) applications and BMS (burner management systems).

The 17 HIMA systems handle around 2500 safety-related signals.

Four of the H51q controllers are used to monitor one medium-pressure and three high-pressure boilers.

Seven other systems monitor the ethylene plant's 18 cracking furnaces.

The remaining six controllers are employed in a butadiene recycler, a hydrotreater, a storage unit and two other units.

In this project the H51q systems were fitted with the new CPUs, which enable self education in redundant systems.

When a CPU is replaced - which can be done while the plant is running - data and programs are automatically imported into the new CPU, which makes handling easier and avoids errors.

The system as a whole fulfils the requirements of SIL 3, even during replacement.

Another advantage of these CPUs is their reload function, which enables programming changes without stopping the system.

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