Rockwell Automation Delivers SIL II Compliance for SAPPI Plant Burner Boxes

Rockwell Automation provided a ControlLogix-based SIL II compliant burner management system solution for SAPPI’s Chemical Recovery Furnace.

In a first for Rockwell Automation South Africa, its SSB division successfully upgraded the burner management system (BMS) at SAPPI’s Ngodwana Mill’s chemical recovery plant in Mpumalanga to SIL II standards using its ControlLogix controllers and I/O modules. The scope of work was to change out the hard-wired BMS to a ControlLogix BMS that complied to SIL II requirements for SAPPI’s chemical recovery furnace – essentially upgrading SAPPI’s BMS to a safer system.

The scope included delivery of the architecture, the hardware, and software combined in a single package format with a customisable configuration to integrate it with the rest of SAPPI’s plant’s system. To achieve this, SIL II certified scalable control modules were used with standard ControlLogix hardware deployed in a SIL II configuration and architecture.

International collaboration with Rockwell Automation in the UK and France was required to confirm that the project complied with all SIL II standards and requirements. “We used standard SIL II certified blocks within the software architecture,” explains Gareth Freese, Project Engineer, Rockwell Automation and technical lead for this project. “This meant that various control modules, programming blocks, and engineering tools were used to develop the system. The result, from a software perspective, is a well-organised and elegant architecture.”

PanelView Plus 7 graphic terminals with dual Ethernet ports, incorporating high levels of integrated diagnostics, were used for operator interfacing and fault finding on each of the four burner boxes. The visualization of the entire start-up process allowed operators to follow it top down, left to right. The software architecture, along with the SIL II combined control modules, interfaces to the rams control module standard using the conventional ControlLogix equipment. This interface is necessary to deliver a fault tolerant system.

To help ensure the upgrade to the safer system was in check, Rockwell Automation used intrinsically secure digital input modules to help ensure the gas lines were all fundamentally safe.

As far as the Ethernet network was concerned, the SAPPI system has separate LANs that now run on a device level ring topology to provide a level of network resilience and help ensure that all systems are on a functionally safe network. To provide communication to the existing distributed control system (DCS), Rockwell Automation provided seamless integration into the system via Ethernet cards, granting SAPPI the ability to view the Rockwell Automation DCS on the Programmable Automation Controller (PAC).

“The customer approached Rockwell Automation because of our domain expertise in that specific area, as well as our high level of standards and delivery procedures that assist customers with a complete project lifecycle delivery,” Freese points out. “We provided a solution for the burner management system on a standard ControlLogix platform with an integrated architecture that complies with SIL II – a first for Rockwell Automation locally,” he reiterates.

The completion of the project needed to be within a compressed time frame to meet the deadline for SAPPI’s Ngodwana Mill plant’s annual month-long shutdown in May. The SAPPI order was placed with Rockwell Automation at the end of December 2016, literally the last day of the year, with Freese and his team beginning work on technical delivery in mid-January 2017.

All equipment, including panel assembly, was constructed within a month, which was necessary as Rockwell Automation had to carry out on site work during the annual plant shut, which sees approximately 1 500 personnel and contractors onsite. The project team leveraged additional staff from Rockwell Automation SSB – the projects division, and CSM – the aftersales and support division to address the condensed timeline and challenging environment.

Installation, pre-start-up commissioning, fine-tuning and monitoring was completed by 20 May, after which live commissioning, and production testing followed. Additional fine-tuning meant a slightly longer production testing time, which resulted in the monitoring period being completed in mid-June.

“Our team ensured that we were able to deliver the full high-quality solution in a greatly reduced turnaround time by providing exceptional all-around service,” Freese concludes. “This commitment has already resulted in repeat orders from SAPPI.”

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