RCL Foods’ Pongola sugar mill is situated in northern KwaZulu-Natal and was operating a proprietary DCS that was installed in 1980. This obsolete and antiquated system resulted in unacceptable production delays due to excessive downtime, aggravated by a lack of production information and limited diagnostics.
The client requested Control Software Solutions (CSS) to institute a phased-in system that would allow the RCL team to run the plant with minimal support. In addition, it needed to be scalable, it had to provide detailed trip diagnostics and sufficient production information to ensure the optimisation of the process by process engineers, as well as being equipped with an effective disaster recovery plan. “It was essential that there was an adequate knowledge transfer to the RCL employees to ensure that they could take over the running of the system, allowing them to maintain and expand it as needed in the future. Aligned to this was the requirement for the system to provide a 25% improvement in lost time availability, together with an increase in production throughput,” says CSS’s Pieter Venter.
Scalability was a driving factor, since the project was planned to take place in various phases over an eight-year period. A number of other requirements outlined by RCL included the improvement of software standards with additional functionality in terms of industry-specific control modules; a user-friendly interface; redundancy in order to secure plant control and information; and intuitive reporting that was easily accessible and with traceability throughout the system.
The solution provided by CSS included System Platform, which would unify all of RCL’s applications and its management in a central hub and InTouch for supervisory interface, together with Historian for data storage and Historian Client for system diagnostics and production analysis. WIS and FLOW software is used for production efficiency reporting, TOP Server provides device connectivity (including for legacy systems) and Unity allows for all PLC configuration. Systems diagnostics and first-up alarming was built into critical control areas of the plant to assist in root cause analysis. In addition, the project team had to develop and document the plant control philosophy from the existing software and old plant manual, as this did not exist.
Once control documentation was finalised, all software coding was performed off site with regular remote collaboration taking place with RCL systems and operation personnel. Technical review meetings ensured the alignment with customer expectations and the CSS solution. Full system simulation was natively built into the system to assist during the FAT testing, which was conducted with the entire team from RCL’s operations, training, maintenance and systems departments. Plant operators were trained in the simulated environment, thereby allowing them to become a part of the commissioning team with a resultant reduction in the time to start-up.
Not only was there a requirement for a new system, but furthermore for old data on the existing system to be transferred to this new system. CSS used the TOP Server OPC DA Driver to extract the legacy data, thereby allowing them to present unified reports on information from both the old and new systems.
The implementation of the new system has contributed immensely to the extremely attractive statistics between 2015 and 2017:
• 40% improvement in lost time availability.
• 20% increase in cane crushed vs budget.
• 39% increase in sugar production vs budget.
• 0,7% reduction in bagasse moisture to boilers.
• Almost zero unplanned blackouts.
“There was a visible improvement in the working relationship between the production and maintenance personnel. All the noted benefits contributed to the plant being awarded two improvement awards from the RCL Group In 2017,” says Venter.
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