Debmarine Namibia mines for diamonds off the southern coast of Namibia and currently owns, operates and maintains five marine diamond mining vessels. Debmarine Namibia contracts De Beers Marine South Africa (based in Cape Town) to provide specialist technical engineering project support services on the vessels during scheduled vessel maintenance dry docking in the Cape Town harbour. De Beers Marine South Africa elected to further subcontract the Yokogawa DCS, over several competitor systems, as the core control platform which communicates to numerous dedicated OEM and automation equipment. The choice was based on the faultless performance of the system under harsh operating environmental conditions, as well as the low cost of ownership to the client who also benefited from Yokogawa’s long term migration policies.
Solutions and technology
The DCS is responsible for the control of mining and plant equipment, and the monitoring of various other systems. The means of communication is a combination of Hardwire, Modbus and Profibus DP signals. The preferred interface is a distributed Profibus DP digital network with remote nodes to reduce wiring. The mining control comprises the control of a rotating drill bit 6 metres in diameter at 120 metres below the surface connected to a series of pipes known as the string. Once the drill is on the seabed it drills for approximately five minutes and is then lifted while the vessel shifts position. Whilst drilling, the gravel is sent up the string and through a processing plant comprising scrubbers, screens, ball mills, density change circuit, driers and finally X-ray machines.
The majority of all the electrical motors are controlled and managed with intelligent Profibus DP starters and variable speed drives. A universal control block was developed for the intelligent starters and variable speed drives, which is used across the fleet. This involved the interaction of the De Beers’ electrical department to develop a control block that met the specified requirements. Once this was developed, thorough verification was done, prior to implementation, on a test phase with all relevant inputs.
Upgrade
Yokogawa performed an upgrade of the current Centum CS3000 and Exaquantum software to the latest Centum VP software, as well as upgrading VNET network to Vnet/IP. All PCs are housed in an environmentally controlled and secure location. The challenge faced by Yokogawa was to execute the project during the short dry dock window. With Yokogawa’s excellent project management skills, planning and execution, as well as continuous communication and liaison with De Beers, it achieved on-time execution and completion of the project within budget, and to specification. In the period between June 2013 and December 2014, a total of three Debmarine Namibia Mining vessels and one De Beers Marine South Africa vessel were upgraded, with the remainder to follow.
For more information contact Christie Cronje, Yokogawa South Africa, +27 (0)11 831 6300, [email protected], www.yokogawa.com/za or Stella Auala, Debmarine Namibia, +264 (61) 297 8643, [email protected], www.debeersgroup.com
| Tel: | +27 11 831 6300 |
| Email: | [email protected] |
| www: | www.yokogawa.com/za |
| Articles: | More information and articles about Yokogawa South Africa |
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