Coal Age

DEC 2014

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cesses — of which grinding and flotation have been the most successful. "Another paradigm shift we've seen in the industry is the use of remote Web access to provide an increased level of collaboration. This has led to the enhanced support of automation sys- tems, as well as enabling real-time moni- toring of mining and processing equipment," Jonas said, adding, "remote support centers and virtual centers allow geographically distributed experts to act as a central support center. "These help customers achieve a higher implementation rate and provide better support of automation technolo- gies, from instrumentation to advanced performance monitoring." Seeing Information in the Right Way Jonas also explained that the inclusion of human factors into the control system has been progressing in the mineral pro- cessing industry. For example, standards developed by the Abnormal Situation Management (ASM) consortium, of which Honeywell is a member, define how operator displays should be built, including the best use of colors and shapes to optimize control-room opera- tor effectiveness. The ASM has also addressed the problem of more alarms being generated by today's intelligent instruments and controls. Rockwell Automation's industry mar- keting lead for mining, minerals and cement, Andrew Bagley, noted that since 2003, the major technological shift in plants has seen proprietary networks being replaced by Ethernet as a common standard. This has allowed much more enterprise-level networking in plants, leading to better network management and security, he said. The integration of instrumentation networks into the con- trol system has also been simplified. The ability to upload plant and configuration data directly into the controller has tremendously accelerated configuration and asset management as well as the abil- ity to leverage smarter instrumentation for data validation and diagnostics. The controllers in traditional PLC-type architectures have increased in perfor- mance that allows far more control, with less reliance on the HMI layer. This signifi- cantly improves software maintainability and the cost of ownership, Bagley explained. "In addition, more determinis- tic MPCs are replacing expert systems as the primary advanced control technolo- gy," he said. "MPCs identify process mod- els to drive optimal operations and deliver higher value in a much more sustainable (easier to maintain) platform." Measuring Improvements Turning to typical plant performance improvements that can be gained through the use of automated plant control sys- tems, Bagley stated that the biggest of these is the long-term steady-state control that they bring. In any hydrometallurgical operation like flotation and milling, the ability to maintain a steady state control over a longer period of time is the biggest advantage, with quality variability being reduced by 30%–75% when using an MPC. "Any advanced control system typi- cally leverages the existing control sys- tem infrastructure, which makes it not only a wise investment but it can be implemented in a relatively short time- frame," Bagley added. "MPCs' other benefits over traditional solutions include increasing capacity between 2% and 10%, depending on the process, and reducing energy costs between 4% and 10% per ton." From Honeywell, Jonas agreed. "Typically 1%–6% throughput and 1%–4% recovery (yield) increases are achievable, depending on the processing methods and technologies deployed," he said. Gekko's Culph looked at the benefits in a wider sense. "If employed correctly, the system can benefit safety, helping to protect personnel and equipment around dangerous activities. It can also benefit predictive maintenance, leading to reduced downtime; optimal resource efficiency — with lower operational costs; and increased productivity, allowing the plant to achieve greater throughput." So You've Got the System... Clearly there can be a significant invest- ment involved in installing a control sys- tem, and the obvious response will be to make the best possible use of it. That does not always happen, however, and Coal Age asked each of the respondents about the most common mistakes that operators make in relation to the control and instru- mentation systems that are installed in their plants. For ABB, Knabenhans pointed out that mistakes often happen in the conceptual design phase of a plant. "Extensive use of vendor package PLC solutions that are integrated later into the overriding pro- cess automation platform makes life diffi- cult for operation and maintenance," he said. "Those sub-system PLCs do not match the plant's common operation and alarming concepts, they also require dif- ferent spare parts and provide limited diagnostic data for the underlying process. This causes problems when fault-finding. "In many mining plants, operators still control individual devices such as motors and valves," Knabenhans said. "Other in- dustries have long relied more on func- tional groups or even process area con- trol, where an overriding group function controls bigger parts of the process. In combination with properly tuned loop controls and advanced process control solutions, both up-time and productivity can be improved." From Siemens Process Automation, business development manager for mining, aggregates and cement, Mark Yseboodt looked at hardware issues that the company has noticed. "One problem is where operators look at the cost of instruments rather than the life- cycle cost (cost of ownership)," he said. "In addition, EPCs sometimes select instruments for new projects based on cost, not performance. "Being unaware of the latest develop- ments in technology might lead to equip- ment being installed that is not the best, and once in operation, if the calibration and maintenance of, say, continuous weighing devices is not done properly, they won't provide accurate data inputs to the control system. Then again, anoth- er problem that we see is where operators try to rely on information from instru- ments that are not suitable for the task, for one reason or another." According to Jan Schilling, global product manager for process control sys- tems at FLSmidth, the natural tendency is for operators to look for simplified pat- terns of operation to help them operate more easily. "This level of 'expertise' means monitoring fewer signals more often, expecting other signals to be linked in some way to the few," he said. "Most often this technique works fine, but there may be some potential opti- mization being missed. And while moni- toring fewer signals would seem to leave more time to keep an eye out for other problems, unfortunately sometimes it results in a general lack of focus, resulting in missed warnings and alarms." Honeywell's Jonas said that the com- pany's experience shows that many well- intentioned efforts fail due to their a u t o m a t e d c o n t r o l s c o n t i n u e d December 2014 www.coalage.com 37

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