With the company’s own quarry and a private harbour, Nuh Cimento Sanayi (Fig. 1), a Turkish cement company, has two outstanding location factors for cement production. The resulting extremely short transport paths in the Hereke plant are a significant reason for the success of the company. To continue to expand its position in the international cement market, Nuh Cimento Sanayi decided to increase plant efficiency. To achieve this goal, Nuh Cimento has invested in the Loesche automation solution LMmaster. The solution was applied first in the raw material mill RM3 (Fig. 2), a vertical roller mill LM 63.4 with a capacity of 505 t/h and a specific power consumption of the main drives (mill motor, mill fan and classifier) of 15.8 kWh/t.
Additional reserves for grinding of raw meal
The mill is a vertical roller mill from Loesche. “We are very satisfied with the Loesche LMmaster and the process experience they are bringing into this solution. We always thought that our RM3 is operating at the performance limit. This benefit shows that process knowledge and experience are the most important assets to provide MPC solutions”, said Oguz Aydinc, Cement Production Manager at Nuh Cimento Sanayi. In November 2010 the decision was made to optimize the system with the help of the LMmaster. The big challenge for the engineers at Loesche was to optimize an already good running system and to increase the performance to the technically achievable high end.
Optimization goal: increasing the throughput
Nuh Cimento Sanayi, founded in 1966, successfully produces in-house quarry cement for the local Turkish market and for export (Fig. 3). The high export quota will force manufacturers to continue competitive and efficient production, due to the highly competitive market. The plant offers ideal logistics for competitive manufacturing. With conventional control technology and an efficient mill, the plant produces large amounts of raw meal for the subsequent production of cement. Nuh Cimento Sanayi’s goal was to increase the throughput of the mill with reduced energy use and increase the availability of the system. Precisely for this requirement, the process optimization of Loesche grinding mills, the LMmaster automation product was designed and developed.
Process optimization with model-predictive control
It is the “standalone” real-time process optimization solution for an optimal operation of the Loesche grinding systems. The focus of the LMmaster is on efficient performance, increased mill throughput, ensuring product consistency and increased plant availability. Compared to competitors in the market there is no additional engineering work necessary after the implementation of the solution.
An MPC (Model Predictive Control) like the LMmaster is based on a specific mathematical model for imaging of dynamic processes with multiple interacting variables. With the model-based control all PID-controllers are contained in one model to consider the process as a whole with the respective influences of each variable. The LMmaster calculates the future state of the system and uses these values to define new operating points of each controller. For the calculation of new operating points, the current actual values, the disturbance variables as well as historical data are taken into account. The model calculates the new set points for the PLC. This happens continously and in real time to avoid any delays using the LMmaster.
Through consideration of future values the early stabilization counteracts the effect of the process. This is a continuous optimization of the operating point of the respective control of the process. The optimal operating point and the associated stabilization having smoother operation resulting in the impact of consistent product quality and lower specific energy consumption. Similarly, the throughput of the system is increased.
Higher availability and less variation
“LMmaster is taking over the grinding process and leaves more time for our operators to concentrate on other processes”, explained Mr. Ismail Dogan, Clinker Production Engineer at Nuh Cimento Sanayi. Through the use of LMmaster, all expectations of Nuh Cemento have been satisfied and even exceeded. The application at Nuh Cimento Sanayi in Hereke was implemented successfully and improved the specific energy consumption with increasing throughput significantly. The plant now runs in a more stable manner and more smoothly with a higher availability of the grinding system and a reduced variation in product quality. Due to the Nuh Cimento owned power plant on site the reduction of the specific energy consumption is combined with reduced CO2 emissions.
The LMmaster system was already online 3 months after the kick-off and pays back very fast. Due to the good performance the ROI is less than 12 months. “We are looking forward to installing the LMmaster also in other Loesche mills in our plant”, stated Mr. Ismail Dogan, Clinker Production Engineer at Nuh Cimento Sanayi. Due to the use of the LMmaster on a separate industrial PC with its own software platform, there is no security threat to the installed control system. Another safety aspect is the “switch back” option that allows the operator to smoothly switch to the original PLC/DCS mode. However, the switch back option has never been used.
ROI under one year
Loesche implemented a turnkey solution without any further operational expenditures and a ROI of under one year. This is allowed by a short implementation time of 2–3 months without any shutdowns and interruptions of the grinding system. The LMmaster delivers significant sustainable improvements to the Loesche mill.
