MPC-based solution for advanced kiln control at Bursa Cimento plant in Turkey

ABB and Bursa Cimento describe how control strategy has been implemented, improving both average kiln feed and thermal energy consumption by 2 – 3%

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ABB Ability™ Expert Optimizer digital application enables higher level of automation and optimization of rotary cement kilns and mills, delivering results fast and consistently. The results achieved at Bursa Cement follow observations made during a site audit before the project and show improvements in the stability of the process and the performance of the kiln system.

Key facts

 Customer: 

Bursa Cimento

 Country: 

Turkey

Customer need: 

Improve the production and energy efficiency of its plant
Application
  • A 50 m rotary kiln with a 5-stage preheater and an in-line calciner, designed by Polysius  for a capacity of 2250 tpd.
  • A waste heat recovery plant (WHR) using exhaust gases to generate electricity
ABB solutions
Customer benefits: Improved stability of the calciner temperature and the cooler operation with subsequent optimisation of the kiln production and energy consumption

Need for advanced kiln control strategy

The Bursa Cimento plant is located near the city of Bursa in the Marmara region of Turkey. Bursa is one of the most populated cities in Turkey and an important industrial area.

Bursa Cimento operates two clinker lines and four cement grinding mills. The Expert Optimiser project was carried out on line 1 which consists of a 50 m rotary kiln with a 5-stage preheater and an in-line calciner, designed by Polysius and commissioned in 1996. The system is designed for a capacity of 2250 tpd. The kiln main burner is fired with coal dust, whereas the calciner burner also fires RDF (refuse-derived fuel) at a rate of about 4 tph. The kiln is followed by a grate cooler with 12 cooling fans. The kiln is also equipped with a waste heat recovery plant (WHR) using exhaust gases to generate electricity.

When Bursa Cimento was looking at improving the production and energy efficiency of its plant, it approached ABB to present our process optimisation system, ABB Ability™ Expert Optimizer.

The cement kiln process is intrinsically unstable, there are long time delays and large perturbations acting on it. The control problem consists of maintaining a given temperature profile along the kiln plus obtaining good burning conditions - at the lowest energy consumption possible.

ABB approach to process optimisation in cement kilns & mills

The collaboration was started with a site audit in October 2014. An ABB engineer visited the Bursa Cimento plant to study the process and evaluate the potential of applying Expert Optimiser to clinker line 1 and two cement mills. In the pyro processing area it was identified that Expert Optimiser would be able to improve the stability of the calciner temperature and the cooler operation with subsequent optimisation of the kiln production and energy consumption.

The potential improvements indicated by ABB convinced Bursa Cimento and the contract to implement Expert Optimiser digital application was signed in September 2015.

In early 2016, two engineers from Bursa Cimento attended an Expert Optimiser training course to learn the essentials about the technology used in Expert Optimiser and ABB’s approach to control and optimise a cement factory.

Commissioning of the system started end of February 2016. The resistance of the operators was minimal as the system quickly showed benefits, including improving little things that made the operators' life easier. Utilisation factors higher than 90% were already achieved at the beginning of commissioning. ABB implemented Model Predictive Control (MPC) for the kiln 1 and the mills. The MPC approach and results from the practical implementation of MPC application for the cement kiln at Bursa Cement plant will be explained in more detail in the next chapters, with focus on the pyro processing section.
The resistance of the operators was minimal as the system quickly showed benefits, including improving little things that made the operators' life easier. Utilisation factors higher than 90% were already achieved at the beginning of commissioning.

Cooler under grate pressure results

The stability of the kiln system has been improved since first day Expert Optimiser was set into automatic mode. Figure 3 shows the trend when Expert Optimiser was first switched into automatic mode.

One can see that the under grate pressure in the cooler stabilised immediately.

Bursa Cimento had issues operating the WHR plant, as the required minimum temperature of 340 ̊C could often not be ensured. After Expert Optimiser stabilised the cooler operation this problem vanished. This will improve the overall performance of the plant outside of the foreseen Expert Optimiser scope.


Figure 3: Cooler under grate pressure trend

Calciner temperature control results

Similar improvement was achieved for the stability of calciner temperature. Figure 4 indicates the control error distribution of the calciner temperature, showing that Expert Optimiser controls the temperature more tightly.

Please note that this statistic includes about 2 days of data when EO was inactive and about 20 days of data when Expert Optimiser was active.

Good control of the calciner temperature is essential as it is important for the stability of entire pyro process. Stable calciner temperature ensures that the material is always well prepared before it enters the kiln. Large variations cannot be corrected anymore after that point.


Figure 4: Calciner temperature control (minute values)

Pre-heater oxygen distribution results

Better process stability is the foundation for improving the productivity of the kiln. Figure 5 shows the distribution of hourly oxygen values for Expert Optimiser active and inactive.

With Expert Optimizer in control the oxygen is operated at a lower level which indicates that the process is operated more efficiently. Both average kiln feed and thermal energy consumption are improved by 2 – 3% compared to typical values before Expert Optimiser was used

Figure 5: Pre-heater oxygen distribution EO active and EO inactive (hourly values)

Kiln feed and energy consumption results

On 7 March, Expert Optimiser was first turned online. After initial tuning, Expert Optimiser was used almost continuously and utilisation of higher 95% has been reached since.
 
In general the results achieved follow the findings made during the site audit at the very beginning of the project.

Similar results have also been achieved for the two raw mills and cement mills by applying the same principles.

This project shows that ABB’s Expert Optimiser continues to produce value for its users. It depicts that the MPC-based approach can deliver results fast and consistently.

Learn more

Advanced Process Control (APC) with Expert Optimizer

For rotary cement kilns and mills, alternative fuel management and material blending
ABB Ability™ Performance Optimization service for cement plants
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Cement plant automation, integration and optimization

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