Reducing energy consumption
The grinding process in cement plants is extremely energy-intensive, accounting for nearly 45 per cent of the overall electrical energy consumption. Many corporates are into a business of designing an expert system, which uses actual plant data to make precise predictions about quality parameters for a given plant. The system can be integrated into the existing control system most of the time without any additional hardware. Mill controls can be optimised on the basis of predicted quality parameters, with an objective to reduce energy consumption. Many such 'Expert Systems' are in use at various plants in India and abroad. We are taking here one real life case of Lafarge plant.
Referred here is a case of Lafarge plant in southwest region of China Dujiangyan. With rising energy costs, accounting for approximately 70 per cent of production expenditure, Lafarge's primary objective included realising reductions in energy consumption levels and costs. In addition, they were faced with increased government regulations, reporting mandates and environmental pressures and concerns.
Operationally, the Dujiangyan plant struggled with limited process measurement tools proving it challenging to identify energy saving opportunities and continuous improvement strategies. With idle equipment, such as large air compressors and numerous conveyor belts left running, power supply costs were rising.
Economic constraints limited CAPEX availability to make significant improvements, which drove them to look at their operational processes to achieve efficiency and financial gains.
- The main contributing factor was the step-wise approach undertaken, the close collaboration with the customer throughout all stages of the process, as well as the in depth training delivered by Schneider Electric to Lafarge stakeholders
- Detailed and comprehensive site audit and energy assessment audit carried out
- Complete energy management solution, integrating process and energy information for use from the operator level onwards
- A solution that both reduce energy consumption as well as energy costs
- Energy assessment tools vital in the provision of regulatory data and ongoing cost effectiveness
- Customisable system functions - such as kiln coach report
- In depth segment (cement) process and application knowledge
- Air compressor optimisation
- Onsite service and support carried out by Schneider Electric energy consultant
- Collaboration and shared objectives between Lafarge and Schneider Electric project team
Results and benefits
- Powerful site-wide energy management tool optimises efficiencies and investment
- Kiln operation optimisation
- Monitoring clinker over-burning and over-cooling
- Improvements in the cement finish grinding operation
- Maximising efficiencies in the operating hours within cement mills
- Air compressor optimisation, with a centralized control system avoiding idle running of air compressors
- Enhancements in crew performance with 'Kiln Coach Report', which evaluates operator KPIs (production, quality, SPC/SHC) as well as the introduction of the 'best operator of the month' programme
- In addition to a timely return on investment, with a project payback period of two years, Lafarge also realised valuable energy improvements by reducing power consumption by 0.8kWh/t cement. As a result, production cost and CO2 emissions have been reduced
- Remote access of the system also facilitated technical support when required, as well as access for ongoing energy analysis consulting and support
Overall, Schneider Electric's Energy Optimisation for cement production solution provided a host of benefits for Lafarge including:
- Reductions in energy costs directly reducing CAPEX
- Increased process visibility and reporting metrics
- Secure, scalable and flexible solution
With all onsite automation and electrical distribution systems provided by Schneider Electric, a collaborative improvement project was designed and implemented over a six month period. Commencing with a detailed business and process analysis, the project included a comprehensive energy assessment, plus site audit across all installed base operations. Additionally, a Schneider Electric power monitoring system had been installed onsite in 2009 as part of the group's commitment to energy optimization and improvement.
In response to the above detailed assessment and analysis findings, the project deployment involved the installation of a customised energy performance system, comprising an optimized metering and communication architecture, as well a plant-wide data management system.
Designed to maximise installations with both Schneider Electric and third-party equipment, the new architecture's open and flexible attributes allow for future expansion and additional installations, whilst processing and transmitting the plant's energy data at high speed.