Process Control and Optimization in Clinker Making

Optimization of the clinker making process is usually done to reduce the heat consumption, to improve the clinker quality and to increase the lifetime of the equipment (the refractory lining, for example) by stabilizing process parameters. Optimization includes measures/techniques like ensuring optimum raw meal composition, properly managing combustion processes and improving the operation of the cooler.  The operating cost of an optimised kiln is usually reduced, among others, due to reduced fuel and refractory consumption, lower maintenance costs and higher productivity. 

Combustion management is of prime importance for optimization and demands attention to be paid to the following:

  1. Fuel grinding management:  fuel grinding should be managed to achieve optimally set fineness
  2. Air ratio management: To maintain an appropriate air ratio, the oxygen concentration in the combustion exhaust gas requires strict management.
  3. Exhaust gas management:  CO and NOx should be measured and their measurement data to be used for combustion management.
  4. Kiln burner management: the basic designs such as the fuel discharge angle of the burner, the primary air ratio, etc., should be reviewed to maintain the optimum combustion conditions.
  5. Cooler operation management:  Heat recovery at the cooler greatly affects the combustion management of the kiln burner. 

Automated computer control systems, for example, can be used to optimize the combustion process and conditions. Improved process control will also help to improve the product quality – for example by fine tuning reactivity and hardness of produced clinker – which may lead to more efficient clinker grinding. Most modern control systems use so-called "expert control" (also known as "fuzzy logic" or "rule-based control") systems or "model predictive" controls. Process control systems include the use of on-line analyzers that permit operators to instantaneously determine the chemical composition of raw materials being processed, thereby allowing for immediate changes in the blend of raw materials. A uniform feed allows for steadier kiln operation, thereby saving ultimately on fuel requirements. Process control of the clinker cooler can help to improve heat recovery, material throughput and improved control of free lime content in the clinker, and to reduce NOx emissions.

Modern versions of process control and optimization systems make use advancements in information and communication technologies and enable real-time monitoring and adjustment of process parameters by multiple users using, among others, mobile devices (NDRC, 2012. p. 65)

Chinese flagUntil 2015, 10% of the dry cement plants are expected to adopt this technology, potentially resulting in annual energy savings of 1.4 million tce (NDRC, 2012. p.65)

Development Status Products
Commercial
clinker, Cement

Process Control and Optimization in Clinker MakingCosts & Benefits

Parent Process: Clinker Making
Energy Savings Potential

Savings vary between 2.5 to 10% and typical values are estimated to be 2.5 to 5%.

Chinese flagFor modern dry kilns with capacities more than 2500 tpd, savings are reported to reach 0.29 GJ/t-clinker (NDRC, 2012. p.66)

Chinese flagIn a 4500 tpd Chinese plant, annual energy consumption was reduced by 395.6 TJ (13500 tce) with the installation of a process control and optimization system (NDRC, 2012. p. 66)

Chinese flagIn a 4000 tpd Chinese plant, annual energy consumption was reduced by 351.7 TJ (12000 tce) with the installation of a process control and optimization system (NDRC, 2012. p. 66)

CO2 Emission Reduction Potential
Costs

The costs of process control optimization measures/techniques vary widely and can be up to $6.8 million [1€=$1.35 US] 
The economics of advanced process control systems are very good and estimated payback periods can be as short as 3 months. In general, estimated payback period is less than 2 years.

Chinese flagIn a 4500 tpd Chinese plant, installation of a process control and optimization system required an investment of 980 thousand RMB, and took one month. The system provided annual savings of 8 million RMB, resulting in a payback time of 2 months (NDRC, 2012. p. 66).

Chinese flagIn a 4000 tpd Chinese plant, installation of a process control and optimization system required an investment of 990 thousand RMB, and took one month. The system provided annual savings of & million RMB, resulting in a payback time of 1.5 months (NDRC, 2012. p. 66).

Parent Process:
Energy Savings Potential
CO2 Emission Reduction Potential

N/A

Costs

Process Control and Optimization in Clinker Making Standards

Reference Document on Best Available Techniques in the Cement, Lime and Magnesium Oxide Manufacturing Industries

This is a reference document for Best Available Technologies available for Cement, Lime and Magnesium Oxide manufacturing industries and that have high relevance within the scope of the European Integrated Pollution Prevention and Control (IPPC) Directive (now titled as Industrial Emissions Directive following the 2010 recast). 

Page Number: 

106-107

Process Control and Optimization in Clinker Making Publications

Energy Efficiency and Resource Saving Technologies in Cement Industry

 

This Cement technologies booklet was compiled by the APP Cement Task Force (CTF) through one of its activities to help its member countries share information on all available energy efficient technologies generally used in the world’s cement industry. The document offers a comprehensive compilation of commercially-available energy efficient technologies used in the cement industry.

Page Number: 

84

Energy Efficiency Improvement Opportunities for the Cement Industry

The U.S. Environmental Protection Agency’s (EPA) energy guide, Energy Efficiency Improvement and Cost Saving Opportunities for Cement Making, discusses energy efficiency practices and technologies that can be implemented in cement manufacturing plants. This ENERGY STAR guide provides current real world examples of cement plants saving energy and reducing cost and carbon dioxide emissions.

Page Number: 

6-7

Development of State of the Art Techniques in Cement Manufacturing: Trying to Look Ahead

The report represents the independent research efforts of the European Cement Research Academy (ECRA) to identify, describe and evaluate technologies which may contribute to increase energy efficiency and to reduce greenhouse gas emissions from global cement production today as well as in the medium and long-term future. 

Page Number: 

38-39

Page Number: 

65-66