Currently three types of thermodynamics system are prevalent. These have been extensively applied in different installations each being an improvement from the previous systems.

  • Gas extracted from the middle of the clinker cooler at the kiln outlet, with usable temperatures of 380 0C - 500 0C to 90 0C - 110 0C;
  • Kiln inlet pre-heater waste gas, with temperatures of 300 0C - 350 0C to 175 0C - 220 0C (the used gas will be sufficient for raw mill drying);
  • Dust settled in boilers shall be recycled for cement production, so as to avoid waste and contamination.

Currently Three Types of Thermodynamic System Are Prevalent:

SINGLE PRESSURE SYSTEM: Without steam filling system, composed of single turbine and single pressure boiler. When raw mill drying requires high temperature (> 210 °C), single pressure boiler can ensure sufficient absorption of wasted heat.

DOUBLE PRESSURE SYSTEM: Steam filling system with additional steam filling turbine. Single AQC boiler or SP boiler, or both AQC and SP boilers simultaneously produce different steam pressure. One as main steam while the other as low pressure steam. Providing kiln outlet cooler gas fluctuates the double pressure overheating system will ensure temperature of gas passing through the AQC boiler lowers down to ensure sufficient absorption of waste heat;

SECONDARY OVERHEATING SYSTEM: With SP boiler steam into AQC boiler high temperature over-heater. The system presents the following advantages and disadvantages:


  • Maximize utilization of waste heat
  • Simple, convenient and efficient
  • Dilute the difference of steam from two sources at their qualities and parameters due to the combination


  • Overheat steam transferring distance is long from the pre-heater to grate cooler which may result in losses of temperature and pressure in steam pipes.

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