As the main energy-consuming and greenhouse-gas–emitting stage of cement manufacture, reducing fuel consumption is a central concern of cement manufacturing technology. Fuel consumptions can range from the most modern 6 stage Precalciner kilns with fuel consumptions of 680-700 Kcal/Kg cl to the oldest wet kilns up to 1600 Kcal/Kg cl. As such it is important to benchmark fuel consumption against similar equipment types.
Therefore CPI has developed a fuel consumption benchmark calculator which estimates benchmark fuel consumption figures for different kiln and cooler combinations.
CAUSES OF HIGH FUEL CONSUMPTION
The four most common causes of higher than benchmark fuel consumption are:
Low output on the kiln. Shell heat losses (per tonne clinker) will increase if the system is being run at a lower than optimum output.
Poor cooler efficiency caused by poor air distribution, poor maintenance, bad design or a combination of all three. It is quite common for coolers to be operating at between 5 and 10% below their maximum efficiency.
Poor heat transfer in the tower, leading to increased tower exit temperatures. Higher exit temperatures are caused by:
- Poor material distribution across one or more stages of the preheater
- Material dropping down to a lower stage rather than being picked up by the gas stream
- Incomplete combustion in the calciner
- Too low oxygen level in calciner
High number of unplanned stops. This is due to the additional fuel used during heat up when no clinker is produced.
The results from the Fuel Consumption Calculator are indicative only; they
are based on CPI experience and are not absolute indicators of performance.
The results are as a guide only and CPI can provide specific assistance to
clients through their Process Optimisation Services. Furthermore the quality
of the results is dependent upon the reliability of the data input to the
calculator.
