Although the suspension pre-heater (SP) system has good thermal efficiency, there were the problems about long time operation or capacity expansion because of the damage to the refractory inside. Then, the new suspension preheater (NSP) system equipped with a pre-calciner was developed in Japan.
The maximum approx. 60% of heat quantity is used in a pre-calciner, the most of decarbonation reaction of limestone is actively carried out in the NSP. Therefore, the over 90% of raw materials are already calcined at the kiln gate with the NSP system. While with SP system, it was only 20-30%. This reduces heat energy consumption in the rotary kiln for clinker production to approx. 40-50%, mitigates damage to the refractory materials in the kiln.
Reduction in average unit consumption of energy (in calorific value): NSP type 2,930-3,350 kJ/kg, SP type 3,470-3,600 kJ/kg
- Max. output increment: NSP type 10,000t/d, SP type 4,000t/d
- Operation days: up to 320 d/y
- NOx: lower than SP type
- Reduction of specific consumption of refractory:
- NSP type 500-600 g/t-cl,
- SP type 800-900 g/t-cl
Low pressure loss cyclone is needed.
Ministry of Economy,Trade and Industry, Japan