Energy saving by conversion of four stage to 5-stage preheater---ZKG –12/1986

The designation M-SP applies to a cyclone preheater which has been developed jointly by Mitsubishi Mining and Cement Co.Ltd. and Mitsubishi Heavy Industries Ltd. With the object of reducing the pressure drop and improving the heat utilization. The first M-SP installation, which was commissioned at Mitsubishi's Higashidani cement plant in 1982, has meanwhile proved satisfactory. It was fitted to kiln No.1 at that plant. Since then, kiln No.3 has also been converted from four to five preheater stages with M-SP technology. This installation was commissioned in October 1983 and has likewise come up to expectations. The principal modifications and their effects on plant operation are described in this paper. Kiln No.3 was a normal cyclone preheater kiln (Dopol kiln) with a clinker production capacity of 1600t/day, which was commissioned in 1965. The object of the conversion was to cut energy expenses, not increase clinker output. To save capital cost it was decided to keep the amount of conversion work to a minimum. Accordingly, the preheater installation, kiln exit gas fan and clinker cooler were left unchanged, and only the cyclones and ducts of stages 2, 3 and 5 were changed to suit M-SP design requirements, while the cyclones of stages 1 and 4 were modified only in their cylindrical parts. After the comversion work had been completed. The exit gas temperature downstream of the preheater was 52 degrees C lower, and the specific heat comsumption was down by 190 KJ/Kg(45 kcal/kg). Moreover, the pressure drop in the preheater was reduced from 645 mm to 610 mm w.g., although an extra stage had been added.

Energy conversion in Cement Industry --- ZKG , 9/1986

There are various possibilities for achieving energy conservation in Indian and similar cement industries. They are discussed here. Lowering of alumina modulus and silica modulus by 0.2 can lead to thermal energy saving of about 10 to 20 kcal/kg clinker. Slurry thinners reduce the water requirement of wet slurries by as high as 7 % and lead to fuel economy up to 5 %. Conversion of wet plants to semi-wet by employing suitable filters and driers and proper system design could lead to a heat saving of 250 - 500 kcal/kg clinker. Use of suitable mineralizers could lead to reduction in heat consumption by 60 - 120 kcal/kg clinker due to lowering of the clinkering temperature to about 100 degrees C. Use of high strength insulating brick lining in the kiln preheating zone leads to fuel economy of 2 - 3 % and better kiln stability. Grinding aids lead to a power economy up to 11 kWh/tonne of cement at 3500 cm2/g fineness. Manufacture of pozzolana cements, slag cements, porsal cement, alinite cement and improving the kiln operations and systems also lead to substantial fuel economy and energy conservation.