CEE Jan-Mar 2012

• At the entry point of cyclone 4 and cyclone 5, substantial horizontal portion in the duct caused frequent material buildups resulting into higher pressure drop. • Cooler modification to increase the effective grate area was necessary to handle higher clinker capacity. • New vent duct from Cooler to Cooler ESP was required to be installed to handle the additional hot air volume from modified cooler. • TAD modification was recommended to be executed in the second phase. 6. IMPLEMENTATION Following recommendations were implemented to achieve production capacity of 2,400 tpd and optimize plant operation: • Installation of higher capacity preheater fan. • Modification of Down Comer duct • Installation of Third cyclone (Cyclone 1C) at top stage • Modification of Cyclone 4 A and 4 B • Modification of Cyclone-S 7. Other Unit Operations • Raw Material Grinding A central discharge close circuit ball mill of size 3.8 m x 13.81 m was used for Raw material grinding. This mill was operated at 175 tph at higher residue. The requirement of raw meal for the enhanced capacity worked out to be 171 tph. Hence no modification was recommended in raw mill system. However, it was observed during the mill audit that at times raw mill feed had substantially large particles of shale limiting the raw mill capacity. It was recommended to install a screen at outlet of tertiary crusher installed in plant to remove the bigger shale particles. • Cement grinding The mills rated for 60 tph were operating at an average output of 68-70 TPH on PPC. It was concluded from mill audit and capacity assessment based on existing mill & motor size, that 70 TPH is the best achievable output from these mills. • Coal Drying And Grinding For coal grinding, one air swept ball mill of size 2.8 m diameter x 7.32 m length was installed. This mill was designed for a capacity of 12 tph and operating at 14 tph . At 2,400 tpd clinkerisation capacity, coal grinding milling requirement worked out as 16 tph considering 21 hours of daily operation. First chamber (drying chamber) was proposed to be converted into grinding chamber for increasing the gri nding path length with an overhanging drying chamber to be installed at the inlet of the mill to meet the drying requirement in coal. The existing grit separator was recommended to be replaceJ by a dynamic separator to further increase the classifying capacity of the system and enhance the mill output. • Limestone Crushing A primary crusher of capacity 350 tph is installed for limestone crushing. At present the crushing plant is operating at an average capacity of about 215 tph. The main reason for low output rate is inadequate feeding to limestone crusher hopper. The required crushing capacity at the sustainable kiln capacity of 2,400 tpd worked out to 328 tph, which can be achieved by improving the feeding system and time cycl e to the crushing plant. Hence for plant expansion no modification was proposed. • Raw meal Storage The raw meal storage capacity for 2,400 tpd kiln capacity considering 2.5 day storage (1.5 days active storage) works out as 9,000 t. The existing silo 7,500 t was manageable. • Kiln Feed System For the kiln feed , the plant had bucket elevators, kiln feed bin on top of the silo with solid flow meter for measuring the feed. The existing capacity of 180 tph of kiln feed was sufficient to take care of kiln feed requirements at the enhanced kiln capacity of 2,400 tpd. Hence no modification was recommended in the kiln feed arrangement. • Clinker Transport and Storage The deep pan conveyor capacity had been selected as 170 tph, which had 70% margin even on 2,400 tpd clinkerization capacity. Hence no modifications were required on the deep pan conveyor arrangement. The present clinker storage capacity of 50,000 t was sufficient for storage of more than 20 days of clinker production, which is adequate. • Cement Packing and Despatch Existing system included two 8 spout packer along with 2 nos. truck loaders, suitable to 10