Cement and Energy

To improve reliability, 6.6 KV bulk oil circuit breaker and mill motor liquid rotor starter (LRS) of BHEL make were substituted by vacuum contactor and 'Pioneer' LRS. Packing Plant One mechanical rotary packer replaced with electronic packer resulting in accurate weighing of cement filled bags. Control desk was installed at packing plant for trouble– free • cement extraction from silos and feeding to respective packer elevators. This has eliminated idle running and also stopped cement spillage. Silo bottom old motor control centres I and 2 were replaced with new ones for trouble-free operation. Interlocking and de-interlocking switches were introduced in packing plant for long belt conveyors, saving about 15 KW in idle running. Similarly interlocking of blowers has also cut down idle running, saving approximately Rs. 1.5 lac per annum. Light controllers were installed to avoid glowing of lights in day time. Energy efficient compact fluorescent lamps (CFL) have been installed for reduced energy consumption. Chain-and bow link bucket elevators were replaced with pin and bush type ones making for minimum maintenance and less down time. Compressor Section Soft starters with energy saving features introduced in place uf uld auto transformer starters. New adequate capacity compressor installed for packing plant section. Compressed air receiver tank installed in packing plant. Capacity reduced for oversized compressor for granulation section. New compressors installed along with PD pumps for cement transportation from mill section to silos. Preventive maintenance schedule introduced. Air leakage in the distribution network eliminated. Miscellaneous Idle running of equipment eliminated by sequential interlocking modified with timers. Public address system introduced throughout the plant, for simultaneous communication with all sections. Capacitor bank installed to take care of the plant's power factor which increased as a result from 0.9 to 0.985. Operation and Ma;ntenance Several steps as enumerated below have been taken for improving the productivity and efficiency of plant operation. Granulation Water-t~molten-slag ratio is the most important factor for better granulation. A higher ratio leads to fine granulated slag with higher glass content. To increase this ratio, nozzle box design of high pressure pumps has been changed. Tilting rate of ladles optimised to produce superior quality of slag granules. This has direct impact on cement mills' output as fine slag is easier to grind. Slag Dryer Dry slag transport system from slag dryer outlet and ESP screw conveyor to dry slag stockyard simplified by eliminating /reorienting conveyor belts. Granulated slag of size above 5mm was found to be inert material and not contributing to strength development in cement. So crusher, located upstream of slag dryer feed, was removed from the circuit and slag exceeding 5-mm size bypassed. Refractory lining in dryer replaced with castables, minimising stoppages of dryer from brick failure and thus enhance productivity. Cement Mill Nibs chute in the mills removed reducing wastage a~d improving productivity. After study of the pneumatic conveying system, one blower from each mill circuit removed and a few air-slide blower motors substituted with lower capacity motors achieving a saving of 13- 14 kW. 6 \ r- · .. I ...