Cement Energy and Environment

Table 4 Comparative fan performance for Butterfly and Vane Dampers Fan For butterny dampers No. Flow m 3 /min KIO 313 Kll 510 K12 540 K1 3 542 Kl 4 520 Kl5 1450 Kl6 856 Total savings Hourl y saving Yearly saving (assuming kiln running 23 h/d. 330 dpa) Yearly saving uo press mmWG 520 500 520 460 370 150 125 (assuming Rs.3.25 per kWh) Damper Pressure open drop % mmWO 43 220 50 190 58 ISO 60 180 41 180 76 NA 75 115 83 amps 53.7 kW 425.260 kWh Rs. I 3.82 lacs Power consum ption amp 120 170 170 142 142 275 96 C hanging open circui t grinding mills to closed circuit for energy saving is well known by most major wet process cement companies. However. if not For vane dampers Flow uo Damper Pressure Power Power m 3 /min press open drop consum Saving mmWO % mmWG ption amp amp 290 500 20 100 110 10 505 511 43 126 155 15 530 500 52 30 160 10 533 520 48 40 130 12 560 430 54 60 132 10 1514 200 70 35 265 10 875 145 85 65 80 16 Conclusion The available information suggests that the company is savi ng about 53kW/hour resulting in an annual saving of Rs. I 3.R million (US $ 32,600) in energy costs with an investment of about Rs. 200,000 (US$ 4728) for the above modi tication. Thus the payback period is around 54 days with the modifications proving to be a highly rewarding option to reduce power consumption i n the cooler section. Raw Grinding Department Advan tages of switch ing from open circuit to closed circuil grinding mills include: • Reduction in moisture con tent in kiln feed by 3 carerully engineered. with proper si; ing and quality per cent equipment. the intended benelits of energy saving arc olk n rarely achieved. * Reproduced from International Cemem Re1•iew, March 1999 • Reduct ion 111 power consumption by 3kWh/t • Increase mill capacity by I 5-20 per cent \ • Reduction in dust load on kiln precipi tator • Rcductioil in mill maintenance costs 6 ,_