Cement and Energy

Operational measures Various other measures for improving overall productivity and reducing energy consumption include : • • • • • • • Prevention of idle running of equipment by providing interlocking arrangement and operating them with a PLC system, resulting in savings of 2.00 kWh/t cement. Minimising ingress of false air into the ESP raw mill, kiln cooler, coal mill and cement mill circuits. A saving of 1.5-2.00 kWh/t was achieved. Optimising raw mix design and using the coal mix aiming at a calorific value of fine coal at about 6000 kcal/kg of coal. Ensuring operational availability of various continuous running equipment by the preventive, predictive and condition monitoring system approach, for maintaining good performance of the plant and machinery. Efficient management information system (MIS) for identifying various important parameters for efficient operation of the equipment, and taking timely remedial measures in case of some abnormal behaviour of continuous running machinery. Setting targets for production and energy consumption in various sections of the plant. Controlling lighting loads on plant and the site, and by using appropriate sized motors resulting in high efficiency and a power saving of 1.5 kWh/t of cement. Mana~ement of raw materials and coal Shree Cement India has its own quarry situated some 3 km from the plant. The limestone is crushed in the quarry and transported to the plant via ropeway and preblended in a stockpile system before being fed to raw mill for preparation as raw meal. As the limestone is marginal in quality, the plant purchases high grade limestone from a source within 20 km of the plant. This is used as sweetener for preparation of optimised raw mix for production of good quality clinker. An automatic blending control system has also been installed in the plant to maintain a minimum standard deviation of various moduli values. Fig 2. Sepax separatorfor the closed circuit cement m ill High ash in coal deteriorates the quality of clinker and req uires a high excess air factor, to achieve complete combustion ; also the quality of limestone should be high. Shree Cement is procuring coal from many sources including imported coal from South Africa, to prepare a pulverised coal mix with an ash content of less than 20% aimed at a calorific value greater than 5500 kcaVkg coal. A typical coal mix composition is presented in Table 2. Table 2 Typical coal mix and its characteristics Source % Proximate analysis composition of fine coal mix Imported from 70 1M % 2.10 - 3.00 South Africa Ash% 19.20 - 19.70 Indigenous 15 VM% 27.0 - 27.70 Assam Nanga! FC% 49.0 - 51.00 Indigenous 15 cv 5800 - 5900 Bituminous kcallkg coal mix ECL Fig 3. High efficiency dynamic separator on top ofthe coal mill tO •