Cement and Energy

Table I: Progressive Reduction in Energy Consumption by Indian Cement Plants 1950-60's 1970's Process/ Wet Semi-dry Plants Dry Capacity, 300-600 600-1200 tonnes/day Heat consumption, 1300-1600 900-1000 kcal/kg clinker Power consumption 115-130 110-125 kWh/t cement While modern cement plants in the country today fa vourahl y compare with international plants wi th regard to the heat consumption of 650-750 kcal/kg cl in ker and power consumption of 80-1 00 kWh/tonne of (OPC-43) cement, the older plants can be modern ised/expanded by technology upgradation and rctrolitiing with energy efficient equipment/systems, such as: Single-stage impact crushers/hammer mi li s - Vertical roller mills and Roller presses Low-pressure preheater cyclones - Mechanical conveying of raw meal/kiln feed and cement - Low primary air multichannel burners - Clinker cooler retrofit High ellic iency fans with SPRS for speed control - Htgh en ICicncy dynamic separators Di~trihutcd Control System and Ex pert System - Waste heat utilisation ror co-generation of power It may he men tioned that by pioneering efforts, some of the cement plants have reduced their energy consumption by 25-30%, through ineorporating/rctroliting most of the above equipmen t/systems during the last 7-8 years giving them the compet it ive advantage over others. 1980's 1990's Dry-4 Stage Dry-5/6 Stage Preheater/ Preca1ciner Preheater/Precalciner 2400-3000 3300-7500 800-900 650-750 105-115 80-100 The existing cement plants, which have inherent peculiarities of energy inefficient process/systems and di sadvantage of scale economy, can ach ieve major productivity enhancement and energy conservation by adopting energy audi t and management systems. In this connection , National Council for Cement and Building Materials (NCB) has taken major ini tiatives towards developing an integrated approach for assisting the industry in energy conservation through technological support and R&D. Energy audit has emerged as a potent tool for identification, analysis and implementation of energy conservation measures and overall energy management. For formulation of Guidelines for energy conservation in Indian cement industry, a joint project is being taken up in collaboration with New Energy & Industri al Technology Development Organisation (NEDO), Japan. Efforts arc also under way to install a demonstration unit for co- generation of power from waste gases in cement pl ants with fund support from international agencies, such as Global Environment Facility (GEF}, NEDO, etc. Energy Audit NCB has so far carried out I 03 energy audit studies including 32 through its Mobile Energy Diagnostic Unit and has helped the plants identify their indi vidual potentials lor energy and cost saving. For some of the plants in the capacity range of 1.0- 1.2 Million TPA, the potential savings identified through energy audit studies arc given in Table II. 3