Cement, Energy and Environment

28 INITIATIVES UNDER DEVELOPMENT • Using green hydrogen as a fuel. • Using carbon capture, utilization, and storage (CCUS) to prevent CO2 from being released. • Using carbon mineralization to convert CO2 into stable mineral forms. • Using precast refractories. • Using advanced blending techniques. The Company’s initiatives to minimize its water consumption including installation of Air-Cooled Condensers in its thermal power plants and the establishment of Waste Heat Recovery based power plants have been highly successful. A case study of WHR plant is discussed below. In cement industry utilization of heat of waste gases is a hot topic and not picked up in India due to high cost of installation and technological risk. Figure 1 SCENARIO BEFORE WHR In the clinker burning process, a large amount of heat is consumed for burning limestone at 1450 degree C to form clinker. From the total heat consumed in the burning process, around 55% is for burning process and the rest 45% is discharged as sensible heat through the exhaust gases of Pre- Heater(PH), AQC, radiation & sensible heat carried out by clinker. However, around 10% of the heat, extracted fromthe PHs &AQCs, is used in drying the raw material and coal while grinding. The rest 35% is generally emitted to the atmosphere as waste heat. The waste exit gases from the pre-heater (PH) pass through a Gas Conditioning Tower (GCT) for dissipating the energy then passed through the Electrostatic Precipitator before being released into the atmosphere. However, waste gases from air clinker cooler (AQC) pass through the Electrostatic Precipitator before being released into the atmosphere. A schematic diagram of clinkerization unit (Fig-1) has been sighted here. CHALLENGES FORWHR SYSTEM • Large capital requirement • Non-availability of proven technology indigenously. • Special design requirements due to • The dust concentration in the flue gases is sticky, abrasive and corrosive in nature. Hence, the dust can accumulated on the surface of the boiler tubes. With continued accumulation of the dust, the passage of the flue gas through the WHRB can blocked. As a result, a pressure imbalance can be created across the Waste Heat Recovery Boiler and the operation of the kiln can adversely affect. The operation of the kiln will to be stopped for over numbers of hours. Cement manufacturing being a continuous process, losses (production and financial) on account of stoppages are very high. • The Waste Heat Recovery Boiler can have