Cement Energy & Environment

43 740 to around 680 kcal/kg clinker and reduce CO 2 intensity below 700 kg/t clinker by 2035. 2. ADVANCED KILN OPERATIONS The kiln is the heart of a cement plant, consuming more than 60% of total process energy. The control of temperature, airflowand material feed must be precise, as small variations directly affect clinker quality. Traditional manual control is limited by human reaction time, while AI-assisted MPC systems can respond to process disturbances within seconds. In Plant 1, MPC implementation reduced specific heat from 735 to 705 kcal/kg clinker and improved kiln stability significantly. The software analysed parameters suchas flame temperature, kiln torque, draftand gas composition to maintain optimal conditions.Similarly,Plant2reporteda3.5%increase in kiln throughput while keeping free limebelow 1.2%. Table 1 – Digital Process-Control Benefits Plant Technology Specific Heat (kcal/kg cl) Throughput Change (%) CO 2 Reduction (%) Plant 1 (India) MPC + AI 735 → 705 2.8 4 Plant 2 (India) CFD–AI 730 → 700 3.5 5 Plant 3 (India) Laser Flow Control — 15 8 These results show that digital control enables consistent burning, stable flame patterns, and smoother calcination. AI predicts deviations in the burning zone temperature and adjusts the fuel-air mix automatically. In global comparison, European plants using similar MPC systems report up to 5% fuel savings and 3–4% higher kiln uptime, demonstrating universal benefits of predictive control. 3. ENERGY AND EXERGY FLOW IN MODERN KILNS Energy audits reveal that nearly one-third of the total heat input in cement manufacturing is lost as waste. Figure 1 illustrates the exergy flow in a modern kiln system, showing useful and wasted energy streams. The preheater and cooler contribute most to thermal losses—often due to high exhaust temperatures and radiation through the shell. Preheater Rotary Kiln Losses fuel losses material Figure 1 - Energy and Exergy Flow Map of a Modern Kiln useful heat ow useful heat ow Exhaust Gas Cooler Figure 1: Energy and Exergy Flow Map of a Modern Kiln (Red arrows = losses; blue arrows = useful heat flow.) In Plant 3, a detailed exergy analysis showed that 31% of total irreversibility occurred in the cooler section. After retrofitting with low-pressure air grates and insulating the tertiary duct, the plant recovered 14 kcal/kg clinker. Shell radiation losses were minimized through advanced coatings and heat shields.