Hard-hitting facts such as scarcity and price hike of fossil fuels and challenges of waste management warn of difficult times ahead for the Indian cement industry, unless the players increase their efforts at increasing the capacity of Waste Heat Recovery Systems to meet their energy requirements. 

The economics of Waste Heat Recovery Systems (WHRS) is preceded by sustainability concerns, as cement manufacturing in kilns continues to produce 8 per cent of the global greenhouse gas (GHG) emissions. The conversion of limestone to clinker is where the bulk of the heat energy is expended. However, this bulk of heat energy that is generated in six-stage preheater kilns by burning of any fossil fuel input actually gets wasted as shown in the pie-chart Fig 1, and only 58 per cent is used in the conversion process yielding clinker. 

Out of the total generated heat there are some unavoidable losses, that include radiation loss, loss for evaporation of residual moisture in fine coal and raw meal and some part of heat going with clinker from cooler. The balance loss in pre-heater exhaust gases and the cooler exhaust gases are completely recoverable through WHRS. 

Balancing the investments

The Indian cement industry must act responsibly and move quickly to put in investments that could raise the waste heat recovery installed capacity to cross the minimum threshold of 25 per cent of electricity consumption. That will still be far from the 20 billion KWhr of total electricity consumption by the industry. 

Thus WHRS could be the natural hedge to fossil fuel price increases for a substantial portion of the electrical consumption. As matters stand today most WHRS would be the highest IRR projects that the industry as an ensemble can think of. 

– Procyon Mukherjee

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