WHR at ACC Gagal
ACC launched its first waste heat recovery (WHR) system at the Gagal cement plant. This marks an important step in energy conservation for the company, as it is the company´s first WHR plant and also the first such project in Himachal Pradesh to deploy WHR technology. A WHR system harnesses waste heat discharged in the manufacturing process as exhaust gases, channelling these gases into a waste heat boiler that runs a steam turbine and converts it into useful electrical energy. The newly commissioned WHR unit, set up at a cost of about $16 million, can generate about 7.5 MW of electricity. This supplements the output of Gagal´s captive power plant. Nantong Wanda supplied the boilers for the project, while the turbine and generators were supplied by Qingdao Jieneng and Shangdong Jinan, respectively.
WHR energy at Gagal has proved to be remarkable in several ways - the first of which is that it requires no additional fuel. The cost of generating such energy has turned out to be significantly lower than that of the captive power plant and only a fraction of the cost of purchasing grid power.
Waste heat to electricity
Waste heat generated in cement manufacture has proven to be amenable to conversion into electrical energy, provided it is tapped in adequate measure and the temperature is sufficiently high to make the project viable. In a typical Indian cement plant, the potential generation of power from waste heat is estimated at about 20-25 kWh/tonne of clinker.
As experienced by ACC at Gagal, the cost of electricity generated by WHR units is cheaper than both captive power and power purchased from an external grid. Encouraged by the Gagal WHR project, ACC has plans to set up similar systems at its other major cement plants in the country in a move towards enhancing energy security.
India´s cement sector already has several working WHR plants and undoubtedly, such plants will become a feature in this fast expanding market. Waste heat recovery can comprise an economical and reliable supplement to captive power generation in an energy-intensive industry like cement, particularly in an energy-deficient country like India. In addition, this practice comprises energy conservation and efficiency that helps the cement industry meet its low carbon technology roadmap for the future.