To reduce fossil energy costs by substituting rice husks for conventional fuels.
The limestone and other rock used in clinker production have a high moisture content and must be dried prior to grinding. The rotary dryer installation used for the purpose traditionally burns bunker fuel oil. In the Philippines, however, the major staple food is rice, which is grown extensively throughout the country. After the harvest, the grain is separated from the husk, generating a significant quantity of waste. Traditionally, husk disposal has meant uncontrolled open burning, leaving its calorific value untapped.
Lafarge decided to install an energy recovery system and utilize the energy from rice husks to fuel the rotary dryer. The farm cooperative collects rice husks in big bags (1 m3) for transport to the cement plant, where the husks are introduced directly into the flame of the rotary dryer. Rice husks are burned in place of bunker fuel oil.
The process allows rice husks to be substituted for fossil fuel in a proportion of 35%, translating to a savings of 2 million liters of bunker fuel oil per year. Taking advantage of biomass energy recovery also decreases air pollution and greenhouse gas emissions by reducing the quantity of fossil fuel burned.
Lafarge Cement, Iligan, the Philippines.