Valmet’s lime kiln system ensures reliable and energy-efficient production of high-quality lime for the recausticizing operation.
A lime kiln is used to convert calcium carbonate CaCO3 into burnt lime CaO. The burned lime reacts with the green liquor and precipitates as CaCO3, thus creating a closed-loop with the recausticizing.
The Valmet lime kiln is based on a long line of successful projects starting in 1904 taking the production from just 15 tpd to 1,250 tpd.
Efficient drying and preheating of the vacuum filtrated lime mud is achieved in a flash drier system operated on kiln off-gasses. The flash drier system is designed to operate at a low-pressure drop and high flexibility via the unique off-gas recirculation system.
The dried mud is fed to the rotary kiln, heated to calcination temperature and burned to the required quality. Insulating lining and kiln internals ensure a high heat transfer rate and energy-efficient operation.
The heat for the kiln is supplied from kiln burners that can be designed for any type of gaseous, liquid or solid fuel such as biofuel or a combination of these.
The product cooler recuperates the heat from the hot kiln product and cools the product to a suitable low temperature for further handling via heat exchange with combustion air for the kiln.
The high efficient triple-pass product cooler is used for standard-sized kilns. An insulated stationary casing minimizes heat and noise loss to the environment.
The travelling grate cooler is used for high capacity kilns. The intimate mixing of air and lime on the travelling grate provides a very efficient heat exchange and the exceptionally high-energy efficiency of the kiln system.
The Valmet lime reburning kiln can support biofuel solutions such as Gasification, LignoBoost or direct wood powder firing.