Biomass in Cupola
The cupola furnace is a melting furnace for the production of cast iron out of raw iron. Beside raw iron, there are also steel scrap, recycled metals and foundry coke which are used in the cupola furnace. The main tasks of the foundry coke in the cupola process are the supply of energy and the use as recarburizer. The price of foundry coke was ca. 550 €/t in May 2011. Through the use of foundry coke for the process, 1.5 M tons of CO2 were emitted in 2011. Hence, companies are not only burdened by the high prices of foundry coke but also by the CO2-certifcat system. As a result, operators of cupola furnaces are looking for alternative substitutes for foundry coke.
A promising alternative carbon carrier for the use in a cupola furnace may be biomass residues, which can be converted into higher class carbon products by thermo-chemical conversion processes such as pyrolysis. Through the use of biogenic input material, fossil resources may be saved. As part of the research project at the Unit of Technology of Fuels, possibilities for the substitution of fossil carbon carriers, for example foundry coke, dust coal, by biogenic carbon/coke are investigated. In a first step, several biomasses, for example straw, bark, green waste, wood residues, nut shells, shall be pyrolysed in pilot scale rotary kiln to investigate the pyrolysis capacity and the properties of the obtained carbonization products. As the carbonization products from the biomass pyrolysis are, other than coke from hard coal, only available in insufficient grain sizes, the carbonization products further need to be briquetted to serve as a substitute for foundry coke. Subsequently, several tons of biogenic carbon carriers from selected biomasses shall be produced in a pilot scale rotary kiln. The produced carbonization products will be briquetted, tested and analyzed in industrial cupola furnace trials.