Effect of crushing conditions of crushing rate in process analysis of sewage-sludge organic solid-fuel crusher using the discrete element method

Owing to environmental problems generated in the course of economie growth, the industry is implementing renewable portfolio stan-dards (RPS) for companies that own power generation facilities with capacities equal to or in excess of 500 MW. In coal-fired electrical power plants, renewable portfolio standards are implemented using sewage sludge organic solid fuels to address environmental problems. Currently, sewage sludge organic solid fuels are crushed using a hammer mill operated in the co-firing mode. However, the hammer mill has low operation efficiency owing to the fast wear and tear and frequent breakdowns of the hammer and grate that constitute two of its key components. Therefore, the development of a crusher with increased durability and high-operation efficiency is necessary. In this study, a roller-type crusher was designed for the organic solid fuels of the sewage sludge that was operated with the use of compression and friction forces. The effect of the crushing condition of the designed roller type sewage-sludge organic solid-fuel crusher was analyzed. In addition, fuel crushing analysis was carried out using the discrete element method (DEM). Based on the DEM analysis results, the effect of process parameters (rotation speed of the rotor, roller size) of the roller type sewage-sludge solid-fuel crusher on the crushing rate was analyzed. A fuel crushing experiment was conducted using the roller-type crusher used for sewage-sludge organic solid fuels. In addition, the crushing rates against the amount of fuel discharge according to the DEM results and fuel crushing experiments were compared.