Evaluation of the Melting Gasification Process for Recovery of Energy and Resources from Automobile Shredder Residues

Abstract

In this study, we investigated the applicability of an automobile shredder residue (ASR) as an energy and recycling resource. First, ASR gasification was conducted in a fixed-bed reactor (throughput = 1 kg/h) at different temperatures (800, 1000, and 1200 °C) and an equivalence ratio of 0.1–0.5. Clay bricks were prepared with the solid residue obtained from the gasification process to address the issue of solid-residue production in pyrolysis. The syngas (H2 + CO) from ASR gasification had maximum and minimum yields of approximately 86 and 40 vol.%, respectively. Furthermore, the yield of syngas increased with the temperature and equivalence ratio (ER); therefore, the optimum conditions for the ASR gasification were determined to be a temperature of 1200 °C and an ER of 0.5. In addition, solid residues, such as char and ash, began to melt due to thermal heating in the range of 1300–1400 °C and were converted into melting slag, which was subsequently used to manufacture clay bricks. The absorption ratios and compressive strengths of the clay bricks were compared to those set by Korean Industrial Standards to evaluate the quality of the clay bricks. As a result, the manufactured clay bricks were estimated to have a compressive strength of over 22.54 N/mm2 and an absorption ratio of less than 10%. Additionally, greenhouse gas (GHG) emissions from the melting–gasification process were estimated and compared with those from ASR incineration, calculated using the greenhouse gas equations provided by the Korean Ministry of Environment. As a result, it was revealed that the GHG emissions from the combined melting–gasification process (gasification, melting system, and clay-brick manufacturing) were approximately ten times higher than those from the ASR-incineration process. Thus, in terms of operation cost on the carbon capture process for GHG reduction, the combined melting–gasification process would be a more efficient process than that of incineration.

Keywords

• bottom ash
• automobile shredder residue
• clay brick
• melting-gasification process
• greenhouse gases