Thermodynamic analysis of thermochemical recovery of high temperature wastes

This paper describes a feasibility study of direct heal recovery system fro m high temperature wastes over 1 700 K by using objective chemical reaction , in which enthalpy-exergy diagram, so-called thermodynamic compass, is int roduced for evaluating various systems. Blast furnace slag was taken as an example for the evaluation and familiar endothermic reactions in the cement production, the chemical industry, etc. were selected as a combination pro cess for the heat recovery. Exergy analysis of cement and methanol plants w as also carried out for further discussion. The results showed that decomposition of limestone, reforming of methane an d gasification of carbon are the most promising for heat recovery of the hi gh temperature wastes; various slag and LD gas, from a viewpoint of effecti ve use of exergy, not energy. This also appeals a possibility of next gener ation symbiotic steelworks with heat cascade utilization, rather than heat recovery.