Waste heat recovery: a review of hardware and applications

This paper emphasizes waste heat recovery methods in the energy intensive iron and steel making, aluminum making, chemical, and glass manufacturing industries. Three waste heat recovery methods--direct, indirect, and secondary--are studied. Direct heating utilizes the flue gases to preheat the fluid or stock that is being thermally processed. Indirect heating uses flue gases to preheat constituents entering the combustion system. The secondary method preheats the external medium. Steam generation, thermal fluid heating, and cogeneration are also considered. Recuperators, ceramic or metallic, of radiative, convective, and canal type, are described. Rotary generators, waste heat boilers, and incinerators are also specified. Proper selection and design of a waste heat recovery system can help any plant reduce its energy dependency.