Cogeneration based on energy recovery from exhaust gases

In the world there are a large number of foundry factories that, thanks to their production processes, are great energy consumers. The factories are equipped with various types of furnaces such as gas, electric induction and the cupola furnace. The study carried out in this article focuses on the last type and particularly on those with a continuous casting output. The gases emitted to the outside by these facilities have a high energy content, since they remain at a high temperature and are therefore susceptible to being energy producers. Currently facilities tend to use this energy for heating the air blown into combustion. But even after that use, exhaust heat can be expelled at temperatures above 600 degrees C and can, therefore, still be of further use. Heat recovery of these gases can be devoted to producing electricity, which is one alternative that leads to: an increase in the efficiency of the process, a reduction in emissions of gaseous pollutants (electricity generation does not emit anything that has not previously been emitted), and a reduction in plant operating costs. In this paper the authors have analyzed two alternative uses of waste heat from cogeneration gases. The first is the use of prefabricated modules and the second is a classic cogeneration facility with a boiler and steam turbine. For each alternative, two analyses have been performed: one economic (considering investment, electricity incomes and operating costs) and another technical (where the installation feasibility, and the advantages and disadvantages of each alternative are considered). This dual analysis method has allowed us to establish some general conclusions that are provided at the end of the article.