Cogeneration based on energy recovery from exhaust gases

Abstract

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 600ºC 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 effi ciency 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 fi rst 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