A second-law analysis of the "hot blast stove gas turbine" combination by applying the parameter "usable exergy"

The aim of this paper is, first of all, to examine a coupled arrangement in which turbine waste gas is used as the oxygen carrier for combustion of the fuel gas in hot blast stoves and preheaters of a blast furnace; in their turn, the blast furnace gas and the turbine waste gas are preheated by the combustion of blast furnace gas, in order to achieve the necessary combustion temperatures. The arrangement makes provision also for utilization of external thermal energy. The coupled process is compared with a hot blast stove system and a gas turbine plant without waste thermal energy recovery, which operate separately. The paper uses the concept of usable exergy, a previously defined parameter, to compare the two configurations and reverses some of the results obtained by a first-law analysis. (C) 1997 Elsevier Science Ltd.