Thermodynamic Analysis of Blast Furnace Production at a Metallurgical Plant

Abstract

The article presents a thermodynamic analysis of various process circuit solutions used to purify blast furnace gas in using a top pressure recovery turbine (TRT). A wet process circuit operating on cooled and heated blast furnace gas, and a dry process circuit including an evaporative scrubber are considered. By using the newly developed and tested methods for calculating wet saturated blast furnace gas and the gas expansion process in the TRT, the parameters of various energy carriers involved in the blast furnace technological processes have been determined. The results of calculating the primary and secondary energy resources consumed in the blast furnace, air blast heaters, and the plant’s combined heat and power station are presented. The amounts of energy consumed by various installations have been estimated, and the blast furnace gas, steam, and exhaust gas exergy fluxes have been determined. The material, energy (thermal), and exergy balances have been drawn up. Based on the material balance drawing up results, the raw materials, fuel, and air consumption values, as well as the cast iron output values, have been obtained. The energy balance is drawn up based on calculating the physical and chemical energy flows of individual energy resources and materials. In drawing up the exergy balance, losses resulted from the irreversible nature of combustion processes and heat transfer into the environment were taken into account. After determining the balances, the wet process circuits were compared with the proposed dry purification version option in terms of thermodynamic efficiency. The production exergetic efficiency has been determined. The results proving the high potential of dry blast furnace gas purification in the process circuit with TRT as an effective alternative to a rather costly conventional wet process circuit are presented.