Research Of The New Fully Dry Dedusting And Waste Heat Recovering Process For Converter Flue Gas

At present, the recovery processes for LDG mainly are OG method and LT method. These methods are improved and innovated in saving water, electricity and inproving the dust collection efficiency. Because of the limited of these processes themselves, many problems are not being solved fundamentally. Such as flue gas is directly cooled by water spraying, wasting of water resources, causing water pollution and reducing the calorific value of LDG; The high temperature waste heat which is from the evaporative cooling flue’s outlet is not recovered, etc.In order to reduce energy consumption in steelmaking process further, realize steelmaking with minus energy consumption (SMEC), according to the generation principle and law of the converter flue gas and the features of the gas itself, the waste heat resources and the shortcomings of the current processes are investigated in this thesis. The research shows:(1)The quantity of total waste heat resources of converter gas is1.21GJ/t, and the total exergy is1.08GJ/t. According to the present processes, the maximum recovery quantity for2.5MPa saturated steam is146.29kg/t.(2)Through the thermodynamic analysis to the recovery processes for LDG at present, we know that LDG is the most efficient to the exergy recovery; heat loss is mainly in spray cooling stage; exergy loss is mainly in heat transfer and spray cooling stages..(3)With the air burning coefficient a increased, it will increase exergy loss in heat transfer and burning stages, reduce the recovery quantity of LDG. The air burning coefficient in recovery period should be control in0.1.For the shortages of the current recovery processes for LDG, a new fully dry dedusting and waste heat recovering process for converter flue gas is proposed. And the structural features, control and operation mode and operating parameters of each major equipment in this new process are researched preliminarily. Advanced and mature technologies and equipments at home and abroad are usd in this new process. It also absorbs successful experiences from the current processes. So it is easy to be implemented. The analysis shows that the energy saving effect is remarkable. The maximum recovery quantity for2.5MPa saturated steam is137.10kg/t, LDG with high calorific value can be recovered94.48Nm3/t. It can achieve to reduce energy consumption more than45.99kgce/t in steelmaking process, and the system’s exergy efficiency will be increased by5.3%.Finally, taking120t converter in NISCO for an example, make case analysis. If apply fully dry dedusting and waste heat recovering process to120t converter, each converter could recover steam32.81t/h on average, increased by67.40%; LDG with calorific value more than9100kJ/m3can be recovered94.48Nm3/t(about0.87GJ/t), and the recovery level will be increased by19.18%. Comprehensive consideration of the water and electricity consumption, the energy consumption in steelmaking can be reduced to-19.14kgce/t.