Research On Green Evaluation Of Short Process Of Coal Gasfication-Gas Based Shaft Furnace-Electric Furnace

After taking into account the conditions of domestics iron resources and the development of iron and steel industry,the coal gasfication-gas based shift furnaceelectric furnace becomes an energy saving and environmental protection technology technique and the main direction of non-blast furnace ironmaking in china.This process can give full play to the advantages of rich non coking coal resources in China,make full use of domestic iron ore resources,change the energy structure of iron and steel production,reduce the energy consumption and environmental load of iron and steel production,and realize high-value utilization of scrap resources.In this paper,the green evaluation system of new technology of coal gasfication-gas based shaft furnace-electric furnace was studied.Firstly,the short process model of coal gasfication-gas based shaft furnace-electric furnace was established to clarify the material trend;Secondly,the energy utilization of the process was evaluated by the method of exergy evaluation to reveal the energy utilization of each link;Finally,based on the whole life cycle of the product,the environmental impact assessment and environmental load of each link,It was beneficial to promote the development of short process technology,and provided an important theoretical basis for design research and industrial application.(1)The per ton of crude steel required 992.83 kg of raw coal mass,1337.23 m3 of reduced gas,306.04 kg of direct reduced iron and 714.09 kg of scrap steel,it the same time,it consumes 470.6 kWh of electricity and emits 432.20 kg of CO2.(2)The exergy efficiency of coal gasfication,pellet oxidation process,the shaft furnace reduction process and electric steelmaking was 55.94%,73.47%,70.70%and 93.14%,respectively.After calculation,the exergy efficiency of the whole process was 66.56%.For the weakest coal gasfication link,the carbon conversion rate can be increased and the waste gas heat recovery can be used to improve the efficiency of this link,thereby increasing the energy utilization of the entire process.(3)Based on the energy balance calculation of the gas-based shaft furnace direct reduction process,the influence of different parameters on its radon efficiency was obtained.With the reduction of the amount of gas entering the furnace,the energy consumption of smelting ton of iron decreases.The increase of H2/CO mass ratio in the reducing gas,the decrease in the amount of gas entering the furnace,the increase in the discharge temperature,and the increase in the amount of carburization of direct reduced iron are all conducive to the efficient use of energy in the shaft furnace.(4)The overall life cycle evaluation result of the whole process process(30%DRI+70%scrap steel)was 1.83E-11.Under this condition,the total energy consumption of per ton of steel was 263.67 kgce and the CO2 emission of per ton steel was 829.89 kg.The life cycle assessment results of the traditional long-flow blast furnace-converter process was 9.31E-11 the total energy consumption per ton of steel was 669.82 kgce,and the CO2 emission of per ton steel was 1722.3 kg.The comparison found that the overall index of life cycle assessment of short process process was only approximately 20%of the traditional long process process,the overall environmental load was smaller and the environmental advantage was obvious;With the increase of proportion of molten iron in the electric furnace charge,the short-process energy consumption and pollutant emissions displayed an upward trend.The overall environmental assessment results of the process increased and environmental performance deteriorated,but the power consumption decreased.