| With the sustained and rapid development of economy in China, the energy problem has become a bottleneck to further economic development. How to improve the energy efficiency to solve the energy problem, is a serious problem in China. The resources and energy consumption of iron-steel enterprises are tremendous, and especially energy consumption in iron-making process is about60%of total energy consumption. Though many technologies such as TRT and CDQ were generally used, high-temperature slags were not effectively used as the secondary energy, how to use the energy in the high-temperature slags more effectively has become a need to overcome.The study proposed a new method of using coal gasification by molten BF slag to recover the energy of molten slag. The basic research of this method was carried out. The research results are as follows:(1) A new heat recovery system was proposed. This system consists of melting gasifier, the2nd gasifier and boiler in order to achieve stepped energy using. The melting gasifier and the2nd gasifier used the endoyhermic heat of gasification reaction instead of sensible heat to recover the energy of molten blast furnace slag.(2) The pyrolysis characteristics of coal-N2with blast furnace slag using the STA409PC thermal analyzer were researched. The influence of the addition of BF slag and coal type on pyrolysis reactivity were emphasized. The results showed that the molten slag could improve the pyrolysis reactivity, and its kinetic parameters were solved.(3) The coal gasification reactions in the molten slag were studied kinetically by the isothermal and non-isothermal thermogravimetry using STA409PC thermal analyzer. According to the TG curves obtained, the gasification effecting factors of the mass addition of BF slag, the coal type, heating rate, the BF slag chemical composition and temperature were studied. The research offered fundamental changes and the main effecting factors for further basic theoretical research.(4) According to experimental data obtained from STA409PC thermal analyzer, combined with Li Chung-Hsiung method, coal gasification reaction mechanisms were speculated, and the kinetic parameters were obtained by Satava-Sestak method. Based on thermogravimetric experiment, gasification reaction mechanistic models of different chars in molten blast furnace slag bath were established.(5) A miniature-testing device with coal gasification by BF molten slag was designed and constructed in this work, based on the previous experiment and theory in laboratory. This work made a deep research on coal gasification characteristics in the molten slag bath. The results showed that the coal gasification in the molten BF slag had extensive adapabitity to the coals supplied from different origin. The carbon conversion and gasification rate of DATONG and SHENNAN coal were both high. The calorific value of the syngas and reaction rate of SHENNAN coal, the representative of coals with high ash and low carbon content, were close to the high-quality bituminous DATONG coal; The system had extensive adaptability to the the coal granularity; Temperature had a significant impact on the gasification reactivity in the BF slag bath. The carbon conversion and gasification efficiency were improved gradually with the increase of temperature. The best temperature of the coal gasification reactions in the molten bath was1623K. Gasifying agent as the carrier gas blew coal into the reactor,which had a directly effect on the residence time of the coal particles and the flow state in the reactor. When the C02-coal ration was1.02, the best gasifying agent was0.14m3/h. The study in the influence of the gasification reaction in the molten slag at constant temperature by the CO2-coal ration showed the density of CO reduced and the density of H2first increased and then decreased with the increase of CO2-coal rations, but the CO/H2volume ratio reduced at first and then increased. |
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