| In the various processes of iron and steel plants,the energy consumption of iron making accounts for more than half of the total energy consumption.At present,more than 90% of China’s steel enterprises choose the water quenching method to treat blast furnace slag,which makes most of the waste heat in the blast furnace slag transfered to the slag flushing water,and the complexity of the water quality of the slag water leads to the low utilization rate of this part of the waste heat resources.In order to efficiently recover the waste heat resources of blast furnace slag on the basis of water quenching method,this paper proposes a blast furnace slag waste heat recovery method based on flash evaporation technology,and the amount of steam generated by slag water flash is the key node of the entire waste heat recovery method.Therefore,based on the flash characteristics of the slag water flash,this paper developed a slag water flash system,studies the steam production of slag water flash under different working conditions,and obtained the empirical formula of slag water flash.The main points of the research are as follows:(1)Simulation study on the flash characteristics of slag flash water.On the basis of considering the special characteristics of the flash evaporation mechanism,a mathematical model of flash was established by applying the basic principles of fluid mechanics and heat and mass transfer,a and the flash process was simulated by coupling the multiphase flow mixing model based on the Euler-Euler method with the flash model.Using the simulation method,the effect of flash pressure and water entry height on the flash evaporation efficiency,and the distribution of the velocity field and pressure field during the flash evaporation process were studied.On this basis,the optimal water entry height of the flash evaporator and their risk-prone locations were obtained,providing operating parameters for slurry water flash experiments.(2)Develop a flash evaporation system for flushing slag water.The system is mainly composed of flash evaporation device,condensation device,solution preparation device and control system.Firstly,based on the simulation results and empirical formulas,the structure of the flash was optimized,and on this basis,the key devices in the system were developed;secondly,the were devices in the system were developed according to the system design requirements;finally,according to the control of the system,the programmable logic controller(PLC)and frequency converter were used,and a feedback adjustment system was introduced to realize the automatic adjustment of flash pressure,feed water flow,liquid level height and real-time monitoring function of temperature,flow,pressure and other parameters in the system,and corresponding hardware selection was completed on which a convenient human-machine interface was developed.(3)Carry out the experimental research on flash evaporation of flushed slag water.On the developed slag flushing water flash system,the relationship between initial temperature,flash pressure,feed water flow and flash steam production was studied by the controlled variable method.Based on a large amount of experimental data,the four variables of initial temperature,flash pressure,feed water flow and flash steam yield were integrated into two composite variables of superheat degree and flash efficiency η,and the nonlinear fitting method was applied to obtain an empirical formula for flash evaporation of flushed slag water in the range of superheat degree 15～30°C,which provides a strong reference for the use of flash evaporation in the field of flushed slag water waste heat recovery. |
PDF Full Text Request