The Research On The Treatment Of Desulfurization Wastewater By Flue Waste Heat

The limestone/gypsum wet FGD wastewater must be disposed to ensure the normal operation of the desulfurization system,the quality of the by-product gypsum and to prevent the excessive concentration of chlorine in the flue gas.This study has explored the flue gas evaporation technology of FGD wastewater,which is of great significance to the treatment of desulfurization wastewater by flue gas residual heat and realize zero discharge.This paper designed a three-flow rotary atomizer(which has been accepted as an invention patent)and alleviated the nozzle clogging for easy cleaning.The experiment studied three factors affecting atomizer angle,which included nozzle structure size,gas-liquid ratio,and internal and external compressed air ratio.The results demonstrate that:The nozzle realizes the optimal atomization structure size when the outer gas channel ab is3.6 cm and nozzle liquid channel be is 1.08 cm;The atomizing angle increases nearly linearly with the increase of gas liquid ratio;The atomizer angle presents an increase first and then decrease trend with the increase of compressed air ratio,and the atomaizing angle achieves the maximum when the gas ratio is 2:1;This designed atomizer has a good anti blocking performance.Based on the relevant parameters of 660MW tail flue of a power plant and the similarity theory,this work deduced similarity experimental criterion and set up the spray evaporation experiment table.An L35 orthorgonal sheet was adopt to arrange the experiments to obtain the evaporation length and the effect law of desulfurization wastewater under different conditions.Besides,the influences on SO2 in flue gas after the spray evaporation of desulfurization wastewater and the spray evaporation differences between tap water and desulfurization wastewater were also discussed.Research shows that the water amount has the greatest effect on the total evaporation length of the wastewater in flue gas,followed by smoke temperature,and the smoke velocity on the evaporation length is relatively small.Secondly,the evaporation length has a negative linear correlation with the smoke temperature,and a positive linear relation with the water amount.Thirdly,no extra SO2 would be produced during the disposal of desulfurization wastewater by fuel gas waste heat.Lastly,little differences of total evaporation characteristics emerge between the tap water and desulfurization wastewater.After simulating the experimental model,the simulation results and experimental data were compared to analyze The results reveal that the numerical simulation coincides preferably with the experimental temperature results,which the maximum relative error is 2.4%and the average error is 1.78%.In addition,simulatiing calculation and experimental results of wastewater total evaporation length are compared with the maximum relative error 13.33%and the average error 6.22%.The evaporation model used in this paper is of high accuracy and can be used for numerical simulation of desulfurization wastewater spray evaporationThe desulfurization wastewater spray evaporation were studied by numerical simulation with verified model equation to explore the effect of various factors on throughput,which includes the installation position and angle of nozzle in the pipeline,flue gas temperature,flue gas velocity,and tomized particle size.The results show that the best effect occurs when the nozzle installation position is in the upside of the lower pipeline,with the insert depth of 1/4 pipe height.The flue gas temperature and atomization particle size have a lager effect on the flue gas velocity field while a lower effect by flue gas velocity.The maximum water evaporation calculation formula of a tail flue of a 660MW power plant was fitting numerically according to different flue gas temperature,flue gas velocity,and droplet size.The error is±5%compared with the simulation results,which can be completely used to for the design,operation and real-time control of this system of the desulfurization wastewater spray evaporation.