| The flue gas desulfurization waste water with spray evaporation treatment is an effective technology that spraying the desulfurization waste water into the tail flue of the boiler,and to realize the complete evaporation of the droplet by the waste heat of the flue gas.It is of great significance for the design of evaporators,the determination of the operating parameters of the evaporator and the economic benefits of the spray evaporation technology of desulfurization waste water to study the evaporation process of liquid droplets and understand the influence of main operation parameters on the spray evaporation technology.Therefore,it is necessary to study and analyze the spray evaporation technology of desulfurization wastewater.In this paper,a mathematical model of spray evaporation technology for desulfurization waste water is established by combining experimental and numerical simulation,and the reliability of the mathematical model is verified by experiments.On this foundation,the effects of flue gas temperature,spray angle,droplet size,flue gas velocity and waste water flow on droplet evaporation characteristics were studied.According to the evaporation characteristics of droplets,how to select operation parameters to realize efficient evaporation of droplets was studied.The effects of flue gas temperature,waste water flow and droplet size on the optimal smoke velocity were quantitatively analyzed.Finally,combined with specific practical cases,the actual power plant desulfurization waste water evaporation in the evaporator under different operating parameters is studied,and the maximum desulfurization waste water treatment capacity is determined.The main conclusions are as follow:?1?The comparison between the experimental and simulation results of the mathematical model shows that the droplet evaporation observed by the experimental fluorescence method and the simulated droplet size field show the same rule.The average relative error between the simulation results and the experimental results is 2.67%when the flue gas temperature is110201?,which verifies the reliability of the mathematical model.?2?For the experimental evaporator,the quantitative relationships between droplet evaporation rate and flue gas temperature,spray angle,droplet size and waste water flow were obtained.Increasing flue gas temperature and spray angle,reducing droplet size and waste water flow can promote droplet evaporation.However,excessive flue gas temperature will not greatly promote droplet evaporation,but will lead to excessive outlet flue gas temperature and waste of heat.When the spray angle is bigger than 40°,the droplet evaporation rate almost remains unchanged,and some droplets touch the wall of evaporator and adhere to the wall to corrode the wall.In addition,it has been found that the complete vaporization length of desulfurization waste water decreases first and then increases with the increase of flue gas velocity.There is an optimum flue gas velocity makes the minimum complete vaporization length,and the high efficiency evaporation of desulfurization waste water can be achieved by adjusting the flue gas velocity to the optimum value.When waste water flow is 14L/h,droplet size is 30?m,spray angle is 30°constant,the optimum flue gas velocity is 1.43 m/s when flue gas temperature is 168?and 0.91 m/s when flue gas temperature is 450?.?3?In the range of parameters studied in this paper,the quantitative relationship between the optimum flue gas velocity and the flue gas temperature,waste water flow,droplet size were obtained respectively.vs=-3.53×10-8Ti3+3.11×10-5Ti2-1.03×10-2Ti+2.5vs=1.59×10-4Gp3-6.67×10-3Gp2+0.152Gp+0.167vs=-7.82×10-6dp3+1.3×10-3dp2-8.28×10-2dp+3 The increase of flue gas temperature,the decrease of waste water flow and the increase of droplet size will mostly lead to the decrease of optimum flue gas velocity.?4?For the actual power plant desulfurization waste water evaporator,the quantitative relationships between the complete vaporization length of of droplets and flue gas velocity,flue gas temperature,droplet size and waste water flow were obtained respectively.The maximum desulfurization waste water treatment flow increases linearly with the increase of flue gas temperature and velocity respectively,when the droplet size is 52?m,flue gas velocity is 37m/s and flue gas temperature is 300400?.The maximum desulfurization waste water treatment flow changing with flue gas temperature and flue gas velocity is as follows:Gpmax=2.173×10-3Ti-0.641ug+3.504×10-3Ti×ugCompared with the simulation results,the error is within±5%and can be completely used for the design,operation and real-time control of the desulfurization waste water evaporator. |
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