Study on the boiling point variation during the evaporation and concentration process of desulfurization waste water
In order to provide guidance for the regulation of the discharge timing and discharge volume of the thickener slurry in the desulfurization wastewater evaporation and concentration process system of a coal-fired power plant.In this paper,four main solutions(MgCl2,MgSO4,NaCl,Na2SO4)were used to simulate the evaporation and concentration process of desulfurization wastewater,and the dependence between the ion concentration and the boiling point elevation during the evaporation and concentration process was studied.The results showed that the boiling points of different salt solutions at the same concentration rose in the order of MgCl2,NaCl,MgSO4 and Na2SO4,MgSO4 and Na2SO4 crystallized when the concentration reached about 0.4 mol/100 gH2O and 0.3 mol/100 gH2O,and it was difficult for MgCl2 to crystallize and precipitate.When NaCl reached saturation concentration,the rise of the boiling point of the solution depended on the MgCl2 concentration,and the boiling point of the solution could be up to 76℃or more.The addition of crystal species reduced the starting temperature of crystallization,evaporation and crystallization of the late stage,the solution is mainly high solubility of MgCl2.When the solution density reached 1.3～1.4 g/mL,stop evaporation and concentration and cooling to room temperature,a large number of crystals could be precipitated,and excessive heat consumption can be avoided.In order to maintain the stable operation of the concentration tower,the saturation temperature of the slurry was between 64.5～68.5℃,and the saturation vapor pressure of the slurry was kept between 18～20 kPa,which improved the solid-liquid separation effect in the late stage of wastewater concentration and crystallization,and was conducive to the improvement of the quality of the mudcake and filtrate recycling and reuse efficiency.
desulfurization wastewaterflue gas waste heatevaporation-concentration-crystallizationboiling point risewastewater zero discharging
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维普
