Research On Zero-emission Technology Of Desulphurization Wastewater By Gradient Using Flue Gas Waste Heat Of Power Plant

The desulfurization wastewater has complicated water quality and difficult treatment.It analyzed the shortcomings of the existing zero-emission technology of desulfurization wastewater.Based on the desulfurization wastewater flue evaporation technology,a new desulfurization wastewater treatment technology has been developed——Step-by-step desulfurization wastewater technology using flue gas residual heat treatment,For the case where the existing flue evaporation droplets were not evaporated,a system process for the atomization and pre-evaporation treatment of the desulfurization wastewater by the venturi was creatively proposed.The atomized droplets were pre-evaporated by the waste heat flue gas introduced from the electrostatic precipitator,the droplet size was reduced,and then send to the main flue to complete evaporation;In the case that the existing flue evaporation treatment was insufficient,it was proposed that the waste heat flue gas after the electrostatic precipitator was directly contacted with the waste water in the form of impact bubbling to perform thermal concentration to ensure the treatment capacity of the desulfurization waste water.When the gas-liquid ratio in the venturi atomization system(Atomizing gas volume / atomizing fluid volume)(Nm3/L)was between 16 and 20,the atomization effect was better;different bubbling air temperatures have different maximum evaporation level intervals,and the optimal evaporating liquid level and the lowest evaporating liquid level have a slow increasing trend with the increase of air temperature.Under the working conditions of the power plant,the bubbling liquid level should be below 20 cm.When the bubbling air temperature was 110 ? and the bubbling liquid level was 20 cm,the amount of concentrated water per unit volume of air was maintained at 0.035 L/m3.As the amount of atomized evaporation liquid increased,the more smoke was extracted,the greater the temperature drop after the air preheater,When the amount of evaporation liquid was 3 t/h,the temperature of the smoke after the air preheater drops within 5 ?,and the amount of atomized smoke was 60,000 Nm3/h,accounting for 4.43 % of the total smoke volume.The temperature drop of the flue gas caused by the evaporation of the wastewater and the increase of the humidity of the flue gas would reduce the specific resistance of the dust and increased the dust removal efficiency of the electrostatic precipitator;the actual flue gas volume increased by 2.4 %(330 MW unit,atomized evaporation 2 t / h wastewater conditions),a small reduction in dust removal efficiency;The integrated smoke temperature drop,the increase of flue gas humidity increase the dust removal efficiency,the increase of the flue gas volume and the dust removal efficiency,the evaporation of the wastewater would not have a significant impact on the dust removal efficiency of the electrostatic precipitator.In the comprehensive utilization process of fly ash as cement admixture,the index of chlorine element was evaluated.The limit of chlorine content in cement was 0.06 % of its mass,and the amount of fly ash in cement was 27.27 %.When the following,the chlorine element in the cement was qualified.