Numerical Simulation Of Atomization And Evaporation And Reaction Characteristic In The Desulfurization Tower

In semi-dry desulfurization technique, the chemical reactions occur in gas, liquid and solid phases in the desulfurization tower, which is very complicated. The atomization and evaporation of the slurry-drops in the desulfurization tower determine the characteristic of desulfurization. Thus, it is very difficult to investigate the process of atomization and evaporation of slurry-drop in the tower by means of experiment. Therefore, the software FLUENT is used to simulate the atomization and evaporation of the slurry-drops and the removal of SO₂ in the tower.Firstly, FLUENT's air-blast atomization model and evaporation model were investigated. The influence of the model parameters on the atomization and evaporation and the choice principle of parameters were the main part of the investigation. The results show that the assisted air strongly disorders the flow field surrounding the atomization particles, and prolongs particle resident time in the tower, but influences little on the diameter of the atomization particles. As the maximum relative velocity between the sheet and air increases, the diameter of the atomization particle decreases, and the rate of the decrease becomes slow gradually. Along with the increase of the sheet thickness, the diameters of the atomization particles also increase. The introduction of the assisted air makes the spray angle influence little on the atomization.By using the atomization and evaporation model and choosing appropriate model parameters, the characteristic of evaporation and flow in the desulfurization tower were simulated. The influences of the technique parameters on the flow field, temperature field, humidity field and evaporation were the main part of the investigation. The results show that the inlet-velocity and inlet-temperature of the flue gas are two key parameters to the particle evaporation. Increasing inlet velocity temperature of the flue gas can both quicken the particle evaporation. Increasing the flux of the assisted air can increase the particle velocity in the near-nozzle area and prolong the residence time of the particles in the tower. Atomization fluid flux has no influences on the flow field and particle diameter in the tower. However, it affects the temperature field greatly. Adding dull-body in the inlet can increase the near-wall velocity in the near-nozzle area. The phenomenon of fouling caused by adhibiting of the liquid-drop to the wall can be effective prevented. The above results lend support to the mid-test and advanced engineering design.Aqueous particle drying model is presented. The paper has coupled the drying model with the gas-solid two phase flow model by a compiler interface. Using this program, FUENT had been secondly developed by UDF interface. The effects of the time step and the coefficient of the restitution on the fluidization in tower were investigated. Along the height of the tower, the concentration of SO₂ gradually decreases. Desulfurization reaction mostly happens in the area about 1.5m behind the nozzle. Along the height of tower, the concentration of CaSO₄, the product of the SO₂ removal reaction, gradually increases from nozzle end. At a certain cross-section, it presents the trend that concentration is high near the wall and low in the center. The process of SO₂ removal can be better simulated by this method.