Study On The Mechanism Of Desulfurization With Ammonia In The Spray Scattering Tower

The sulfur dioxide?SO₂?is the main atmospheric pollutant,and the coal-fired power plant is the most important source of sulfur dioxide.Therefore,reducing the emission of sulfur dioxide from coal-fired power stations has an important impact on easing environmental pressure.With the continuous introduction of strict environmental protection policies in China,the innovation of desulfurization technology for coal-fired power stations has become a research hotspot.The research hotspots of desulfurization technology mainly focus on desulfurization methods and desulfurization equipment.Among them,ammonia desulfurization is the effective and environmentally friendly desulfurization technology for controlling sulfur dioxide pollution because of its high desulfurization efficiency and non-contamination of by-products.At the same time,the researchers also proposed a new type of desulfurization tower combined with spray desulfurization and bubble desulfurization-spray scattering tower,due to its low energy consumption and high efficiency characteristics have attracted widespread attention.The reaction zone of spray scattering tower combine spray zone with bubble zone.Flue gas enter the spray zone and contacts with the slurry droplets to remove the part of sulfur dioxide.And the preliminary purified flue gas enters the bubble zone and contact with the slurry to deeply remove another part of sulfur dioxide.Based on the process characteristics of the spray scatter tower,the mechanism model and mathematical model of multi-phase flow,heat transfer,mass transfer and chemical reaction in the tower was established.Eulerian-Lagrangian method was used to describe the gas-liquid two-phase flow in spray zone,and the Eulerian-Eulerian model was adopt to simulate the gas-liquid two-phase flow in the bubbling zone.Meanwhile,a mathematical model of ammonia desulfurization in the tower was established.In this paper,the gas-liquid flow field and SO₂ concentration field of the typical spray scattering tower with ammonia desulfurization were numerically simulated to verify and modify the physical and chemical model.On this basis,the influence of operation parameters such as liquid-gas ratio,inlet SO₂ concentration,immersion depth of the scatter tube and flue gas amount on the desulfurization efficiency of the spray-scattering tower were studied.The following conclusions were obtained:the increase of the liquid-gas ratio,the desulfurization efficiency of the spray scatter tower increased,mainly improving desulfurization efficiency in spray zone;the SO₂ concentration at the inlet increases,and the desulfurization efficiency of the spray scatter tower hardly changes;as the immersion depth of scattering tube increased,the desulfurization efficiency of tower was improved through the enhancement of desulfurization ability of bubble zone;with the increase of flue gas amount,desulfurization efficiency of spray scatter tower decreased,and desulfurization efficiency in spray zone and bubble zone decrease to varying degrees,and the decrease desulfurization efficiency in bubble zone is smaler.This paper proposes an optimization scheme of the spray scatter tower based on the simulation analysis,which changes the spray scatter tower with the single entrance to the one with the double inlets.The numerical simulation results show that the desulfurization efficiency of spray scatter tower with the double inlet is 97.4%,and the desulfurization efficiency is added by 1%compared with the spray scatter tower with the single inlet.