Study On Dry Sorbent Injection For Desulfuration And Its Byproducts Regeneration And The Simulation Of Spray-dry Flue Gas Desulfuration

In recent years,with the continuous promotion of ultra-low emission in power industry,steel industry has gradually become the key object of ultra-low emission management of industrial flue gas.In this paper,aiming at the problem that the desulphurization efficiency after Spray-dry desulphurization failed to meet the requirement of ultra-low emission and the treatment of sodium-based desulphurization by-product,the dry sorbent injection for desulphurization technology and the desulphurization by-product regeneration technology were studied.Based on sodium-based and calcium-based semi-dry desulphurization technology,exploring the gas-liquid mass transfer models and their characteristics in the process of flue gas desulfurization by comparing model simulation data with experimental research.In this paper,a desulfurization experiment was performed on a simulated flue gas based on a pilot test bench for injection of dry sorbent.The characteristics of direct spray Na HCO₃ dry sorbent in the flue after semi-dry desulfurization were studied.The effects of some important operating parameters such as temperature,Na/S ratio,soot concentration,inlet SO₂ concentration,and pipe residence time on dry powder desulfurization efficiency were tested.The experimental results show that the desulfurization efficiency can reach the 78.72%when the temperature is 175℃and the Na/S ratio is 1.5.Therefore,the flue gas desulfurized by spray-dry process and dry sorbent injection can reach the requirement of ultra-low emission.In addition,the concentration of inlet SO₂ had little effect on the removal of SO₂ by injecting Na HCO₃sorbent.The experimental results show that the soot had little effect on the removal of SO₂.The by-products of desulphurization produced by sodium desulphurization were regenerated.The effects of temperature,stirring rate,calcium-sulfur ratio,temperature,concentration of[Na⁺]and oxidation time on regeneration efficiency were researched.When the concentration of[Na⁺]is 0.4mol/L,the Ca/S ratio is 1.25,the temperature is55℃,the stirring rate is 500r/min,and the oxidation time is 30min,the regeneration rate of Na₂SO₃ is up to 77.18%,and the oxidation rate of CaSO₃ is up to 77.39%.When the oxidation time is increased to 180min,the oxidation efficiency of CaSO₃ is increased to 92.97%.Based on the experimental study of semi-dry sodium method and calcium method,the numerical simulation of sodium method and calcium method was carried out.The results show that the model is effective by comparing experimental data with simulation data.The calcium-based simulated data is 6.45%is lower than experimental data while the sodium-based simulation data is 3.23%higher than the test data.The sodium-based desulfurization efficiency is higher than that of the calcium-based,and under the same conditions,the sodium method has a lower temperature drop than the calcium method.