Experimental Studies On Simultaneous Desulfurization And Denitrification By Calcium-based Sorbent In Spouted Bed

The current status of the desulfurization and the denitrification researches was reviewed in this paper. A spouted bed reactor test system was designed and built. The effects of the operating parameters and gas composition on the characteristics of desulfurization and denitrification were studied. Due to the efficiency of calcium-based sorbents in denitrification is low, alkaline additives, sulfite additives, promoting the dissolution additives, oxide additives were used to modify the calcium-based sorbents in this paper. The desulfurization and denitrification characteristics of modified calcium-based sorbents were analyzed and compared.The influence of the combination mode of water and calcium-based sorbents, spray water volume, atomizing air volume, Ca/(S+0.5N) mole ratio, inlet gas temperature and gas composition concentration on desulfurization and denitrification characteristics were studied. It was found that: absorbers has the characteristics of desulfurization and denitrification only when it is co-exist with water, and the water play a role of intermediary in the process of desulfurization and denitrification; the desulfurization and denitrification rate increase with the increasing of the spray water volume; desulfurization and denitrification efficiency increases with the amount of atomizing at first and then decreased; the SO₂ absorption rate increases with the Ca/(S+0.5N) rise, but Ca/(S+0.5N) has little effect on the efficiency of denitrification; desulfurization and denitrification rate decrease with temperature rise; the denitrification rate and the total SO₂ removal increase with the concentration of SO₂ rise, but it will decrease the desulfurization rate; the desulfurization rate and the total NO₂ removal increase with the concentration of NO₂ rise, the denitrification rate rate increases with the entry concentration of NO₂ rise at first and then decreases.On the basis of above research, experimental study of calcium-based sorbent modification is investgated for improving desulfurization and denitrification rates. In order to improve the efficiency of desulfurization and denitrification of the calcium-based sorbents, alkaline additives, sulfite additives, promoting the dissolution additives, oxide additives were used to modify the calcium-based sorbents in this paper. And the characteristics of desulfurization and denitrification of modified calcium-based sorbents were studied. It was found that: alkaline additives NaOH improves the removal of SO₂ and NOx; sulfite additives Na₂SO₃, NaHSO₃ can improve the desulfurization and denitrification of the calcium-based sorbent, but CaSO₃ has significant effect to the desulfurization and denitrification; promoting the dissolution additives MgSO₄ has a negative effect to desulfurization, but when the mount of MgSO₄ is greater than 0.76%, MgSO₄ play a role in promoting the process of denitrification. SO₂ removal efficiency increases with the addition of sucrose increases at first and then decreased. Sucrose can promote denitrification reaction; oxide additives NaClO₄ will improve the desulfurization efficiency, but it has a negative effect to denitrification.