Experiment Study On Semi-dry Desulfurization Of Sintering Flue Gas

Acid rain displayed important harm to the nature and human health. The inorganic acids in acid rain are mainly composed of sulfuric acid and nitric acid. The main type of acid rain in China is sulfuric acid rain and large amounts of the SO₂ emissions are from steel industry. After 2000, SO₂ emissions from iron and steel industry in China are only a little fewer than electric power industry. Therefore, sintering flue gas desulfurization is coming to a critical state. It is listed as the key task in China's "Eleventh Five-Year Plan", and 14 sintering flue gas desulfurization demonstration projects have to be completed. This thesis took a systematic study of sintering flue gas, including serials desulfurizer optimization, FGD operating conditions and a variety of ions.Firstly, the digestion process of quicklime was studied. At first, the effects of some process parameters on the digestion process were studied, including the initial temperature of digestive water, water-solid ratio, stirring speed and the particle size of lime. It can be concluded that the initial temperature 40⁵0℃, water-solid ratio 4/1⁶/1, stirring speed 300rpm and the particle size 0.105⁰.09mm were favorable to digestion. At the same time, the influence of sintering ash and the metal elements contained (such as F-, Cl-, Mn2+ and Zn) on lime digestion were investigated. It was found that the addition of F, Cl and Zn is favorable for lime digestion, however sintering ash and Mn showed bad impact on the lime digestion.Then, the effects of operation parameters in CFB semi-dry desulfurization technology on system desulfurization efficiency and utilization rate of the calcium-based sorbent were studied, including: Ca/S molar ratio, input gas temperature, concentration of input SO₂ and bed height. The increasing Ca/S molar ratio, concentration of input SO₂, can improve the desulfurization efficiency; however, the increasing of input gas temperature did not show good effect.At last, respected to the difference between sintering flue gas and conventional power plant flue gas, the property of sintering flue gas and the formation of SO₂ were summarized and analyzed. Simultaneously, the effects of trace ions (F, Cl, Mn and Zn, etc.) contained in sintering flue gas on were investigated. It was observed that the addition of trace ions showed significant influence on the desulfurization efficiency improving.In the thesis, based on the preparation of lime slurry, theoretical reference for the efficient use of desulfurizer was summarized. The semi-dry FGD system experiments respected to sintering flue gas were performed and the optimized operating condition was found. The experimental methods and conclusions will supply significant reference for the engineering application in the future.