Experimental Study on Sintering Flue Gas Desulfurization by Dry Digestion Circulating Fluidized Bed
|Keywords||Sintering flue gas Dry Digestion Circulating fluidized bed Flue gasdesulfurization Energy saving and emissions reduction|
The SO2emission from iron and steel industry is a serious problem, and the emission of the sintering flue gas is more than70percent of that from iron and steel industry. Energy and emissions reduction of sintering process in steel industry will become new state-focus in SO2emission control. Based on the analysis of the characteristics of some typical circulating fluidized beds (CFB) for flue gas desulfurization, a new dry digestion CFB flue gas desulfurization process was developed, and an experimental CFB installation with maximum flow rate8000m3/h for flue gas desulfurization was setup. The equipment consists of a multifunctional reactor, a flue gas generator, a dust and powder circulatory system and a convey system. The new process eliminated the traditional digestion procedure out of reactor, the functions of the reactor include preliminary dust collection, digestion, desulfurization.The desulfurization effects of calces, converter slag and blast furnace slag were investigated under the following experiemental conditions:temperature of sintering flue gas,156℃; relative humidity,6.8%; flow rate,6848m3/h and inlet SO2concentration,364mg/m3. The results showed that all of the desulfurization agents had desulfurization capability and the desulfurization efficiency of calces is the best, followed by converter slag and blast furnace slag.The effects of operating parameters on desulfurization efficiency were studied and the mechanisms were analyzed. The operation parameters including gas temperature, inlet SO2concentration and recycle of desulfurization ash were investigated. The results are as follows:(1) The influence of temperature on SO2removal efficiency is obvious, SO2removal efficiency decreases along with temperature increase. Under the condition of temperature156℃, relative humidity6.8%, flow rate7049m3/h and inlet SO2concentration483mg/m3,the removal efficiency is about93.1%.(2) The inlet concentration of SO2on removal efficiency is not obvious. When the inlet concentration of SO2is566mg/m3, removal efficiency is about92.3%.(3) The recycle of desulfurization ash affected SO2removal efficiency, desulfurization efficiency increase along with the increase of the thickness of ash on bag filter.The investigation can be a practical guide for new desulfurization processin the iron and steel industry. Using steel slag as a desulfurization agent has the advantages of operating cost savings and utilization of waste, which has important practical significance on the achievement of carbon emission reduction.