Study On Design Of High Efficiency Flue Gas Desulfurization Process For Cement Kiln

The three main pollutants of clinker calcination in cement industry include particulate matter,nitrogen oxides（calculated by NO₂）and sulfur dioxide（SO₂）.According to GB4915-2013standard,the emission limits are 30 mg/Nm³,400 mg/Nm³and 200 mg/Nm³respectively.SO₂in flue gas mainly comes from raw materials and combustion.Elemental sulfur and low price sulfide are oxidized to produce SO₂at high temperature.In recent years,with the strengthening of domestic environmental protection awareness and supervision,the quota standards are different in different places,and some places have introduced a more stringent standard-"ultra-low emission".Under the stimulation of overcapacity and rising profits,the cement industry generally has the demand and willingness for pollutant emission reduction and transformation.In the application of cement kiln flue gas desulfurization technology,the wet desulfurization technology is relatively mature,with high desulfurization efficiency,generally more than90%,and wide adaptability of SO₂background emission concentration.However,there are limitations in application due to complex system,large investment,high operation cost and energy consumption.The investment and operation cost of dry desulfurization are small,but the desulfurization efficiency is low,about 30%.Research and application tests have been carried out at home and abroad,and some results have been achieved.This paper studies how to improve the efficiency of dry desulfurization process.Through the research,this paper puts forward a new dry desulfurization process scheme,which extracts the active CaO generated in the calciner with large specific surface area and high activity.After the gas-solid separation of cyclone separator,it is sent to the flue gas duct at the outlet of preheater through double high-pressure ejector,which strengthens the rapid dispersion of CaO and flue gas,increases the reaction contact area,and makes use of the multi pipe shunt of SP boiler The characteristics and long residence time of the desulfurizer were used as the desulfurizer reaction vessel.The desulfurizer activity,particle size,reaction area and reaction time were studied.Under the condition of lower molar ratio of calcium to sulfur,the desulfurization reaction rate was improved,and the dry desulfurization efficiency was predicted to be 80～85%.On the basis of this process plan,this paper selects the representative 5000 t/d cement kiln production line as the model,carries out the application design research on this plan,including the extraction of hot raw meal,air volume,cyclone separator and high-pressure ejector,and carries out a full set of design selection,process layout,non-standard pipeline and refractory design based on the model,and evaluates the economic benefits Combined with the actual operation of the cement plant,the influencing factors of the application of the desulfurization technology are studied and discussed,and the rationality and feasibility of the process scheme are verified.This scheme has the conditions and foundation of automatic control,and further improves the stability and economy of desulfurization control.The purpose of this study is to improve the flue gas desulfurization technology of cement kiln,provide a new idea and new choice in the aspects of high desulfurization efficiency,low investment and operation cost,simple control and high reliability,and promote the technical progress of clean production of cement kiln.