Effect Of Ammonium Bisulfate On Ash Deposition Characteristies Of Rotary Air Preheater

China's relevant policies have become more and more strict on NOx emission requirements,which has given birth to a huge SCR denitration market.The NH3 leaking in the denitration process reacts with SO3 and H2O in the flue gas to form ammonium bisulfate.The ammonium bisulfate may adhere to the heat exchange element in the rotary air preheater and adsorb the fly ash,causing blockage and corrosion of the air preheater.The blockage and corrosion of the device seriously endanger the safety of production.In view of the above problems,this paper mainly focuses on the influence of ammonium bisulfate on the ash deposition characteristics of the rotary air preheater.The combination of theory and experiment is used to explore the effect of ammonium bisulfate on the morphology of fly ash and the ash deposition characteristics in the rotary air preheater.Using a hot stage microscope to observe the morphological changes of the artificial ash heating process containing ammonium bisulfate,using a synchronous thermal analyzer to observe the effect of ammonium bisulfate on the melting point of ash and the FLUENT software is used to simulate the ash accumulation in the air preheater,the critical dust accumulation speed is selected as the criterion of dust accumulation,the ash deposition characteristics such as ash strength and ash thickness at different positions are calculated,and the effects of inlet flue temperature,inlet flue gas velocity and particle median particle size on the ash deposition characteristics are analyzed.The results show that Al2O3 has a lowering effect on the temperature at which ash begins to change in morphology,and CaO and Fe2O3 have an effect on the temperature at which ash begins to undergo morphological changes;when only SiO2 or Fe2O3 is added to the synthetic ash sample,the temperature at which the sample begins to undergo morphological changes increases with the addition of ammonium bisulfate;when Al2O3 or CaO is doped in the synthetic ash sample,the temperature at which the sample begins to undergo a morphological change decreases as the amount of ammonium sulphate added increases.Ammonium bisulfate has no effect on the melting point of SiO2,and it has an effect on the melting points of Al2O3,CaO and Fe2O3,both decrease as the amount of ammonium bisulfate added increases.Ammonium bisulfate has a great influence on the melting point of CaO and has little effect on the melting point of Fe2O3.For the type of heat storage plate selected in this study,the corrugated board of the right board is more serious than the ash of the left board,and the closer to the outlet low temperature area,the more serious the ash is formed;the acute angle area generated by the contact between the left and right plates at the entrance and the left and right sides and the board contacts are prone to dust.The structure of the improved heat storage plate can reduce the ash accumulation.For the left plate,the ash thickness and strength of the ABS viscous ash area is about twice that of the ordinary ash area.For the right plate,the ash accumulation strength of the ABS viscous ash area is about 5 times that of the ordinary ash area,and the ash deposition thickness is about 14 times,indicating that ammonium bisulfate has a great influence on the ash deposition characteristics.In the direction of smoke flow,the higher the inlet smoke temperature,the faster the smoke temperature decreases.The inlet smoke temperature has no effect on particle distribution,ash thickness and ash strength;the lower the inlet smoke speed,the faster the smoke temperature decreases.As the inlet smoke velocity decreases,the ash strength and thickness increase gradually.As the median particle size decreases,the particle size distribution becomes narrower and the ash thickness and strength decrease.