| Waste heat utilization is a research hotspot of large-scale utilization of renewable energy,which conforms to the direction of large-scale utilization of renewable energy in the field of energy science and technology innovation in the 13th five-year plan.Waste incineration flue gas is rich in water vapor,complex acid gas,complex solid particles and other extreme conditions,therefore,It is necessary for major theoretical and technical requirements to break low temperature corrosion and complex solid particles deposition caused by heat transfer deterioration,in order to put forward the design criterion of heat exchanger and the limit of waste heat utilization,and better guide a theoretical foundation for waste incineration waste heat utilization.This article conducts research for gray samples of two test points at different wall temperatures,by the low temperature corrosion experiment of flue gas atmosphere in power plant.The aggregate law,mechanism of deposition and corrosion resistance of complex solid particles were analyzed by the way of SEM,XRD and EDS.Test point 1 results show that:the shape of pipe wall ash accumulation can be divided into four stages:177℃>T1>130℃,loose dry ash region;30℃>T1>110℃,loose dry ash and adhesive wet ash conversion region;110℃>T1>70℃,adhesive wet ash region;Ti<65℃,corrosion region.There were two turning points for the fouling coefficient of the ash layer,and the corresponding inlet temperatures were 110℃ and 70℃ respectively,the engineering acid dew point temperature is 70℃,when the temperature of pipe surface running at 45℃,Serious corrosion,corrosion layer have three parts,The inner layer is the first adhesive layer,which is mainly FeCl2,4H2O,high SiO2;the intermediate layer is chloride(NaCl、KCl)and FeCl2.4H2O;the outer layer is mainly the oxide SiO2 with high melting point.The order of rive kinds of corrosion-resistance materials is:316L>ND>corten>20#>Q235.In addition,it was found that the corrosion resistance of fluoroplastic is much higher than that of 316 L.The corrosion products at test point 1 were mainly FeCl2.2H2O;FeC12.4H2O,and the corrosion reaction was chlorination.Due to the low content of hydrochloric acid and flue gas in the flue gas after dust removal and deacidification,the ash accumulation is relatively thin at the inlet temperature range of 40℃-70℃;with decreasing temperature of wall,The ash layer on the wall has obvious changes in morphology,the color changes from reddish brown to reddish brown,the compounds are mainly converted from NH4Cl to α-Fe2O3 and oxidation is the main corrosion reaction. |
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