Experimental study of purifying flue gas after wet desulfurization in thermal power 300 MW units by acoustic agglomeration
At present,the limestone-gypsum wet desulfurization system is widely used in domestic thermal coal-fired power units,which generates a large amount of particulate matter,and the traditional dust and mist elimination devices have a relatively limited effect on the removal of particulate matter with small particle size,especially PM10.Acoustic agglomeration is important for controlling the emission of fine particulate matter,especially PM10,and can be used as a pretreatment link for soot in combination with conventional dust and mist eliminators.To solve the problem of fugitive dust,especially PM10,in the flue gas of thermal power units after wet desulfurization,engineering modification tests are conducted on the flue,configured with different combinations of 3 200,1 600 and 800 Hz frequencies to investigate their effects on PM10 quantity concentration and particle size distribution,and the combination of acoustic waves with the best agglomeration effect was selected.The dust removal efficiency is tested under background conditions,acoustic wave alone,and acoustic wave coupled with spray.The results show that the number concentration of PM10 is higher when the acoustic wave is not turned on,which is 2.75×104 cm-3,and the peak particle size is about 0.05 μm.The number concentration of PM10 decreases significantly after the acoustic wave is turned on,the peak particle size increases,and the number concentration of PM10 is the lowest in the combination of 3 200 Hz×4+1 600 Hz×2,which is 2.26×104 cm 3.This number represents the highest agglomeration efficiency of 17.82％ .In the test of dust removal efficiency,the dust removal efficiency is low when the mist eliminator acts alone,only 34.3％ ,with the above-mentioned acoustic waves,the dust removal efficiency increases to 52.1％ ,and then the highest dust removal efficiency is achieved when the auxiliary spray is used,reaching 60.4％ ,at which time the dust concentration at the outlet of the mist eliminator drops to below 5 mg/m3,meeting the ultra-low emission requirements.In addition,for the low concentration PM10 environment in the test,the acoustic wave agglomeration law is still applicable,but the particle collision probability is low,which can be compensated by a combination of high and low frequency acoustic wave.
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