A Cold Model Experimental Research On The Tri-series Cyclone Preheater With High Solid-gas Ratio

For further decreasing the calorific consumption and improving thermal efficiency, the research of preheater system and development for the preheating-precalcining system with high solid-gas ratio (HSGR) have been conducted for several years by Institute of Powder Engineering in Xi'an University of Architecture & Technology. Based on this point, the paper presents the research works and results of a kind of tri-series cyclone preheater with HSGR.Through the experiments on lowering the pressure drop of cyclone preheater, the pressure drop of the lifter tube and the cold model of tri-series cyclone preheater with HSGR, effects of four types of guide vanes which are fitted in the cyclone inlet wall on the cyclone separator performance have been analyzed;the construction of the pressure drop of the lifter tube and the influences of changing materials feeding point on the pressure drop of the lifter tube and cyclone separator have been investigated;the designed model of tri-series one stage cyclone preheater with HSGR has been tested to evaluate the construction of system pressure drop, gas distribution and the total collection efficiency.The results show that all of the four different guide vanes reduce the cyclone pressure drop and also influence the collection efficiency in different degrees. 1# inlet vane causes a pressure drop reduction about 13% under pure gas flow condition;effects of pressure drop reduction deteriorate with the increasing solid-gas ratio. But 1# has high collection efficiency. Of all the guide vanes, the effect of 2# on pressure drop reduction is in the second place and has no reduction in collection efficiency;3#, 4# guide vanes cause a higher pressure drop reduction up to 40%, and a lower collection efficiency than the one without an inlet vane, but cyclone with 4# inlet vane has a better collectionefficiency than the one with 3#.The pressure drop over the whole lifter tube was separately measured in there sections: section of solids accelerating upwards, section of solids uniformly moving and the lifter bend. Measurement indicates that most pressure drop (over 60%) existed in the acceleration section. Shift of the feeding point of raw meal from the lower part of the lifter to the bend results in a decrease of 60% in the whole lifter pressure drop, and also decreases the pressure drop of the cyclone.The computed results indicate that when the system solid-gas ratio is 1.0, thermal efficiency for single series preheater is 40.1%, 44.9% for double series and 46.9% for tri-series. Based on the results, it is easy to know that the tri-series preheater with HSGR is beneficial for improving thermal efficiency.In the tri-series cyclone preheater with HSGR, the pressure drop of cyclone makes up the main part of system pressure drop. With greater cyclone inlet velocity(21 m^ 24m/s) and higher solid-gas ratio(over 2.0),cyclone pressure drop keeps increasing instead of decreasing;the pressure drop of elbow is also higher, it influences with the pressure drop of other parts in the system, and there will be a little down;the pressure drop of the outlet tube cannot be disregarded either, it is meaningful to eliminate the pressure drop of this part. Under different gas velocity, system collection efficiency keeps over 85%.Gas running distribution for the tri-series keeps relatively balance, and the departure is less than ± 4% for each series.In a word, the experiment model of the tri-series cyclone preheater with HSGR has a stable structure and function and it provides a basis for the further studies.