深型空气重介流化床密度均匀性研究
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摘要
采用床层空间各处局部压降波动表征深床层密度在径向分布的非均匀性结构,并通过布风结构的设计探索了由布风室结构改变优化深床密度分布的可行性。在床体直径为600mm,初始床高为520~760mm流化床中进行实验。研究表明,预布风室结构的改变可以有效改善床层密度径向分布均匀性,在新型布风室作用下床层径向高密度区域由集中于床层中轴部变为分散于床层四周,且床层密度均匀分布的区域范围也明显增加。床层密度径向分布随着流化气速的增加高密度区域先减小再增加,当流化数为1.6时,密度分布标准差为最小值0.1035g/cm3;随着初始床高的增加,床层径向密度分布规律越来越不明显,且波动越来越剧烈;此外,处于最均匀状态下的深床层分选50~150mm大块煤时,可能性偏差达到0.042g/cm3。
The feasibility of optimizing the density distribution of the deep air dense medium fluidized bed(DADMFB)was explored by changing the air chamber structural design.The local pressure drop fluctuation throughout bed space is used to characterize the non-uniformity of bed density in radial direction.Experimental tests were performed in a deep bed with the diameter of600 mm and the height of 520-760 mm.Test results indicate that the non-uniformity of bed density in radial distribution can be effectively improved by changing the structure of air chamber when a new type air chamber is used.With applying the new air chamber,the high density region shifts from central axis of the bed to its periphery,and the density uniform area also can obviously increase.With fluidizing gas velocity increase,the radial distribution of bed density decreases in the beginning and then increases,and the minimum standard deviation is 0.1035 g/cm3.With the increase of initial bed height,the regularities of radial density distribution become less obvious,and the density fluctuations become more intense.In addition,the Ecart probable Moyen value can be reduced to 0.042 g/cm3,when the large size coal(50-150 mm)was beneficiated in the DADMFB under the most uniform state.
The feasibility of optimizing the density distribution of the deep air dense medium fluidized bed(DADMFB)was explored by changing the air chamber structural design.The local pressure drop fluctuation throughout bed space is used to characterize the non-uniformity of bed density in radial direction.Experimental tests were performed in a deep bed with the diameter of600 mm and the height of 520-760 mm.Test results indicate that the non-uniformity of bed density in radial distribution can be effectively improved by changing the structure of air chamber when a new type air chamber is used.With applying the new air chamber,the high density region shifts from central axis of the bed to its periphery,and the density uniform area also can obviously increase.With fluidizing gas velocity increase,the radial distribution of bed density decreases in the beginning and then increases,and the minimum standard deviation is 0.1035 g/cm3.With the increase of initial bed height,the regularities of radial density distribution become less obvious,and the density fluctuations become more intense.In addition,the Ecart probable Moyen value can be reduced to 0.042 g/cm3,when the large size coal(50-150 mm)was beneficiated in the DADMFB under the most uniform state.
引文
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[12]DONG L,ZHOU E H,CAI L H,et al.Fluidization characteristics of a pulsing dense-phase gas-solid fluidized bed for high-density separation of fine anthracite[J].Energy&Fuels,2016,30(9):7180-7186.
[13]YU X D,LUO Z F,LI H,et al.Beneficiation of 6-0mm fine-grain oil shale using vibrating air-dense medium fluidized bed separator[J].Fuel,2017,203:341-351.
[14]VERMA V,PADDING J T,DEEN N G,et al.Effect of bed size on hydrodynamics in 3Dgas solid fluidized beds[J].AIChE Journal,2015,61(5):1492-1506.
[15]LETURIA M,BENALI M,LAGARDE S,et al.Characterization of flow properties of cohesive powders:A comparative study of traditional and new testing methods[J].Powder Technology,2014,253(2):406-423.
[16]HE J F,ZHAO Y M,HE Y Q,et al.Distribution characteristic of bed density in air dense medium fluidized bed based on the Euler-Euler model[J].Journal of China Coal Society,2013,38(7):1277-1282.
[2]王成金,王伟.中国港口煤炭进出口格局演变及动力机制[J].资源科学,2016,38(4):631-644.(WANGChengjin,WANG Wei.Development of import-export coal trade by port on minal and China:Spatial pattern,evolution and dynamics[J].Resources Science,2016,38(4):631-644)
[3]张亚东,王翔宇,董鹤翔,等.影响细粒煤振动流化床分选的关键因素[J].煤炭学报,2016,41(12):3128-3135.(ZHANG Yadong,WANG Xiangyu,DONGHexiang,et al.Study on key factors affecting separation of fine coal vibrated fluidized bed[J].Journal of China Coal Society,2016,41(12):3128-3135.)
[4]LIU B W,TANG Z H,DONG S G,et al.Vegetation recovery and groundwater pollution control of coal gangue field in a semi-arid area for a field application[J].International Biodeterioration&Biodegradation,2018,128:134-140.
[5]ZHANG G L,SONG S L,YANG W Q,et al.Mercury removal and ash reduction from coal by an air dense medium fluidized bed[J].International Journal of Coal Preparation&Utilization,2017,(4):1-13.
[6]ZHOU N H,LUO Z F,HUANG W,et al.Effect of scraper movement on the separation performance of air dense medium fluidized bed[J].International Journal of Mineral Processing,2017,165:15-19.
[7]郭慕孙,李洪钟.流态化手册[M].北京:化学工业出版社,2008:1037.
[8]SAHU A K,BISWAL S K,PARIDA A.Development of air dense medium fluidized bed technology for dry beneficiation of coal-A review[J].International Journal of Coal Preparation&Utilization,2009,29(4):216-241.
[9]CHEN Qingru,WEI Lubin.Coal dry beneficiation technology in China:The state-of-the-art[J].Particuology,2003,1(2):52-56.
[10]JAIBOON O A,CHALERMSINSUWAN B,MEKASUT L,et al.Effect of flow pattern on power spectral density of pressure fluctuation in various fluidization regimes[J].Powder Technology,2013,233(2):215-226.
[11]OMMEN J R V,SASIC S,SCHAAF J V D,et al.Time-series analysis of pressure fluctuations in gas-solid fluidized beds---A review[J].International Journal of Multiphase Flow,2011,37(5):403-428.
[12]DONG L,ZHOU E H,CAI L H,et al.Fluidization characteristics of a pulsing dense-phase gas-solid fluidized bed for high-density separation of fine anthracite[J].Energy&Fuels,2016,30(9):7180-7186.
[13]YU X D,LUO Z F,LI H,et al.Beneficiation of 6-0mm fine-grain oil shale using vibrating air-dense medium fluidized bed separator[J].Fuel,2017,203:341-351.
[14]VERMA V,PADDING J T,DEEN N G,et al.Effect of bed size on hydrodynamics in 3Dgas solid fluidized beds[J].AIChE Journal,2015,61(5):1492-1506.
[15]LETURIA M,BENALI M,LAGARDE S,et al.Characterization of flow properties of cohesive powders:A comparative study of traditional and new testing methods[J].Powder Technology,2014,253(2):406-423.
[16]HE J F,ZHAO Y M,HE Y Q,et al.Distribution characteristic of bed density in air dense medium fluidized bed based on the Euler-Euler model[J].Journal of China Coal Society,2013,38(7):1277-1282.