Study On The Buble Dynamic Behavior In Vibrating Separation Fluidized Bed Based On Multi-signal Coupling Analysis

Coal is the main energy source in our country,and it is an important energy foundation for national economic development and industrial production.The research and development of clean and efficient coal utilization technology is the prominent move for promoting green and sustainable development of coal industry,under the background of slowing economic growth,accelerating the adjustment of economic structure and energy structure,and strengthening environmental protection.Fluidized dry coal preparation technology as a high–efficiency dry coal preparation method which has been industrialized and applied as well as mainly suitable for the separation of lump coal above 6 mm.However,there is no significant breakthrough in the research and development of dry separation technology for–6+1 mm fine coal,which is the technical bottleneck restricting the large–scale dry separation of full size coal.Vibrated fluidized bed can form a separation environment suitable for fine coal separation according to density,and enhance the dry separation effect of fine coal.However,the existence of bubbles in the vibrated fluidized bed is not conducive to the regulation and control of the separation process of fine coal,and the motion behavior of bubbles and the interaction mechanism between bubbles and fine coal separation behavior are not clear.Therefore,the movement behavior of bubbles and its influence on the separation behavior of fine coal was systematically conducted in this study.Through the analysis of the standard deviation of the pressure drop signal in the vibrated fluidized bed,the transition law of the bed flow pattern is studied,and the operating range of gas velocity suitable for fine coal separation is defined.Based on the collection and analysis of bed pressure signals,the temporal and spatial distribution characteristics of bed density are reconstructed,and the influence of bubble behavior on the uniformity and stability of bed density is explained,and the correlation between bed density distribution and bubble generation frequency is established.Meanwhile,the nonlinear multi–scale characteristics and energy distribution law of bed pressure fluctuation signal in time domain and frequency domain under different flow patterns were analyzed,and the mechanism of bed flow pattern transition was revealed.In addition,the pressure wave propagation velocity equation and the correlation formula of pressure wave energy attenuation were established.Based on the correlation characteristics of the adjacent pressure signals,a method of extracting the pressure signals caused by bubbles based on wavelet analysis is proposed.The response relationship between bubble motion behavior and pressure signal as well as the physical relevance between operating parameters and property of bubble motion behavior are revealed.In addition,the average distribution characteristics of void fraction under different operating conditions were analyzed,and the dynamic evolution law of bubble phase and emulsion phase was revealed.According to the measurement of the force between particles in the bed,combining with the change law of the emulsion phase height,the formation mechanism of quasi dispersive fluidization stability of granular bed is described.Based on the analysis of the energy evolution law of the particle system,the generation mechanism of the bubbles in the bed is revealed from the energy perspective.By analyzing the inhibition mechanism of operation factors on bubble movement behavior,the fluidized bed quality is improved,which provides a theoretical basis for fine coal separation and control.Two kinds of raw coal with different properties were selected for dry separation test of vibrated fluidized bed.The mechanism of bubble on the separation behavior of fine coal and the regulation of various factors on the separation behavior of fine coal were studied.The evaluation indexes of particle mixing and separation in the separation process of fine coal are put forward.The mechanism of regulating and controlling the separation behavior of fine coal by different operating parameters is revealed as well as the adaptability of vibrating fluidized bed to different coal separation is explored.The experimental results show that after dry separation of anthracite,the ash content of clean coal is reduced to 8.2%,the clean coal yield is56.1%,and the separation accuracy E value is 0.15 g/cm~3.the separation performance of coking coal is the best with the separation accuracy value,E=0.13 g/cm~3 and the clean coal yield is 56.1%as well as the clean coal whose ash content reaches 8.2%.Moreover,anthracite and coking coal are evenly separated by vibrated fluidized bed,and the separation effect of coking coal is obviously higher than that of anthracite.The dissertation consists of 87 figures,12 tables and 234 references.