Gas-Solid Fluidization Characteristics Based On Gas Distribution With Variable Pore Size

Air heavy medium fluidized bed dry coal preparation process uses gas-solid suspension(fluidized bed)as the sorting medium,and light and heavy density coal samples are separated according to the density of the fluidized bed.Due to the uneven radial distribution of the pressure of the air distribution plate,the phenomenon of uneven radial density distribution is easy to occur in the fluidization process,which in turn affects the results of the sorting test.According to relevant simulation experiments,it is found that the use of variable-diameter air distribution plates can suppress the problem of uneven pressure distribution in the fluidized bed separation process.Exploring the influence of variable pore gas distribution on the uniformity and stability of the bed density and the fluidization and separation characteristics of the fluidized bed under these conditions are of great significance for forming a good fluidization state and optimizing the equipment structure.In the process of fluidizing separation,with the increase of fluidizing gas velocity,the pressure distribution of air distribution plate is uneven,and the spatial density distribution of the bed changes from basically uniform distribution to non-uniform distribution.Three kinds of air distribution plates with different pore size and arrangement are selected according to the relevant test simulation.In order to ensure the uniformity of the density distribution of the fluidized bed and improve the separation effect of the fluidized bed,the air distribution plate with variable pore diameter is used to regulate the spatial density distribution of the bed.Under the condition of the static bed height H_o=150mm,the radial pressure distribution of the variable aperture air distribution plate was measured,and the effect of the variable aperture air distribution plate on the pressure distribution and the spatial density distribution of the bed was studied.In the experiment,the measured pressure distribution of the air distribution plate is drawn as a bed pressure distribution cloud map by MATLAB software,and the influence of the variable aperture air distribution plate on the stability of the fluidized bed is explored.A single factor exploratory test was carried out on the three operating parameters of the variable-diameter airflow plate fluidized bed,the variable-diameter airflow plate,variable gas velocity and bed height,and the optimal test results of the variable-diameter airflow plate fluidized bed under various conditions.According to the single factor test results,it can be found that under the condition of the static bed height H_o=150 mm and the fluidization number is low(N=1.1),the density distribution standard deviation of the fluidized bed with the central large hole and variable aperture air distribution plate is the smallest,and the fluidization bed is relatively more stable under this condition.With the increase of the fluidizing gas velocity,the stability of the center large hole variable aperture air distribution plate fluidized bed is slightly worse than that of the center small hole variable aperture air distribution plate fluidized bed due to the influence of variable aperture.According to the test results,the optimal parameters are selected for orthogonal test.Under this condition,when the fluidization number is N=1.1,the static bed height is H_o=150 mm,and the air distribution plate is the center large hole variable aperture air distribution plate,the bed density standard deviation is the minimum value,and its value is 0.071.According to the data of fluidization test,variable aperture air distribution plate and uniform aperture air distribution plate are selected to conduct orthogonal test on13-6mm raw coal.The possible deviation E is taken as the index to evaluate the separation performance of fluidized bed,and the effect of variable aperture air distribution plate on the separation effect is explored.The possible deviation E was taken as the index to evaluate the separation performance of fluidized bed,and the effect of variable aperture air distribution plates on the separation effect was explored.The experimental results show that when the air distribution plate is the central small hole and the fluidization number N=1.4,the separation effect of the fluidized bed is the best,the possible deviation E value and the ash separation degree are 0.102 g/cm~3and 1.18,which are obviously superior to the separation effect of the central large hole air distribution plate fluidized bed.The paper has 70 pictures,21 tables and 97 references.