Study On Simulation And Sequential Separation Of Multi-product Liquid-solid Fluidized Bed

When traditional liquid-solid fluidized bed separates the difficult-to-separationcoarse coal slime, a problem of―low ash of tailings, high ash of overflow‖is alwayscoming out. In order to solve the problem, the paper presented a separation method of―discharging gangue preliminarily and then separating again‖with a multi-productliquid-solid fluidized bed to complete two stages separation for improving separationeffect of the difficult-to-separation coarse coal.The flow field inside the multi-product liquid-solid fluidized bed was simulatedat different velocities of teeter water, and the separation process of coal particles ofsame size and different densities was forecasted with the Fluent software. The studyshows that the upper chamber of the multi-product liquid-solid fluidized bed can forma stable separation environment at two teeter water, which can reach―big in the lowerand small in the upper‖of water velocity and build a stable and multiple flowenvironment, and it’s conducive to layer and separation of the light and the middleparticles, then the secondary separation of low density can be obtained.Based on the difficult-to-separation coarse coal slime of1-0.25mm, the effect ofbed pressure and teeter rate on separation effect in the multi-product liquid-solidfluidized bed was researched. Research results in the lower chamber show that thechange of bed pressure and teeter rate in upper chamber has a small effect on theseparation of lower chamber; the work of discharging gangue preliminarily in thelower chamber narrows the size range of inlet of the upper chamber, and improves theseparation accuracy. Research results in the upper chamber show that theclassification plays an important role in the low bed pressure, and change of teeter ratehas obvious effect on quality of clean coal; the separation plays an important role inthe high bed pressure, and change of teeter rate has an small effect on quality of cleancoal; the separation density increases obviously with increasing bed pressure, anddensity distribution of products is close to the feeding coal; the separation sizeincreases with increasing water rate.Results show that, at14.5KPa bed pressure and10mm/s teeter rate in the lowerchamber,1.85g/cm3separation density and tailings of67.68%ash can be obtained,and the E value is0.125g/cm3, which indicates the effect of discharging is good. At4.13KPa bed pressure and5.90mm/s complex teeter rate in the upper chamber,1.47g/cm3separation density,11.70%ash of concentration and84.04%organic efficiency can be obtained, and the E value is0.082g/cm3，and it indicates that twice low densityseparation can come true.With comparison of two kind of liquid-solid fluidized beds, separation effect of twomulti-product liquid-solid fluidized bed is much better than the traditional liquid-solidfluidized bed, and it can obtain higher efficiency and better clean coal. It can beconcluded that three products of overflow, middle flow and underflow can beobtained in the multi-product liquid-solid fluidized bed by discharging ganguepreliminarily at high separation density and then separating again at low separationdensity, and its separation effect is good.The multi-product liquid-solid fluidized bed has the multiple separationenvironments with two chambers, and it can adjust the two stage separation densitieseasily to adapt the demand of different quality of coal inlet and clean coal. It canenforce the material separated step by step and achieve more products with differentquality. This technology is simple and efficient for separating difficult-to-separationcoarse coal slime, which is completed easily and quickly in process, and it is expectedto be a new technology to improve the separate effect of difficult-to-separation coarsecoal slime.