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Material handling by airlift

Q: I have a question about material handling by airlift to height of 80m. If a portion of piping route at begining at top of airlift be inclined, what is its effect on assumed capacity and blower specifications? What are the restrictions in pipng route for material handling by airlift?

A: If the angle of inclination is less than 10 degrees, there is little effect of the capacity and blower back pressure.  Between 10 and 30 degrees the pipeline velocity needs to be over two times the choking velocity to avoid slug flow in a dilute phase conveyor or the solids to air ratio could be kept below 1 to avoid slugging and excessive pressure drop.  Beyond 30 degrees of inclination is not recommended because the effect is unpredictable for dilute phase conveyors.  For dense phase conveyors, there is little effect; however, a blower would probably not be sufficient to convey the material unless the system has only vertical lift with no horizontal runs.  Even then, the solids to air ratio should be kept below 5 to avoid excessive slugging in the sloped section.  This last point has to do with the line size selection and mechanical strength of the installation (i.e. breakage of pipe).

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