Flow Type of Material in Silo, Influence Factors and Adjustment Methods
Aug.28, 2017Keywords: flow type, Silo, adjustment
Silo is a kind of solution for storing grain, chemical fertilizer, cement and bulk material, widely applied to industry and agriculture field. There are two common failure forms of silo, material block and silo structure damage, both are closely related to the material flow type.
1. Flow type division
Mass flow: when the silo is discharging, all the silo materials are moving and the flow is steady and uniform, which results in sharp increase of the lateral compression of the silo wall, which is also called power flow.
Funnel flow: When unloading, only the silo material within certain range above the discharge nozzle silo is in funnel flow, and the dead material area exists in the bin, there are dead material area in silo. Tubular flow: When unloading, only the material in the central part is moving, and the surrounding material is stagnant. Tubular flow is one of the situations of funnel flow, when the material is stored, the wall pressure is close to the static value.
Diffusion flow: It is a deviant form of whole flow, which is the whole flow at the lower part and the upper part also become whole flow by diffusion.
2. Flow-type comparisonMass flow: stable discharging rate, uniform discharge density, the discharge order is first-in first-out, the bunker cost is higher ang short life, the storage time is consistent.Funnel flow: the discharge rate is not stable, and the discharge density is nonuniform, the discharging order is first-in last-out, the bunker cost is low, and the storage time is inconsistent.The silo should be safe, reasonable and economical in the design time, and reasonable flow pattern should be chosen according to the actual needs.
Geometrical factor: hopper inclination, discharge size, adopt the curve discharge hopper.
Effects of silo material and material physical properties: the inside and outside friction angle of material, silo wall rigidity, the density and compactness of the material.
Feeding form: central feed and disperse feed.Install the reasonable insert in silo can also improve the material flow environment and the distribution of material flow area.
A: Adopt the central feeding form, make the material form cone top in silo.
B: Adopt the center discharge form with the biggest outlet opening so that the discharge outlet is unobstructed.
C: Use insert appropriately, install the straight clapboard, horizontal clapboard, or cone insert in the upper part of the hopper.
D: Adopt the arch drainage device for the non-free flow material.
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