6' to 12' Bulk Feed Bins. Basic Packages include: Ground control fill cap, roof panels, 2.66 corrugated sidewalls and 16” hopper opening. Bulk Feed Bin Accessory Options include: side ladders, cages, hopper stiffeners, slide valves, poly boots, unloaders, augers and motors. Bushel capacities of 111 to 1,842 bushels. Compute answers using Wolfram's breakthrough technology & knowledgebase, relied on by millions of students & professionals. For math, science, nutrition, history. Cone Bottom Silo Size Calculator Answer a few simple questions, and our silo sizing calculator will give you an estimate of the silo size you need for your materials. We recommend that you try to achieve a 3:1 or 2.8:1 height to diameter ratio for the most economical silo size.
What this page is about
Powder handling processes are made of many unit operations, some complex, some that can seem easier. Discharging powder is often overlooked, however, issues in this a priori simple operation can lead to huge losses.
Discharging powder must be
- Reliable
- Fast enough
- Controlled
- Fast enough
- Controlled
The performance of an industrial process will be judged, among other parameters, according to its capacity to reach a nominal speed (expressed in terms of throughput, cycle time or number of batches / h). If a hopper which is supposed to deliver powder at a given rate cannot do it, be it placed at the beginning, middle, or end of the process, the whole installation 'speed' will be affected.
This page will allow you to :
- Design a silo / hopper in order to ensure a good flow
- Estimate the discharge rate of a silo / hopper
- Take action in case of flow problems
Note that the way a powder is flowing is depending on its properties. General powder properties, including flow properties, are listed in this page : Powder Properties.
1. Silo / Hopper Design Calculation methods
1.1 Why it is important
Powder has a given ability to slide and fall when it is stored in a hopper. A key variable that will have an impact on the flow of product outside of a bin is its cohesive strength.
In a bin, the powder is submitted to pressure, due to the fact that there is a height of powder in the bin, the powder on top pushing on the powder below the hopper. Due to the pressure, some solids tend to be more cohesive, when powders become cohesive, they can form archs or rathole, 2 phenomena very detrimental to the flow of powder and the discharge of hoppers.
However, it must be noted that the stress (pressure) in a silo filled with bulk solids has a very different profile compared to what happens with liquid.
Silo 2 5 6 X 2 5
Figure 1 : Stress profile in bulk solids silos
Silo 2 5 6 X 24
The powder is consolidated in the top part due to pressure. But in the cone, the stress applied to the powder decreases which means that the forces pushing the product to flow are minimal : arching (powder is blocked in a stable state) can thus happen at this level in the hopper. The design of the silo has as an objective to find the couple cone angle + diameter of outlet that will manage to keep a constraint on the powder high enough to break arches and make the product flow naturally.
Silo 2 5 6 X 2 3 As A Fraction
The diameter of the outlet of a bin can be calculated in order to avoid both arching and ratholing, thus maximizing the chances to ensure a proper flow of product. When designing a silo, the following parameters must be calculated :