Discrete Element Method (DEM) & Transfer Point Solutions
The proper flow of material is vital to a bulk handling operation. However, each operation also contends with its particular material challenges, and they can surface anywhere from silos to bins to hoppers to the conveyor belt.
Bulk material flow results from how its particles move, changing when subjected to gravity and other forces, such as the equipment that is moving it. Some of the properties that affect a material’s movement include shape, size, hardness, and moisture.
Free-flowing bulk material is one with a relatively low resistance to movement and the freedom to continue moving when forced into motion. Therefore, a free-flowing bulk material will rarely by itself be the cause of flow problems. When the movement of the material becomes hindered, it is usually because of other factors.
What Causes Poor Material Flow?
Conditions such as arching (bridging), ratholing, segregation, limited discharge rate, flooding or flushing, and degrading particles will interfere with the proper flow of bulk material.
- Arching or bridging. The bulk material forms an arch-shaped construction over a hopper outlet and halts the material flow. The arch can be interlocking with large particles connecting to form the obstruction, or it can be cohesive with particles bonding because of factors such as moisture, temperature, particle shape, or concentration of fines.
- Ratholing. If the material is cohesive, it forms a stable channel above the outlet during discharge. Stagnant material outside of the flow channel does not empty. When the flow channel is emptied, ratholing can cause an erratic flow or complete flow stoppage. It can also lower the bin’s live capacity by up to 90%.
- Segregation. A material’s particles separate, mainly according to size differences, which potentially leads to changes in product size, density, and chemistry. This can lead to an out-of-spec and non-uniform product, as well as fluctuations in package weight. In some cases, costly reprocessing can be required.
- Limited discharge rate. Counter-flowing air at the hopper outlet slows the discharge rate of fine powders, resulting in insufficient material flow.
- Flooding or flushing. A bulk solid behaves like a liquid and flows without limit through the bin outlet if the downstream feeder is not designed to handle fluid-like material, thus creating a problem with too much material flow.
- Degrading particles. Stagnant material spoils, oxidizes, or cakes into a solid or hardened mass, causing flow stoppage and compromising product quality.
Off-center loading of material from the transfer chute to the conveyor belt often causes poor flow as well. Engineered transfer chutes are made to achieve bulk material center loading with a central flow based on a consistent trajectory of a material’s characteristics. However, these traits can change during production and make the material build in the chute. This can then alter the stream and result in disproportionate loading onto the receiving belt.
Poor material flow can be resolved with state-of-the-art tools such as discrete element modeling and engineered transfer point solutions.
Discrete Element Modeling: Precise Computations for Control of Material Flow
A Benetech material flow analysis using discrete element modeling helps bulk material handlers gain more control of their material stream by evaluating the product at the molecular level.
An intuitive approach to understanding material flow, the discrete element method involves modeling events in which large numbers of discrete particles collide during a dynamic simulation.
Each particle is modeled with a single-node element with a rigid spherical shape representing the bulk material being assessed according to its type and properties.
This discrete element modeling allows our engineers to compute the motion and effect of the material’s particles as they travel through the production stream. In addition, DEM creates an animation that shows how the particles interact and behave as they move.
Our engineers interpret this information to identify current and potential material flow problems. They can then design the optimal solution for each material handling transfer point at your facility with that data.
Transfer Point Solutions: Engineered Transfer Chutes & MaxZone® Plus
A steady bulk material flow requires equipment that is designed for and adaptive to the challenges to the material stream.
It starts with transfer point solutions such as engineered transfer chutes that ensure consistent center loading. For example, Benetech’s patented InteliFlo® load chute with the J-Glide® discharge features a distinctive round chute design and adjustable horizontal loading for proper center loading of material.
Benetech engineered transfer chutes also significantly reduce fugitive dust emissions, pluggage, and spillage while maximizing material flow. We can design, fabricate, and install engineered transfer chutes wherever you need them, including for your transfer tower cascade conveyors and post-crusher load zones.
We understand the trouble that can arise from a flawed material transition onto the receiving belt. Improper or off-center loading can cause the material to be loaded to either side of the belt, creating excessive spillage and dust and threatening to mistrack the belt. Mistracking can then damage the conveyor, cause uneven wear, make the motor work harder, and even create safety issues.
Compounding the issue, time and budget constraints do not always allow for an expensive engineered load zone chute replacement. To address this, we developed our patented MaxZone® Plus system. An entirely new concept for bulk material handling, the system acts as a modified load zone chute that keeps material flowing while reducing transfer point spillage and dust through proper center loading.
The MaxZone® Plus system includes a deflector and side kicker plates that can both be adjusted to correctly center-load material for a smoother transition onto the moving belt. In addition, removable 6” side panels further allow height adjustment according to your load zone requirements.
Benetech: Your Partner in Material Flow Enhancement
Each day at Benetech, we remain busy developing ways for you to better control material flow, which in turn helps you lower operating costs, extend production life, and eliminate spillage and airborne dust. If you are looking for greater transfer point solutions, contact us at (630) 844-1300 to speak with a specialist.