When a material doesn’t flow, production grinds to a halt. ABHR learns more about how AGI designs its silos to facilitate flow in almost any condition.
Non-flowing materials pose a challenge to silo designers. How do you build a silo that can store and, more importantly, retrieve the material?
That was the exact dilemma facing a Mexican company that needed to store mill meal, a product that sticks to silo walls, absorbs moisture and clumps together. In a conventional silo, the commodity would not move at all due to bridging.
Peter Forster, Ag Growth International’s (AGI) Australia and New Zealand business manager, said designing purely for flow rate is just one piece of the puzzle.
“A combination of factors helps us to create solutions for some of the hardest storage problems,” he told ABHR.
“On top of flow rate, you need to factor in the seismic conditions, wind, the moisture and temperature of the product, how long it will be stored, external temperatures and fumigation requirements, just to name a few.”
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When a silo is not designed to handle all of these factors, material hang-ups can halt the process entirely. In extreme situations, jackhammers are brought out to dislodge the loads – a risky proposition for crew and equipment.
The Mexican company got in touch with AGI to see what a potential solution would look like. Following several questions to determine the local environment, bulk density and the nature of the material, AGI began an investigation into the design.
Its team of engineering specialists made several recommendations, drawing on years of experience working in the industry.
Forster said the team knows what will work and what won’t thanks to its global reach and extensive install base.
“In this case, we had prior experience with this kind of product. We knew the meal wouldn’t flow on its own, which is why AGI recommended combining a smooth-wall bin storage system with the Hydracone,” he said.
The Hydracone system, supplied by AGI partner Morillon, is specifically designed to unload products that do not naturally flow from conical bottom silos. An Archimedes screw driven by a hydraulic motor sweeps the cone of the silo in a rotating movement to completely extract all of the product.
It can completely empty the silo while reducing the risk of product bridging. Maintenance is possible when the silo is full, and all moving parts are enclosed.
Forster said the system was designed by silo unloading system specialist Morillon, with extensive expertise in unloading the most difficult materials.
“Our silos and Morillon’s products often go together – they make highly specialised equipment for highly complex situations,” he said. “We worked closely with them to ensure to ensure the whole storage and handling solution will work for their requirements.”
The end result was a flat-wall silo, which was selected to ensure the material would flow with minimal issue.
Forster said the company usually uses corrugated steel, due to the additional strength it provides. But in this case, it was important to reduce as much friction as possible.
Design expertise
AGI has designed silos for use all around the world, engineering its equipment to operate in some of the largest mills and most demanding environments.
The company is spread across the entire agriculture and food supply chain, handling products like high oil seeds, dense non-flowing feed products, powders, food, and more.
AGI’s investigative process plays a key role in the design and engineering of a customer’s unique silo system.
On top of learning about the material, AGI also determines the desired throughput and an estimate of how long the material will be stored.
Forster said there is a major difference between the design of a 100-tonne silo and a 1000-tonne silo, or a storage system that holds grain for a few days and one that holds grain for a few years.
To ensure its products can withstand almost any condition, AGI uses finite element analysis and computer-aided design for structural performance. In addition, its silos are tested for strength and durability in earthquake simulators using the US shake tables.
Forster said the company uses thermocouple technologies to monitor and test the temperatures and moisture control within silos so that it knows material will not stick to the walls.
“AGI has a range of mixed flow dryers and aeration systems and partners with a refrigeration company to add cooling systems if needed,” Forster said.
“We use some of the highest tensile steel in the world and one of the highest rated galvanisations in the industry.
“All of our equipment is feature-rich, designed to international codes, and places safety and sustainability at the highest level.”
With more than 200 engineers, the company is looking to continue improving on the design and availability of its products. It plans to incorporate more technology into its systems.
“We’re also looking at making our products available to a wider array of customers,” Forster said. “Soon, you’ll be able to buy the same product from anywhere in the world.
“AGI is at the forefront of grain, feed and food handling systems and silo design and we’re seeing more sophisticated technologies on a daily basis.”