Steve Kennedy
Business Development Manager
What is Rotoflo?
Severfield purchased the rights to the patented Rotoflo silo discharge unit from Portasilo in 2020, following more than a decade of proven Rotoflo performance as a unique market-leading silo-discharge unit.
As an exciting addition to Severfield's product solutions, this exceptional silo discharge system has been continuously developed and improved to ensure it remains the leader in silo discharge and material handling solutions technology. Its purpose as a discharge solution for silos and hoppers, is to prevent powder flow problems and bridging of materials in storage, providing a reliable, consistent, and controlled rate of discharge.
To find out more about Rotoflo, contact rotoflo@severfield.com.
- Features
- Benefits
- Applications
- Technical Data
- Downloads
- Partners
- Available in carbon steel or stainless steel
- ATEX Cat.1 certified
- Controlled discharge rate
- Multiple outlets (1 to 4)
- Four machine sizes
- Totally sealed and dust free
- Variable feed rate.
- Robust design
- Outlets can be supplied with discharge chutes or isolation valves
- Complete silo emptying – Promotes Mass Flow
- Suitable for installation on new silos or retrofit installations
- Design can prevent formation of ‘Bridging’ or ‘Rat-Holing’
- Can feed up to four outlets simultaneously or individually.
- Maintainable even if the silo is full
- Suitable for use with potentially explosive powders (ATEX and IECEx Cat.1 Cert.)
- Hygienic applications
- Simple, quick and inexpensive to maintain
- Controlled and accurate discharge of a wide range of materials
- Increases productivity efficiency
- Reduces production downtime
- Customised to meet your specific throughput and application requirements
- No vibration or aeration
- Hydrated lime – Water Treatment
- Chocolate crumb, sugar – Confectionery
- Titanium Dioxide – Paint
- Clays
- Chemicals
- Minerals
- Any kind of powders, granules or pellets
* Low speed gear box option or frequency inverter can be used to achieve lower throughputs.
Canada
PROMAT Engineering Sales (2003) Inc
6790 Kitimat Road, Unit #2
Mississauga,
ON, L5N 5L9
Canada
Email: promat@promatengineering.com
Tel. +1 (905) 567 7819
www.promatengineering.com
USA
PneuVey Systems - TX, LA, OK, AR
3076 Luke Drive
Farmersville
Texas 75442
USA
Tel. +1 (214) 471 3362
Email: sales@pneuveysystems.com
www.pneuveysystems.com
Prairie States Industrial Supply - KS, NE, IA, MO
Overland Park,
Kansas
USA
Tel. +1 (864) 542-7455
www.prairiestatesind.com
Sol-Tech Group Inc. - OH, KY, IN
7791 Yellowwood Drive
Mason,
Ohio 45040
USA
Email: contact@sol-techgroup.com
www.sol-techgroup.com
Stephens & Krizner Company, Inc. – Eastern PA, NJ, DE, MD, VA and WV
1220 PA-143, Lenhartsville,
PA 19534,
United States
Tel. +1 (484) 240-1543
www.skcoinc.com
"Rotoflo is the best silo discharger! Multiple outlets, no aeration, no vibration and runs almost maintenance free."
Get in touch with us
Do you want to speak with one of the team about the Rotoflo Silo Discharger?
If you'd like to find out more or discuss pricing, please email us or contact one of our team members listed at the bottom of this page.
What are silos and silo discharge systems?
Silos are generally used for the storage and discharge of powdered or granular bulk solids; a silo discharge system is designed to aid in the discharge of materials quickly and efficiently, thereby eliminating the risk of powder bridging, ratholing or blockage.
Rotoflo silo discharge units can be built-in or retrofitted to existing vessels and, as such, will allow materials to be safely and efficiently discharged from a silo or hopper. With multiple configurable outlets, a Rotoflo silo discharge unit can both reduce the risk of material flow problems within a vessel and provide a controlled rate of discharge to multiple downstream processes.
What causes powder flow problems in silos and hoppers?
There are a number of reasons why you might experience flow problems in bulk material silo storage. These range from moisture causing compaction/blockages, to poor silo design or unsuitability. The types of issues can be related to the silo itself, its shape and geometry, or the material, or both. However, poor equipment design is usually what causes the majority of issues.
Common causes of flow problems:
- Vessel geometry include angle of the hopper and outlet size
- Wall friction – friction between the material being stored and the vessel wall material.
- Internal friction – friction within the material being stored.
- Consolidation of the material within the vessel due to materials self-weight.
- Ratholing
- Powder bridging
- Segregation of particles in the materials
- Flooding or flushing of the flow
- Degradation of the particles
- Consolidation with time of the material within the vessel.
- Attraction of the material particles (electrostatic or Van-der-Waals forces)
- Liquid bridges due to moisture within the stored material or adsorbed from the atmosphere.
Two of the most common issues are Ratholing and Powder Bridging. So, let’s look at what they are and why they happen.
What is powder bridging?
Powder bridging occurs when materials in a silo or hopper become interlocked, thereby forming a stable arch over the designated outlet. When powder bridging occurs, materials stored in the silo become trapped as the arch prevents the flow and means product cannot be released.
Traditional, short-term solutions to powder bridging (ways of breaking up the arch of materials) include manual hammering of the silo, pneumatic shaking/application of a vibration to stir a breakdown or, if that fails, manual rodding of the material in the silo.
Silos should be fitted with an appropriate discharge aid to avoid this and ensure correct and efficient discharge.
What is ratholing?
Ratholing is the formation of a stable column of material on the side walls of the silo or hopper.
Generally, as a result of unsuitable hopper geometry, in these cases the product will only flow through a channel at the centre of the storage vessel; the rest of the product will stay on the sides. This particular issue can reduce flow, stop it all together and dramatically reduce the live storage capacity of the silo.
What is the solution to powder flow problems in silos and hoppers?
The solution to these issues is a silo discharge system, like the Rotoflo. Silo discharge systems address issues commonly faced in silos, ensuring space is not wasted and flow is optimised.
They help by providing the following benefits:
- Large diameter active silo outlet
- Elimination of dead space where contents may otherwise consolidate
- Low headroom design maximising silo contents
- Control of discharge rate
- Consistent feeding over a wide range of throughput
Why choose the Rotoflo Silo Discharger?
Unlike traditional methods involving aeration or vibration, which can lead to issues like equipment damage, inconsistent discharge rates, and environmental hazards, our Rotoflo Silo Discharger offers a superior alternative. You can read more about the disadvantages of aeration and vibration below.
Aeration disadvantages
- Can over fluidise powders causing flooding of equipment downstream.
- Aeration can expand the bulk solid, leading to a lower and more variable density, which can make it difficult to maintain a consistent discharge rate.
- Not able to be used successfully with coarse materials or powders containing moisture or fat content.
- Pneumatic air is generally more expensive than using electricity to discharge materials.
- Can make the powder more prone to dust and potentially create an explosion hazard.
- Aeration can lead to variations in discharge rate, making it difficult to control flow precisely. E.g. in applications like metering feeders or in processes requiring consistent dosing.
- Can worsen flow problems by encouraging drying out of materials or segregation.
Vibration disadvantages
- Vibration of vessels can cause stress cracking and metal fatigue. This can damage hoppers or other equipment, resulting in additional expense for repairs.
- Noise of vibration can make the working environment unpleasant for operatives.
- Material compaction can be caused by overuse of vibrators. This can result in material bridging.
- Vibration can be detrimental to friable materials.
- Vibration can lead to increased friction which accelerates wear on conveying belts, chutes, and other discharge components.
- Vibration can cause powder segregation, as different size particles or densities separate, affecting product quality and consistency.
- Vibrators are not always effective for discharging highly cohesive or elastic materials.
- Some powders can stick to the walls of vibrating containers, causing flow stagnation and reduced discharge rates.
UK and International
Rocco Mastrolonardo
Sales Manager
