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Monday March 21 2022

Silo blockages and how to prevent them

Silos are the beating heart of any production or manufacturing process, supplying the materials, chemicals and ingredients needed to continually deliver consistency and quality. As a result, when something goes wrong with a silo, it can have far-reaching and costly consequences throughout the manufacturing and production process.

While the operation of silos may seem simple, when problems and blockages occur the solution can be complex.

If a silo becomes blocked or the flow of materials is affected, the production process or end product will inevitably be compromised and manufacturing could even be forced to stop while the silo blockage is cleared.

Blockages will not only result in reduced storage capacity, slow the pace of operations and disruption, they can also cause bad flow characteristics, which will affect the quality of the end product. Consider how much would a silo blockage cost your business or reputation?

There a number of factors to consider when it comes to preventing a silo blockage, but the most important aspect is ensuring you are operating your silo in the most efficient and effective way and that takes careful monitoring and management.

What are the types of silo blockage?

Material blockages can be hazardous and costly and they should be tackled immediately. However, you must first understand the types of blockages that can occur in silos.

Regardless of the type of materials stored or the design of the silo, there is always a risk of blockages and especially if the silo isn’t monitored or managed carefully.

There are a number of different types of blockages possible in silos and these include ratholing, caking, bridging funneling, doming, plugging and wall-building or scaling. Silo blockages can also be caused by a combination of these.

The most common forms of blockage are bridging, caking and ratholing.

Bridging is when the material inside a silo sticks together and forms an arch, completely blocking the flow and this can also place huge pressure on the silo walls.  Doming is similar to bridging and is when an arch forms over the discharge point in a silo, preventing any material above it from escaping.

Caking usually occurs when material becomes stagnant or moist and clumps together. This can have a major impact on flow within the silo and can result in plugging. It can occur anywhere in the silo and will most likely affect the flow.

Ratholing (also known as tunnel flow or chimney) occurs when the material clings to the sides of a silo, creating a small hole down the silo for material to escape. The problem will only get worse as time goes on with more material sticking to the sides of the hole, further restricting flow. This again affects flow and puts strain on silo walls, risking the integrity of the silo structure.

What are the causes of silo blockages?

Silo blockages can be caused by a number of factors ranging from improper silo design through to simple mismanagement. The key to preventing blockages is actively monitoring and maintaining your silos and ensuring they are always running at optimum efficiency.

Design will be critical for each material and a number of factors have to be considered ranging from the angle of the outflow through to internal components that will ensure the material will flow freely. Each material will need a specific design and a mistake here will lead to blockages.

Other issues that can cause blockages in silos include putting the wrong material in the wrong silo structure, getting moisture in the material and it leading to clumping or build-up on the walls and when preventative maintenance and structural inspections are neglected.

Tips for avoiding blocked silos

Preventing blockages in silos is key to getting the most out of your production or manufacturing process. Included below are some of the key considerations in preventing potential blockages.

First and foremost is regular maintenance and careful monitoring of your silos. By maintaining good housekeeping, you can ensure your silo is in top condition and always ready for the next load of materials. By carefully maintaining silos and closely monitoring them, you can help to prevent any problems in the future.

Another key consideration is the correct unloading of your silo as this is another likely location for blockages. Make sure all unloading is carried out correctly and that the dispersal is aligned to the exit. If not, you will end up with material blocking the exit points

Poor exits are another thing to consider. While the path to the exit needs to be clear for materials to flow freely, you need to ensure the exit can flow freely too.

One of the biggest challenges for effective silo management is refilling materials. Ideally, you want to be filling up just as the silo is about to run out. Not only does this ensure you keep a good flow of new material running through the silo, rather than piling new material on a batch of old, but it is also the most efficient way to operate and cuts deliveries to the site.

Remote monitoring can be a valuable tool to ensure you are running a silo efficiently as this constant flow of new material will also help to prevent blockages from forming.

Finally, make sure your silo is regularly cleaned to prevent blockages, at least once a year but preferably every six months.

Cleaning your silos to prevent blockages

Making sure your silos are clean is one of the most important factors for preventing potential blockages. If they are left uncleaned, debris can build-up over time and will lead to one or multiple versions of the types of blockages we discussed. Even without a blockage, the flow of materials will inevitably be affected by unclean silos.

A regular cleaning schedule is critical, especially if you’re storing foodstuffs or animal feed as it will prevent mould, ensure the contents are fresh and palatable and no build-up or blockages form.

There are a number of effective ways to clean silos and there are some more detailed descriptions about these options in this blog.  However, remember that health and safety must be your top priority when cleaning silos and staff must be protected when tackling this important, but dangerous job.

There are a number of effective and safe methods for cleaning silos and we provide a quick overview below, but it’s important to carefully consider the best cleaning method based on the materials you are storing. Make sure it can’t damage the silo walls and also consider if tools could cause a spark or build up a static charge and trigger an explosion in a dusty or potentially volatile atmosphere.

One method of cleaning is vacuuming and this is usually the first step in cleaning a silo and helping to prevent blockages. Vacuuming is carried out with a truck-mounted system or can be built into the silo design. It prevents the need for staff to enter the silo and is ideal for removing loose powder. However, it is less effective against build-up or clumping.

Another effective method is a silo whip, which literally whips stuck material from the insides of the silo with a boom arm. Whips are usually pneumatically or hydraulically operated, but we prefer to use an air whip as it removes any risk of oil leaking and contaminating a silo.

A silo whip is very effective at removing any build-up or blockages and the loose material just falls to the silo discharge.

Managing silos with remote monitoring tools

We’ve discussed a range of methods for preventing blockages in silos but the most important thing to remember is that effective monitoring and management of your silos is the best way to prevent any issues. Not only does careful monitoring and management prevent blockages, but it brings a range of other benefits including fewer deliveries to site, reduced costs and less carbon as a result.

For example, by carefully monitoring levels you can ensure deliveries arrive just before a silo runs out. This ensures you can take full loads from a wagon and you’re not placing a part load on old materials at the bottom of the silo. This will help improve flow but will also result in fewer deliveries.

Remote monitoring is the best way for managing a silo and Minsterport’s online portal, MySilo, will allow you to monitor multiple silos to prevent overfill and track when they need to be refilled.

Remote monitoring systems also ensure blockages can be quickly identified. For example, if clumping or a blockage obscures a viewing window in a silo, you could make the mistake of thinking levels are higher and run out of materials at a critical point. A monitoring system provides live data that ensures you can see materials are flowing properly. If not, you are instantly alerted to a silo blockage in the system.

To find out more about Kistler Morse sensors or MySilo, get in touch.