From the earliest times, bulk materials handling systems have had multiple applications. Typically, raw materials are moved from the receiving area to the storage area and then conveyed to the process area. From here they can then be transported to the packaging area.

Modern bulk materials handling solutions

Nowadays, to handle bulk materials, you can choose among a wide range of solutions: from mechanical conveying systems (including elevator, belt and screw conveyors) to pneumatic conveying systems in dense or dilute phase. When selecting the appropriate type of conveying system, the decision must be made after a careful evaluation of the material characteristics, plant layout and flow rate.

How bulk materials handling solutions work

Let’s take an example.

Abrasive materials handling (e.g., ashes) causes considerable wear in a conveying system. A mechanical transport system is particularly unsuitable in such cases, as they would require continuous maintenance and replacements of components. Moreover, using these systems the dispersion of volatile substances in the working environment is inevitable, and most inconvenient.

Also, contamination with air makes mechanical systems unsuitable for the handling of food, chemical and pharmaceutical bulk materials. Another limitation of these kind of conveyors is the high probability of product breakage which, in the case of fragile materials, has a considerable impact.

Benefits of pneumatic bulk materials handling

Contrary to mechanical conveying systems, pneumatic conveying technology moves the product inside a closed pipe, which greatly reduces the possibility of material loss and air contamination. The length of the line can reach even several hundred meters, with capacities that can reach up to 100 tons per hour and more. In particular, a dense phase system conveys the material at a slower speed. The amount of friction on the system’s walls is considerably lower and thus prevents line wear.

In case of complex plants layouts, with vertical and curved sections, pneumatic conveyors are the best choice due to their flexibility as opposed to the bulkier and more rigid mechanical conveyors.
Therefore, if you need to transport high flow rates on long and difficult routes – as often happens for example in cement and in general in the building industry – pneumatic transport is the right choice.

In short, it seems clear that, compared to older and outdated systems for moving materials that relied solely on human strength, today we can choose durable solutions for handling bulk materials that offer more significant benefits.

Benefits of dense phase pneumatic conveying

Conveying speed and product-to-air ratio are the two variables that most distinguish dense phase conveyors from dilute phase conveyors. The air or gas flow accelerates the material at a given speed, the particles come into contact with the walls of the pipeline, change direction in the bends and then fall back to their original state of rest only at the destination. In general, the percentage of material breakage is proportional to the average material velocity in the conveying line.
In a dense phase conveying system, the material is slowed to a lower point than in dilute phase systems so as to avoid breakages and damages, that would have a major impact in the case of fragile products such as coffee, rice or glass.

Compared to a dilute phase system, a dense phase system typically requires a smaller amount of air to transport the same amount of product.

Pneumatic conveyors allow bulk materials to be handled within a closed pipe system by means of a gas (usually compressed air or nitrogen).

Pneumatic conveyors are used primarily for granules and powders. This type of conveyor is extremely flexible in terms of routing and length of the pipeline.

Working of pneumatic conveyors

The material is loaded onto a pressure vessel, where high pressure leads the material inside the conveying line to its destination.

The system is totally enclosed within a pipeline, where differences in pressure on either side cause a flow of product.

This pressure differential can be made via increasing or decreasing the pressure on either side of the tube.

Dense phase pneumatic conveying vs. dilute phase pneumatic conveying

With dense phase conveying, comparing to dilute phase, the flow of air is not around each particle.

Instead, granular agglomerates (in the shape of dunes) and plugs are pushed by compressed air at a low velocity and a higher pressure through the conveying pipe.

Nowadays the supply of feed ranges between different formats and consistencies of product based on the animal species for which they are intended.

Feed may include raw materials of plant or animal origin whose main objective is to meet the nutritional needs of the animals. Often these products include derivatives of industrial transformation or are obtained by mixing raw materials and additives.

The processes of each type of feed, however, have one thing in common, that is, the movement of raw materials according to the different production phases up to the storage stations or packaging machines.

Animal feedstuffs are fragile products and often tend to be damaged during transport. The high percentages of fat that compose them can represent a difficulty in handling and subsequent sanitizing of the line. It is therefore essential that the transport technology is able to guarantee both the integrity of the product and high operating performance in order to optimize the production process.

A crushed pellet or croquette is no longer marketable. Frequent blockages in the pipeline or plant shutdowns are not economically convenient.

The dense phase pneumatic transport of pet food is able to avoid these problems. It is suitable for fragile materials and mixtures. Thanks to the low operating speed, it preserves the integrity of the product and prevents its deterioration. It also allows easy sliding of the material within the lines and offers the possibility of rapid sanitization of the lines.

But what makes dense phase pneumatic conveying the most suitable method for handling animal feed is the flexibility of application.

If you have already used mechanical transport systems, you know that they are not suitable for complex layouts, with vertical and curved sections. On the contrary the pneumatic conveying systems are distinguished from the previous ones by the closed pipes and the possibility of covering even long distances. They have few moving parts and require less maintenance, precisely because they allow less wear.

Our goal is to provide you with a solution designed according to your needs, whatever the path required. We take care of your product and make sure it arrives intact to the destination you require.

There are many solutions for the transport in dense phase of pet food. But the design of our engineers and the customization of our systems makes the difference.

Most of the innovative conveying systems offer the possibility of being stopped and restarted during operation. This does not happen with many conventional mechanical systems and could generate considerable inconvenience in clearing pipelines, if this is necessary.

Therefore, for plants where a pipeline clearing phase is required, more innovative systems would be well worthwhile considering. These latter solutions offer further advantages, since they are capable of handling large quantities of materials with a reduced quantity of air. Consequently, operating costs are lower than other types of pneumatic transport.

Fluidized bed conveyor systems are generally not recognized as pneumatic conveying solutions because they use very low pressure air and the material does not flow through a pipeline. In any case they are not part of the mechanical transport systems. Their driving force is gravity so that they are able to operate only with an inclination downwards, although at a very low angle.

Air-assisted gravity transport: the fluidized motion conveyors 

In situations where the flow of a material is directed downwards, air-assisted gravity transport has numerous advantages compared with pneumatic conveying systems. The costs of the plants are significantly lower as well as the operating costs are lower; in addition, a wide range of materials can be handled at a very low speed.

Gravity conveyors consist of a channel divided longitudinally by a continuous porous membrane on which the material flows, as shown in the figure above. The operation of these systems is based on the introduction of a small amount of low pressure air through the membrane.

The fluidized conveyors are able to move bulk material up to 100 meters and are suitable for flow rates up to 300 m3. In general, materials with a particle size from 40 to 500 µm and a density between 1400 and 5000 kg / m3, are the easiest to transport and will flow very smoothly down shallow slopes.

In our specialized, fully-equipped laboratory, we conduct complete and detailed powder analysis to verify the feasibility of a gravity conveyor system.

Material scientists, manufacturers and anyone who handles and process powder know how variable they can be and how much the efficence of the process could be affected.
In our specialized, fully-equipped laboratories, we conduct complete and detailed powder analysis, including aeration test, flow analysis, segregation test, attrition test, abrasive wear test and hygroscopic test.
After our evalutations, we can predict how a material behaves during pneumatic convey, and we are allowed to specify best conveying mode (i.e, dilute or dense phase), as well as process parameters, such as gas\solid loading ratio, booster opening, size of pressure vessel.

We have to truly understand everything about particles, so we look at every property such as size distribution, particle shape, bulk density, granulometry, dustiness, abrasiveness, hardness.

Our laboratory is equipped with SZM-2 Trinocular stereozoom microscope, with a sieve shaker and with a powder rhometer to analyse dynamic properties.
After the laboratory work, your powder could be compared with our collection of samples, including more than 500 items, and a comprehensive report is given, which summerize all the procedures of tests apparatus and machinery,graph and quantification of powder dynamic behaviour, conclusions and reccomandations to achieve the right grade of fluidization.

Flow analysis

In order to accomplish a complete study, we also have to investigate dynamic properties.
In our laboratories we then measure dynamic flow features, together with shear and bulk properties of powders and granules. It is also crucial to take into account the influence of all external variables, to entirely predict the powder behaviour in the process:

• Consolidation
• Air content
• Air permeability
• Vibration
• Moisture content

Aeration properties

To evaluate powder aeration properties, we perform the following tests:
Fluidization test.
Permeability test.
Consolidation test.
Compressibility test.
Segregation test.

Then, a comprehensive report package is given, which contains

• all the procedures of tests apparatus and machinery,
• graph and quantification of powder fludization behaviour
• definition of powder permeability properties
• conclusions and reccomandations to achieve the right grade of fluidization

Pneumatic conveying

After the laboratory work, each powder behaviour could be evaluated in our pilot plant, whose characteristics are as follows:

• System type: Full-Line
• Conveying vessel model: 8TPA100
• Volume: 280 lt
• Line actual lenght: 45 mt
• Pipe line diameter: 4” (Inside diameter = 110 mm)
• Average distance between Booster: 0,75 – 1,5 – 3 m
• N° bends: 6
• Vertical stretch: 4 mt
• Horizontal stretch: 41 mt

For several years, we have carried out pneumatic conveying tests on more than 500 powders, flakes, pellets, granules and fibers; our know-how is at your service to quantify and ensure the feasibility of every project.

Pneumatic conveying can be defined as the art of handling powdered or granular material into a pipeline by using the flow of air that passes through it. The management of a pressure difference at the ends of the pipeline lets to obtain an air flow that, if it reaches and maintains the right speed, manages to transport the product to the desired destination. Pressure and speed are therefore the main parameters that characterize the pneumatic transport, but many others must be considered.

The weight, the shape, the moisture, the permeability, the eventual free flowing or propensity to aggregate, are just some of the many elements to deal with a pneumatic transport. Since the early decades of the ‘900, when we began to use the pneumatic technology to convey bulk material, many efforts have been made to realize a mathematical model able to describe its dynamics, but despite everything, the variables involved are too many and pneumatic transport, although widely used in modern industrial technology, remains essentially an art. In order to define an efficient system, it is necessary to get into the hands of specialists of the sector, to whom have gained experience and a specific knowledge of the transport of the product to handle and manufacture powder and granules conveyor systems.
Above all, it is necessary to contact companies that have test facilities capable of concretely and preventively testing and measuring the reaction of the product, thus avoiding sizing errors and unpleasant surprises after the start-up of the system.

I don’t want to see them anymore!
Even though they have a very nice name, angel hair is for a production responsible worse than hail just before a harvest.

All those who have had to do with this, in a production line, with the pneumatic conveying of plastic material have had to deal with this inconvenience.

But what are angel hair?
How can they be prevented or avoided?

There is nothing angelic, in fact they are a real scourge for those who have to work with plastic materials.

During pneumatic conveying the velocity, friction and heat, generate long filaments called “angel hair”, which compromise the quality of the material of the batch being processed. This happens, in particular, where there are long paths or in curves, rather than in the joints.

The integrity of the plastic granule is fundamental throughout the line and the transport in dense phase guarantees you to avoid, or drastically reduce, the abrasions to the material, and therefore also to limit waste. And we know that waste leads to costs and times that go to invalidate the productive capacity of a company.

If a lot of raw material is degraded, there can be many problems, some of which are very serious.
The quality of the raw material, if degraded due to transport, can cause a lot of problems downstream. Let’s analyze one of them: a plastic film that does not reflect the expected quality and agreed with the end customer cannot be proposed on the market.

Production waste or non-salable product, in all ways the angel’s hair only leads to stomach aches for the company and its partners. This is why those who use this type of raw material must absolutely use dense phase transport technology so they can finally say: “I don’t want to see them anymore!”

Italy has no coffee cultivation, nevertheless it has become a world excellence in the processing and production of coffee.
In Italy alone there are more than 700 coffee roaster factories, a world record.

As you drink coffee in Italy you don’t drink anywhere in the world and I don’t say that I’m biased.

Coffee has a rather long chain before arriving in the cup.
Today I would like to show you a small piece of this chain that can have important defects and of course how you can eliminate them.
These problems only concern all those who want a high quality finished product.

The transport of the grain before processing has defects that are difficult to predict if you are not a specialist.

Anyone who has a production line for roasting, but not only, knows that coffee during its “process” undergoes some “traumas” that it would be better to avoid.
One of these is the breaking of the grain.
During conveying, the grain suffers traumas 😉 with consequent breakages.
Companies that want the best for their customers know perfectly well that they can’t afford it!

Producers of the production lines are not always able to overcome this very important inconvenience, but it is not due to incompetence, it is “only” that designing, implementing, installing and testing an entire production line has 100,000 precautions of which “the trauma of the bean ”it is normal that it can take second place.

For us it is different, we only have one thing to do, to pamper your grain and bring it intact to its destination while respecting the speed of processing that remains essential.
Dense phase transport avoids, or drastically reduces this and other problems such as segregation, the end result is that the mixture always retains the same properties.

Many believe they know pneumatic transport in dense phase …… but it is not only this that preserves the raw material, this is the tip of the iceberg.
The customization is what makes the difference.
If you want you can go to see our Case Studies I am sure you will find something that will help you improve your process of cuddle with the coffee bean.

Now I’ll explain and show you why our (future) customer can sleep peacefully and will never have any risk.

When a company, or a technician / designer knows the advantages of dense phase pneumatic transport, inevitably there is interested in trying to mark the pros and cons.

I do not want to list the many advantages that dense phase pneumatic transport offers,
but I want to talk about a fear that is sometimes highlighted to us: “the unknown of the new”.

By thinking that this technology is not new, and that Air Tec has used and implemented it for over 25 years, but I understand that some people don’t know the details and believe it is new for them.

Fortunately this was something new for some when Air-Tec System was founded, for others it was 10 years ago, for some still actually is and certainly for others it will be in 10 years.
Listening to our (future) customers we understood that the uncertainty of what is “new”, sometimes, quite rightly, doesn’t let you make decisions even if they are, as in this case, patently advantageous.

So how did we want to eliminate all your uncertainty?
We created a scientific laboratory within the company to analyze all the materials that will be transported.

In our laboratory we carry out tests on your material and in the end you will have a technical report with lots of information and graphics such as:

• fragility of the material;
• speed and transport capacity;
• internal friction and friction on piping;
• filling coefficient;
• particle size and if it is free flowing according for example of loading time of the pressure vessel;
• tendency to agglomerate, form lumps;
• material angle;
• further information on request.

This test will be very useful because it let us design a system in which your raw material can be transported and reach a speed where we are sure that it will not be altered, this means guaranteeing the quality of the finished product in relation to the greater speed possible production therefore lower production costs.

These are some of the pluses, even if what matters most is the customization of this conveying process. because everything depends on your production goals, what you transport and how your customer wants you to produce his “jewel”.

Price has always been important, but never important as well as in these recent years.
From the “crisis” to nowadays , companies have been obliged to make a choice: decrease prices, and dramatically reduce their margins, or rolling up their sleeves and bringing a real value to their customers and keeping prices “consistent”.

But bringing true value is difficult.
It is not just about having a good product: this is obvious.
Having a good after-sales … it’s normal.
The customer expects this as a minimum.

Obviously Air Tec System has chosen to keep away from the “price war”.
We have chosen the most difficult path, but the one that gives more satisfaction: giving a real value to the customer.

So what means for Air Tec System giving a value to its customers?
First you can count on the only company specialized in the design and production of pneumatic conveying systems.
We DO NOT do anything else, we are specialized ONLY in this!
And we are proud of it.
Being specialized has always paid off.

We do not deal with 1000 things, we are specialized in pneumatic dense phase conveying of powders and granules…
This allows us to have an extraordinary standard production that we obviously customize “tailored” to the specific needs of each customer.

I don’t want to tell to you about patents, quality, assistance, services etc. everyone mention it, especially those who can’t maintain it.

Air Tec System exists from over 25 years and our expansion plans are at least ambitious.
Who purchases from us improve their production processes and therefore their profitability, in addition to efficiency.
Our customers sleep peacefully.

That’s why we cost a little more than “others”, but our quality / price ratio is unbeatable.
We want to “stay out of the price war” because we are focused on satisfying customers all over the world.

Click here to see some Case Studies

So what is the right price to pay?
To answer this question, I copied a consideration by John Ruskin that goes back over 100 years.

It is unwise to pay too much.
But paying too little is worse.
When you pay too much you lose a little bit of money, and that’s it.
But if you pay too little you risk to lose everything,
because the thing bought may
not suit your needs.
The law of balance in exchanges does not allow
to pay a little and receive a lot:
it is absurd.
If it deals with the lowest bidder,
it will be prudent to add something
for the risk you run;
but if you do this you will have enough
to buy something better.

John Ruskin (1819 – 1900)