The design of bulk materials handling systems involves not only the choice of the type of technology, but also the ability of that technology to be integrated into existing production systems, thus ensuring continuity.

The benefits of using a new solution become the driver of a decision-making process that can be undertaken by both manufacturing companies and system designers.

On the one hand, the end user wants to achieve a return on production and a competitive advantage; on the other hand, the systems engineer must design a complete system in which each component integrates seamlessly with the others. The ability to meet this multitude of requirements in a well-structured yet flexible manner is the key to choosing a supplier of bulk materials handling solutions today.
Let us take a closer look at the different applications of these solutions for manufacturing companies in all industries and for systems engineers.

Manufacturing companies

End users of powder and granule handling systems are often faced with issues relating to conveying or processing raw materials. Important factors to consider include: economic commitment, product and production environment characteristics, and compatibility with technologies already in use.
Previous experience and in-depth knowledge of the product are the basis for an informed choice of the most suitable handling system.
Starting with an initial technical consultation phase, Air-Tec System applications are designed, built, and installed according to the intended use. The handling systems, whether extensions of existing installations or new solutions, are complete and ready to use.

Systems engineers and engineering companies

They are specialists in the design of even the most complex systems that include various processing stages: from storage and conveying to dosing and mixing of bulk materials. These are complete systems based on the concept of automating production processes by combining different technologies.
Each part of the system must be selected taking into account the characteristics of the equipment, the intended end use, and the need to fulfil the economic agreement entered into with the customer. The solutions aim to develop synergies between the various existing systems by properly interfacing them.
It is essential that all selected technologies can be fully interfaced to ensure an integrated production flow. Air-Tec System’s systems are specifically designed for efficient data exchange. Entire system sections, including the necessary accessories, are adapted to the context in which they are to be used.

Air-Tec System offers complete solutions and accessories to meet the needs of both end users and systems engineers.

As part of the Transition 4.0 project in support of the digital transformation of companies, there are still a number of beneficial opportunities.
Today it is more important than ever to be resilient in the face of dynamically changing economic conditions.

Digitalising your company means not only taking advantage of available tax credits, but also gaining full control over your production processes through the ability to collect automated data in real time.

Pneumatic conveying systems as enablers of Industry 4.0 change

Pneumatic conveying systems are able to connect with each other and with the other components of a production plant in order to create a perfectly integrated processing flow. This makes it possible to achieve a high level of efficiency and optimise production costs.
These machines, developed for data exchange and remote assistance, are among the enabling technologies for Industry 4.0.

Let’s take a detailed look at the requirements for their inclusion among the functional assets for the technological and digital transformation of companies, according to the Transition 4.0 model:

Applications involving pneumatic conveying alone are not covered by Industry 4.0. standards; however, when they are integrated into systems that comply with the standards, they become part of the production process and acquire the necessary requirements.

In the planning stages of a production system, the advice of Air-Tec System engineers is aimed at ensuring effective integration to fulfil regulatory requirements.

Pneumatic transport sizing: find out the right technology for your product

To select the best system for your needs, you should consider a number of factors including material properties, desired throughput and conveying distance.

Other factors to consider are for example air pressure, air flow and velocity.

Typical pressure values for dilute conveying systems are:

ΔP: from + 0,2 to + 0,8 bar for pressure systems
from -0,2 to – 0,5 bar for vacuum systems

Typical pressure values for dense phase pneumatic systems are higher, ranging between 0,5-5 bar.

Air flow, which is the amount of compressed air needed to obtain the speed for the conveying process, is affected by three factors:

• Material properties
• Conveying distance
• Throughput

If you handle bulk materials with different physical and/or chemical properties, you might be familiar with segregation issues.

Whatever your industrial sector is (food industry, pharmaceutical, chemical, etc…), it is important that the mixture transported remains homogenous and uniform.

Taking a binary mixture as an example, we can have three degrees of blending:

Therefore, you can understand why segregation is such a common issue when handling material mixtures. In many applications, it’s almost impossible to obtain a uniform and homogenous blend.

Dense phase pneumatic conveying can overcome efficiently this issue. Dense phase systems use approximately 30 litres of gas to move 1 kg of product but, due to the high pressure inside the pipeline (more than 1 barg), powders form compacted plugs which are then carried along the line. This does not allow fine particles to segregate from the others.

We have tested more than 500 powders in our laboratories and we have come to the conclusion that only dense phase pneumatic conveying can avoid powder stratification.

Francesco Pozzi
Head of Air-Tec System Research and Development Department

The selection of a pneumatic conveying system for a particular application involves consideration of numerous parameters associated with the conveyed material and the conveying conditions.

When considering which system to use, we need to take into account the material to be conveyed at a specified flow rate over a given distance. Other factors that can be used in the decision-making process are power consumption, and hence system operating costs.

Dense phase or dilute phase?

Materials can either be conveyed in batches through a pipeline, or they can be conveyed on a continuous basis, even 24 hours a day if necessary. In batch conveying, the material may be handled as a single plug if the lot size is relatively small.
If the batch size is large, two possible ways  of conveying are possible.
If the material remains in suspension in the air through the pipeline, it is referred to as dilute phase conveying. If the material is conveyed at low velocity in a non-suspension mode, we refer to as dense phase conveying.

Dilute and dense phase systems are the two most common technologies. They differ from the concentration of the products inside of the pipeline.

In dilute phase the particles are held in suspension in the air as they are blown or sucked through the pipeline. A relatively high velocity is required and so power requirements can also be high. There is virtually no limit to the range of materials that can be conveyed but some considerations must be done about friable and abrasive materials. In fact the contact between the product and the pipeline, and particularly the bends, could degrade the particles.

In dense phase pneumatic conveying the air pushes a considerable quantity of product inside the pipe, generating an actual plug.
The possibility to control the pressure of the fluid acting on the plug allows to give the minimum power necessary to move it.

Conveying velocity

In dilute phase conveying the air velocity in the pipeline is very high, usually in the range of 16-20 m/s at the start and final speeds not exceeding 30 m/s on the outlet.

For dense phase conveying, air velocitiy can be reduced to 3 m/s. Low speed allows to reduce the breakage of delicate products and the wear of the pipes when they are crossed by abrasive products.

The best-known abrasive particles of natural origin include corundum, quartz, silica, diatomaceous earth and salt. Among synthetic abrasive particles, glass and some types of oxides are also well known.

How the pneumatic transport of abrasive products works

When designing a pneumatic conveyor system, the chemical composition of the abrasive material needs to be taken into account since it will affect its behavior when in contact with another material.

If you need to handle an abrasive powder, besides choosing a low-speed transport with full pipeline, you can also opt for specially designed curves, made of suitable alloys to prevent wear over time.

Francesco Pozzi
R&D Manger at Air-Tec System

When you choose metal powders pneumatic conveying you using a technology that can guarantee safety and efficiency.

When disposing exhausted batteries, you need to handle lithium, cobalt or other substances that may be potentially harmful for the environment. For this reason, it is important to follow every step of the disposal process to ensure compliance with legal requirements. These substances cannot be released out in the environment and they need to be handled with caution since they are highly corrosive powders.

How the pneumatic transport of powders in recycling batteries works

It is only in recent years that dense phase pneumatic transport for powders has been applied to the disposal of exhausted batteries.
In fact, it is with the increased use of electric cars and electronic devices in the last decade, that the recycling market of metal powders has become more and more important.

The recycling process of metal powders recovered from exhausted batteries involves the separation of each substance, which will be further treated in order to be reused for the benefit of electric mobility and the environment.

Why choose dense phase pneumatic conveying system?

Because it delivers a great deal of benefits!

The metal powders pneumatic conveying is composed of a completely closed structure able to avoid the dispersion of material into the environment.
In our dense phase pneumatic conveying system of powders, safety is essential.

Recycled metals powders from exhausted batteries represents over 40% of the total production of lead in Italy and 37% of the national demand for metal (Source: automazione-plus.it). This market presents good opportunities.

As far as the abrasiveness of these powders is concerned, thanks to the low speed of a dense phase pneumatic conveyor, the wear of the pipes is reduced to a minimum. In this way high performance levels and reduced maintenance costs are assured.

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.