Many materials are produced and transported in powder form. From plastics (polyethylene and polypropylene) to pigments (titanium dioxide) and food (milk powder). In addition, lots of powdered products, such as zinc, have different uses across various industries.
There is one thing all of these powders have in common: Once they are manufactured, they have to be moved from their production site to some means of transportation and, later, from there to their final destination.
Dry powders are often transported and stored in bulk. To simplify the unloading or transport process, you could make use of a pneumatic conveying system. This will ensure easy, safe, and cost-efficient movement of the material. But how do you pick the right powder conveying system? To do that, you first have to take a look at the different pneumatic conveying methods and technologies.
Powder can be transported using either pressure (positive) conveying or vacuum (negative) conveying. Pressure conveying uses compressed air at the start of the system to push the powder through the piping. In the case of vacuum conveying, the material is “sucked” toward its destination. Whether you need to use the positive or negative conveying method depends on the type of powder that has to be moved as well as system requirements, such as the distance the material has to be transported.
It is also important to remember that there are further safety or hygiene requirements for some powders. For example, some of them are combustible, in which case the relevant components of the pneumatic conveying system, such as blowers and compressors, need the correct certifications that protect the system from explosion.
In addition, powders used in certain industries, such as the food and pharmaceutical sectors, have to meet stringent hygiene and quality standards. Making sure your equipment is Class 0 certified will help you avoid oil contamination.
Aftercoolers & ancillaries
In this case, a conveying system needs to include an aftercooler, which guarantees that the powder is transported at perfectly safe temperatures not exceeding 40°C. While some compressors have integrated aftercoolers, others do not, in which case the system needs to include a standalone model.
If you decide to use a water-cooled aftercooler, it may also be necessary to add a chiller. It lowers the water temperature to a manageable and constant level to ensure that the aftercooler can do its job.
Furthermore, a water separator or dryer that removes moisture from the compressed air may be needed as well to maintain the quality of the transported powder.
Silo fluidization for powder
When conveying powder from a silo, compressed air can also be used for the so-called “fluidization” process. Here, very low-pressure air is injected at the bottom side walls of the silo. This ensures that the powder does not stick to the sides of the silo and makes it easier to convey, which reduces energy costs. While fluidization is considered to be a form of pneumatic conveying, it usually does not require ancillaries such as aftercoolers. There are some exceptions, however. If you’re dealing with a food-related powder, international quality standards do require you to cool and remove the moisture from the air, even at such low air pressures.
If you find this wealth of options, technologies and processes confusing, you can simply contact us with your specific needs and we will help you.
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