Dust and streamers are one of the most common problems in pneumatic conveying systems – and a frustrating one, too. Despite a carefully designed plant layout and additional measures, plant operators will eventually be confronted with some sort of dust and streamers. This does not only affect the product being conveyed but also leads to a lot of waste.
Why does dust and streamers occur in the first place?
Throughout the conveying process the pellets go through various phases in which the conveying pressure and consequently the conveying velocity may vary. Especially in the phases where the pellets are transported with high speed, the product slights along and bumps into the walls of the pipes, elbows or couplings. This contact between the product and the system causes friction and the material partially breaks and releases small particles into the system which accumulates as dust. Depending on the conditions of your pipes or components as well as the timing of your last maintenance and cleaning cycle, this can add up to a significant amount of unwanted dust. For environmental reasons, dust is always kept in the system and not released to the atmosphere.
What is the problem with dust and streamers?
On a small scale, dust seems to be trivial and simply a byproduct of pneumatic conveying. However, it comes with many disadvantages and problems.
- The product quality suffers: Friction creates stress on your product which will inevitably take a toll on the product quality.
- More frequent maintenance cycles: Through friction and e.g. antiblock additives the pipes wear out more quickly. Depending on the conveying system, you have to plan in frequent maintenance and cleaning cycles to keep up a high-quality level. In addition, system failures and outages are more likely to occur due to e.g. congestion of angel hairs.
- You have to deal with waste: Dust and streams equals waste – and there can be a lot of it at the end of the day. The collection and disposal of waste can represent a significant part of your operational costs.
Is there a solution to avoid dust and streamers in pneumatic conveying lines?
Fortunately, there are various designs and retrofitting options to reduce or even avoid the occurrence of dust and streamers in your pneumatic conveying system. Usually, operators will focus on the prevention, reduction or active removal of dust and streamers in order to maintain a high product quality. Which option is the most suitable for you depends on the properties of your product, the set-up of your plant as well as your general objectives.
Prevention
When processes are especially susceptible to dust and streamers operators need to find a solution to prevent its formation before they occur. Due to different environments and requirements there is no one size fits all solution. When handling both, powder and pellets, a plant constructor can only design a reliably functioning and economical bulk materials handling system with in-depth knowledge and comprehensive understanding of bulk materials. Coperion meets the increasing demands with a wide and selectively developed range of innovative conveying processes and components. Our conveying technologies are therefore already adapted to tomorrow’s continuously increasing production capacities and conveying distances today.
Especially big polyolefin plants are known to be especially affected by a reduced product quality and tremendous operation costs due to dust. With the needs of polyolefin plants in mind, Coperion has developed a completely new approach (FLUIDLIFT® ecoblue) of conveying thermoplastic polyolefins such as LLDPE or PP pellets. By inserting a controlled amount of water, the conveying air is provided with a minor water film which provenly prevents friction before it occurs. This water is later effectively removed from the process. As a result, the pellets have a much higher product quality while the moisture content remains the same as before.
Separation
The purity of bulk materials is a decisive factor for the quality of the end product. Regardless of whether the assignment is to minimize attrition, clean products perfectly or to determine the degree of residual dust in line with valid standards – our solutions are an ideal combination of many years of process competence and the most advanced bulk materials know-how in the world. Our specialists already focus on minimizing dust generation when the conveying systems is being designed. Minimum conveying velocities, suitable pipe materials and connections ensure minimum attrition during production. A varied range of separator concepts are employed to suit the product properties and application requirements. One example is Coperion’s Diverting Counter-flow Elutriator UGS, Horizontal Fluid Bed Separator HFS or Gravity Rotation Separator SRS.
To summarize, dust and streamers can be indeed a tricky part of pneumatic conveying. Nonetheless, there is a number of effective dedusting equipment which can immediately improve your process.
