Lisa A. Little | Progressive Products
If the material flowing through your pneumatic conveying system is agglomerated or lumpy and jamming up the process, you may want to consider incorporating a lump breaker into your system. A lump breaker reduces the material’s particle size, eliminating agglomeration and ensuring a smooth material flow. This article details the benefits of a lump breaker and how to determine if you need a lump breaker in your pneumatic conveying system.
Pneumatic conveying is an excellent method of transporting bulk solid materials, but if your material has agglomerations or clumps or if the material’s particles are just too big, you may experience flow problems or clogging. Variables such as humidity, material transportation conditions, and material storage time can cause unwanted agglomeration in powders and other bulk solid materials. The resulting clumps may affect the material’s ability to flow through a pneumatic conveying system. Materials that are prone to agglomeration can reduce a conveying system’s performance and may require an operator to stand on guard, watching the system for clumps that could block the line. Clumping can also cause problems in processes that combine multiple ingredients according to a specific recipe.
A lump breaker can prepare such materials for pneumatic conveying and ensure adequate flow. Various industries from foods to chemicals use lump breakers to deagglomerate materials and ensure smooth, efficient conveying while maintaining product quality.
Lump breaker operation
A lump breaker is usually equipped with two or more motor-driven rotating shafts mounted parallel to each other within a rectangular frame, as shown in Figure 1. The shafts are equipped with cutting teeth, also called breakers, that draw in material fed from above, breaking down lumpy or oversized particles as they pass between the shafts with minimal dust generation. The desired particle size is determined by the space between the teeth and the shafts. The material then discharges by gravity through a screen below the shafts.
Lump breakers come in a range of sizes, with 12- and 24-inch-square openings being the most common. They’re generally made from either carbon steel or Type 304 or 316 stainless steel, but cast iron or more heavy-duty steel options are also available, depending on the equipment supplier.
Factors to consider
The ability to predict a material’s flowrate through a lump breaker is impacted by the material’s characteristics and the feeding method into the lump breaker. Mounting a lump breaker directly below a hopper or bin can cause the material to flow into the lump breaker too quickly and may result in bridging. Bridging is when agglomerated material in a hopper forms a stable arch just above the hopper outlet, stopping material flow. A belt feeder or screw conveyor allows you to control the material feedrate, providing a more measured feeding method.
You should also consider how quickly and to where the material will discharge from the lump breaker. If the material is fed into the lump breaker faster than it discharges, it can get backed up and jam the equipment, resulting in downtime. Upon exiting the lump breaker, if the particles are small and uniform enough, the material can proceed to downstream process equipment, but if the particles aren’t the right size, the material can also be recirculated back through the lump breaker.
Lump breakers versus other size reduction equipment
Lump breakers are best suited for use with powdery materials, such as cement, food, fertilizers, and solid chemicals, that tend to form unwanted clumps due to moisture or humidity. Mills and other crusher types are designed for more specialized size-reducing applications and materials, such as logs or heavy metals. Hammermills, another common size reduction equipment type, are usually used to crush, pulverize, grind, and shatter hard or abrasive materials. Other size reduction equipment types, including cage mills, grinders, pulverizers, and shredders, have specific applications as well.
To determine which type of size reduction equipment you should use, consider the following questions.
- What is the material that needs to be broken down?
- How hard, big, and abrasive are the material’s particles?
- Is the material prone to moisture absorption, clumping, or any other quality changes?
- Does heat or cold affect the material?
- What is the desired particle size?
- Do the particles need to be uniform in size?
The answers to these questions will help you determine whether adding a lump breaker to your process is right for your pneumatic conveying system.
For further reading
Lisa A. Little (620-235-1712) is the director of sales at Progressive Products. She’s been with the company for more than 9 years, beginning as a sales engineer in 2012.
Progressive Products • Pittsburg, KS
888-235-1732 • progressiveproductsinc.com
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