In the world of agglomeration equipment, a disc granulator (sometimes called a pan granulator) is often chosen for its ability to produce a refined product. It is widely used to process everything from chemical powders, fly ash, and soil conditioners to minerals and ores, fertilizers, and more.
Part of the reason disc granulators are so successful is that they allow operators to adjust multiple variables during the production process to fine-tune the size and quality of the product, whether in response to changes in the feedstock or to adjust the characteristics of the product that comes off the disc.
This high level of flexibility has led to some confusion about how these machines work. Here is an explanation of how to use a disc granulator.
How to Operate a Disc Granulator
The operation of a disc granulator has been likened to a fusion of science and art. During the production process, operators can use multiple variables to control the formation and growth of the particles on the disc, as well as the characteristics of the product. The process of operating a disc granulator involves paying attention to upstream processing conditions and understanding how different variables interact to affect the product that comes off the disc. Therefore, it is critical that operators are trained on disc granulators.
Disc Granulator Variables
The operator can use a combination of the following variables to control product characteristics and respond to changes in production.
Disc Speed
Disc speed is the rate at which the disc rotates. Speed is adjusted via a variable frequency drive, which gives the operator greater control over speed adjustment during startup and shutdown or fluctuations. Speed is the least important variable and is used only with angle adjustment to obtain the best material coverage on the pelletizer (material should cover the entire disc when the spray system is off).
Disc Angle
The translation angle is adjusted by the handwheel jack screw. To a certain extent, the angle and speed adjustments are complementary. The greater the translation angle, the greater the speed required.
The greater the angle, the less time the particles spend on the disc, resulting in smaller particles; the lower the angle, the longer the particle spends on the disc, resulting in larger particles because the particles have more time to go around the disc and collect more particles.
Feed Speed and Position
The feed speed and position are also adjustable. However, to maintain product size and quality, the feed rate of the feed disc must be constant. Any disturbance in the feed will result in product disturbance.
Binder Spray Rate and Position
The binder spray rate is also adjustable, as is the binder spray position. The operator can use the binder spray rate and position to respond to changes in the feed and encourage larger or smaller pellets.
Plow/Scraper Position
As liquid is sprayed onto the pan and mixed with the powder feed, buildup will begin to form on the bottom and side walls of the pan. This buildup must be removed or the process will not work properly. The plow or scraper removes this buildup and creates a smooth surface. As mentioned previously, they also help direct the pellets into their respective streams as they sort themselves.
Conclusion
The granulator is an extremely useful tool in the agglomeration field. The adjustment and customization capabilities allow for fine tuning and customization, which can produce an extremely high quality product.
