In the PelHeat Mobile Pelletizer we are using flat die pellet mills. These pellet mills consist of a die, which is horizontal mounted with rollers resting on the die applying vertical pressure down onto the die surface. Below is a diagram to demonstrate the process.
A = Raw Material
B = Die
C = Material Carpet
D = Pellet Compression
E = Pellet
There are two main types of pellet mill used to produce pellets, and they are ring die and flat die, the reasons we are adopting a flat die pellet mill are as follows.
Size and Weight
Flat die pellet mills are a lot more compact than ring die pellet mills. Building a mobile pelletizer on a trailer platform space to place the equipment is very limited. Therefore a flat die pellet mill is better suited for the application on this scale.
Maintenance
In designing the mobile pelletizer we are focused on making the unit as easy to maintain and clean as possible. This includes the pellet mill, for example on how easy it is to disassemble the pellet mill to change or clean the die. Ring die pellet mills are notoriously awkward to access to clean and change the die. However with the flat die pellet mill the die can be removed within a couple of minutes.
Visibility
As stated in the PelHeat Making Pellets Guide and throughout the website and blog I indicate that producing pellets from multiple biomass raw materials is a skilled process. As such not every material when placed in the pellet mill will create good pellets first time. With ring die pellet mills the pelletizing chamber is sealed and covered. With the flat die pellet mill it is possible to view directly into the pelletizing chamber. By viewing how the material performs in the chamber and what quality of pellets are produce the user can use that information to alter the material. A view of the pelletizing chamber also gives an indication if the die has become blocked, so it can be cleaned or changed as quickly as possible.
Summary
Ring die pellet mills have their place in the industry, particularly large scale pelletizing, however flat die pellet mills are more suitable for small scale applications.
Thank you for your interest
