Grass Pellet Mill

Grass pellets have been traditionally produced for animal feed, however there has been a growing interest in grass pellets for the pellet fuel industry. Grass pellet mills can have different features to wood pellet mills. Grass pellet mills generally operate a higher speeds than wood pellet mills. As grass has a lower density than wood, and is easier to gelatinise, higher productivities through higher die speeds can also be achieved.

In many cases flat die pellet mills are chosen for grass pellet mills. One of the reasons for this is due to the design of the flat die pellet mills, it is easier to feed grass into the mill. Flat die pellet mills work on a vertical design, with raw material entering the mill mainly through gravity. As grass is a low density material it is easier to get the grass into the compression chamber. As ring die pellet mills require a feed system, it is harder to get sufficient material into the die at the required level.  Also due to the vertical design of the ring die pellet mill, it is sometimes difficult to get the material to spread across the surface of the die.

Grass pellets have very different combustion characteristics to wood pellets for example. Grass pellets in general will produce a much higher ash content, and possibly create a clinker and slag formations. Another aspect of grass pellets that must be looking at before using in a pellet stove or boiler, is the increased risk of corrosion. During combustion many grass pellets will generate at a higher temperature corrosive, chloride. Most pellet stoves and boilers are designed to purely burn premium wood pellets. If grass pellets are used in most pellet stoves and boilers, accelerated corrosion could destroy the unit within a few years. For more information on pellet stoves and boilers which can burn grass pellets, please visit the Pellet Stove and Boiler Guide

Hemp Pellets

Hemp pellets are one of the few exceptions to grass pellets in terms of their combustion characteristics. Hemp is used in the production of paper, plastics, clothes, rope, oil and even food. Hemp and waste hemp residues after processing can also be used to create fuel pellets. Hemp fuel pellets, unlike other grass pellets produce very little ash, no clinker or slag formations and a very low corrosion risk. These properties will see hemp pellets as key biomass fuel pellet in the future.

Grass Pellet Production Guide