Wood pellets provide a clean and efficient energy source. However, not all wood pellets are created equal. Lower-quality pellets won’t burn as cleanly or as efficiently. If you use pellets to heat a private home, a public school, or an industrial factory, you want to choose pellets that will produce the desired heat while protecting your equipment. And if you produce biomass pellets, you obviously want to make reliable, high-quality pellets for your clients. What characteristics determine the quality of a biomass pellet? This post will reveal those important traits and offer tips for producing the best pellets possible.
What Traits Make a Good Wood Pellet?
The quality of biomass pellets depends on several factors, including the state of the materials, the equipment you use to make the pellets, and steps in the manufacturing process.
The wood that becomes biomass pellets must be ground or milled before it’s formed into pellets. Finer particles can bind together better and will produce more durable pellets. Any particles that are too large can cause cracks in the final product. However, the particles should not all be the same size; some variance in particle size also encourages the particles to bind together tighter, creating more compact pellets.
Pellet materials do require some moisture to properly bind the particles together, but too much moisture can be problematic, and the pellets may not burn as well. The best moisture content is between 8 and 12 percent. Keeping within this range produces the highest quality pellets, and wandering outside these percentages can produce poor-quality pellets.
For strong inter-particle bonding, the proper amount of pressure must be applied to the materials. This pressure releases natural binding agents that are present inside the wood particles. Common natural binding agents include pectin and lignin. Many pellet mills apply high pressures between 100 and 150 megapascals to form wood pellets.
Equipment Parts and Operation
When producing biomass pellets, the right equipment determines in part whether durable pellets are the final product. The machine must be set to cut pellets with a small diameter. If the pellet diameter is too small, the machine may clog easily. The speed at which the equipment operates also plays a part in the quality of the pellets. Less dense woods should be cut into pellets at a slower pace, about four or five meters per second. That speed allows the material to press together and release the air between the particles. For denser materials, if you’re looking to get pellets between three and six millimeters thick, run the materials through at about ten meters per second. For pellets with a diameter of six to seven millimeters in diameter, the ideal speed is around six to seven meters per second.
Binders can be added to improve pellet density and durability. Some typical wood pellet binders are bentonite, colloids, starches, calcium hydroxide, proteins, and calcium lignosulfonate. However, some binders may cost more than others, and price can determine or limit which binders are used during pellet production.
If the pellets aren’t properly cooled after processing, they can easily develop cracks. These cracks occur as the inside of the pellet cools as a slower pace than the outer portion. Cracks decrease the durability of pellets. Correct cooling practices can help solidify the pellets and strengthen inter-particle bonds. A common practice is to cool the particles to about five degrees Celsius above room temperature. Pellets cooled this way should appear smooth and have no visible cracks.
Why Does Wood Pellet Quality Matter?
In summary, poor-quality wood pellets typically have one or more of the following traits:
- Contain cracks
- Are improperly sized
- Have high dust or ash content
- Contain too much moisture
Wood pellets with these traits won’t burn cleanly or efficiently as possible. Also, they may not feed easily into the burner pot, causing clogs. Excessive dust can also clog up the feed process. High amounts of moisture can lead to inefficient burning. High ash content affects how cleanly the pellets burn.
How Can You Make High-Quality Wood Pellets?
If you’re looking to make excellent pellets, start with quality materials, and use top-notch equipment. If you see excessive dust on or cracks in the finished product, do a little troubleshooting to figure out what the problem is. For example, alter the pellet diameter or the speed at which you cut them. Once you’ve successfully manufactured your pellets, test them and ensure they’re meeting quality standards. Again, a little troubleshooting can help. If the pellets burn slowly, thoroughly examine your materials and ensure the particles have an optimum moisture content.
If you’re searching for reliable equipment, depend on biomass specialists such as Uzelac Industries Inc. They can discuss your needs and help you make the most of any potential biofuel. They’ll work with you to determine what equipment you need before writing up project plans.