Through burning biomass pellets, whether they are made from wood, straw, grass or any other form of biomass they produce ash. The percentage of ash and possibly a clinker is specific to that raw material.
Premium Wood Pellets
These pellets are currently sold on the open market, and are the most common type of fuel pellet. They are produced from the residue from the wood processing industry. The residue is mainly from softwood, i.e. pine or spruce. The residue contains no or very little bark. These pellets are a pale yellow in colour and tend to be very shiny.
In terms of ash content they will produce very little, in most cases between 0.5% and 1%. If you are using ‘premium wood pellets’ and you are getting more ash than this, there is either some bark in them or other materials. You shouldn’t really experience any clinker (sinter) from these pellets, unless there are a high percentage of fines. Fines are loose particles, which burn too quickly and reach very high temperatures where the ash begins to melt and form a hard deposit (clinker/sinter).
Other Wood Pellets
Other species of wood and wood pellets, which contain bark, will have higher ash content. Generally the percentage will be between 1-3%. For example producing wood pellets from Willow is becoming popular, as coppiced Willow is a relatively fast growing wood species. However you cannot separate the bark, therefore the pellets will produce higher ash content. Again though these pellets should not produce any clinker. However due to the higher ash percentage the ash pot needs to be empted more frequently, and the boiler tubes cleaned more often.
Premium wood pellets due their low ash level and low maintenance currently dominates the fuel pellet market, and the domestic market prefers them. However premium wood pellets do have their issues, for example the video I posted a few weeks ago on the pellet shortage. If the wood processing industry goes into decline, for example with few houses been built, this affects the supply of residue to the wood pellet plants. With less wood pellets been produced and a high demand the price will rapidly increase. For example currently the US has seen wood pellet prices double. This is why when purchasing a pellet boiler or stove I would recommend finding a more flexible burner that can handle more than premium wood pellets.
If you would like to register your interest in the PelHeat Mobile Pelletizer please contact us at:
Contact @ PelHeat . com
Thank you for your interest
