Physical characteristics of biomass pellet fuel

One of the great advantages of biomass pellet fuel is that it can be used in small biomass boilers, and continuous automatic boiler combustion through pellet burners. At present, in Europe and the United States and other countries, the general household biomass pellet fuel and supporting high-efficiency combustion equipment have been very popular. These biomass pellet fuels are mainly wood pellet fuels, which have the advantages of high calorific value, low ash content, not easy slagging after combustion and so on. Wood pellets are made from different raw material, there are great differences in physical properties and chemical components, which lead to differences in combustion characteristics. Therefore, the requirements of pellet forming machines’ technical parameters and combustion equipment are also different.

1.Density

The bulk density of biomass pellet fuel can affects energy density and also transportation and storage costs of producers and consumers. The density of biomass pellet fuel, except for the bulk density of bark, is larger than the reference value of standard first-class pellet (600 kg/m3), and the others are 535-590 kg/m3, but they all meet the requirements of second-class pellet (> 500 kg/m3), in which the bulk density of wheat straw pellet fuel is the lowest.
The density of biomass fuel pellet can affect the bulk density and combustion characteristics. The higher the pellet density, the longer the combustion duration. The density of wood pellet and bark pellet fuel can meet the reference value of SS187120 (>1.12g/cm3), which is respectively 1.18 and 1.14 g/cm3.

2.Durability

Durability is a very important parameter of pellet fuel, because in the process of transportation and storage, the pellet fuel with lower mechanical strength is easy to break up, which leads to the increase of powder and affects the feed. At the same time, in the process of combustion, it also affects the emission of flue gas. The durability of biomass pellet fuel is more than 95% in the standard of biomass pellet fuel. Among pellet fuels, wood pellets have the highest durability, but other biomass pellet fuels have little difference.

3.Heating value

The heating value of pellet fuels of different raw materials is quite different. The heating value of wood pellet fuels is 19.13MJ/kg, while the heating value of other pellet fuels is lower than that of wood pellets, but higher than the standard reference value of 16.9MJ/kg.