Properties of Biomass
The properties of biomass are as diverse as the sources from which they come. Typical data for some vegetable biomasses is included in Table 4-12.
Typical proximate and ultimate analyses are given in Table 4-13. Quaak, Knoef, and Stassen (1999) give a range for the bulk density of 150-200kg/m3 for straw shavings and 600-900 kg/m3 for solid wood.
Ash Properties. The major difference between biomass and coal ashes is that for the majority of most biomasses the ash consists mainly of salts. Most of the biomass ash consists of potassium, calcium, phosphorus, and, further, sodium, magnesium, iron, silicon, and trace elements. Some examples are given in Table 4-14.
As a result biomass ashes have low ash-melting points of, for example, 800°C for some straws. Because these ashes are extremely aggressive towards refractory materials—K2C03 can be used to dissolve minerals before further analysis—biomass does not lend itself for slagging gasification unless it is mixed with large quantities of coal.
