Sintering describes a process, where single ash particles stick together. During this process the sample may change its original dimension without showing characteristics typical at the softening point.
HOME SEARCH LITERATURE NOMENCLATURE INFO
Ash from biomass and other inorganic compounds does not have a definite melting point but can
be divided into four steps. Real melting begins after
sintering in a more or less large temperature range and before becoming liquid the ash goes
through several plastic and viscous states.
The determination of the ash thermal behaviour is given in DIN 51730 (DIN 51730, 1976).
The various stages of melting can be described as follows:
SIT: beginning of sintering
Sintering describes a process, where single ash particles stick together.
During this process the sample may change its original dimension without showing
characteristics typical at the softening point.
SOT: beginning of softening
At the softening temperature the sample shows the first signs of softening, e.g. surface changes,
the rounding of the edges are complete and the sample starts filling out the gas volume between the particles.
If the edges are still sharp, a shrinkage of the sample should not be regarded as softening.
HT: hemispheric point
The hemispheric point gives the temperature, when the sample takes on the approximate form of a hemisphere.
The height of the melted sample is approximate half the length of the base line.
FT: flowing point
At this temperature the sample has shrunk to one third of its original height.
UNIVERSITY OF TECHNOLOGY VIENNA
Institute of Chemical Engineering, Fuel and Environmental Technology
Getreidemarkt 9/159
A-1060 Vienna
Austria