4. Problems of low melting points of the ashes
4.1. Introduction
As has already been mentioned, some agricultural residues
have high contents of alkali oxides and salts, the low
melting points of which may lead to various problems
during combustion. Table 5 shows the composition of the
ashes from some agricultural residues [1] and for comparison,
the compositions of the ashes from sewage sludge,
bituminous coal, peat and wood are also included. It is seen
that the Na2O contents of the residues are low and