An innovative hydrothermal treatment experiment for MSW
has been performed in a commercial-scale plant to obtain the process
characteristics for converting the MSW into solid fuel. The uniform
raw slump products exited the reactor.
It was observed that the reaction temperature and the holding
period were important operating parameters to obtain a usable solid
fuel. Higher reaction temperature and longer holding period
will produce more uniform and denser product. In addition, higher
reaction temperature and longer holding period will produce products
with lower organic chlorine content. The organic chlorine in
the products was converted to inorganic chlorine, with the lowest
organic chlorine content of 0.16% (1600 ppm), decreased from an
average of 0.97% (9700 ppm) in the raw MSW. The inorganic chlorine
can then be water washed and dewatered to reduce the total
chlorine content in the products.
Heating values of the hydrothermally treated products were not
substantially altered. The highest heating value recorded was
24 MJ/kg, with an average for all products of 20 MJ/kg, which is almost
equal to that of low-grade sub-bituminous coal. The products
also showed good drying performance.
Considering its advantages, the innovative hydrothermal treatment
can be considered as an alternative MSW treatment that produces
a safe, usable, and low chlorine content solid fuel.