The invention relates to a method for the thermal hydrolysis of sludge characterized
in that it is carried out in at least two reactors operating in parallel, in each
of which the sludge undergoes a complete thermal hydrolysis cycle. Said cycle comprises
different stages consisting in supplying the reactor with the sludge, injecting
live stream in order to bring said sludge to a pressure P and a temperature T at
which hydrolysis can occur, maintaining the sludge at said pressure P and said
temperature T for a certain amount of time, suddenly bringing said sludge to the
atmospheric pressure by releasing the flash steam and emptying said reactor of
the hydrolysed sludge. Furthermore, the inventive method consists in time shifting
the cycle of one reactor to the other in order to use the flash steam produced
from one reactor to inject it into the other reactor.