| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a method and system that perform methane fermentation of sludge with high energy efficiency, stably for a long time by using circulation-type hydrothermal reactions. <P>SOLUTION: In the method where the moisture content of sludge S is adjusted to a predetermined moisture content and then the sludge Sa whose moisture content has been adjusted is supplied into a circulation path 14a, 14b connecting a hydrothermal reactor 11 and a gas-liquid separator 12 and circulated for a predetermined time at a predetermined temperature and pressure to reduce the molecular weight thereof, and the sludge Sc having being reduced in the molecular weight outputted from the circulation path 14a, 14b is held in a fermentation tank 20 to be subjected to methane fermentation, a scale deposit state in the circulation path 14a, 14b is continuously detected, and the predetermined moisture content of the sludge Sa supplied into the circulation path 14a, 14b is adjusted according to a change in the scale deposit state. Preferably, a flowmeter 31 and a flow control valve 32 that control the circulation flow rate of the sludge Sa in the circulation path 14a, 14b at a predetermined flow rate are provided to detect the scale deposit state from an opening degree of the flow control valve 32, or the scale deposit state is detected from the surface temperature of the circulation path 14a, 14b. <P>COPYRIGHT: (C)2013,JPO&INPIT |
