Gravitational settling tank and ash-free coal production method using the same

摘要

A gravitational settling tank is provided that makes it possible to detect the boundary surface of a liquid concentrate of solids content. A multipoint temperature sensor (18) that comprises a plurality of thermocouples (17) and that determines the temperature of an internal liquid inside a pressurized container (11) is provided to the pressurized container (11). A plurality of the temperature-determining contact points (17a) of the thermocouples (17) are arranged inside of the pressurized container (11) at differing heights so as to be immersed in an internal liquid. The boundary surface of the liquid concentrate of solids content is detected on the basis of the temperature distribution of the internal liquid in the pressurized container (11) as determined by the multipoint temperature sensor (18).