Gravitational settling tank and method for producing ash-free coal

#The present invention relates to a gravitational settling tank configured to allow a slurry containing coal and a solvent to be separated into a solid-content concentrated liquid and a supernatant liquid, and a method for producing ash-free coal in which ash is removed from coal.

#Coal has been extensively used as a fuel for thermal power generation and boilers or a raw material for chemicals. As one of the environmental measures, there has been a strong demand for the development of a technique for efficiently removing ash in coal. For example, in a high-efficiency hybrid power system using gas turbine combustion, an attempt has been made to use ash-free coal, in which ash is removed, as an alternative fuel to a liquid fuel, such as LNG.

#In a known method as a method for producing ash-free coal (for example, PTL 1), a slurry prepared by mixing coal and a solvent is heated to extract a coal component soluble in the solvent (hereinafter, referred to as a “soluble component in the solvent). A supernatant liquid containing the soluble component in the solvent and a solid-content concentrated liquid containing a coal component, such as ash, which is insoluble in the solvent (hereinafter, referred to as an “insoluble component in the solvent”) are separated. Separating the solvent from the supernatant liquid provides ash-free coal.

#FIG. 1 is a schematic drawing illustrating an apparatus for producing ash-free coal with a gravitational settling tank according to an embodiment of the present invention.

#FIG. 2(a) is a front view of a gravitational settling tank according to an embodiment of the present invention, and (b) is a cross-sectional view taken along line A-A in (a).

#FIG. 3(a) is a perspective view of FIG. 2, and (b) is an enlarged cross-sectional view of a slurry supply pipe taken along line B-B in (a).

#Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic drawing illustrating an apparatus for producing ash-free coal with a gravitational settling tank according to an embodiment of the present invention.

#An apparatus for producing ash-free coal 100 includes a slurry preparation tank 1, an extraction vessel 2, a gravitational settling tank 3, a filter 4, a receiver 5, a solvent recovery unit 6, a receiver 7, and a solvent recovery unit 8.

#In the slurry preparation tank 1, coal and a solvent, which are raw materials, are mixed together to prepare a slurry. In the extraction vessel 2, the resulting slurry is heated to extract a soluble component in the solvent. In the gravitational settling tank 3, the slurry is separated into a solid-content concentrated liquid containing an insoluble component in the solvent and a supernatant liquid containing the soluble component in the solvent by the use of gravitational settling. In the filter 4, the supernatant liquid is filtered. In the receiver 5, the filtered supernatant liquid is temporarily stored. In the solvent recovery unit 6, the solvent is separated from the supernatant liquid to provide ash-free coal. In the receiver 7, the solid-content concentrated liquid is temporarily stored. In the solvent recovery unit 8, the solvent is separated from the solid-content concentrated liquid to provide residual coal.