Experimental method for coal desulfurization and deashing using permeation and solvating power of a supercritical fluid

An experimental method for coal desulfurization and deashing using permeation and solvating power of a supercritical fluid, comprising:

• 1) grinding a coal sample;
• 2) preparing an extraction kettle with a cover;
• opening an inlet valve and an outlet valve of the extraction kettle, so that the extraction kettle is connected to a container in which a supercritical CO2 fluid is stored;
• circulating the supercritical CO2 fluid in a closed system of the extraction kettle;
• introducing ethanol into a pipeline of the closed system by a pump to clean the pipeline;
• and closing the outlet valve of the extraction kettle to ensure an air tightness of the extraction kettle;
• 3) loading the coal sample obtained in step 1) into the extraction kettle;
• and screwing the cover of the extraction kettle to seal the extraction kettle;
• 4) adjusting a density of the supercritical CO2 fluid by adjusting a temperature and a pressure in the extraction kettle, so that the supercritical CO2 fluid is kept at its critical point;
• re-adjusting the temperature and the pressure in the extraction kettle to allow the supercritical CO2 fluid to permeate the coal sample and then dissolve organic sulfur, inorganic sulfur and ash in the coal sample, thereby separating the organic sulfur, the inorganic sulfur and the ash from the coal sample;
• 5) depressurizing the extraction kettle, and adjusting the temperature in the extraction kettle by a heat exchanger, such that the supercritical CO2 fluid is gasified, and the organic sulfur, the inorganic sulfur and part of the ash are separated from the supercritical CO2 fluid and precipitated at a bottom of the extraction kettle, thereby completing coal desulfurization and deashing;
• and
• 6) closing the inlet valve of the extraction kettle and opening the outlet valve of the extraction kettle to discharge gaseous CO2 or recycle the gaseous CO2 by a cooling system;
• disconnecting a gas piping;
• stopping heating to allow the coal sample to cool down;
• opening the extraction kettle to take out the coal sample;
• soaking the obtained coal sample in acetone for extraction;
• and washing the coal sample using deionized water and then drying the coal sample.