Study On Liquefaction Of Brown Coal Sub - Supercritical Water

China is abound of lignite. The exploitation of utilize of it has always bothering us for a long time because of its high moisture (>40%), high volatiles, low calorific value (<2000kcal/kg). The sub/supercritical water can make lignite efficient conversion come true and during the lignite direct liquidation process, water work as the reaction medium can also hydrolysis and extract lignite molecules.Withing high added value products like gas fuel and oil and high carbon of residue.during the processThe paper analyzed the technological conditions of lignite liquidation in sub/supercritical water systematically by which work it provide the basic reference of industry optimize condition. The paper roundly discussed the influence of reaction temperature, the residence time, the ration of lignite and water and the density of water in the self-made reactor of oil yield of ZhaoTong lignite direct liquidation. The result shows that the reaction temperature and the residence time have remarkable influence of oil yield. The compare results of oil yield under different reaction conditions shows that higher temperature (400℃) and short residence time (5min) can achieve lignite’efficient liquidation and can obtained higher oil yield. Therefore, comparing traditional technologies, higher temperature and rapid coal crack technique of lignite in supercritical water is a feasible method of the low rank coal use.Because of the existence of hydrolysis reactions, the GC-MS and FTIR analyzes also demonstrate the fact that liquid phase products contain abundant of organic acids. The paper further developed a fast detection method of the acids in liquefied products in the progress of sub/supercritical water.Parts of the results(1)The total gas conversions have the tendency to become higher and they are6.72%-8.40%,9.38%-14.94%.10.72%-15.34%,12.02%-17.32%, respectively when the residence time changed from lmin to40min while the water density is0.225g/mL, the ration of lignite and water is1:9and the temperatures are320℃、38℃、400℃、450℃; the maximum conversions of oil arel7.89%、22.36%、27.89%、34.41%and the minimum proportion of residue is17.46%when the temperature is320℃and the residence time is lmin.. (2)Gas conversion has the tendency to become higher and then reduce when the water density varied from0.1125g/mL to0.3375g/mL,the residence time is20min,the lignite is0.1000g. The maximum conversions of oil is44.91%when the temperature is400℃and the water density is0.3375g/mL(3)When the water density is0.225g/mL,the residence time is20min and the ration of lignite and water are1:19,1:9and2:8, the gas and the oil conversion decrease. The maximum conversions of oil is65.19%when the temperature is450℃and the ration of lignite and water is1:19.(4)The GC-MS and FTIR analyzes demonstrate that the liquid products are phenols like phenol and adjacent two phenol, the hydrocarbon compounds like alkane and olefin and long-chain fatty acids. The rest products are mainly oxygenated chemicals like ketone and nitrogenous compounds like hydrazines.Comparing the influence of residence time, the ration of lignite-water and the density of water, reaction temperature always has remarkable effects on the gas, the liquid composition and also the residue types.We concluded that that the higher reaction temperature the shorter the time of gas yield and the output of the liquefied products come to the maximum.In conclusion, reaction temperature and residence time are the key factors to influencing the oil yields and the products.the experiments combined pilot plant test and the higher temperature and rapid coal crack technique has been used in the pilot Scale.The research work provided the basis of lignite liquidation in sub/supercritical water and laid the foundation for the technical generalization.