Study On The Slurryability Of Shenfu Dongsheng Coal And The Preparation Of Coal Coke Water Slurry(CCWS)

Coal gasification is an important way for coal cleanly conversion.Due to the problems such as the lower concentration of Shenfu Dongsheng coal water slurry,the blindness of the dispersant selection and the utilization of the semi-coke,the Shenfu Dongsheng coal field and its semi-coke were used as the research object to prepare coal water slurry(CWS)and semi-coke water slurry(SCWS).The effects of coal property on the slurryability of coal water slurry were systematically studied,and using Materials Studio software to study the interaction mechanism between coal and water/dispersant.And the coal coke water slurry(CCWS)was prepared by blending the semi-coke with coal to explore the factors which influencing the slurryability of CCWS.This paper will provide some guidance and theoretical basis for the selection of dispersant for coal and the preparation of CCWS.Because of the complexity of the influence of coal quality on slurryability,the effects of coal quality,coal petrography composition,ash oxide and functional group structure on the slurryability of coal were discussed by single factor analysis and Spearman correlation analysis method.The results show that the solid concentration corresponds to fixed viscosity of coal water slurry(?1000)decreases with the increasing of water content,volatile matter,fixed carbon and O/C value.With the increasing of specific surface area and pore volume of coal particles,the solid concentration corresponds to fixed viscosity of coal water slurry decreases.There was a negative correlation between the fusain and exinite,while the vitrinite and clay minerals were positively correlated,and the absolute value of the correlation coefficient was fusain>clay minerals>vitrinite = exinite.When the ash content is 5.47%?22.48%,the solid concentration corresponds to fixed viscosity of CWS increases with the increasing of ash content.The CaO,SiO2,Al2O3 and Fe2O3 in the ash are positively correlated with the solid concentration corresponds to fixed viscosity,and the relative value of the correlation coefficient is SiO2>Fe2O3>Al2O3>CaO>SO3.With the increasing of C=O/C-O in coal,the solid concentration corresponds to fixed viscosity of CWS decreases,which indicated that-C=O had a great influence on the solid concentration corresponds to fixed viscosity of coal water slurry.Dissipative Particle Dynamics(DPD)and molecular dynamics(MD)were used to study the micro-morphology of coal water slurry system and the interaction between coal/water/dispersant.The results show that when the concentration of the dispersant is 1%,the coal water slurry system is gradually transformed into a layered structure from the random dispersion with the concentration of the coal water slurry increased to 56%.In addition,the adsorption density of the dispersant on the surface of coal particles increases gradually,and is mainly monolayer adsorption.The diffusion coefficient of water molecules decreases from 4×10-0m2·s-1 to 2×10-7m2·s-1 with the increasing of the molar ratio of coal to water in the simulated coal water slurry system.There are obvious hydrogen bonds between water molecules and also increases strength,which is mainly produced for the-OH and-H in water molecules,indicating that the hydrogen bonds for the water molecules could affect the diffusion coefficient of water molecules,which result in the viscosity of the CWS system increases.The interaction between the coal molecules and the SAF(aliphatic dispersant)molecules is stronger than that between the coal molecules and the water molecules,and the hydroxyl groups in the coal molecules are interacted with the hydroxyl groups in the dispersant,especially,the hydrogen bonding are interacted between the oxygen in hydroxyl of the coal and hydrogen in hydroxyl of the dispersant.Based on the coal quality factor,the ?1000 prediction model for coal with different dispersant by the partial least squares method.Furthermore,to bulid the selected prediction method for the coal water slurry dispersant which based on the ?1000 prediction model.The results shown that the main coal quality factors that have significant affect on the coal slurryability are water content,volatile and O/C value;To use the water content,volatiles and O/C values as model parameter,the R2 for the fitting result between predicted value and experimental value of model are both higher than 0.84,so the model is more accurate.The predicted value is more higher,the adaptability between the dispersant and coal slurryability is better.Based on the distribution characteristics of the functional groups of the dispersant,the results of the full-reflection infrared spectroscopy(ATR-FTIR)of the dispersant were conducted by PeakFit software.The distribution characteristics of hydrophilic groups(-OH,-SO3-,-CO,-C=O)and hydrophobic groups(-CH2,-CH3,-C=C)were used as parameters to build the matching rules model between dispersants and coal slurryability by the partial least squares.When the MD>1,and the MD value is larger,the adaptability between the dispersant and the coal slurryability is better.When MD<1,the compatibility between the dispersant and the coal is worse.To prepare the coal coke water slurry by blending semi-coke with coal,with the increasing of semi-coke content a,the stability and flowability of CCWS are gradually deteriorated,and the appropriate content of semi-coke is under 40%.The semi-coke blending with coal to prepare CCWS can improve the shortcomings of lower concentration of coal water slurry and poorer stability,fluidity of semi-coke water slurry.In order to improve the existing problems of semi-coke water slurry,the ZJM semi-coke was prepared in the laboratory by low temperature thermal modification method.The surface properties and slurryability of ZJM semi-coke were investigated under different thermal treatment temperature and time.After modification,the oxygen-containing functional groups on the surface of ZJM are reduced,but the surface hydrophobicity of the semi-coke particles are enhanced,and the specific surface area and total pore volume are also reduced.When the modification temperature is 350?,the viscosity on fixed concentration of ZJM semi-coke water slurry decreased from 826 mPa·s to 405 mPa·s,and the fluidity of the slurry was better,in addition,nearly 3%coal tar was also obtained.When the modification temperature is 400?,the syneresis rate of slurry is highest,and it increases with the increasing of modification time.