| Coal Water Slurry (CWS) as a new fuel, which is coal-based, has many advantages, including high combustion efficiency, low emissions, easy storage and transportation. CWS can burn instead of oil, and has benefits such as environmental protection and energy saving. It is an important part of China’s clean technology. Experiments show that it is very critical to study the action rules of the dispersants and the physical and chemical properties of coal surface for changing the blindness in process of research. This paper studies the factors influencing the adsorption of coal, the changes on the coal surface characteristics and their influence to slurry-ability. The main work is carried out as follows:Experiments study the adsorption characteristics of three kinds of dispersants on different rank coals, including Ximeng coal and Datong coal, Pingdingshan coal and petroleum coke. The results show that the adsorption mass is increased with the dispersant concentration increased first. When the concentration reaches a certain value, the adsorption capacity tends to be balanced. Adsorption mass is related to the micropore volume and specific surface area of coal. If the temperature is lower, it is not conducive to adsorption. With the increase of coal rank, the rise of temperature is helpful for the adsorption. Acidic PH is helpful to the adsorption. However, the alkaline PH is not. And stronger shock can increase the adsorption mass.Experiments measure the contact angle with water of four kinds of coals. The results show that the contact angle of Ximeng is about 45°, the Datong and Pingdingshan coal are above 70°,the petroleum coke is about 86°. After adding dispersant, the contact angle of Ximeng is increased, the others’is decreased. Coal surface with negative charges, and Zeta potential absolute value is increased with the percentage of dispersants increased. When the proportion of dispersant is near 1.0%, the potential tends to be gentle, even slightly decreased. Dispersant reduces the surface tension of water. With the percentage increased of dispersant, the slurry surface tension has decreasing trend. With the increase of slurry concentration, the surface tension decreases and then increases.Experiments study the slurry concentration of coal with different dispersant. The results show that ximeng coal is about 53%, datong is about 58%, pipngdingshan coal is about 64%, and the petroleum coke reaches about 70%. The higher rank has the higher concentration. Rheological characteristic of slurry is not only related to coal quality characteristic, also associated with the types of dispersants. Drainage rate of XiMeng is the lowest, less than 1%, but cokes’ is very high, at 14.91%. The impact of proportion of different types of dispersants to concentration is different. The percentage of dispersant is just 0-10% more than saturated adsorption amount, and the slurry concentration can reaches to the max. The concrete percentage is different from different dispersants. The adsorption amount can influence the percentage which adds to CWS, but its impact is associated with the types of dispersants. And the relationship between slurry concentration and stability is different with different coals. The coal having bigger contact angle has higher concentration. The higher Zeta potential absolute value on coal surface, the better the slurry stability. The adsorption speed is closely related to the ability of dispersant to reduce the surface tension of the water. |
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