Abstract
Coal slurry is a liquid-solid two-phase system with many fine particles in coal and water. Its rheological properties are the basis of its physical and chemical properties. Coal slurry viscosity is one of the most important physical properties that can measure the physical properties of coal slurry, which is the main indicator used to evaluate the water requirements of coal slurry, conveyor performance and combustion performance. In this paper, a research on the viscometer test method of coal pulp is introduced. Through a comparative analysis of the viscosity test of coke, the viscosity of different concentrations under different conditions is measured. The results show that the viscosity of coal slurry increases with the increase of concentration, and the viscosity at different temperatures follows the Arrhenius equation. This study provides reference for the process design of coal-water slurry production.
Introduction
Coal slurry is a two-phase system of water and coal, including coal ash, these two materials. The concentration of coal-water slurry ranges from 25% to 60%. In coal-water slurry production process, viscosity is one of the most important physical properties. Slurry viscosity is an important index to evaluate the process performance, pumping capacity and the performance of later use. At present, the determination of the viscosity of coal slurry mainly depends on rotational viscometer. However, the viscometer has high requirements on the sample, and generally only separated coal samples can be tested. In the actual production process of coal-water slurry, its composition is complex, and pure coal samples cannot be directly obtained. Therefore, a viscometer suitable for coal slurry has become an important issue.
The aim of this study is to investigate the viscosity of coal-water slurry and its influence factors, so as to provide the basis for the design, preparation and operation of coal-water slurry production.
Methods
(1) Experimental device
The test device mainly includes stirring equipment and viscometer. The stirring equipment is JRD-2K stirring instrument. The viscosity test instrument is a PT-EX3 rotational viscometer manufactured by GrandTech Instrument Co., Ltd.
(2) Experimental sample
Coal-slurry samples with different concentrations were prepared by manual mixing and electric stirring. The concentration range of coal-water samples was from 4 mass fraction % to 15 mass fraction %. The physical and chemical properties of samples in each group were tested. The measured parameters include density, ash content and viscosity.
(3) Experimental conditions
The test temperature is controlled at 20~40℃. The rotational speed is controlled at 100 rpm and 200 rpm.
Results and Discussion
(1) The relationship between coal-slurry concentration and viscosity
Figure 1 shows the relationship between coal slurry concentration and viscosity at different speeds. With the increase of coal-slurry concentration, the viscosity of the slurry gradually increases. When the rotational speed is fixed at 100 and 200 rpm, the viscosity also increases with the increase of concentration. The results show that the effect of rotational speed on slurry viscosity increases with the increase of concentration.
(2) The temperature effect
Figure 2 shows the changes of coal slurry viscosity with different temperatures at different rotational speeds. As can be seen from the figure, the viscosity rapidly increases with the decrease of temperature, and then rises slowly with the increase of temperature. This is thought to be due to the fact that, as the temperature decreases, the internal structure of the particles becomes denser and viscosity increases.
Conclusion
This study introduces a coal-slurry viscosity test and discusses its influencing factors. Through the comparative analysis of the viscosity of coke, the viscosity of different concentrations under different conditions is measured. The results show that the viscosity of coal slurry increases with the increase of concentration, and the viscosity at different temperatures follows the Arrhenius equation. This study provides reference for the process design of coal-water slurry production.
