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New coal-charging method: analysis of force characteristics and velocity distribution of coal particles with dense phase continuous flow in cylinder

ABSTRACT Low-moisture coal used in coking has the advantages of increasing production capacity and reducing power consumption but produce a lot of dust during coal charging. A new method of coking coal charged into top-charge coke oven was built, in which the cylinder with telescopic and high-temperature resistant was used to realize the coal flow as dense phase continuous. Based on the 400 kg top-charged coke oven, theoretical analysis, calculation, and numerical simulation were used to study the forces and motion of coal particles under the conditions of temperature gradient. The temperature distribution and particle motion characteristics were simulated by FLUENT when the distance between the coal outlet and the bottom of the coking chamber is 0 mm, 0.5 m, 0.7 m, and 0.9 m. The results show that the dust formed by coal particles was mainly affected by thermophoretic force and air resistance. In the non-uniform temperature field, the radiative heat transfer drop reduces the deposition rate of coal particles. The initial thermal migration velocity of particles in the lower part of the coking chamber is 0.4 m/s, and that of particles in the upper is only 0.1 m/s. As the temperature gradient of coking chamber tends to be uniform, the thermal velocity of particles gradually stabilizes. After the time of particles in the furnace exceeds 0.5 ~1s, the thermophoretic velocity of each part tends to be the same. There was no dust escapes from the coal charging hole during the cylinder lifting process, the escape velocity of dust was controlled below 0.4 m/s by new method. Through simulation and experiment, the simulation results were similar to the experimental when the distance between coal outlet and the bottom of coking chamber is 0 m and 0.7 m, and the maximum error is less than 0.1.