| As the economy of our country developed rapidly, the demand for calcium carbide (CaC2) is soaring sharply in the industry, because of the problem existing in the production of CaC2by electricity-heating, Zhenyu Liu came up with oxygen-heating synthesis process for CaC2production and combined-moving bed reactor for this process. This paper mainly researchs the motion and distribution of particles, and heat transfer between gas and particles when the annual output reach to10thousand tons in the combined-moving bed reactor, determines appropriate geometric and operation parameters, and provides reference for reactor’s industrialization.At first, discrete element model for particles motion had been built, and DEM was used to solve the model, the comparisons between the results (including the flow character, dimensionless time-averaged velocity and root mean square of the velocity fluctuations of particles) of simulation and experiments have been made to show that they well agreed with each other, the accuracy of DEM have been demonstrated. Second, particles motion was simulated by EDEM software in the combined-moving bed reactor, the influence of factor, including geometric and operation parameters of two kinds of distributing devices, on mass flux, distribution and velocity of particles, the results show that:(1) There are two kinds of flow patterns for different distributing devices, including plug flow and funnel flow.(2) Mass fluxes increase sensitively with increasing of the rotational speed and open-hole size of the distributing device, but they were not linear correlation. For fan-shaped hole distributing device, the mass fluxes exhibit a periodical change with periods always lower than the rotation period of the distributing device. Along the radial direction, particles are distributed more uniformly with increasing of the rotational speed and open-hole size, and the distribution present type’U’and type’M’for two kinds of distributing devices.(3) The radial distribution of particles get more uniformly downwardly along the axial direction, values of the variance coefficient exceed1.0for fan-shaped hole distributing device, while for another distributing device, values are about0.5. For rectangular-hole distributing device, at different heights, dimensionless time-averaged velocity (X and Y direction) profiles is symmetrical about the center, while root mean square of the velocity fluctuations is symmetrical about the axis.(4) To achieve this goal that particles are distributed more uniformly and coal heating processes get more uniformly, the preferred option of the distributing device is rectangular-hole distributing device, and the rate of the hole of distributing device and particle diameter is w/dp=0.15, the operation parameters is n=10r/min.At last, for pilot-scale, the annual output reach10thousand tons, choose rectangular-hole distributing device, study the heat transfer in the preheating zone, the results show that:(1) Based on1D computing, the height of the moving bed decrease with increasing of the diameter of the reactor when the diameter of particles was fixed, the height increase with increasing of the diameter of particles when the diameter of the reactor was fixed. According to the variation, the preferred option for the3D simulation is that the reactor diameter is1.6m and the particles diameter is4cm, the moving-bed height is4m.(2) Based on3D simulation, particles were heated by gas with the time increasing, the heat transfer advanced along the axis, and the height of the bed with temperature gradients increased with the time increasing. The thermal conductivity of reactor decreased along the axis. In the operating mode,75minutes were needed for preheating particle from room temperature to design temperature.(3) The axial distributions of temperature of gas and particle had the same situation at different radial positions, the temperature reduced gradually upwardly along the axis of the reactor, the temperature of particle sharply decreased when axial height is between2m and4m, the axial distributions of temperature of gas and particle had the same situation at different radial positions.By analyse and simulation study, when the annual output reach10thousand tons in the combined-moving bed reactor, the preferred option of the distributing device is rectangular-hole distributing device, and the rate of the hole of distributing device and particle diameter is w/dp=0.15, the operation parameters is n=10r/min; the diameter and height of the moving reactor are1.6m and4m, and the diameter of particle is4cm for the preheating zone... |
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