煤粒尺寸对气体扩散过程影响的数值模拟研究

Numerical Simulation Study of the Influence of Coal Particle Size on Gas Diffusion Process

为了研究煤粒尺寸对气体解吸扩散过程的影响,采用单孔模型和扩散因子模型对柳塔煤矿不同吸附平衡压力下0.074~3 mm之间的多种粒度煤的解吸过程进行模拟。通过对比不同扩散因子下模拟数据与试验结果的拟合程度,分析扩散因子随粒径变化的规律。研究结果表明:扩散系数并不是恒定的,其与解吸扩散过程中温度、压力的变化有关。随着煤粒粒径的增大,气体解吸率降低,单孔模型的扩散系数D存在着增大的趋势,扩散因子值单调增加,扩散因子模型在解吸过程的中期阶段比单孔模型的拟合效果好,且由于煤粒球心处压力不断降低,扩散系数值会不断增大。可以根据扩散因子随粒径变化的规律得到同种煤试验粒径区间内任一粒径下的扩散因子,进而得到完整的解吸曲线,对实际工程具有一定的指导作用。

In order to study the influence of coal particle size on gas desorption and diffusion process, the single hole model and diffusion factor model were used to simulate the desorption process of grain sizes of 0.074~3 mm in Liuta coal under different adsorption equilibrium pressures. By comparing the fitting degree of simulation data and experimental results under different diffusion factors, the change law of diffusion factor with particle size was analyzed. The results show that the diffusion coefficient is not constant, which is related to the change of temperature and pressure during desorption and diffusion. With the increase of coal particle size, the gas desorption rate decreases, the diffusion coefficient D of single hole model increases, and the diffusion factor value increases monotonously. The fitting effect of diffusion factor model is better than that of single hole model in the middle stage of desorption process, and because the pressure at the center of coal particle decreases continuously, the diffusion coefficient value increases continuously. According to the change law of diffusion factor with particle size, the diffusion factor of the same coal at any particle size can be obtained, and then the complete desorption curve can be obtained, which has a certain guiding for practical engineering.