吸附势理论中饱和蒸汽压参数k探讨
Study on Saturated Vapor Pressure Parameter k of Adsorption Potential Theory
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摘要: 吸附势理论可预测不同温度下煤吸附甲烷的等温吸附曲线，但往往由于饱和蒸汽压参数k和吸附相密度ρad选取的不当，导致预测出现较大偏差。鉴于此，选取粒径180~250 μm的煤样分别开展30、40、50 ℃的等温吸附实验，并利用30 ℃单一温度吸附特性曲线和30、40、50 ℃多个温度综合吸附曲线预测40、50 ℃的等温吸附曲线。结果表明，k对获得单一温度的吸附特性曲线影响甚微，但对获得多温度下的综合吸附特性曲线影响较大，存在最优k值为3；单一温度下吸附特性曲线预测结果的偏差大于多个温度下综合吸附特性曲线预测的，在40、50 ℃的预测结果中，后者的预测精度分别为前者的2倍和2.5倍。多温度下的综合吸附特性曲线对吸附相密度的选择较敏感，预测40、50 ℃的等温吸附曲线时，应分别使用吸附相密度ρad2和ρad1。Abstract: Adsorption potential theory can be used to predict the adsorption isotherm of coal at different temperatur,but because the saturated vapor pressure parameter k and the adsorption phase density ρad are not selected appropriately,it often leads to a large deviation in prediction.Because of this,the coal samples with the particle size of 0.18 mm to 0.25 mm were selected in this paper,isothermal adsorption experiments were carried out at 30 ℃,40 ℃and 50 ℃,and two types of adsorption characteristic curves of 30 ℃ and 30 ℃, 40 ℃, 50 ℃ have been derived and were used to predict the isothermal adsorption curve of 40 ℃and 50 ℃.The results showed that the saturated vapor pressure parameter k on the adsorption characteristic curve obtained from a single temperature has little effect, but a greater impact on the comprehensive adsorption characteristic curve at multiple temperature, the existence of the optimal saturated vapor pressure parameter k value is 3;the average deviation of single temperature adsorption characteristic curve prediction results is bigger than multiple temperature comprehensive adsorption characteristic curve prediction;the prediction accuracy of the latter is 2 times of the former in 40 ℃ and 2.5 times of the former in 50 ℃.Multiple temperature adsorption characteristic curve is sensitive to adsorbed phase density,predicting the isothermal adsorption curve of 40 ℃ and 50 ℃ should use adsorption phase density ρad2 and ρad1 respectively.
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