Phase equilibria of hydrates from ternary mixtures of methane + ethane + propane and methane + propane + carbon dioxide

Hydrate–liquid–vapour (HLV) equilibrium of aqueous clathrates formed from gas mixtures can be complex compared to hydrates formed with single guests. Typically, pressure and temperature are controlled to obtain these data, but for multicomponent systems, it is necessary to control/report more intensive variables, namely, composition. Metastability, manifested as impractically long experimental times, has been reported to be a challenge with some multicomponent systems. We present HLV equilibrium conditions of two ternary gas mixtures: methane + ethane + propane (90:7:3 molar ratio) and methane + propane + carbon dioxide (55:5:40 molar ratio). Conditions varied in the temperature range of 275–285 K and the pressure range of 1.24–4.75 MPa. Experimental standard uncertainties were on average 0.10 K and 0.005 MPa for methane + ethane + propane and 0.19 K and 0.005 MPa for methane + propane + carbon dioxide. Our technique allowed us to bypass the limitations reported in the literature and provided fast, reproducible HLV equilibria for gas-dominated systems.     

单乙醇胺和二乙醇胺甲酸盐离子液体对水、甲醇和乙醇挥发度的影响(英文)

Vapor pressures were measured for six binary systems containing water, ethanol, or methanol with one of the two ionic liquids （ILs） at different component concentrations and temperatures using a quasi-static ebulliometer, with the ILs mono-ethanolammonium formate （[HMEA][HCOO]） and di-ethanolammonium formate （[HDEA][HCOO]）. The vapor pressures of the IL-containing binary systems are well correlated using the NRTL model with an overall average absolute relative deviation （AARD） of 0.0062. The effect of ILs on the vapor pressure depression of sol-vents at 0.050 mole fraction of IL is that [HDEA][HCOO]〉[HMEA][HCOO], and the vapor pressure lowering de-gree follows the order of water〉methanol〉ethanol. Further, the activity coefficients of three solvents （viz. water, ethanol, and methanol） for the binary systems{solvent （1）＋IL （2）}predicted based on the fitted NRTL parameters at T=333.15 K indicate that the two ILs generate a negative deviation from Raoult’s law for water and methanol and a positive deviation for ethanol to a varying degree, change the relative volatility of a solvent. [HMEA][HCOO] may be a promising entrainer to efficiently separate ethanol aqueous solutions by special rectification.     

1,2-环氧环己烷和1,2-二氯乙烷二元体系汽液平衡数据的测定与关联(英文)

Vapor-liquid equilibrium data (T, x, y) of binary system 1,2-epoxycyclohexane + 1,2-dichloroethane were determined experimentally by using a modified ROSE-Williams equilibrium vaporization system at 101.33 kPa. The results show that this binary system does not have azeotropic point. The vapor-liquid equilibrium data are in thermodynamic consistency. The binary interaction parameters in the Wilson equation are presented with the correlation of vapor-liquid equilibrium data. The measurements of liquid phase composition and bubble point temperature are well represented by the Wilson equation. Values of vapor molecular fractions and activity coefficients from the Wilson equation are presented. This work provides important engineering data for the separation of 1,2-dichloroethane and 1,2-epoxycyclohexane .     

Experimental Measurements and Correlations Isobaric Vapor-Liquid Equilibria for Water + Acetic Acid + Sec-butyl Acetate at 101.3 kPa

Isobaric vapor-liquid equilibrium(VLE) data for acetic acid+sec-butyl acetate and water+acetic acid+sec-butyl acetate systems were determined at 101.3 kPa using a modified Rose type. The nonideality of the vapor phase caused by the association of the acetic acid was corrected by the chemical theory and Hayden-O’Connell method. Thermodynamic consistency was tested for the binary VLE data. The experimental data were correlated successfully with the Non-Random Two Liquids (NRTL) model. The Root Mean Square Deviation (RMSD) of the ternary system was 0.0038. The saturation vapor pressure of sec-butyl acetate at 329 to 385 K was measured by means of two connected equilibrium cells. The vapor pressures of water and sec-butyl acetate were correlated with the Antoine equation. The binary interaction parameters and the ternary VLE data were obtained from this work.     

C8芳烃异构体+叔丁醇体系在12.666kPa下的汽液平衡

采用CP-I型汽液平衡双循环釜，测定了12．666kPa压力下叔丁醇 乙苯、叔丁醇 o-二甲苯、叔丁醇 m-二甲苯、叔丁醇 p-二甲苯4个体系的汽液平衡数据，计算了该压力下4个体系中各组分的活度系数。并对所测数据进行了恒压下热力学一致性检验。用Wilson方程关联了实验数据，拟合精度令人满意。     

乙二胺/磷酸溶液化学吸收法烟气脱硫的研究

提出了一种有机胺吸收二氧化硫的新型烟气脱硫工艺,并建立了有机胺吸收烟气中二氧化硫的气液平衡模型,首次较好预测了二氧化硫-乙二胺-磷酸水溶液体系的气液平衡。对比0.3mol?L?1乙二胺缓冲溶液的预测结果与实验结果,最大相对偏差不超过7%。同时,以乙二胺/磷酸混合溶液作为吸收剂,在φ30mm×600mm的填料塔中进行了逆流吸收和解吸实验,确定了实验室规模下适宜的吸收工艺条件:液气比L/G=0.6~1.0L?m?3,乙二胺浓度0.3mol?L?1,吸收液初始SO2浓度4~6g?L?1,pH值6.0~7.5;解吸工艺条件为:预热温度60℃,塔釜温度103℃,喷淋密度0.7m3?m?2?h?1,富液中SO2浓度14~16g?L?1。进一步的经济分析表明,乙二胺/磷酸法脱硫费用相当于石灰石法的1/3,低于氨法和新近开发的NADS法,具有较好的经济性。     

用NRTL方程计算含离子液体体系的汽液平衡

离子液体作为环境友好溶剂在反应和分离过程中具有良好的应用前景,含离子液体体系汽液平衡的计算及模型化研究具有重要的理论和实际意义.采用非电解质溶液NRTL方程表示溶液的非理想性,关联了［bmim］［PF₆］H₂O及［C₈mim］［PF₆］H₂O二元体系的等温汽液平衡,关联误差在2%之内;预测了这些体系在其他温度下的汽液平衡,预测的总平均误差均在5%之内.通过关联不同温度下有机物在离子液体C₈H₁₄S₂O₄F₆N₃和C₉H₁₆S₂O₄F₆N₃中的无限稀释活度因子的实验数据,得到了有关NRTL方程的二元作用参数,在此基础上预测了离子液体对二元共沸体系汽液平衡的影响.结果表明,含离子液体体系的汽液平衡可以采用传统的非电解质溶液模型如NRTL方程来描述,离子液体的“盐效应”可以显著改善组分的相对挥发度甚至消除共沸现象.     

含(CH4+CO2+H2S)酸性天然气水合物形成条件实验与计算

采用高压全透明蓝宝石水合物相平衡装置,测定了(CH₄+CO₂+H₂S)三元酸性天然气在纯水条件下的水合物生成条件数据.实验温度范围为274.2～299.7 K,压力范围为0.58～8.68 MPa.混合物气体中H₂S和CO₂的浓度分别为 4.95%（mol）～26.62％（mol）和6.81%（mol）～10.77%（mol）.采用Chen-Guo水合物模型对实验数据进行了计算,结果表明,在不同的H₂S浓度下,Chen-Guo水合物模型的预测精度优于CSMHYD 模型.随着H₂S浓度的增加,计算的绝对偏差增大.针对H₂S浓度较高［＞10％（mol）］的体系,该两种水合物模型均有待改进.     

叔丁醇-异戊醇二元体系的汽液平衡数据测定及关联

采用双循环汽液平衡釜测定了叔丁醇一异戊醇二元体系在常压下的汽液平衡数据。实验数据通过了热力学一致性检验,分别用Wilson和NRTL两种活度系数模型对实验数据进行关联,采用单纯形法回归方程参数,关联结果和实验数据吻合良好。     

溴化锂制冷蒸发器中钛椭圆管外降膜流动及传热特性

为了提高溴化锂中央空调系统中制冷蒸发器的耐腐蚀性,采用钛管代替铜管,并提出椭圆管代替圆管方式提高钛管外制冷剂蒸发效率,数值模拟研究椭圆系数E对椭圆钛管外制冷剂流动过程、液膜厚度分布及传热系数影响规律.结果 表明:在椭圆系数E=l.0～1.7范围内,随着E增大,管外液膜平均厚度减薄、液膜速度增大、干壁面积减少、传热边界层...