Distillation Efficiency for Removal of Solved Minute Water in a Light Hydrocarbon

去除轻质烃中溶解微量水的蒸馏效率

• 批准号: 03650776
• 负责人: MUNAKATA Tsuyoshi
• 金额: $ 1.15万
• 依托单位: KYUSHU UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1991
• 资助国家: 日本
• 起止时间: 1991 至 1992
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-03650776/
• 关键词: DEHYDRATING DISTILLATION; DISTILLATION EFFICIENCY; VAPOR-LIQUID EQUILIBRIUM RELATION; HYDROCARBON-WATER SYSTEM; TRAY COLUMN; 炭化水素ー水系

The purpose of this work is to clarify the reason why it is said that the efficiency of dehydrating distillation in hydrocarbon-water system is extremely low. The research results obtained so far are summarized as follows. 1.Distillation experiment with a single-tray column In dehydrating distillation experiments for three systems of benzene-water,toluene-water,and hexane-water,it was shown that in a range of relatively high water concentration the tray efficiency reached as high as those for heptane-toluene system(about 70%),but in a low water concentration range the efficiency became low as the water concentration decreases. 2.Distillation experiment with a five-tray column In this experiment,we examined a concentration profile in a five-tray column by measuring the water concentration on each stage. The results showed that the water concentration below the third or fourth stage from the top of the column does not change and hence the limit of the dehydration exists.The tray efficien … More cy in item 1 above is the calculated result based on the vapor-liquid equilibrium (VLE) relation obtained in a range of relatively high water concentration,where the VLE ratio was assumed to be constant. Taking into account also the above results,it was considered that the reason of the efficiency drop may be largely due to the VLE relation in a range of low water concentration, which have not been yet measured. Therefore we conducted careful measurement of the VLE relation mainly in that range. 3.Measurement of the VLE relation in a range of low water concentration Using the liquid on the bottom stage of the five-tray column and molecular sieves as a dehydrating agent,we could measure the VLE relation up to about 2wt-ppm in water content. For benzene-water and hexane-water systems it was found that in a range above 100wt-ppm in water content the VLE ratio is almost constant,but in a range of the lower concentration it decreases gradually with decrease of the water concentration and tends to approach unity abruptly below 5wt-ppm. The calculated values of the tray efficiency based on this VLE data became higher than those obtained in item 1, but still gave its low value in a low water concentration range. Consequently,we could not reduce the reason of the efficiency drop to the VLE relation only. So we intend to clarify this questionable point in future. Less

本工作的目的是澄清油气水体系脱水蒸馏效率极低的原因。目前所获得的研究成果总结如下：1.在苯-水、甲苯-水和己烷-水三种体系的脱水蒸馏实验中，在较高的水浓度范围内，塔板效率与庚烷-甲苯体系的效率相当（约为70%），但在较低的水浓度范围内，塔板效率随着水浓度的降低而降低。2.在这个实验中，我们通过测量每个阶段的水浓度来检查五盘塔中的浓度分布。结果表明：塔顶三、四段以下的水浓度变化不大，存在脱水极限；以上第1项是在较高的水浓度范围内汽液平衡（VLE）关系的计算结果，其中汽液平衡比是恒定的。考虑到上述结果，我们认为效率下降的原因可能主要是由于低水浓度范围内的VLE关系，而这一范围尚未测量。因此，我们主要在该范围内对VLE关系进行了仔细测量。3.在低水浓度范围内VLE关系的测量利用五塔塔底级的液体和分子筛作为脱水剂，我们可以测量到2wt-ppm左右的水含量的VLE关系。对于苯-水和己烷-水体系，在水含量大于100wt-ppm的范围内，VLE比基本不变，但在较低浓度范围内，随着水浓度的降低，VLE比逐渐减小，在5wt-ppm以下趋于一致。根据该VLE数据计算出的塔板效率值高于第1项，但在低水浓度范围内仍为低值。因此，不能将效率下降的原因归结为VLE关系。因此，我们打算在将来澄清这一点。少